maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity
llvm-project/llvm/unittests/Analysis/LazyCallGraphTest.cpp

2143 lines
79 KiB
C++
Raw Normal View History

[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
//===- LazyCallGraphTest.cpp - Unit tests for the lazy CG analysis --------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/LazyCallGraph.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/Function.h"
Re-sort #include lines for unittests. This uses a slightly modified clang-format (https://reviews.llvm.org/D33932) to keep primary headers at the top and handle new utility headers like 'gmock' consistently with other utility headers. No other change was made. I did no manual edits, all of this is clang-format. This should allow other changes to have more clear and focused diffs, and is especially motivated by moving some headers into more focused libraries. llvm-svn: 304786
2017-06-06 19:06:56 +08:00
#include "llvm/IR/Instructions.h"
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/SourceMgr.h"
#include "gtest/gtest.h"
#include <memory>
using namespace llvm;
namespace {
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
std::unique_ptr<Module> parseAssembly(LLVMContext &Context,
const char *Assembly) {
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
SMDiagnostic Error;
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
std::unique_ptr<Module> M = parseAssemblyString(Assembly, Error, Context);
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
std::string ErrMsg;
raw_string_ostream OS(ErrMsg);
Error.print("", OS);
// A failure here means that the test itself is buggy.
Modernize the .ll parsing interface. * Use StringRef instead of std::string& * Return a std::unique_ptr<Module> instead of taking an optional module to write to (was not really used). * Use current comment style. * Use current naming convention. llvm-svn: 215989
2014-08-20 00:58:54 +08:00
if (!M)
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
report_fatal_error(OS.str().c_str());
return M;
}
Silence gcc's -Wcomment gcc's (4.7, I think) -Wcomment warning is not "as smart" as clang's and warns even if the line right after the backslash-newline sequence only has a line comment that starts at the beginning of the line. llvm-svn: 220360
2014-10-22 10:16:06 +08:00
/*
IR forming a call graph with a diamond of triangle-shaped SCCs:
d1
/ \
d3--d2
/ \
b1 c1
/ \ / \
b3--b2 c3--c2
\ /
a1
/ \
a3--a2
All call edges go up between SCCs, and clockwise around the SCC.
*/
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
static const char DiamondOfTriangles[] =
"define void @a1() {\n"
"entry:\n"
" call void @a2()\n"
" call void @b2()\n"
" call void @c3()\n"
" ret void\n"
"}\n"
"define void @a2() {\n"
"entry:\n"
" call void @a3()\n"
" ret void\n"
"}\n"
"define void @a3() {\n"
"entry:\n"
" call void @a1()\n"
" ret void\n"
"}\n"
"define void @b1() {\n"
"entry:\n"
" call void @b2()\n"
" call void @d3()\n"
" ret void\n"
"}\n"
"define void @b2() {\n"
"entry:\n"
" call void @b3()\n"
" ret void\n"
"}\n"
"define void @b3() {\n"
"entry:\n"
" call void @b1()\n"
" ret void\n"
"}\n"
"define void @c1() {\n"
"entry:\n"
" call void @c2()\n"
" call void @d2()\n"
" ret void\n"
"}\n"
"define void @c2() {\n"
"entry:\n"
" call void @c3()\n"
" ret void\n"
"}\n"
"define void @c3() {\n"
"entry:\n"
" call void @c1()\n"
" ret void\n"
"}\n"
"define void @d1() {\n"
"entry:\n"
" call void @d2()\n"
" ret void\n"
"}\n"
"define void @d2() {\n"
"entry:\n"
" call void @d3()\n"
" ret void\n"
"}\n"
"define void @d3() {\n"
"entry:\n"
" call void @d1()\n"
" ret void\n"
"}\n";
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
/*
IR forming a reference graph with a diamond of triangle-shaped RefSCCs
d1
/ \
d3--d2
/ \
b1 c1
/ \ / \
b3--b2 c3--c2
\ /
a1
/ \
a3--a2
All call edges go up between RefSCCs, and clockwise around the RefSCC.
*/
static const char DiamondOfTrianglesRefGraph[] =
"define void @a1() {\n"
"entry:\n"
" %a = alloca void ()*\n"
" store void ()* @a2, void ()** %a\n"
" store void ()* @b2, void ()** %a\n"
" store void ()* @c3, void ()** %a\n"
" ret void\n"
"}\n"
"define void @a2() {\n"
"entry:\n"
" %a = alloca void ()*\n"
" store void ()* @a3, void ()** %a\n"
" ret void\n"
"}\n"
"define void @a3() {\n"
"entry:\n"
" %a = alloca void ()*\n"
" store void ()* @a1, void ()** %a\n"
" ret void\n"
"}\n"
"define void @b1() {\n"
"entry:\n"
" %a = alloca void ()*\n"
" store void ()* @b2, void ()** %a\n"
" store void ()* @d3, void ()** %a\n"
" ret void\n"
"}\n"
"define void @b2() {\n"
"entry:\n"
" %a = alloca void ()*\n"
" store void ()* @b3, void ()** %a\n"
" ret void\n"
"}\n"
"define void @b3() {\n"
"entry:\n"
" %a = alloca void ()*\n"
" store void ()* @b1, void ()** %a\n"
" ret void\n"
"}\n"
"define void @c1() {\n"
"entry:\n"
" %a = alloca void ()*\n"
" store void ()* @c2, void ()** %a\n"
" store void ()* @d2, void ()** %a\n"
" ret void\n"
"}\n"
"define void @c2() {\n"
"entry:\n"
" %a = alloca void ()*\n"
" store void ()* @c3, void ()** %a\n"
" ret void\n"
"}\n"
"define void @c3() {\n"
"entry:\n"
" %a = alloca void ()*\n"
" store void ()* @c1, void ()** %a\n"
" ret void\n"
"}\n"
"define void @d1() {\n"
"entry:\n"
" %a = alloca void ()*\n"
" store void ()* @d2, void ()** %a\n"
" ret void\n"
"}\n"
"define void @d2() {\n"
"entry:\n"
" %a = alloca void ()*\n"
" store void ()* @d3, void ()** %a\n"
" ret void\n"
"}\n"
"define void @d3() {\n"
"entry:\n"
" %a = alloca void ()*\n"
" store void ()* @d1, void ()** %a\n"
" ret void\n"
"}\n";
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
static LazyCallGraph buildCG(Module &M) {
TargetLibraryInfoImpl TLII(Triple(M.getTargetTriple()));
TargetLibraryInfo TLI(TLII);
LazyCallGraph CG(M, TLI);
return CG;
}
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
TEST(LazyCallGraphTest, BasicGraphFormation) {
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
LLVMContext Context;
std::unique_ptr<Module> M = parseAssembly(Context, DiamondOfTriangles);
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
// The order of the entry nodes should be stable w.r.t. the source order of
// the IR, and everything in our module is an entry node, so just directly
// build variables for each node.
auto I = CG.begin();
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
LazyCallGraph::Node &A1 = (I++)->getNode();
[LCG] Switch the primary node iterator to be a *much* more normal C++ iterator, returning a Node by reference on dereference. llvm-svn: 207048
2014-04-24 07:34:48 +08:00
EXPECT_EQ("a1", A1.getFunction().getName());
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
LazyCallGraph::Node &A2 = (I++)->getNode();
[LCG] Switch the primary node iterator to be a *much* more normal C++ iterator, returning a Node by reference on dereference. llvm-svn: 207048
2014-04-24 07:34:48 +08:00
EXPECT_EQ("a2", A2.getFunction().getName());
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
LazyCallGraph::Node &A3 = (I++)->getNode();
[LCG] Switch the primary node iterator to be a *much* more normal C++ iterator, returning a Node by reference on dereference. llvm-svn: 207048
2014-04-24 07:34:48 +08:00
EXPECT_EQ("a3", A3.getFunction().getName());
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
LazyCallGraph::Node &B1 = (I++)->getNode();
[LCG] Switch the primary node iterator to be a *much* more normal C++ iterator, returning a Node by reference on dereference. llvm-svn: 207048
2014-04-24 07:34:48 +08:00
EXPECT_EQ("b1", B1.getFunction().getName());
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
LazyCallGraph::Node &B2 = (I++)->getNode();
[LCG] Switch the primary node iterator to be a *much* more normal C++ iterator, returning a Node by reference on dereference. llvm-svn: 207048
2014-04-24 07:34:48 +08:00
EXPECT_EQ("b2", B2.getFunction().getName());
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
LazyCallGraph::Node &B3 = (I++)->getNode();
[LCG] Switch the primary node iterator to be a *much* more normal C++ iterator, returning a Node by reference on dereference. llvm-svn: 207048
2014-04-24 07:34:48 +08:00
EXPECT_EQ("b3", B3.getFunction().getName());
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
LazyCallGraph::Node &C1 = (I++)->getNode();
[LCG] Switch the primary node iterator to be a *much* more normal C++ iterator, returning a Node by reference on dereference. llvm-svn: 207048
2014-04-24 07:34:48 +08:00
EXPECT_EQ("c1", C1.getFunction().getName());
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
LazyCallGraph::Node &C2 = (I++)->getNode();
[LCG] Switch the primary node iterator to be a *much* more normal C++ iterator, returning a Node by reference on dereference. llvm-svn: 207048
2014-04-24 07:34:48 +08:00
EXPECT_EQ("c2", C2.getFunction().getName());
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
LazyCallGraph::Node &C3 = (I++)->getNode();
[LCG] Switch the primary node iterator to be a *much* more normal C++ iterator, returning a Node by reference on dereference. llvm-svn: 207048
2014-04-24 07:34:48 +08:00
EXPECT_EQ("c3", C3.getFunction().getName());
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
LazyCallGraph::Node &D1 = (I++)->getNode();
[LCG] Switch the primary node iterator to be a *much* more normal C++ iterator, returning a Node by reference on dereference. llvm-svn: 207048
2014-04-24 07:34:48 +08:00
EXPECT_EQ("d1", D1.getFunction().getName());
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
LazyCallGraph::Node &D2 = (I++)->getNode();
[LCG] Switch the primary node iterator to be a *much* more normal C++ iterator, returning a Node by reference on dereference. llvm-svn: 207048
2014-04-24 07:34:48 +08:00
EXPECT_EQ("d2", D2.getFunction().getName());
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
LazyCallGraph::Node &D3 = (I++)->getNode();
[LCG] Switch the primary node iterator to be a *much* more normal C++ iterator, returning a Node by reference on dereference. llvm-svn: 207048
2014-04-24 07:34:48 +08:00
EXPECT_EQ("d3", D3.getFunction().getName());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
EXPECT_EQ(CG.end(), I);
// Build vectors and sort them for the rest of the assertions to make them
// independent of order.
std::vector<std::string> Nodes;
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
for (LazyCallGraph::Edge &E : A1.populate())
[LCG] Build an edge abstraction for the LazyCallGraph and use it to differentiate between indirect references to functions an direct calls. This doesn't do a whole lot yet other than change the print out produced by the analysis, but it lays the groundwork for a very major change I'm working on next: teaching the call graph to actually be a call graph, modeling *both* the indirect reference graph and the call graph simultaneously. More details on that in the next patch though. The rest of this is essentially a bunch of over-engineering that won't be interesting until the next patch. But this also isolates essentially all of the churn necessary to introduce the edge abstraction from the very important behavior change necessary in order to separately model the two graphs. So it should make review of the subsequent patch a bit easier at the cost of making this patch seem poorly motivated. ;] Differential Revision: http://reviews.llvm.org/D16038 llvm-svn: 259463
2016-02-02 11:57:13 +08:00
Nodes.push_back(E.getFunction().getName());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
std::sort(Nodes.begin(), Nodes.end());
EXPECT_EQ("a2", Nodes[0]);
EXPECT_EQ("b2", Nodes[1]);
EXPECT_EQ("c3", Nodes[2]);
Nodes.clear();
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
A2.populate();
EXPECT_EQ(A2->end(), std::next(A2->begin()));
EXPECT_EQ("a3", A2->begin()->getFunction().getName());
A3.populate();
EXPECT_EQ(A3->end(), std::next(A3->begin()));
EXPECT_EQ("a1", A3->begin()->getFunction().getName());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
for (LazyCallGraph::Edge &E : B1.populate())
[LCG] Build an edge abstraction for the LazyCallGraph and use it to differentiate between indirect references to functions an direct calls. This doesn't do a whole lot yet other than change the print out produced by the analysis, but it lays the groundwork for a very major change I'm working on next: teaching the call graph to actually be a call graph, modeling *both* the indirect reference graph and the call graph simultaneously. More details on that in the next patch though. The rest of this is essentially a bunch of over-engineering that won't be interesting until the next patch. But this also isolates essentially all of the churn necessary to introduce the edge abstraction from the very important behavior change necessary in order to separately model the two graphs. So it should make review of the subsequent patch a bit easier at the cost of making this patch seem poorly motivated. ;] Differential Revision: http://reviews.llvm.org/D16038 llvm-svn: 259463
2016-02-02 11:57:13 +08:00
Nodes.push_back(E.getFunction().getName());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
std::sort(Nodes.begin(), Nodes.end());
EXPECT_EQ("b2", Nodes[0]);
EXPECT_EQ("d3", Nodes[1]);
Nodes.clear();
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
B2.populate();
EXPECT_EQ(B2->end(), std::next(B2->begin()));
EXPECT_EQ("b3", B2->begin()->getFunction().getName());
B3.populate();
EXPECT_EQ(B3->end(), std::next(B3->begin()));
EXPECT_EQ("b1", B3->begin()->getFunction().getName());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
for (LazyCallGraph::Edge &E : C1.populate())
[LCG] Build an edge abstraction for the LazyCallGraph and use it to differentiate between indirect references to functions an direct calls. This doesn't do a whole lot yet other than change the print out produced by the analysis, but it lays the groundwork for a very major change I'm working on next: teaching the call graph to actually be a call graph, modeling *both* the indirect reference graph and the call graph simultaneously. More details on that in the next patch though. The rest of this is essentially a bunch of over-engineering that won't be interesting until the next patch. But this also isolates essentially all of the churn necessary to introduce the edge abstraction from the very important behavior change necessary in order to separately model the two graphs. So it should make review of the subsequent patch a bit easier at the cost of making this patch seem poorly motivated. ;] Differential Revision: http://reviews.llvm.org/D16038 llvm-svn: 259463
2016-02-02 11:57:13 +08:00
Nodes.push_back(E.getFunction().getName());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
std::sort(Nodes.begin(), Nodes.end());
EXPECT_EQ("c2", Nodes[0]);
EXPECT_EQ("d2", Nodes[1]);
Nodes.clear();
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
C2.populate();
EXPECT_EQ(C2->end(), std::next(C2->begin()));
EXPECT_EQ("c3", C2->begin()->getFunction().getName());
C3.populate();
EXPECT_EQ(C3->end(), std::next(C3->begin()));
EXPECT_EQ("c1", C3->begin()->getFunction().getName());
D1.populate();
EXPECT_EQ(D1->end(), std::next(D1->begin()));
EXPECT_EQ("d2", D1->begin()->getFunction().getName());
D2.populate();
EXPECT_EQ(D2->end(), std::next(D2->begin()));
EXPECT_EQ("d3", D2->begin()->getFunction().getName());
D3.populate();
EXPECT_EQ(D3->end(), std::next(D3->begin()));
EXPECT_EQ("d1", D3->begin()->getFunction().getName());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Now lets look at the RefSCCs and SCCs.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
auto J = CG.postorder_ref_scc_begin();
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
LazyCallGraph::RefSCC &D = *J++;
ASSERT_EQ(1, D.size());
for (LazyCallGraph::Node &N : *D.begin())
Nodes.push_back(N.getFunction().getName());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
std::sort(Nodes.begin(), Nodes.end());
[LCG] Re-order expectations to provide more useful output when debugging an issue. This way you see that the number of nodes was wrong before a crash due to accessing too many nodes. llvm-svn: 207094
2014-04-24 17:59:56 +08:00
EXPECT_EQ(3u, Nodes.size());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
EXPECT_EQ("d1", Nodes[0]);
EXPECT_EQ("d2", Nodes[1]);
EXPECT_EQ("d3", Nodes[2]);
Nodes.clear();
[LCG] Add some basic methods for querying the parent/child relationships of SCCs in the SCC DAG. Exercise them in the big graph test case. These will be especially useful for establishing invariants in insertion logic. llvm-svn: 207749
2014-05-01 20:12:42 +08:00
EXPECT_FALSE(D.isParentOf(D));
EXPECT_FALSE(D.isChildOf(D));
EXPECT_FALSE(D.isAncestorOf(D));
EXPECT_FALSE(D.isDescendantOf(D));
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
EXPECT_EQ(&D, &*CG.postorder_ref_scc_begin());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
LazyCallGraph::RefSCC &C = *J++;
ASSERT_EQ(1, C.size());
for (LazyCallGraph::Node &N : *C.begin())
Nodes.push_back(N.getFunction().getName());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
std::sort(Nodes.begin(), Nodes.end());
[LCG] Re-order expectations to provide more useful output when debugging an issue. This way you see that the number of nodes was wrong before a crash due to accessing too many nodes. llvm-svn: 207094
2014-04-24 17:59:56 +08:00
EXPECT_EQ(3u, Nodes.size());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
EXPECT_EQ("c1", Nodes[0]);
EXPECT_EQ("c2", Nodes[1]);
EXPECT_EQ("c3", Nodes[2]);
Nodes.clear();
[LCG] Add some basic methods for querying the parent/child relationships of SCCs in the SCC DAG. Exercise them in the big graph test case. These will be especially useful for establishing invariants in insertion logic. llvm-svn: 207749
2014-05-01 20:12:42 +08:00
EXPECT_TRUE(C.isParentOf(D));
EXPECT_FALSE(C.isChildOf(D));
EXPECT_TRUE(C.isAncestorOf(D));
EXPECT_FALSE(C.isDescendantOf(D));
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
EXPECT_EQ(&C, &*std::next(CG.postorder_ref_scc_begin()));
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
LazyCallGraph::RefSCC &B = *J++;
ASSERT_EQ(1, B.size());
for (LazyCallGraph::Node &N : *B.begin())
Nodes.push_back(N.getFunction().getName());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
std::sort(Nodes.begin(), Nodes.end());
[LCG] Re-order expectations to provide more useful output when debugging an issue. This way you see that the number of nodes was wrong before a crash due to accessing too many nodes. llvm-svn: 207094
2014-04-24 17:59:56 +08:00
EXPECT_EQ(3u, Nodes.size());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
EXPECT_EQ("b1", Nodes[0]);
EXPECT_EQ("b2", Nodes[1]);
EXPECT_EQ("b3", Nodes[2]);
Nodes.clear();
[LCG] Add some basic methods for querying the parent/child relationships of SCCs in the SCC DAG. Exercise them in the big graph test case. These will be especially useful for establishing invariants in insertion logic. llvm-svn: 207749
2014-05-01 20:12:42 +08:00
EXPECT_TRUE(B.isParentOf(D));
EXPECT_FALSE(B.isChildOf(D));
EXPECT_TRUE(B.isAncestorOf(D));
EXPECT_FALSE(B.isDescendantOf(D));
EXPECT_FALSE(B.isAncestorOf(C));
EXPECT_FALSE(C.isAncestorOf(B));
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
EXPECT_EQ(&B, &*std::next(CG.postorder_ref_scc_begin(), 2));
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
LazyCallGraph::RefSCC &A = *J++;
ASSERT_EQ(1, A.size());
for (LazyCallGraph::Node &N : *A.begin())
Nodes.push_back(N.getFunction().getName());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
std::sort(Nodes.begin(), Nodes.end());
[LCG] Re-order expectations to provide more useful output when debugging an issue. This way you see that the number of nodes was wrong before a crash due to accessing too many nodes. llvm-svn: 207094
2014-04-24 17:59:56 +08:00
EXPECT_EQ(3u, Nodes.size());
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
EXPECT_EQ("a1", Nodes[0]);
EXPECT_EQ("a2", Nodes[1]);
EXPECT_EQ("a3", Nodes[2]);
Nodes.clear();
[LCG] Add some basic methods for querying the parent/child relationships of SCCs in the SCC DAG. Exercise them in the big graph test case. These will be especially useful for establishing invariants in insertion logic. llvm-svn: 207749
2014-05-01 20:12:42 +08:00
EXPECT_TRUE(A.isParentOf(B));
EXPECT_TRUE(A.isParentOf(C));
EXPECT_FALSE(A.isParentOf(D));
EXPECT_TRUE(A.isAncestorOf(B));
EXPECT_TRUE(A.isAncestorOf(C));
EXPECT_TRUE(A.isAncestorOf(D));
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
EXPECT_EQ(&A, &*std::next(CG.postorder_ref_scc_begin(), 3));
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(CG.postorder_ref_scc_end(), J);
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
EXPECT_EQ(J, std::next(CG.postorder_ref_scc_begin(), 4));
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
}
[LCG] Implement Tarjan's algorithm correctly this time. We have to walk up the stack finishing the exploration of each entries children before we're finished in addition to accounting for their low-links. Added a unittest that really hammers home the need for this with interlocking cycles that would each appear distinct otherwise and crash or compute the wrong result. As part of this, nuke a stale fixme and bring the rest of the implementation still more closely in line with the original algorithm. llvm-svn: 206966
2014-04-23 18:31:17 +08:00
static Function &lookupFunction(Module &M, StringRef Name) {
for (Function &F : M)
if (F.getName() == Name)
return F;
report_fatal_error("Couldn't find function!");
}
[LCG] Add the most basic of edge insertion to the lazy call graph. This just handles the pre-DFS case. Also add some test cases for this case to make sure it works. llvm-svn: 207411
2014-04-28 19:10:23 +08:00
TEST(LazyCallGraphTest, BasicGraphMutation) {
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
LLVMContext Context;
std::unique_ptr<Module> M = parseAssembly(Context, "define void @a() {\n"
"entry:\n"
" call void @b()\n"
" call void @c()\n"
" ret void\n"
"}\n"
"define void @b() {\n"
"entry:\n"
" ret void\n"
"}\n"
"define void @c() {\n"
"entry:\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Add the most basic of edge insertion to the lazy call graph. This just handles the pre-DFS case. Also add some test cases for this case to make sure it works. llvm-svn: 207411
2014-04-28 19:10:23 +08:00
LazyCallGraph::Node &A = CG.get(lookupFunction(*M, "a"));
LazyCallGraph::Node &B = CG.get(lookupFunction(*M, "b"));
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
A.populate();
EXPECT_EQ(2, std::distance(A->begin(), A->end()));
B.populate();
EXPECT_EQ(0, std::distance(B->begin(), B->end()));
LazyCallGraph::Node &C = CG.get(lookupFunction(*M, "c"));
C.populate();
CG.insertEdge(B, C, LazyCallGraph::Edge::Call);
EXPECT_EQ(1, std::distance(B->begin(), B->end()));
EXPECT_EQ(0, std::distance(C->begin(), C->end()));
CG.insertEdge(C, B, LazyCallGraph::Edge::Call);
EXPECT_EQ(1, std::distance(C->begin(), C->end()));
EXPECT_EQ(&B, &C->begin()->getNode());
CG.insertEdge(C, C, LazyCallGraph::Edge::Call);
EXPECT_EQ(2, std::distance(C->begin(), C->end()));
EXPECT_EQ(&B, &C->begin()->getNode());
EXPECT_EQ(&C, &std::next(C->begin())->getNode());
CG.removeEdge(C, B);
EXPECT_EQ(1, std::distance(C->begin(), C->end()));
EXPECT_EQ(&C, &C->begin()->getNode());
CG.removeEdge(C, C);
EXPECT_EQ(0, std::distance(C->begin(), C->end()));
CG.removeEdge(B, C);
EXPECT_EQ(0, std::distance(B->begin(), B->end()));
[LCG] Add the most basic of edge insertion to the lazy call graph. This just handles the pre-DFS case. Also add some test cases for this case to make sure it works. llvm-svn: 207411
2014-04-28 19:10:23 +08:00
}
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
TEST(LazyCallGraphTest, InnerSCCFormation) {
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
LLVMContext Context;
std::unique_ptr<Module> M = parseAssembly(Context, DiamondOfTriangles);
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Now mutate the graph to connect every node into a single RefSCC to ensure
// that our inner SCC formation handles the rest.
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
LazyCallGraph::Node &D1 = CG.get(lookupFunction(*M, "d1"));
LazyCallGraph::Node &A1 = CG.get(lookupFunction(*M, "a1"));
A1.populate();
D1.populate();
CG.insertEdge(D1, A1, LazyCallGraph::Edge::Ref);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Build vectors and sort them for the rest of the assertions to make them
// independent of order.
std::vector<std::string> Nodes;
// We should build a single RefSCC for the entire graph.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
auto I = CG.postorder_ref_scc_begin();
LazyCallGraph::RefSCC &RC = *I++;
EXPECT_EQ(CG.postorder_ref_scc_end(), I);
// Now walk the four SCCs which should be in post-order.
auto J = RC.begin();
LazyCallGraph::SCC &D = *J++;
for (LazyCallGraph::Node &N : D)
Nodes.push_back(N.getFunction().getName());
std::sort(Nodes.begin(), Nodes.end());
EXPECT_EQ(3u, Nodes.size());
EXPECT_EQ("d1", Nodes[0]);
EXPECT_EQ("d2", Nodes[1]);
EXPECT_EQ("d3", Nodes[2]);
Nodes.clear();
LazyCallGraph::SCC &B = *J++;
for (LazyCallGraph::Node &N : B)
Nodes.push_back(N.getFunction().getName());
std::sort(Nodes.begin(), Nodes.end());
EXPECT_EQ(3u, Nodes.size());
EXPECT_EQ("b1", Nodes[0]);
EXPECT_EQ("b2", Nodes[1]);
EXPECT_EQ("b3", Nodes[2]);
Nodes.clear();
LazyCallGraph::SCC &C = *J++;
for (LazyCallGraph::Node &N : C)
Nodes.push_back(N.getFunction().getName());
std::sort(Nodes.begin(), Nodes.end());
EXPECT_EQ(3u, Nodes.size());
EXPECT_EQ("c1", Nodes[0]);
EXPECT_EQ("c2", Nodes[1]);
EXPECT_EQ("c3", Nodes[2]);
Nodes.clear();
LazyCallGraph::SCC &A = *J++;
for (LazyCallGraph::Node &N : A)
Nodes.push_back(N.getFunction().getName());
std::sort(Nodes.begin(), Nodes.end());
EXPECT_EQ(3u, Nodes.size());
EXPECT_EQ("a1", Nodes[0]);
EXPECT_EQ("a2", Nodes[1]);
EXPECT_EQ("a3", Nodes[2]);
Nodes.clear();
EXPECT_EQ(RC.end(), J);
}
[LCG] Implement Tarjan's algorithm correctly this time. We have to walk up the stack finishing the exploration of each entries children before we're finished in addition to accounting for their low-links. Added a unittest that really hammers home the need for this with interlocking cycles that would each appear distinct otherwise and crash or compute the wrong result. As part of this, nuke a stale fixme and bring the rest of the implementation still more closely in line with the original algorithm. llvm-svn: 206966
2014-04-23 18:31:17 +08:00
TEST(LazyCallGraphTest, MultiArmSCC) {
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
LLVMContext Context;
[LCG] Implement Tarjan's algorithm correctly this time. We have to walk up the stack finishing the exploration of each entries children before we're finished in addition to accounting for their low-links. Added a unittest that really hammers home the need for this with interlocking cycles that would each appear distinct otherwise and crash or compute the wrong result. As part of this, nuke a stale fixme and bring the rest of the implementation still more closely in line with the original algorithm. llvm-svn: 206966
2014-04-23 18:31:17 +08:00
// Two interlocking cycles. The really useful thing about this SCC is that it
// will require Tarjan's DFS to backtrack and finish processing all of the
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// children of each node in the SCC. Since this involves call edges, both
// Tarjan implementations will have to successfully navigate the structure.
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
std::unique_ptr<Module> M = parseAssembly(Context, "define void @f1() {\n"
"entry:\n"
" call void @f2()\n"
" call void @f4()\n"
" ret void\n"
"}\n"
"define void @f2() {\n"
"entry:\n"
" call void @f3()\n"
" ret void\n"
"}\n"
"define void @f3() {\n"
"entry:\n"
" call void @f1()\n"
" ret void\n"
"}\n"
"define void @f4() {\n"
"entry:\n"
" call void @f5()\n"
" ret void\n"
"}\n"
"define void @f5() {\n"
"entry:\n"
" call void @f1()\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Implement Tarjan's algorithm correctly this time. We have to walk up the stack finishing the exploration of each entries children before we're finished in addition to accounting for their low-links. Added a unittest that really hammers home the need for this with interlocking cycles that would each appear distinct otherwise and crash or compute the wrong result. As part of this, nuke a stale fixme and bring the rest of the implementation still more closely in line with the original algorithm. llvm-svn: 206966
2014-04-23 18:31:17 +08:00
// Force the graph to be fully expanded.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
auto I = CG.postorder_ref_scc_begin();
LazyCallGraph::RefSCC &RC = *I++;
EXPECT_EQ(CG.postorder_ref_scc_end(), I);
LazyCallGraph::Node &N1 = *CG.lookup(lookupFunction(*M, "f1"));
LazyCallGraph::Node &N2 = *CG.lookup(lookupFunction(*M, "f2"));
LazyCallGraph::Node &N3 = *CG.lookup(lookupFunction(*M, "f3"));
LazyCallGraph::Node &N4 = *CG.lookup(lookupFunction(*M, "f4"));
LazyCallGraph::Node &N5 = *CG.lookup(lookupFunction(*M, "f4"));
EXPECT_EQ(&RC, CG.lookupRefSCC(N1));
EXPECT_EQ(&RC, CG.lookupRefSCC(N2));
EXPECT_EQ(&RC, CG.lookupRefSCC(N3));
EXPECT_EQ(&RC, CG.lookupRefSCC(N4));
EXPECT_EQ(&RC, CG.lookupRefSCC(N5));
ASSERT_EQ(1, RC.size());
LazyCallGraph::SCC &C = *RC.begin();
EXPECT_EQ(&C, CG.lookupSCC(N1));
EXPECT_EQ(&C, CG.lookupSCC(N2));
EXPECT_EQ(&C, CG.lookupSCC(N3));
EXPECT_EQ(&C, CG.lookupSCC(N4));
EXPECT_EQ(&C, CG.lookupSCC(N5));
[LCG] Implement Tarjan's algorithm correctly this time. We have to walk up the stack finishing the exploration of each entries children before we're finished in addition to accounting for their low-links. Added a unittest that really hammers home the need for this with interlocking cycles that would each appear distinct otherwise and crash or compute the wrong result. As part of this, nuke a stale fixme and bring the rest of the implementation still more closely in line with the original algorithm. llvm-svn: 206966
2014-04-23 18:31:17 +08:00
}
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
TEST(LazyCallGraphTest, OutgoingEdgeMutation) {
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
LLVMContext Context;
std::unique_ptr<Module> M = parseAssembly(Context, "define void @a() {\n"
"entry:\n"
" call void @b()\n"
" call void @c()\n"
" ret void\n"
"}\n"
"define void @b() {\n"
"entry:\n"
" call void @d()\n"
" ret void\n"
"}\n"
"define void @c() {\n"
"entry:\n"
" call void @d()\n"
" ret void\n"
"}\n"
"define void @d() {\n"
"entry:\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Reorder the tests to be a bit more logical: inter-SCC mutation before intra-SCC mutation, insertion before removal. No functionality changed. llvm-svn: 207934
2014-05-04 17:38:23 +08:00
// Force the graph to be fully expanded.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
for (LazyCallGraph::RefSCC &RC : CG.postorder_ref_sccs())
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
dbgs() << "Formed RefSCC: " << RC << "\n";
[LCG] Reorder the tests to be a bit more logical: inter-SCC mutation before intra-SCC mutation, insertion before removal. No functionality changed. llvm-svn: 207934
2014-05-04 17:38:23 +08:00
LazyCallGraph::Node &A = *CG.lookup(lookupFunction(*M, "a"));
LazyCallGraph::Node &B = *CG.lookup(lookupFunction(*M, "b"));
LazyCallGraph::Node &C = *CG.lookup(lookupFunction(*M, "c"));
LazyCallGraph::Node &D = *CG.lookup(lookupFunction(*M, "d"));
LazyCallGraph::SCC &AC = *CG.lookupSCC(A);
LazyCallGraph::SCC &BC = *CG.lookupSCC(B);
LazyCallGraph::SCC &CC = *CG.lookupSCC(C);
LazyCallGraph::SCC &DC = *CG.lookupSCC(D);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
LazyCallGraph::RefSCC &ARC = *CG.lookupRefSCC(A);
LazyCallGraph::RefSCC &BRC = *CG.lookupRefSCC(B);
LazyCallGraph::RefSCC &CRC = *CG.lookupRefSCC(C);
LazyCallGraph::RefSCC &DRC = *CG.lookupRefSCC(D);
EXPECT_TRUE(ARC.isParentOf(BRC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(AC.isParentOf(BC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(ARC.isParentOf(CRC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(AC.isParentOf(CC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_FALSE(ARC.isParentOf(DRC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_FALSE(AC.isParentOf(DC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(ARC.isAncestorOf(DRC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(AC.isAncestorOf(DC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_FALSE(DRC.isChildOf(ARC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_FALSE(DC.isChildOf(AC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(DRC.isDescendantOf(ARC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(DC.isDescendantOf(AC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(DRC.isChildOf(BRC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(DC.isChildOf(BC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(DRC.isChildOf(CRC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(DC.isChildOf(CC));
[LCG] Reorder the tests to be a bit more logical: inter-SCC mutation before intra-SCC mutation, insertion before removal. No functionality changed. llvm-svn: 207934
2014-05-04 17:38:23 +08:00
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
EXPECT_EQ(2, std::distance(A->begin(), A->end()));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
ARC.insertOutgoingEdge(A, D, LazyCallGraph::Edge::Call);
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
EXPECT_EQ(3, std::distance(A->begin(), A->end()));
const LazyCallGraph::Edge &NewE = (*A)[D];
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(NewE);
EXPECT_TRUE(NewE.isCall());
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
EXPECT_EQ(&D, &NewE.getNode());
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Only the parent and child tests sholud have changed. The rest of the graph
// remains the same.
EXPECT_TRUE(ARC.isParentOf(DRC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(AC.isParentOf(DC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(ARC.isAncestorOf(DRC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(AC.isAncestorOf(DC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(DRC.isChildOf(ARC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(DC.isChildOf(AC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(DRC.isDescendantOf(ARC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(DC.isDescendantOf(AC));
[LCG] Reorder the tests to be a bit more logical: inter-SCC mutation before intra-SCC mutation, insertion before removal. No functionality changed. llvm-svn: 207934
2014-05-04 17:38:23 +08:00
EXPECT_EQ(&AC, CG.lookupSCC(A));
EXPECT_EQ(&BC, CG.lookupSCC(B));
EXPECT_EQ(&CC, CG.lookupSCC(C));
EXPECT_EQ(&DC, CG.lookupSCC(D));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(&ARC, CG.lookupRefSCC(A));
EXPECT_EQ(&BRC, CG.lookupRefSCC(B));
EXPECT_EQ(&CRC, CG.lookupRefSCC(C));
EXPECT_EQ(&DRC, CG.lookupRefSCC(D));
ARC.switchOutgoingEdgeToRef(A, D);
EXPECT_FALSE(NewE.isCall());
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
// Verify the reference graph remains the same but the SCC graph is updated.
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(ARC.isParentOf(DRC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_FALSE(AC.isParentOf(DC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(ARC.isAncestorOf(DRC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(AC.isAncestorOf(DC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(DRC.isChildOf(ARC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_FALSE(DC.isChildOf(AC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(DRC.isDescendantOf(ARC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(DC.isDescendantOf(AC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(&AC, CG.lookupSCC(A));
EXPECT_EQ(&BC, CG.lookupSCC(B));
EXPECT_EQ(&CC, CG.lookupSCC(C));
EXPECT_EQ(&DC, CG.lookupSCC(D));
EXPECT_EQ(&ARC, CG.lookupRefSCC(A));
EXPECT_EQ(&BRC, CG.lookupRefSCC(B));
EXPECT_EQ(&CRC, CG.lookupRefSCC(C));
EXPECT_EQ(&DRC, CG.lookupRefSCC(D));
ARC.switchOutgoingEdgeToCall(A, D);
EXPECT_TRUE(NewE.isCall());
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
// Verify the reference graph remains the same but the SCC graph is updated.
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(ARC.isParentOf(DRC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(AC.isParentOf(DC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(ARC.isAncestorOf(DRC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(AC.isAncestorOf(DC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(DRC.isChildOf(ARC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(DC.isChildOf(AC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(DRC.isDescendantOf(ARC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(DC.isDescendantOf(AC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(&AC, CG.lookupSCC(A));
EXPECT_EQ(&BC, CG.lookupSCC(B));
EXPECT_EQ(&CC, CG.lookupSCC(C));
EXPECT_EQ(&DC, CG.lookupSCC(D));
EXPECT_EQ(&ARC, CG.lookupRefSCC(A));
EXPECT_EQ(&BRC, CG.lookupRefSCC(B));
EXPECT_EQ(&CRC, CG.lookupRefSCC(C));
EXPECT_EQ(&DRC, CG.lookupRefSCC(D));
ARC.removeOutgoingEdge(A, D);
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
EXPECT_EQ(2, std::distance(A->begin(), A->end()));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Now the parent and child tests fail again but the rest remains the same.
EXPECT_FALSE(ARC.isParentOf(DRC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_FALSE(AC.isParentOf(DC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(ARC.isAncestorOf(DRC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(AC.isAncestorOf(DC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_FALSE(DRC.isChildOf(ARC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_FALSE(DC.isChildOf(AC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(DRC.isDescendantOf(ARC));
[LCG] Start using SCC relationship predicates in the unittest. This mostly gives us nice unittesting of the predicates themselves. I'll start using them further in subsequent commits to help test the actual operations performed on the graph. llvm-svn: 287698
2016-11-23 04:35:32 +08:00
EXPECT_TRUE(DC.isDescendantOf(AC));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(&AC, CG.lookupSCC(A));
EXPECT_EQ(&BC, CG.lookupSCC(B));
EXPECT_EQ(&CC, CG.lookupSCC(C));
EXPECT_EQ(&DC, CG.lookupSCC(D));
EXPECT_EQ(&ARC, CG.lookupRefSCC(A));
EXPECT_EQ(&BRC, CG.lookupRefSCC(B));
EXPECT_EQ(&CRC, CG.lookupRefSCC(C));
EXPECT_EQ(&DRC, CG.lookupRefSCC(D));
[LCG] Reorder the tests to be a bit more logical: inter-SCC mutation before intra-SCC mutation, insertion before removal. No functionality changed. llvm-svn: 207934
2014-05-04 17:38:23 +08:00
}
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
TEST(LazyCallGraphTest, IncomingEdgeInsertion) {
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
LLVMContext Context;
[LCG] Add the last (and most complex) of the edge insertion mutation operations on the call graph. This one forms a cycle, and while not as complex as removing an internal edge from an SCC, it involves a reasonable amount of work to find all of the nodes newly connected in a cycle. Also somewhat alarming is the worst case complexity here: it might have to walk roughly the entire SCC inverse DAG to insert a single edge. This is carefully documented in the API (I hope). llvm-svn: 207935
2014-05-04 17:38:32 +08:00
// We want to ensure we can add edges even across complex diamond graphs, so
// we use the diamond of triangles graph defined above. The ascii diagram is
// repeated here for easy reference.
//
// d1 |
// / \ |
// d3--d2 |
// / \ |
// b1 c1 |
// / \ / \ |
// b3--b2 c3--c2 |
// \ / |
// a1 |
// / \ |
// a3--a2 |
//
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
std::unique_ptr<Module> M = parseAssembly(Context, DiamondOfTriangles);
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Add the last (and most complex) of the edge insertion mutation operations on the call graph. This one forms a cycle, and while not as complex as removing an internal edge from an SCC, it involves a reasonable amount of work to find all of the nodes newly connected in a cycle. Also somewhat alarming is the worst case complexity here: it might have to walk roughly the entire SCC inverse DAG to insert a single edge. This is carefully documented in the API (I hope). llvm-svn: 207935
2014-05-04 17:38:32 +08:00
// Force the graph to be fully expanded.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
for (LazyCallGraph::RefSCC &RC : CG.postorder_ref_sccs())
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
dbgs() << "Formed RefSCC: " << RC << "\n";
[LCG] Add the last (and most complex) of the edge insertion mutation operations on the call graph. This one forms a cycle, and while not as complex as removing an internal edge from an SCC, it involves a reasonable amount of work to find all of the nodes newly connected in a cycle. Also somewhat alarming is the worst case complexity here: it might have to walk roughly the entire SCC inverse DAG to insert a single edge. This is carefully documented in the API (I hope). llvm-svn: 207935
2014-05-04 17:38:32 +08:00
LazyCallGraph::Node &A1 = *CG.lookup(lookupFunction(*M, "a1"));
LazyCallGraph::Node &A2 = *CG.lookup(lookupFunction(*M, "a2"));
LazyCallGraph::Node &A3 = *CG.lookup(lookupFunction(*M, "a3"));
LazyCallGraph::Node &B1 = *CG.lookup(lookupFunction(*M, "b1"));
LazyCallGraph::Node &B2 = *CG.lookup(lookupFunction(*M, "b2"));
LazyCallGraph::Node &B3 = *CG.lookup(lookupFunction(*M, "b3"));
LazyCallGraph::Node &C1 = *CG.lookup(lookupFunction(*M, "c1"));
LazyCallGraph::Node &C2 = *CG.lookup(lookupFunction(*M, "c2"));
LazyCallGraph::Node &C3 = *CG.lookup(lookupFunction(*M, "c3"));
LazyCallGraph::Node &D1 = *CG.lookup(lookupFunction(*M, "d1"));
LazyCallGraph::Node &D2 = *CG.lookup(lookupFunction(*M, "d2"));
LazyCallGraph::Node &D3 = *CG.lookup(lookupFunction(*M, "d3"));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
LazyCallGraph::RefSCC &ARC = *CG.lookupRefSCC(A1);
LazyCallGraph::RefSCC &BRC = *CG.lookupRefSCC(B1);
LazyCallGraph::RefSCC &CRC = *CG.lookupRefSCC(C1);
LazyCallGraph::RefSCC &DRC = *CG.lookupRefSCC(D1);
ASSERT_EQ(&ARC, CG.lookupRefSCC(A2));
ASSERT_EQ(&ARC, CG.lookupRefSCC(A3));
ASSERT_EQ(&BRC, CG.lookupRefSCC(B2));
ASSERT_EQ(&BRC, CG.lookupRefSCC(B3));
ASSERT_EQ(&CRC, CG.lookupRefSCC(C2));
ASSERT_EQ(&CRC, CG.lookupRefSCC(C3));
ASSERT_EQ(&DRC, CG.lookupRefSCC(D2));
ASSERT_EQ(&DRC, CG.lookupRefSCC(D3));
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
ASSERT_EQ(1, std::distance(D2->begin(), D2->end()));
[LCG] Add the last (and most complex) of the edge insertion mutation operations on the call graph. This one forms a cycle, and while not as complex as removing an internal edge from an SCC, it involves a reasonable amount of work to find all of the nodes newly connected in a cycle. Also somewhat alarming is the worst case complexity here: it might have to walk roughly the entire SCC inverse DAG to insert a single edge. This is carefully documented in the API (I hope). llvm-svn: 207935
2014-05-04 17:38:32 +08:00
// Add an edge to make the graph:
//
// d1 |
// / \ |
// d3--d2---. |
// / \ | |
// b1 c1 | |
// / \ / \ / |
// b3--b2 c3--c2 |
// \ / |
// a1 |
// / \ |
// a3--a2 |
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
auto MergedRCs = CRC.insertIncomingRefEdge(D2, C2);
[LCG] Add the last (and most complex) of the edge insertion mutation operations on the call graph. This one forms a cycle, and while not as complex as removing an internal edge from an SCC, it involves a reasonable amount of work to find all of the nodes newly connected in a cycle. Also somewhat alarming is the worst case complexity here: it might have to walk roughly the entire SCC inverse DAG to insert a single edge. This is carefully documented in the API (I hope). llvm-svn: 207935
2014-05-04 17:38:32 +08:00
// Make sure we connected the nodes.
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
for (LazyCallGraph::Edge E : *D2) {
if (&E.getNode() == &D3)
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
continue;
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
EXPECT_EQ(&C2, &E.getNode());
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
}
// And marked the D ref-SCC as no longer valid.
EXPECT_EQ(1u, MergedRCs.size());
EXPECT_EQ(&DRC, MergedRCs[0]);
[LCG] Add the last (and most complex) of the edge insertion mutation operations on the call graph. This one forms a cycle, and while not as complex as removing an internal edge from an SCC, it involves a reasonable amount of work to find all of the nodes newly connected in a cycle. Also somewhat alarming is the worst case complexity here: it might have to walk roughly the entire SCC inverse DAG to insert a single edge. This is carefully documented in the API (I hope). llvm-svn: 207935
2014-05-04 17:38:32 +08:00
// Make sure we have the correct nodes in the SCC sets.
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(&ARC, CG.lookupRefSCC(A1));
EXPECT_EQ(&ARC, CG.lookupRefSCC(A2));
EXPECT_EQ(&ARC, CG.lookupRefSCC(A3));
EXPECT_EQ(&BRC, CG.lookupRefSCC(B1));
EXPECT_EQ(&BRC, CG.lookupRefSCC(B2));
EXPECT_EQ(&BRC, CG.lookupRefSCC(B3));
EXPECT_EQ(&CRC, CG.lookupRefSCC(C1));
EXPECT_EQ(&CRC, CG.lookupRefSCC(C2));
EXPECT_EQ(&CRC, CG.lookupRefSCC(C3));
EXPECT_EQ(&CRC, CG.lookupRefSCC(D1));
EXPECT_EQ(&CRC, CG.lookupRefSCC(D2));
EXPECT_EQ(&CRC, CG.lookupRefSCC(D3));
[LCG] Add the last (and most complex) of the edge insertion mutation operations on the call graph. This one forms a cycle, and while not as complex as removing an internal edge from an SCC, it involves a reasonable amount of work to find all of the nodes newly connected in a cycle. Also somewhat alarming is the worst case complexity here: it might have to walk roughly the entire SCC inverse DAG to insert a single edge. This is carefully documented in the API (I hope). llvm-svn: 207935
2014-05-04 17:38:32 +08:00
// And that ancestry tests have been updated.
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_TRUE(ARC.isParentOf(CRC));
EXPECT_TRUE(BRC.isParentOf(CRC));
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
// And verify the post-order walk reflects the updated structure.
auto I = CG.postorder_ref_scc_begin(), E = CG.postorder_ref_scc_end();
ASSERT_NE(I, E);
EXPECT_EQ(&CRC, &*I) << "Actual RefSCC: " << *I;
ASSERT_NE(++I, E);
EXPECT_EQ(&BRC, &*I) << "Actual RefSCC: " << *I;
ASSERT_NE(++I, E);
EXPECT_EQ(&ARC, &*I) << "Actual RefSCC: " << *I;
EXPECT_EQ(++I, E);
[LCG] Add the last (and most complex) of the edge insertion mutation operations on the call graph. This one forms a cycle, and while not as complex as removing an internal edge from an SCC, it involves a reasonable amount of work to find all of the nodes newly connected in a cycle. Also somewhat alarming is the worst case complexity here: it might have to walk roughly the entire SCC inverse DAG to insert a single edge. This is carefully documented in the API (I hope). llvm-svn: 207935
2014-05-04 17:38:32 +08:00
}
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
TEST(LazyCallGraphTest, IncomingEdgeInsertionRefGraph) {
LLVMContext Context;
// Another variation of the above test but with all the edges switched to
// references rather than calls.
std::unique_ptr<Module> M =
parseAssembly(Context, DiamondOfTrianglesRefGraph);
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
// Force the graph to be fully expanded.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
for (LazyCallGraph::RefSCC &RC : CG.postorder_ref_sccs())
dbgs() << "Formed RefSCC: " << RC << "\n";
LazyCallGraph::Node &A1 = *CG.lookup(lookupFunction(*M, "a1"));
LazyCallGraph::Node &A2 = *CG.lookup(lookupFunction(*M, "a2"));
LazyCallGraph::Node &A3 = *CG.lookup(lookupFunction(*M, "a3"));
LazyCallGraph::Node &B1 = *CG.lookup(lookupFunction(*M, "b1"));
LazyCallGraph::Node &B2 = *CG.lookup(lookupFunction(*M, "b2"));
LazyCallGraph::Node &B3 = *CG.lookup(lookupFunction(*M, "b3"));
LazyCallGraph::Node &C1 = *CG.lookup(lookupFunction(*M, "c1"));
LazyCallGraph::Node &C2 = *CG.lookup(lookupFunction(*M, "c2"));
LazyCallGraph::Node &C3 = *CG.lookup(lookupFunction(*M, "c3"));
LazyCallGraph::Node &D1 = *CG.lookup(lookupFunction(*M, "d1"));
LazyCallGraph::Node &D2 = *CG.lookup(lookupFunction(*M, "d2"));
LazyCallGraph::Node &D3 = *CG.lookup(lookupFunction(*M, "d3"));
LazyCallGraph::RefSCC &ARC = *CG.lookupRefSCC(A1);
LazyCallGraph::RefSCC &BRC = *CG.lookupRefSCC(B1);
LazyCallGraph::RefSCC &CRC = *CG.lookupRefSCC(C1);
LazyCallGraph::RefSCC &DRC = *CG.lookupRefSCC(D1);
ASSERT_EQ(&ARC, CG.lookupRefSCC(A2));
ASSERT_EQ(&ARC, CG.lookupRefSCC(A3));
ASSERT_EQ(&BRC, CG.lookupRefSCC(B2));
ASSERT_EQ(&BRC, CG.lookupRefSCC(B3));
ASSERT_EQ(&CRC, CG.lookupRefSCC(C2));
ASSERT_EQ(&CRC, CG.lookupRefSCC(C3));
ASSERT_EQ(&DRC, CG.lookupRefSCC(D2));
ASSERT_EQ(&DRC, CG.lookupRefSCC(D3));
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
ASSERT_EQ(1, std::distance(D2->begin(), D2->end()));
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
// Add an edge to make the graph:
//
// d1 |
// / \ |
// d3--d2---. |
// / \ | |
// b1 c1 | |
// / \ / \ / |
// b3--b2 c3--c2 |
// \ / |
// a1 |
// / \ |
// a3--a2 |
auto MergedRCs = CRC.insertIncomingRefEdge(D2, C2);
// Make sure we connected the nodes.
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
for (LazyCallGraph::Edge E : *D2) {
if (&E.getNode() == &D3)
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
continue;
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
EXPECT_EQ(&C2, &E.getNode());
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
}
// And marked the D ref-SCC as no longer valid.
EXPECT_EQ(1u, MergedRCs.size());
EXPECT_EQ(&DRC, MergedRCs[0]);
// Make sure we have the correct nodes in the SCC sets.
EXPECT_EQ(&ARC, CG.lookupRefSCC(A1));
EXPECT_EQ(&ARC, CG.lookupRefSCC(A2));
EXPECT_EQ(&ARC, CG.lookupRefSCC(A3));
EXPECT_EQ(&BRC, CG.lookupRefSCC(B1));
EXPECT_EQ(&BRC, CG.lookupRefSCC(B2));
EXPECT_EQ(&BRC, CG.lookupRefSCC(B3));
EXPECT_EQ(&CRC, CG.lookupRefSCC(C1));
EXPECT_EQ(&CRC, CG.lookupRefSCC(C2));
EXPECT_EQ(&CRC, CG.lookupRefSCC(C3));
EXPECT_EQ(&CRC, CG.lookupRefSCC(D1));
EXPECT_EQ(&CRC, CG.lookupRefSCC(D2));
EXPECT_EQ(&CRC, CG.lookupRefSCC(D3));
// And that ancestry tests have been updated.
EXPECT_TRUE(ARC.isParentOf(CRC));
EXPECT_TRUE(BRC.isParentOf(CRC));
// And verify the post-order walk reflects the updated structure.
auto I = CG.postorder_ref_scc_begin(), E = CG.postorder_ref_scc_end();
ASSERT_NE(I, E);
EXPECT_EQ(&CRC, &*I) << "Actual RefSCC: " << *I;
ASSERT_NE(++I, E);
EXPECT_EQ(&BRC, &*I) << "Actual RefSCC: " << *I;
ASSERT_NE(++I, E);
EXPECT_EQ(&ARC, &*I) << "Actual RefSCC: " << *I;
EXPECT_EQ(++I, E);
}
TEST(LazyCallGraphTest, IncomingEdgeInsertionLargeCallCycle) {
LLVMContext Context;
std::unique_ptr<Module> M = parseAssembly(Context, "define void @a() {\n"
"entry:\n"
" call void @b()\n"
" ret void\n"
"}\n"
"define void @b() {\n"
"entry:\n"
" call void @c()\n"
" ret void\n"
"}\n"
"define void @c() {\n"
"entry:\n"
" call void @d()\n"
" ret void\n"
"}\n"
"define void @d() {\n"
"entry:\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
// Force the graph to be fully expanded.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
for (LazyCallGraph::RefSCC &RC : CG.postorder_ref_sccs())
dbgs() << "Formed RefSCC: " << RC << "\n";
LazyCallGraph::Node &A = *CG.lookup(lookupFunction(*M, "a"));
LazyCallGraph::Node &B = *CG.lookup(lookupFunction(*M, "b"));
LazyCallGraph::Node &C = *CG.lookup(lookupFunction(*M, "c"));
LazyCallGraph::Node &D = *CG.lookup(lookupFunction(*M, "d"));
LazyCallGraph::SCC &AC = *CG.lookupSCC(A);
LazyCallGraph::SCC &BC = *CG.lookupSCC(B);
LazyCallGraph::SCC &CC = *CG.lookupSCC(C);
LazyCallGraph::SCC &DC = *CG.lookupSCC(D);
LazyCallGraph::RefSCC &ARC = *CG.lookupRefSCC(A);
LazyCallGraph::RefSCC &BRC = *CG.lookupRefSCC(B);
LazyCallGraph::RefSCC &CRC = *CG.lookupRefSCC(C);
LazyCallGraph::RefSCC &DRC = *CG.lookupRefSCC(D);
// Connect the top to the bottom forming a large RefSCC made up mostly of calls.
auto MergedRCs = ARC.insertIncomingRefEdge(D, A);
// Make sure we connected the nodes.
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
EXPECT_NE(D->begin(), D->end());
EXPECT_EQ(&A, &D->begin()->getNode());
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
// Check that we have the dead RCs, but ignore the order.
EXPECT_EQ(3u, MergedRCs.size());
EXPECT_NE(find(MergedRCs, &BRC), MergedRCs.end());
EXPECT_NE(find(MergedRCs, &CRC), MergedRCs.end());
EXPECT_NE(find(MergedRCs, &DRC), MergedRCs.end());
// Make sure the nodes point to the right place now.
EXPECT_EQ(&ARC, CG.lookupRefSCC(A));
EXPECT_EQ(&ARC, CG.lookupRefSCC(B));
EXPECT_EQ(&ARC, CG.lookupRefSCC(C));
EXPECT_EQ(&ARC, CG.lookupRefSCC(D));
// Check that the SCCs are in postorder.
EXPECT_EQ(4, ARC.size());
EXPECT_EQ(&DC, &ARC[0]);
EXPECT_EQ(&CC, &ARC[1]);
EXPECT_EQ(&BC, &ARC[2]);
EXPECT_EQ(&AC, &ARC[3]);
// And verify the post-order walk reflects the updated structure.
auto I = CG.postorder_ref_scc_begin(), E = CG.postorder_ref_scc_end();
ASSERT_NE(I, E);
EXPECT_EQ(&ARC, &*I) << "Actual RefSCC: " << *I;
EXPECT_EQ(++I, E);
}
TEST(LazyCallGraphTest, IncomingEdgeInsertionLargeRefCycle) {
LLVMContext Context;
std::unique_ptr<Module> M =
parseAssembly(Context, "define void @a() {\n"
"entry:\n"
" %p = alloca void ()*\n"
" store void ()* @b, void ()** %p\n"
" ret void\n"
"}\n"
"define void @b() {\n"
"entry:\n"
" %p = alloca void ()*\n"
" store void ()* @c, void ()** %p\n"
" ret void\n"
"}\n"
"define void @c() {\n"
"entry:\n"
" %p = alloca void ()*\n"
" store void ()* @d, void ()** %p\n"
" ret void\n"
"}\n"
"define void @d() {\n"
"entry:\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
// Force the graph to be fully expanded.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
for (LazyCallGraph::RefSCC &RC : CG.postorder_ref_sccs())
dbgs() << "Formed RefSCC: " << RC << "\n";
LazyCallGraph::Node &A = *CG.lookup(lookupFunction(*M, "a"));
LazyCallGraph::Node &B = *CG.lookup(lookupFunction(*M, "b"));
LazyCallGraph::Node &C = *CG.lookup(lookupFunction(*M, "c"));
LazyCallGraph::Node &D = *CG.lookup(lookupFunction(*M, "d"));
LazyCallGraph::RefSCC &ARC = *CG.lookupRefSCC(A);
LazyCallGraph::RefSCC &BRC = *CG.lookupRefSCC(B);
LazyCallGraph::RefSCC &CRC = *CG.lookupRefSCC(C);
LazyCallGraph::RefSCC &DRC = *CG.lookupRefSCC(D);
// Connect the top to the bottom forming a large RefSCC made up just of
// references.
auto MergedRCs = ARC.insertIncomingRefEdge(D, A);
// Make sure we connected the nodes.
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
EXPECT_NE(D->begin(), D->end());
EXPECT_EQ(&A, &D->begin()->getNode());
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
// Check that we have the dead RCs, but ignore the order.
EXPECT_EQ(3u, MergedRCs.size());
EXPECT_NE(find(MergedRCs, &BRC), MergedRCs.end());
EXPECT_NE(find(MergedRCs, &CRC), MergedRCs.end());
EXPECT_NE(find(MergedRCs, &DRC), MergedRCs.end());
// Make sure the nodes point to the right place now.
EXPECT_EQ(&ARC, CG.lookupRefSCC(A));
EXPECT_EQ(&ARC, CG.lookupRefSCC(B));
EXPECT_EQ(&ARC, CG.lookupRefSCC(C));
EXPECT_EQ(&ARC, CG.lookupRefSCC(D));
// And verify the post-order walk reflects the updated structure.
auto I = CG.postorder_ref_scc_begin(), End = CG.postorder_ref_scc_end();
ASSERT_NE(I, End);
EXPECT_EQ(&ARC, &*I) << "Actual RefSCC: " << *I;
EXPECT_EQ(++I, End);
[LCG] Add the last (and most complex) of the edge insertion mutation operations on the call graph. This one forms a cycle, and while not as complex as removing an internal edge from an SCC, it involves a reasonable amount of work to find all of the nodes newly connected in a cycle. Also somewhat alarming is the worst case complexity here: it might have to walk roughly the entire SCC inverse DAG to insert a single edge. This is carefully documented in the API (I hope). llvm-svn: 207935
2014-05-04 17:38:32 +08:00
}
[LCG] Add the necessary functionality to the LazyCallGraph to support inlining. The basic inlining operation makes the following changes to the call graph: 1) Add edges that were previously transitive edges. This is always trivial and this patch gives the LCG helper methods to make this more convenient. 2) Remove the inlined edge. We had existing support for this, but it contained bugs that needed to be fixed. Testing in the same pattern as the inliner exposes these bugs very nicely. 3) Delete a function when it becomes dead because it is internal and all calls have been inlined. The LCG had no support at all for this operation, so this adds that support. Two unittests have been added that exercise this specific mutation pattern to the call graph. They were extremely effective in uncovering bugs. Sadly, a large fraction of the code here is just to implement those unit tests, but I think they're paying for themselves. =] This was split out of a patch that actually uses the routines to implement inlining in the new pass manager in order to isolate (with unit tests) the logic that was entirely within the LCG. Many thanks for the careful review from folks! There will be a few minor follow-up patches based on the comments in the review as well. Differential Revision: https://reviews.llvm.org/D24225 llvm-svn: 283982
2016-10-12 15:59:56 +08:00
TEST(LazyCallGraphTest, InlineAndDeleteFunction) {
LLVMContext Context;
// We want to ensure we can delete nodes from relatively complex graphs and
// so use the diamond of triangles graph defined above.
//
// The ascii diagram is repeated here for easy reference.
//
// d1 |
// / \ |
// d3--d2 |
// / \ |
// b1 c1 |
// / \ / \ |
// b3--b2 c3--c2 |
// \ / |
// a1 |
// / \ |
// a3--a2 |
//
std::unique_ptr<Module> M = parseAssembly(Context, DiamondOfTriangles);
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Add the necessary functionality to the LazyCallGraph to support inlining. The basic inlining operation makes the following changes to the call graph: 1) Add edges that were previously transitive edges. This is always trivial and this patch gives the LCG helper methods to make this more convenient. 2) Remove the inlined edge. We had existing support for this, but it contained bugs that needed to be fixed. Testing in the same pattern as the inliner exposes these bugs very nicely. 3) Delete a function when it becomes dead because it is internal and all calls have been inlined. The LCG had no support at all for this operation, so this adds that support. Two unittests have been added that exercise this specific mutation pattern to the call graph. They were extremely effective in uncovering bugs. Sadly, a large fraction of the code here is just to implement those unit tests, but I think they're paying for themselves. =] This was split out of a patch that actually uses the routines to implement inlining in the new pass manager in order to isolate (with unit tests) the logic that was entirely within the LCG. Many thanks for the careful review from folks! There will be a few minor follow-up patches based on the comments in the review as well. Differential Revision: https://reviews.llvm.org/D24225 llvm-svn: 283982
2016-10-12 15:59:56 +08:00
// Force the graph to be fully expanded.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Add the necessary functionality to the LazyCallGraph to support inlining. The basic inlining operation makes the following changes to the call graph: 1) Add edges that were previously transitive edges. This is always trivial and this patch gives the LCG helper methods to make this more convenient. 2) Remove the inlined edge. We had existing support for this, but it contained bugs that needed to be fixed. Testing in the same pattern as the inliner exposes these bugs very nicely. 3) Delete a function when it becomes dead because it is internal and all calls have been inlined. The LCG had no support at all for this operation, so this adds that support. Two unittests have been added that exercise this specific mutation pattern to the call graph. They were extremely effective in uncovering bugs. Sadly, a large fraction of the code here is just to implement those unit tests, but I think they're paying for themselves. =] This was split out of a patch that actually uses the routines to implement inlining in the new pass manager in order to isolate (with unit tests) the logic that was entirely within the LCG. Many thanks for the careful review from folks! There will be a few minor follow-up patches based on the comments in the review as well. Differential Revision: https://reviews.llvm.org/D24225 llvm-svn: 283982
2016-10-12 15:59:56 +08:00
for (LazyCallGraph::RefSCC &RC : CG.postorder_ref_sccs())
dbgs() << "Formed RefSCC: " << RC << "\n";
LazyCallGraph::Node &A1 = *CG.lookup(lookupFunction(*M, "a1"));
LazyCallGraph::Node &A2 = *CG.lookup(lookupFunction(*M, "a2"));
LazyCallGraph::Node &A3 = *CG.lookup(lookupFunction(*M, "a3"));
LazyCallGraph::Node &B1 = *CG.lookup(lookupFunction(*M, "b1"));
LazyCallGraph::Node &B2 = *CG.lookup(lookupFunction(*M, "b2"));
LazyCallGraph::Node &B3 = *CG.lookup(lookupFunction(*M, "b3"));
LazyCallGraph::Node &C1 = *CG.lookup(lookupFunction(*M, "c1"));
LazyCallGraph::Node &C2 = *CG.lookup(lookupFunction(*M, "c2"));
LazyCallGraph::Node &C3 = *CG.lookup(lookupFunction(*M, "c3"));
LazyCallGraph::Node &D1 = *CG.lookup(lookupFunction(*M, "d1"));
LazyCallGraph::Node &D2 = *CG.lookup(lookupFunction(*M, "d2"));
LazyCallGraph::Node &D3 = *CG.lookup(lookupFunction(*M, "d3"));
LazyCallGraph::RefSCC &ARC = *CG.lookupRefSCC(A1);
LazyCallGraph::RefSCC &BRC = *CG.lookupRefSCC(B1);
LazyCallGraph::RefSCC &CRC = *CG.lookupRefSCC(C1);
LazyCallGraph::RefSCC &DRC = *CG.lookupRefSCC(D1);
ASSERT_EQ(&ARC, CG.lookupRefSCC(A2));
ASSERT_EQ(&ARC, CG.lookupRefSCC(A3));
ASSERT_EQ(&BRC, CG.lookupRefSCC(B2));
ASSERT_EQ(&BRC, CG.lookupRefSCC(B3));
ASSERT_EQ(&CRC, CG.lookupRefSCC(C2));
ASSERT_EQ(&CRC, CG.lookupRefSCC(C3));
ASSERT_EQ(&DRC, CG.lookupRefSCC(D2));
ASSERT_EQ(&DRC, CG.lookupRefSCC(D3));
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
ASSERT_EQ(1, std::distance(D2->begin(), D2->end()));
[LCG] Add the necessary functionality to the LazyCallGraph to support inlining. The basic inlining operation makes the following changes to the call graph: 1) Add edges that were previously transitive edges. This is always trivial and this patch gives the LCG helper methods to make this more convenient. 2) Remove the inlined edge. We had existing support for this, but it contained bugs that needed to be fixed. Testing in the same pattern as the inliner exposes these bugs very nicely. 3) Delete a function when it becomes dead because it is internal and all calls have been inlined. The LCG had no support at all for this operation, so this adds that support. Two unittests have been added that exercise this specific mutation pattern to the call graph. They were extremely effective in uncovering bugs. Sadly, a large fraction of the code here is just to implement those unit tests, but I think they're paying for themselves. =] This was split out of a patch that actually uses the routines to implement inlining in the new pass manager in order to isolate (with unit tests) the logic that was entirely within the LCG. Many thanks for the careful review from folks! There will be a few minor follow-up patches based on the comments in the review as well. Differential Revision: https://reviews.llvm.org/D24225 llvm-svn: 283982
2016-10-12 15:59:56 +08:00
// Delete d2 from the graph, as if it had been inlined.
//
// d1 |
// / / |
// d3--. |
// / \ |
// b1 c1 |
// / \ / \ |
// b3--b2 c3--c2 |
// \ / |
// a1 |
// / \ |
// a3--a2 |
Function &D2F = D2.getFunction();
CallInst *C1Call = nullptr, *D1Call = nullptr;
for (User *U : D2F.users()) {
CallInst *CI = dyn_cast<CallInst>(U);
ASSERT_TRUE(CI) << "Expected a call: " << *U;
if (CI->getParent()->getParent() == &C1.getFunction()) {
ASSERT_EQ(nullptr, C1Call) << "Found too many C1 calls: " << *CI;
C1Call = CI;
} else if (CI->getParent()->getParent() == &D1.getFunction()) {
ASSERT_EQ(nullptr, D1Call) << "Found too many D1 calls: " << *CI;
D1Call = CI;
} else {
FAIL() << "Found an unexpected call instruction: " << *CI;
}
}
ASSERT_NE(C1Call, nullptr);
ASSERT_NE(D1Call, nullptr);
ASSERT_EQ(&D2F, C1Call->getCalledFunction());
ASSERT_EQ(&D2F, D1Call->getCalledFunction());
C1Call->setCalledFunction(&D3.getFunction());
D1Call->setCalledFunction(&D3.getFunction());
ASSERT_EQ(0u, D2F.getNumUses());
// Insert new edges first.
CRC.insertTrivialCallEdge(C1, D3);
DRC.insertTrivialCallEdge(D1, D3);
// Then remove the old ones.
LazyCallGraph::SCC &DC = *CG.lookupSCC(D2);
auto NewCs = DRC.switchInternalEdgeToRef(D1, D2);
EXPECT_EQ(&DC, CG.lookupSCC(D2));
EXPECT_EQ(NewCs.end(), std::next(NewCs.begin()));
LazyCallGraph::SCC &NewDC = *NewCs.begin();
EXPECT_EQ(&NewDC, CG.lookupSCC(D1));
EXPECT_EQ(&NewDC, CG.lookupSCC(D3));
[LCG] Switch one of the update methods for the LazyCallGraph to support limited batch updates. Specifically, allow removing multiple reference edges starting from a common source node. There are a few constraints that play into supporting this form of batching: 1) The way updates occur during the CGSCC walk, about the most we can functionally batch together are those with a common source node. This also makes the batching simpler to implement, so it seems a worthwhile restriction. 2) The far and away hottest function for large C++ files I measured (generated code for protocol buffers) showed a huge amount of time was spent removing ref edges specifically, so it seems worth focusing there. 3) The algorithm for removing ref edges is very amenable to this restricted batching. There are just both API and implementation special casing for the non-batch case that gets in the way. Once removed, supporting batches is nearly trivial. This does modify the API in an interesting way -- now, we only preserve the target RefSCC when the RefSCC structure is unchanged. In the face of any splits, we create brand new RefSCC objects. However, all of the users were OK with it that I could find. Only the unittest needed interesting updates here. How much does batching these updates help? I instrumented the compiler when run over a very large generated source file for a protocol buffer and found that the majority of updates are intrinsically updating one function at a time. However, nearly 40% of the total ref edges removed are removed as part of a batch of removals greater than one, so these are the cases batching can help with. When compiling the IR for this file with 'opt' and 'O3', this patch reduces the total time by 8-9%. Differential Revision: https://reviews.llvm.org/D36352 llvm-svn: 310450
2017-08-09 17:05:27 +08:00
auto NewRCs = DRC.removeInternalRefEdge(D1, {&D2});
ASSERT_EQ(2u, NewRCs.size());
LazyCallGraph::RefSCC &NewDRC = *NewRCs[0];
[LCG] Add the necessary functionality to the LazyCallGraph to support inlining. The basic inlining operation makes the following changes to the call graph: 1) Add edges that were previously transitive edges. This is always trivial and this patch gives the LCG helper methods to make this more convenient. 2) Remove the inlined edge. We had existing support for this, but it contained bugs that needed to be fixed. Testing in the same pattern as the inliner exposes these bugs very nicely. 3) Delete a function when it becomes dead because it is internal and all calls have been inlined. The LCG had no support at all for this operation, so this adds that support. Two unittests have been added that exercise this specific mutation pattern to the call graph. They were extremely effective in uncovering bugs. Sadly, a large fraction of the code here is just to implement those unit tests, but I think they're paying for themselves. =] This was split out of a patch that actually uses the routines to implement inlining in the new pass manager in order to isolate (with unit tests) the logic that was entirely within the LCG. Many thanks for the careful review from folks! There will be a few minor follow-up patches based on the comments in the review as well. Differential Revision: https://reviews.llvm.org/D24225 llvm-svn: 283982
2016-10-12 15:59:56 +08:00
EXPECT_EQ(&NewDRC, CG.lookupRefSCC(D1));
EXPECT_EQ(&NewDRC, CG.lookupRefSCC(D3));
[LCG] Switch one of the update methods for the LazyCallGraph to support limited batch updates. Specifically, allow removing multiple reference edges starting from a common source node. There are a few constraints that play into supporting this form of batching: 1) The way updates occur during the CGSCC walk, about the most we can functionally batch together are those with a common source node. This also makes the batching simpler to implement, so it seems a worthwhile restriction. 2) The far and away hottest function for large C++ files I measured (generated code for protocol buffers) showed a huge amount of time was spent removing ref edges specifically, so it seems worth focusing there. 3) The algorithm for removing ref edges is very amenable to this restricted batching. There are just both API and implementation special casing for the non-batch case that gets in the way. Once removed, supporting batches is nearly trivial. This does modify the API in an interesting way -- now, we only preserve the target RefSCC when the RefSCC structure is unchanged. In the face of any splits, we create brand new RefSCC objects. However, all of the users were OK with it that I could find. Only the unittest needed interesting updates here. How much does batching these updates help? I instrumented the compiler when run over a very large generated source file for a protocol buffer and found that the majority of updates are intrinsically updating one function at a time. However, nearly 40% of the total ref edges removed are removed as part of a batch of removals greater than one, so these are the cases batching can help with. When compiling the IR for this file with 'opt' and 'O3', this patch reduces the total time by 8-9%. Differential Revision: https://reviews.llvm.org/D36352 llvm-svn: 310450
2017-08-09 17:05:27 +08:00
LazyCallGraph::RefSCC &D2RC = *NewRCs[1];
EXPECT_EQ(&D2RC, CG.lookupRefSCC(D2));
EXPECT_FALSE(NewDRC.isParentOf(D2RC));
EXPECT_TRUE(CRC.isParentOf(D2RC));
[LCG] Add the necessary functionality to the LazyCallGraph to support inlining. The basic inlining operation makes the following changes to the call graph: 1) Add edges that were previously transitive edges. This is always trivial and this patch gives the LCG helper methods to make this more convenient. 2) Remove the inlined edge. We had existing support for this, but it contained bugs that needed to be fixed. Testing in the same pattern as the inliner exposes these bugs very nicely. 3) Delete a function when it becomes dead because it is internal and all calls have been inlined. The LCG had no support at all for this operation, so this adds that support. Two unittests have been added that exercise this specific mutation pattern to the call graph. They were extremely effective in uncovering bugs. Sadly, a large fraction of the code here is just to implement those unit tests, but I think they're paying for themselves. =] This was split out of a patch that actually uses the routines to implement inlining in the new pass manager in order to isolate (with unit tests) the logic that was entirely within the LCG. Many thanks for the careful review from folks! There will be a few minor follow-up patches based on the comments in the review as well. Differential Revision: https://reviews.llvm.org/D24225 llvm-svn: 283982
2016-10-12 15:59:56 +08:00
EXPECT_TRUE(CRC.isParentOf(NewDRC));
[LCG] Switch one of the update methods for the LazyCallGraph to support limited batch updates. Specifically, allow removing multiple reference edges starting from a common source node. There are a few constraints that play into supporting this form of batching: 1) The way updates occur during the CGSCC walk, about the most we can functionally batch together are those with a common source node. This also makes the batching simpler to implement, so it seems a worthwhile restriction. 2) The far and away hottest function for large C++ files I measured (generated code for protocol buffers) showed a huge amount of time was spent removing ref edges specifically, so it seems worth focusing there. 3) The algorithm for removing ref edges is very amenable to this restricted batching. There are just both API and implementation special casing for the non-batch case that gets in the way. Once removed, supporting batches is nearly trivial. This does modify the API in an interesting way -- now, we only preserve the target RefSCC when the RefSCC structure is unchanged. In the face of any splits, we create brand new RefSCC objects. However, all of the users were OK with it that I could find. Only the unittest needed interesting updates here. How much does batching these updates help? I instrumented the compiler when run over a very large generated source file for a protocol buffer and found that the majority of updates are intrinsically updating one function at a time. However, nearly 40% of the total ref edges removed are removed as part of a batch of removals greater than one, so these are the cases batching can help with. When compiling the IR for this file with 'opt' and 'O3', this patch reduces the total time by 8-9%. Differential Revision: https://reviews.llvm.org/D36352 llvm-svn: 310450
2017-08-09 17:05:27 +08:00
EXPECT_TRUE(D2RC.isParentOf(NewDRC));
[LCG] Add the necessary functionality to the LazyCallGraph to support inlining. The basic inlining operation makes the following changes to the call graph: 1) Add edges that were previously transitive edges. This is always trivial and this patch gives the LCG helper methods to make this more convenient. 2) Remove the inlined edge. We had existing support for this, but it contained bugs that needed to be fixed. Testing in the same pattern as the inliner exposes these bugs very nicely. 3) Delete a function when it becomes dead because it is internal and all calls have been inlined. The LCG had no support at all for this operation, so this adds that support. Two unittests have been added that exercise this specific mutation pattern to the call graph. They were extremely effective in uncovering bugs. Sadly, a large fraction of the code here is just to implement those unit tests, but I think they're paying for themselves. =] This was split out of a patch that actually uses the routines to implement inlining in the new pass manager in order to isolate (with unit tests) the logic that was entirely within the LCG. Many thanks for the careful review from folks! There will be a few minor follow-up patches based on the comments in the review as well. Differential Revision: https://reviews.llvm.org/D24225 llvm-svn: 283982
2016-10-12 15:59:56 +08:00
CRC.removeOutgoingEdge(C1, D2);
[LCG] Switch one of the update methods for the LazyCallGraph to support limited batch updates. Specifically, allow removing multiple reference edges starting from a common source node. There are a few constraints that play into supporting this form of batching: 1) The way updates occur during the CGSCC walk, about the most we can functionally batch together are those with a common source node. This also makes the batching simpler to implement, so it seems a worthwhile restriction. 2) The far and away hottest function for large C++ files I measured (generated code for protocol buffers) showed a huge amount of time was spent removing ref edges specifically, so it seems worth focusing there. 3) The algorithm for removing ref edges is very amenable to this restricted batching. There are just both API and implementation special casing for the non-batch case that gets in the way. Once removed, supporting batches is nearly trivial. This does modify the API in an interesting way -- now, we only preserve the target RefSCC when the RefSCC structure is unchanged. In the face of any splits, we create brand new RefSCC objects. However, all of the users were OK with it that I could find. Only the unittest needed interesting updates here. How much does batching these updates help? I instrumented the compiler when run over a very large generated source file for a protocol buffer and found that the majority of updates are intrinsically updating one function at a time. However, nearly 40% of the total ref edges removed are removed as part of a batch of removals greater than one, so these are the cases batching can help with. When compiling the IR for this file with 'opt' and 'O3', this patch reduces the total time by 8-9%. Differential Revision: https://reviews.llvm.org/D36352 llvm-svn: 310450
2017-08-09 17:05:27 +08:00
EXPECT_FALSE(CRC.isParentOf(D2RC));
[LCG] Add the necessary functionality to the LazyCallGraph to support inlining. The basic inlining operation makes the following changes to the call graph: 1) Add edges that were previously transitive edges. This is always trivial and this patch gives the LCG helper methods to make this more convenient. 2) Remove the inlined edge. We had existing support for this, but it contained bugs that needed to be fixed. Testing in the same pattern as the inliner exposes these bugs very nicely. 3) Delete a function when it becomes dead because it is internal and all calls have been inlined. The LCG had no support at all for this operation, so this adds that support. Two unittests have been added that exercise this specific mutation pattern to the call graph. They were extremely effective in uncovering bugs. Sadly, a large fraction of the code here is just to implement those unit tests, but I think they're paying for themselves. =] This was split out of a patch that actually uses the routines to implement inlining in the new pass manager in order to isolate (with unit tests) the logic that was entirely within the LCG. Many thanks for the careful review from folks! There will be a few minor follow-up patches based on the comments in the review as well. Differential Revision: https://reviews.llvm.org/D24225 llvm-svn: 283982
2016-10-12 15:59:56 +08:00
EXPECT_TRUE(CRC.isParentOf(NewDRC));
[LCG] Switch one of the update methods for the LazyCallGraph to support limited batch updates. Specifically, allow removing multiple reference edges starting from a common source node. There are a few constraints that play into supporting this form of batching: 1) The way updates occur during the CGSCC walk, about the most we can functionally batch together are those with a common source node. This also makes the batching simpler to implement, so it seems a worthwhile restriction. 2) The far and away hottest function for large C++ files I measured (generated code for protocol buffers) showed a huge amount of time was spent removing ref edges specifically, so it seems worth focusing there. 3) The algorithm for removing ref edges is very amenable to this restricted batching. There are just both API and implementation special casing for the non-batch case that gets in the way. Once removed, supporting batches is nearly trivial. This does modify the API in an interesting way -- now, we only preserve the target RefSCC when the RefSCC structure is unchanged. In the face of any splits, we create brand new RefSCC objects. However, all of the users were OK with it that I could find. Only the unittest needed interesting updates here. How much does batching these updates help? I instrumented the compiler when run over a very large generated source file for a protocol buffer and found that the majority of updates are intrinsically updating one function at a time. However, nearly 40% of the total ref edges removed are removed as part of a batch of removals greater than one, so these are the cases batching can help with. When compiling the IR for this file with 'opt' and 'O3', this patch reduces the total time by 8-9%. Differential Revision: https://reviews.llvm.org/D36352 llvm-svn: 310450
2017-08-09 17:05:27 +08:00
EXPECT_TRUE(D2RC.isParentOf(NewDRC));
[LCG] Add the necessary functionality to the LazyCallGraph to support inlining. The basic inlining operation makes the following changes to the call graph: 1) Add edges that were previously transitive edges. This is always trivial and this patch gives the LCG helper methods to make this more convenient. 2) Remove the inlined edge. We had existing support for this, but it contained bugs that needed to be fixed. Testing in the same pattern as the inliner exposes these bugs very nicely. 3) Delete a function when it becomes dead because it is internal and all calls have been inlined. The LCG had no support at all for this operation, so this adds that support. Two unittests have been added that exercise this specific mutation pattern to the call graph. They were extremely effective in uncovering bugs. Sadly, a large fraction of the code here is just to implement those unit tests, but I think they're paying for themselves. =] This was split out of a patch that actually uses the routines to implement inlining in the new pass manager in order to isolate (with unit tests) the logic that was entirely within the LCG. Many thanks for the careful review from folks! There will be a few minor follow-up patches based on the comments in the review as well. Differential Revision: https://reviews.llvm.org/D24225 llvm-svn: 283982
2016-10-12 15:59:56 +08:00
// Now that we've updated the call graph, D2 is dead, so remove it.
CG.removeDeadFunction(D2F);
// Check that the graph still looks the same.
EXPECT_EQ(&ARC, CG.lookupRefSCC(A1));
EXPECT_EQ(&ARC, CG.lookupRefSCC(A2));
EXPECT_EQ(&ARC, CG.lookupRefSCC(A3));
EXPECT_EQ(&BRC, CG.lookupRefSCC(B1));
EXPECT_EQ(&BRC, CG.lookupRefSCC(B2));
EXPECT_EQ(&BRC, CG.lookupRefSCC(B3));
EXPECT_EQ(&CRC, CG.lookupRefSCC(C1));
EXPECT_EQ(&CRC, CG.lookupRefSCC(C2));
EXPECT_EQ(&CRC, CG.lookupRefSCC(C3));
EXPECT_EQ(&NewDRC, CG.lookupRefSCC(D1));
EXPECT_EQ(&NewDRC, CG.lookupRefSCC(D3));
EXPECT_TRUE(CRC.isParentOf(NewDRC));
// Verify the post-order walk hasn't changed.
auto I = CG.postorder_ref_scc_begin(), E = CG.postorder_ref_scc_end();
ASSERT_NE(I, E);
EXPECT_EQ(&NewDRC, &*I) << "Actual RefSCC: " << *I;
ASSERT_NE(++I, E);
EXPECT_EQ(&CRC, &*I) << "Actual RefSCC: " << *I;
ASSERT_NE(++I, E);
EXPECT_EQ(&BRC, &*I) << "Actual RefSCC: " << *I;
ASSERT_NE(++I, E);
EXPECT_EQ(&ARC, &*I) << "Actual RefSCC: " << *I;
EXPECT_EQ(++I, E);
}
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
TEST(LazyCallGraphTest, InternalEdgeMutation) {
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
LLVMContext Context;
std::unique_ptr<Module> M = parseAssembly(Context, "define void @a() {\n"
"entry:\n"
" call void @b()\n"
" ret void\n"
"}\n"
"define void @b() {\n"
"entry:\n"
" call void @c()\n"
" ret void\n"
"}\n"
"define void @c() {\n"
"entry:\n"
" call void @a()\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Add the first round of mutation support to the lazy call graph. This implements the core functionality necessary to remove an edge from the call graph and correctly update both the basic graph and the SCC structure. As part of that it has to run a tiny (in number of nodes) Tarjan-style DFS walk of an SCC being mutated to compute newly formed SCCs, etc. This is *very rough* and a WIP. I have a bunch of FIXMEs for code cleanup that will reduce the boilerplate in this change substantially. I also have a bunch of simplifications to various parts of both algorithms that I want to make, but first I'd like to have a more holistic picture. Ideally, I'd also like more testing. I'll probably add quite a few more unit tests as I go here to cover the various different aspects and corner cases of removing edges from the graph. Still, this is, so far, successfully updating the SCC graph in-place without disrupting the identity established for the existing SCCs even when we do challenging things like delete the critical edge that made an SCC cycle at all and have to reform things as a tree of smaller SCCs. Getting this to work is really critical for the new pass manager as it is going to associate significant state with the SCC instance and needs it to be stable. That is also the motivation behind the return of the newly formed SCCs. Eventually, I'll wire this all the way up to the public API so that the pass manager can use it to correctly re-enqueue newly formed SCCs into a fresh postorder traversal. llvm-svn: 206968
2014-04-23 19:03:03 +08:00
// Force the graph to be fully expanded.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
auto I = CG.postorder_ref_scc_begin();
LazyCallGraph::RefSCC &RC = *I++;
EXPECT_EQ(CG.postorder_ref_scc_end(), I);
[LCG] Add the first round of mutation support to the lazy call graph. This implements the core functionality necessary to remove an edge from the call graph and correctly update both the basic graph and the SCC structure. As part of that it has to run a tiny (in number of nodes) Tarjan-style DFS walk of an SCC being mutated to compute newly formed SCCs, etc. This is *very rough* and a WIP. I have a bunch of FIXMEs for code cleanup that will reduce the boilerplate in this change substantially. I also have a bunch of simplifications to various parts of both algorithms that I want to make, but first I'd like to have a more holistic picture. Ideally, I'd also like more testing. I'll probably add quite a few more unit tests as I go here to cover the various different aspects and corner cases of removing edges from the graph. Still, this is, so far, successfully updating the SCC graph in-place without disrupting the identity established for the existing SCCs even when we do challenging things like delete the critical edge that made an SCC cycle at all and have to reform things as a tree of smaller SCCs. Getting this to work is really critical for the new pass manager as it is going to associate significant state with the SCC instance and needs it to be stable. That is also the motivation behind the return of the newly formed SCCs. Eventually, I'll wire this all the way up to the public API so that the pass manager can use it to correctly re-enqueue newly formed SCCs into a fresh postorder traversal. llvm-svn: 206968
2014-04-23 19:03:03 +08:00
[LCG] Switch the SCC lookup to be in terms of call graph nodes rather than functions. So far, this access pattern is *much* more common. It seems likely that any user of this interface is going to have nodes at the point that they are querying the SCCs. No functionality changed. llvm-svn: 207045
2014-04-24 07:12:06 +08:00
LazyCallGraph::Node &A = *CG.lookup(lookupFunction(*M, "a"));
LazyCallGraph::Node &B = *CG.lookup(lookupFunction(*M, "b"));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
LazyCallGraph::Node &C = *CG.lookup(lookupFunction(*M, "c"));
EXPECT_EQ(&RC, CG.lookupRefSCC(A));
EXPECT_EQ(&RC, CG.lookupRefSCC(B));
EXPECT_EQ(&RC, CG.lookupRefSCC(C));
EXPECT_EQ(1, RC.size());
EXPECT_EQ(&*RC.begin(), CG.lookupSCC(A));
EXPECT_EQ(&*RC.begin(), CG.lookupSCC(B));
EXPECT_EQ(&*RC.begin(), CG.lookupSCC(C));
// Insert an edge from 'a' to 'c'. Nothing changes about the graph.
RC.insertInternalRefEdge(A, C);
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
EXPECT_EQ(2, std::distance(A->begin(), A->end()));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(&RC, CG.lookupRefSCC(A));
EXPECT_EQ(&RC, CG.lookupRefSCC(B));
EXPECT_EQ(&RC, CG.lookupRefSCC(C));
EXPECT_EQ(1, RC.size());
EXPECT_EQ(&*RC.begin(), CG.lookupSCC(A));
EXPECT_EQ(&*RC.begin(), CG.lookupSCC(B));
EXPECT_EQ(&*RC.begin(), CG.lookupSCC(C));
// Switch the call edge from 'b' to 'c' to a ref edge. This will break the
// call cycle and cause us to form more SCCs. The RefSCC will remain the same
// though.
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
auto NewCs = RC.switchInternalEdgeToRef(B, C);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(&RC, CG.lookupRefSCC(A));
EXPECT_EQ(&RC, CG.lookupRefSCC(B));
EXPECT_EQ(&RC, CG.lookupRefSCC(C));
auto J = RC.begin();
// The SCCs must be in *post-order* which means successors before
// predecessors. At this point we have call edges from C to A and from A to
// B. The only valid postorder is B, A, C.
EXPECT_EQ(&*J++, CG.lookupSCC(B));
EXPECT_EQ(&*J++, CG.lookupSCC(A));
EXPECT_EQ(&*J++, CG.lookupSCC(C));
EXPECT_EQ(RC.end(), J);
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
// And the returned range must be the slice of this sequence containing new
// SCCs.
EXPECT_EQ(RC.begin(), NewCs.begin());
EXPECT_EQ(std::prev(RC.end()), NewCs.end());
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Test turning the ref edge from A to C into a call edge. This will form an
// SCC out of A and C. Since we previously had a call edge from C to A, the
// C SCC should be preserved and have A merged into it while the A SCC should
// be invalidated.
[LCG] Switch the SCC lookup to be in terms of call graph nodes rather than functions. So far, this access pattern is *much* more common. It seems likely that any user of this interface is going to have nodes at the point that they are querying the SCCs. No functionality changed. llvm-svn: 207045
2014-04-24 07:12:06 +08:00
LazyCallGraph::SCC &AC = *CG.lookupSCC(A);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
LazyCallGraph::SCC &CC = *CG.lookupSCC(C);
[PM] Fix a nasty bug in the new PM where we failed to properly invalidation of analyses when merging SCCs. While I've added a bunch of testing of this, it takes something much more like the inliner to really trigger this as you need to have partially-analyzed SCCs with updates at just the right time. So I've added a direct test for this using the inliner and verifying the domtree. Without the changes here, this test ends up finding a stale dominator tree. However, to handle this properly, we need to invalidate analyses *before* merging the SCCs. After talking to Philip and Sanjoy about this they convinced me this was the right approach. To do this, we need a callback mechanism when merging SCCs so we can observe the cycle that will be merged before the merge happens. This API update ended up being surprisingly easy. With this commit, the new PM passes the test-suite again. It hadn't since MemorySSA was enabled for EarlyCSE as that also will find this bug very quickly. llvm-svn: 307498
2017-07-09 21:45:11 +08:00
EXPECT_TRUE(RC.switchInternalEdgeToCall(A, C, [&](ArrayRef<LazyCallGraph::SCC *> MergedCs) {
ASSERT_EQ(1u, MergedCs.size());
EXPECT_EQ(&AC, MergedCs[0]);
}));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(2, CC.size());
EXPECT_EQ(&CC, CG.lookupSCC(A));
EXPECT_EQ(&CC, CG.lookupSCC(C));
J = RC.begin();
EXPECT_EQ(&*J++, CG.lookupSCC(B));
EXPECT_EQ(&*J++, CG.lookupSCC(C));
EXPECT_EQ(RC.end(), J);
[LCG] Add the first round of mutation support to the lazy call graph. This implements the core functionality necessary to remove an edge from the call graph and correctly update both the basic graph and the SCC structure. As part of that it has to run a tiny (in number of nodes) Tarjan-style DFS walk of an SCC being mutated to compute newly formed SCCs, etc. This is *very rough* and a WIP. I have a bunch of FIXMEs for code cleanup that will reduce the boilerplate in this change substantially. I also have a bunch of simplifications to various parts of both algorithms that I want to make, but first I'd like to have a more holistic picture. Ideally, I'd also like more testing. I'll probably add quite a few more unit tests as I go here to cover the various different aspects and corner cases of removing edges from the graph. Still, this is, so far, successfully updating the SCC graph in-place without disrupting the identity established for the existing SCCs even when we do challenging things like delete the critical edge that made an SCC cycle at all and have to reform things as a tree of smaller SCCs. Getting this to work is really critical for the new pass manager as it is going to associate significant state with the SCC instance and needs it to be stable. That is also the motivation behind the return of the newly formed SCCs. Eventually, I'll wire this all the way up to the public API so that the pass manager can use it to correctly re-enqueue newly formed SCCs into a fresh postorder traversal. llvm-svn: 206968
2014-04-23 19:03:03 +08:00
}
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
TEST(LazyCallGraphTest, InternalEdgeRemoval) {
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
LLVMContext Context;
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// A nice fully connected (including self-edges) RefSCC.
std::unique_ptr<Module> M = parseAssembly(
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
Context, "define void @a(i8** %ptr) {\n"
"entry:\n"
" store i8* bitcast (void(i8**)* @a to i8*), i8** %ptr\n"
" store i8* bitcast (void(i8**)* @b to i8*), i8** %ptr\n"
" store i8* bitcast (void(i8**)* @c to i8*), i8** %ptr\n"
" ret void\n"
"}\n"
"define void @b(i8** %ptr) {\n"
"entry:\n"
" store i8* bitcast (void(i8**)* @a to i8*), i8** %ptr\n"
" store i8* bitcast (void(i8**)* @b to i8*), i8** %ptr\n"
" store i8* bitcast (void(i8**)* @c to i8*), i8** %ptr\n"
" ret void\n"
"}\n"
"define void @c(i8** %ptr) {\n"
"entry:\n"
" store i8* bitcast (void(i8**)* @a to i8*), i8** %ptr\n"
" store i8* bitcast (void(i8**)* @b to i8*), i8** %ptr\n"
" store i8* bitcast (void(i8**)* @c to i8*), i8** %ptr\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Add the really, *really* boring edge insertion case: adding an edge entirely within an existing SCC. Shockingly, making the connected component more connected is ... a total snooze fest. =] Anyways, its wired up, and I even added a test case to make sure it pretty much sorta works. =D llvm-svn: 207631
2014-04-30 18:48:36 +08:00
// Force the graph to be fully expanded.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
auto I = CG.postorder_ref_scc_begin(), E = CG.postorder_ref_scc_end();
LazyCallGraph::RefSCC &RC = *I;
EXPECT_EQ(E, std::next(I));
[LCG] Add the really, *really* boring edge insertion case: adding an edge entirely within an existing SCC. Shockingly, making the connected component more connected is ... a total snooze fest. =] Anyways, its wired up, and I even added a test case to make sure it pretty much sorta works. =D llvm-svn: 207631
2014-04-30 18:48:36 +08:00
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
LazyCallGraph::Node &A = *CG.lookup(lookupFunction(*M, "a"));
LazyCallGraph::Node &B = *CG.lookup(lookupFunction(*M, "b"));
LazyCallGraph::Node &C = *CG.lookup(lookupFunction(*M, "c"));
EXPECT_EQ(&RC, CG.lookupRefSCC(A));
EXPECT_EQ(&RC, CG.lookupRefSCC(B));
EXPECT_EQ(&RC, CG.lookupRefSCC(C));
// Remove the edge from b -> a, which should leave the 3 functions still in
// a single connected component because of a -> b -> c -> a.
SmallVector<LazyCallGraph::RefSCC *, 1> NewRCs =
[LCG] Switch one of the update methods for the LazyCallGraph to support limited batch updates. Specifically, allow removing multiple reference edges starting from a common source node. There are a few constraints that play into supporting this form of batching: 1) The way updates occur during the CGSCC walk, about the most we can functionally batch together are those with a common source node. This also makes the batching simpler to implement, so it seems a worthwhile restriction. 2) The far and away hottest function for large C++ files I measured (generated code for protocol buffers) showed a huge amount of time was spent removing ref edges specifically, so it seems worth focusing there. 3) The algorithm for removing ref edges is very amenable to this restricted batching. There are just both API and implementation special casing for the non-batch case that gets in the way. Once removed, supporting batches is nearly trivial. This does modify the API in an interesting way -- now, we only preserve the target RefSCC when the RefSCC structure is unchanged. In the face of any splits, we create brand new RefSCC objects. However, all of the users were OK with it that I could find. Only the unittest needed interesting updates here. How much does batching these updates help? I instrumented the compiler when run over a very large generated source file for a protocol buffer and found that the majority of updates are intrinsically updating one function at a time. However, nearly 40% of the total ref edges removed are removed as part of a batch of removals greater than one, so these are the cases batching can help with. When compiling the IR for this file with 'opt' and 'O3', this patch reduces the total time by 8-9%. Differential Revision: https://reviews.llvm.org/D36352 llvm-svn: 310450
2017-08-09 17:05:27 +08:00
RC.removeInternalRefEdge(B, {&A});
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(0u, NewRCs.size());
EXPECT_EQ(&RC, CG.lookupRefSCC(A));
EXPECT_EQ(&RC, CG.lookupRefSCC(B));
EXPECT_EQ(&RC, CG.lookupRefSCC(C));
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
auto J = CG.postorder_ref_scc_begin();
EXPECT_EQ(I, J);
EXPECT_EQ(&RC, &*J);
EXPECT_EQ(E, std::next(J));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
[LCG] Switch one of the update methods for the LazyCallGraph to support limited batch updates. Specifically, allow removing multiple reference edges starting from a common source node. There are a few constraints that play into supporting this form of batching: 1) The way updates occur during the CGSCC walk, about the most we can functionally batch together are those with a common source node. This also makes the batching simpler to implement, so it seems a worthwhile restriction. 2) The far and away hottest function for large C++ files I measured (generated code for protocol buffers) showed a huge amount of time was spent removing ref edges specifically, so it seems worth focusing there. 3) The algorithm for removing ref edges is very amenable to this restricted batching. There are just both API and implementation special casing for the non-batch case that gets in the way. Once removed, supporting batches is nearly trivial. This does modify the API in an interesting way -- now, we only preserve the target RefSCC when the RefSCC structure is unchanged. In the face of any splits, we create brand new RefSCC objects. However, all of the users were OK with it that I could find. Only the unittest needed interesting updates here. How much does batching these updates help? I instrumented the compiler when run over a very large generated source file for a protocol buffer and found that the majority of updates are intrinsically updating one function at a time. However, nearly 40% of the total ref edges removed are removed as part of a batch of removals greater than one, so these are the cases batching can help with. When compiling the IR for this file with 'opt' and 'O3', this patch reduces the total time by 8-9%. Differential Revision: https://reviews.llvm.org/D36352 llvm-svn: 310450
2017-08-09 17:05:27 +08:00
// Increment I before we actually mutate the structure so that it remains
// a valid iterator.
++I;
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Remove the edge from c -> a, which should leave 'a' in the original RefSCC
// and form a new RefSCC for 'b' and 'c'.
[LCG] Switch one of the update methods for the LazyCallGraph to support limited batch updates. Specifically, allow removing multiple reference edges starting from a common source node. There are a few constraints that play into supporting this form of batching: 1) The way updates occur during the CGSCC walk, about the most we can functionally batch together are those with a common source node. This also makes the batching simpler to implement, so it seems a worthwhile restriction. 2) The far and away hottest function for large C++ files I measured (generated code for protocol buffers) showed a huge amount of time was spent removing ref edges specifically, so it seems worth focusing there. 3) The algorithm for removing ref edges is very amenable to this restricted batching. There are just both API and implementation special casing for the non-batch case that gets in the way. Once removed, supporting batches is nearly trivial. This does modify the API in an interesting way -- now, we only preserve the target RefSCC when the RefSCC structure is unchanged. In the face of any splits, we create brand new RefSCC objects. However, all of the users were OK with it that I could find. Only the unittest needed interesting updates here. How much does batching these updates help? I instrumented the compiler when run over a very large generated source file for a protocol buffer and found that the majority of updates are intrinsically updating one function at a time. However, nearly 40% of the total ref edges removed are removed as part of a batch of removals greater than one, so these are the cases batching can help with. When compiling the IR for this file with 'opt' and 'O3', this patch reduces the total time by 8-9%. Differential Revision: https://reviews.llvm.org/D36352 llvm-svn: 310450
2017-08-09 17:05:27 +08:00
NewRCs = RC.removeInternalRefEdge(C, {&A});
ASSERT_EQ(2u, NewRCs.size());
LazyCallGraph::RefSCC &BCRC = *NewRCs[0];
LazyCallGraph::RefSCC &ARC = *NewRCs[1];
EXPECT_EQ(&ARC, CG.lookupRefSCC(A));
EXPECT_EQ(1, std::distance(ARC.begin(), ARC.end()));
EXPECT_EQ(&BCRC, CG.lookupRefSCC(B));
EXPECT_EQ(&BCRC, CG.lookupRefSCC(C));
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
J = CG.postorder_ref_scc_begin();
EXPECT_NE(I, J);
[LCG] Switch one of the update methods for the LazyCallGraph to support limited batch updates. Specifically, allow removing multiple reference edges starting from a common source node. There are a few constraints that play into supporting this form of batching: 1) The way updates occur during the CGSCC walk, about the most we can functionally batch together are those with a common source node. This also makes the batching simpler to implement, so it seems a worthwhile restriction. 2) The far and away hottest function for large C++ files I measured (generated code for protocol buffers) showed a huge amount of time was spent removing ref edges specifically, so it seems worth focusing there. 3) The algorithm for removing ref edges is very amenable to this restricted batching. There are just both API and implementation special casing for the non-batch case that gets in the way. Once removed, supporting batches is nearly trivial. This does modify the API in an interesting way -- now, we only preserve the target RefSCC when the RefSCC structure is unchanged. In the face of any splits, we create brand new RefSCC objects. However, all of the users were OK with it that I could find. Only the unittest needed interesting updates here. How much does batching these updates help? I instrumented the compiler when run over a very large generated source file for a protocol buffer and found that the majority of updates are intrinsically updating one function at a time. However, nearly 40% of the total ref edges removed are removed as part of a batch of removals greater than one, so these are the cases batching can help with. When compiling the IR for this file with 'opt' and 'O3', this patch reduces the total time by 8-9%. Differential Revision: https://reviews.llvm.org/D36352 llvm-svn: 310450
2017-08-09 17:05:27 +08:00
EXPECT_EQ(&BCRC, &*J);
++J;
EXPECT_NE(I, J);
EXPECT_EQ(&ARC, &*J);
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
++J;
EXPECT_EQ(I, J);
[LCG] Switch one of the update methods for the LazyCallGraph to support limited batch updates. Specifically, allow removing multiple reference edges starting from a common source node. There are a few constraints that play into supporting this form of batching: 1) The way updates occur during the CGSCC walk, about the most we can functionally batch together are those with a common source node. This also makes the batching simpler to implement, so it seems a worthwhile restriction. 2) The far and away hottest function for large C++ files I measured (generated code for protocol buffers) showed a huge amount of time was spent removing ref edges specifically, so it seems worth focusing there. 3) The algorithm for removing ref edges is very amenable to this restricted batching. There are just both API and implementation special casing for the non-batch case that gets in the way. Once removed, supporting batches is nearly trivial. This does modify the API in an interesting way -- now, we only preserve the target RefSCC when the RefSCC structure is unchanged. In the face of any splits, we create brand new RefSCC objects. However, all of the users were OK with it that I could find. Only the unittest needed interesting updates here. How much does batching these updates help? I instrumented the compiler when run over a very large generated source file for a protocol buffer and found that the majority of updates are intrinsically updating one function at a time. However, nearly 40% of the total ref edges removed are removed as part of a batch of removals greater than one, so these are the cases batching can help with. When compiling the IR for this file with 'opt' and 'O3', this patch reduces the total time by 8-9%. Differential Revision: https://reviews.llvm.org/D36352 llvm-svn: 310450
2017-08-09 17:05:27 +08:00
EXPECT_EQ(E, J);
}
TEST(LazyCallGraphTest, InternalMultiEdgeRemoval) {
LLVMContext Context;
// A nice fully connected (including self-edges) RefSCC.
std::unique_ptr<Module> M = parseAssembly(
Context, "define void @a(i8** %ptr) {\n"
"entry:\n"
" store i8* bitcast (void(i8**)* @a to i8*), i8** %ptr\n"
" store i8* bitcast (void(i8**)* @b to i8*), i8** %ptr\n"
" store i8* bitcast (void(i8**)* @c to i8*), i8** %ptr\n"
" ret void\n"
"}\n"
"define void @b(i8** %ptr) {\n"
"entry:\n"
" store i8* bitcast (void(i8**)* @a to i8*), i8** %ptr\n"
" store i8* bitcast (void(i8**)* @b to i8*), i8** %ptr\n"
" store i8* bitcast (void(i8**)* @c to i8*), i8** %ptr\n"
" ret void\n"
"}\n"
"define void @c(i8** %ptr) {\n"
"entry:\n"
" store i8* bitcast (void(i8**)* @a to i8*), i8** %ptr\n"
" store i8* bitcast (void(i8**)* @b to i8*), i8** %ptr\n"
" store i8* bitcast (void(i8**)* @c to i8*), i8** %ptr\n"
" ret void\n"
"}\n");
LazyCallGraph CG = buildCG(*M);
// Force the graph to be fully expanded.
CG.buildRefSCCs();
auto I = CG.postorder_ref_scc_begin(), E = CG.postorder_ref_scc_end();
LazyCallGraph::RefSCC &RC = *I;
EXPECT_EQ(E, std::next(I));
LazyCallGraph::Node &A = *CG.lookup(lookupFunction(*M, "a"));
LazyCallGraph::Node &B = *CG.lookup(lookupFunction(*M, "b"));
LazyCallGraph::Node &C = *CG.lookup(lookupFunction(*M, "c"));
EXPECT_EQ(&RC, CG.lookupRefSCC(A));
EXPECT_EQ(&RC, CG.lookupRefSCC(B));
EXPECT_EQ(&RC, CG.lookupRefSCC(C));
// Increment I before we actually mutate the structure so that it remains
// a valid iterator.
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
++I;
[LCG] Switch one of the update methods for the LazyCallGraph to support limited batch updates. Specifically, allow removing multiple reference edges starting from a common source node. There are a few constraints that play into supporting this form of batching: 1) The way updates occur during the CGSCC walk, about the most we can functionally batch together are those with a common source node. This also makes the batching simpler to implement, so it seems a worthwhile restriction. 2) The far and away hottest function for large C++ files I measured (generated code for protocol buffers) showed a huge amount of time was spent removing ref edges specifically, so it seems worth focusing there. 3) The algorithm for removing ref edges is very amenable to this restricted batching. There are just both API and implementation special casing for the non-batch case that gets in the way. Once removed, supporting batches is nearly trivial. This does modify the API in an interesting way -- now, we only preserve the target RefSCC when the RefSCC structure is unchanged. In the face of any splits, we create brand new RefSCC objects. However, all of the users were OK with it that I could find. Only the unittest needed interesting updates here. How much does batching these updates help? I instrumented the compiler when run over a very large generated source file for a protocol buffer and found that the majority of updates are intrinsically updating one function at a time. However, nearly 40% of the total ref edges removed are removed as part of a batch of removals greater than one, so these are the cases batching can help with. When compiling the IR for this file with 'opt' and 'O3', this patch reduces the total time by 8-9%. Differential Revision: https://reviews.llvm.org/D36352 llvm-svn: 310450
2017-08-09 17:05:27 +08:00
// Remove the edges from b -> a and b -> c, leaving b in its own RefSCC.
SmallVector<LazyCallGraph::RefSCC *, 1> NewRCs =
RC.removeInternalRefEdge(B, {&A, &C});
ASSERT_EQ(2u, NewRCs.size());
LazyCallGraph::RefSCC &BRC = *NewRCs[0];
LazyCallGraph::RefSCC &ACRC = *NewRCs[1];
EXPECT_EQ(&BRC, CG.lookupRefSCC(B));
EXPECT_EQ(1, std::distance(BRC.begin(), BRC.end()));
EXPECT_EQ(&ACRC, CG.lookupRefSCC(A));
EXPECT_EQ(&ACRC, CG.lookupRefSCC(C));
auto J = CG.postorder_ref_scc_begin();
EXPECT_NE(I, J);
EXPECT_EQ(&BRC, &*J);
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
++J;
[LCG] Switch one of the update methods for the LazyCallGraph to support limited batch updates. Specifically, allow removing multiple reference edges starting from a common source node. There are a few constraints that play into supporting this form of batching: 1) The way updates occur during the CGSCC walk, about the most we can functionally batch together are those with a common source node. This also makes the batching simpler to implement, so it seems a worthwhile restriction. 2) The far and away hottest function for large C++ files I measured (generated code for protocol buffers) showed a huge amount of time was spent removing ref edges specifically, so it seems worth focusing there. 3) The algorithm for removing ref edges is very amenable to this restricted batching. There are just both API and implementation special casing for the non-batch case that gets in the way. Once removed, supporting batches is nearly trivial. This does modify the API in an interesting way -- now, we only preserve the target RefSCC when the RefSCC structure is unchanged. In the face of any splits, we create brand new RefSCC objects. However, all of the users were OK with it that I could find. Only the unittest needed interesting updates here. How much does batching these updates help? I instrumented the compiler when run over a very large generated source file for a protocol buffer and found that the majority of updates are intrinsically updating one function at a time. However, nearly 40% of the total ref edges removed are removed as part of a batch of removals greater than one, so these are the cases batching can help with. When compiling the IR for this file with 'opt' and 'O3', this patch reduces the total time by 8-9%. Differential Revision: https://reviews.llvm.org/D36352 llvm-svn: 310450
2017-08-09 17:05:27 +08:00
EXPECT_NE(I, J);
EXPECT_EQ(&ACRC, &*J);
++J;
EXPECT_EQ(I, J);
[LCG] Redesign the lazy post-order iteration mechanism for the LazyCallGraph to support repeated, stable iterations, even in the face of graph updates. This is particularly important to allow the CGSCC pass manager to walk the RefSCCs (and thus everything else) in a module more than once. Lots of unittests and other tests were hard or impossible to write because repeated CGSCC pass managers which didn't invalidate the LazyCallGraph would conclude the module was empty after the first one. =[ Really, really bad. The interesting thing is that in many ways this simplifies the code. We can now re-use the same code for handling reference edge insertion updates of the RefSCC graph as we use for handling call edge insertion updates of the SCC graph. Outside of adapting to the shared logic for this (which isn't trivial, but is *much* simpler than the DFS it replaces!), the new code involves putting newly created RefSCCs when deleting a reference edge into the cached list in the correct way, and to re-formulate the iterator to be stable and effective even in the face of these kinds of updates. I've updated the unittests for the LazyCallGraph to re-iterate the postorder sequence and verify that this all works. We even check for using alternating iterators to trigger the lazy formation of RefSCCs after mutation has occured. It's worth noting that there are a reasonable number of likely simplifications we can make past this. It isn't clear that we need to keep the "LeafRefSCCs" around any more. But I've not removed that mostly because I want this to be a more isolated change. Differential Revision: https://reviews.llvm.org/D24219 llvm-svn: 281716
2016-09-16 18:20:17 +08:00
EXPECT_EQ(E, J);
[LCG] Add the really, *really* boring edge insertion case: adding an edge entirely within an existing SCC. Shockingly, making the connected component more connected is ... a total snooze fest. =] Anyways, its wired up, and I even added a test case to make sure it pretty much sorta works. =D llvm-svn: 207631
2014-04-30 18:48:36 +08:00
}
[LCG] Teach the ref edge removal to handle a ref edge that is trivial due to a call cycle. This actually crashed the ref removal before. I've added a unittest that covers this kind of interesting graph structure and mutation. llvm-svn: 290645
2016-12-28 10:24:58 +08:00
TEST(LazyCallGraphTest, InternalNoOpEdgeRemoval) {
LLVMContext Context;
// A graph with a single cycle formed both from call and reference edges
// which makes the reference edges trivial to delete. The graph looks like:
//
// Reference edges: a -> b -> c -> a
// Call edges: a -> c -> b -> a
std::unique_ptr<Module> M = parseAssembly(
Context, "define void @a(i8** %ptr) {\n"
"entry:\n"
" call void @b(i8** %ptr)\n"
" store i8* bitcast (void(i8**)* @c to i8*), i8** %ptr\n"
" ret void\n"
"}\n"
"define void @b(i8** %ptr) {\n"
"entry:\n"
" store i8* bitcast (void(i8**)* @a to i8*), i8** %ptr\n"
" call void @c(i8** %ptr)\n"
" ret void\n"
"}\n"
"define void @c(i8** %ptr) {\n"
"entry:\n"
" call void @a(i8** %ptr)\n"
" store i8* bitcast (void(i8**)* @b to i8*), i8** %ptr\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Teach the ref edge removal to handle a ref edge that is trivial due to a call cycle. This actually crashed the ref removal before. I've added a unittest that covers this kind of interesting graph structure and mutation. llvm-svn: 290645
2016-12-28 10:24:58 +08:00
// Force the graph to be fully expanded.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Teach the ref edge removal to handle a ref edge that is trivial due to a call cycle. This actually crashed the ref removal before. I've added a unittest that covers this kind of interesting graph structure and mutation. llvm-svn: 290645
2016-12-28 10:24:58 +08:00
auto I = CG.postorder_ref_scc_begin(), E = CG.postorder_ref_scc_end();
LazyCallGraph::RefSCC &RC = *I;
EXPECT_EQ(E, std::next(I));
LazyCallGraph::SCC &C = *RC.begin();
EXPECT_EQ(RC.end(), std::next(RC.begin()));
LazyCallGraph::Node &AN = *CG.lookup(lookupFunction(*M, "a"));
LazyCallGraph::Node &BN = *CG.lookup(lookupFunction(*M, "b"));
LazyCallGraph::Node &CN = *CG.lookup(lookupFunction(*M, "c"));
EXPECT_EQ(&RC, CG.lookupRefSCC(AN));
EXPECT_EQ(&RC, CG.lookupRefSCC(BN));
EXPECT_EQ(&RC, CG.lookupRefSCC(CN));
EXPECT_EQ(&C, CG.lookupSCC(AN));
EXPECT_EQ(&C, CG.lookupSCC(BN));
EXPECT_EQ(&C, CG.lookupSCC(CN));
// Remove the edge from a -> c which doesn't change anything.
SmallVector<LazyCallGraph::RefSCC *, 1> NewRCs =
[LCG] Switch one of the update methods for the LazyCallGraph to support limited batch updates. Specifically, allow removing multiple reference edges starting from a common source node. There are a few constraints that play into supporting this form of batching: 1) The way updates occur during the CGSCC walk, about the most we can functionally batch together are those with a common source node. This also makes the batching simpler to implement, so it seems a worthwhile restriction. 2) The far and away hottest function for large C++ files I measured (generated code for protocol buffers) showed a huge amount of time was spent removing ref edges specifically, so it seems worth focusing there. 3) The algorithm for removing ref edges is very amenable to this restricted batching. There are just both API and implementation special casing for the non-batch case that gets in the way. Once removed, supporting batches is nearly trivial. This does modify the API in an interesting way -- now, we only preserve the target RefSCC when the RefSCC structure is unchanged. In the face of any splits, we create brand new RefSCC objects. However, all of the users were OK with it that I could find. Only the unittest needed interesting updates here. How much does batching these updates help? I instrumented the compiler when run over a very large generated source file for a protocol buffer and found that the majority of updates are intrinsically updating one function at a time. However, nearly 40% of the total ref edges removed are removed as part of a batch of removals greater than one, so these are the cases batching can help with. When compiling the IR for this file with 'opt' and 'O3', this patch reduces the total time by 8-9%. Differential Revision: https://reviews.llvm.org/D36352 llvm-svn: 310450
2017-08-09 17:05:27 +08:00
RC.removeInternalRefEdge(AN, {&CN});
[LCG] Teach the ref edge removal to handle a ref edge that is trivial due to a call cycle. This actually crashed the ref removal before. I've added a unittest that covers this kind of interesting graph structure and mutation. llvm-svn: 290645
2016-12-28 10:24:58 +08:00
EXPECT_EQ(0u, NewRCs.size());
EXPECT_EQ(&RC, CG.lookupRefSCC(AN));
EXPECT_EQ(&RC, CG.lookupRefSCC(BN));
EXPECT_EQ(&RC, CG.lookupRefSCC(CN));
EXPECT_EQ(&C, CG.lookupSCC(AN));
EXPECT_EQ(&C, CG.lookupSCC(BN));
EXPECT_EQ(&C, CG.lookupSCC(CN));
auto J = CG.postorder_ref_scc_begin();
EXPECT_EQ(I, J);
EXPECT_EQ(&RC, &*J);
EXPECT_EQ(E, std::next(J));
// Remove the edge from b -> a and c -> b; again this doesn't change
// anything.
[LCG] Switch one of the update methods for the LazyCallGraph to support limited batch updates. Specifically, allow removing multiple reference edges starting from a common source node. There are a few constraints that play into supporting this form of batching: 1) The way updates occur during the CGSCC walk, about the most we can functionally batch together are those with a common source node. This also makes the batching simpler to implement, so it seems a worthwhile restriction. 2) The far and away hottest function for large C++ files I measured (generated code for protocol buffers) showed a huge amount of time was spent removing ref edges specifically, so it seems worth focusing there. 3) The algorithm for removing ref edges is very amenable to this restricted batching. There are just both API and implementation special casing for the non-batch case that gets in the way. Once removed, supporting batches is nearly trivial. This does modify the API in an interesting way -- now, we only preserve the target RefSCC when the RefSCC structure is unchanged. In the face of any splits, we create brand new RefSCC objects. However, all of the users were OK with it that I could find. Only the unittest needed interesting updates here. How much does batching these updates help? I instrumented the compiler when run over a very large generated source file for a protocol buffer and found that the majority of updates are intrinsically updating one function at a time. However, nearly 40% of the total ref edges removed are removed as part of a batch of removals greater than one, so these are the cases batching can help with. When compiling the IR for this file with 'opt' and 'O3', this patch reduces the total time by 8-9%. Differential Revision: https://reviews.llvm.org/D36352 llvm-svn: 310450
2017-08-09 17:05:27 +08:00
NewRCs = RC.removeInternalRefEdge(BN, {&AN});
NewRCs = RC.removeInternalRefEdge(CN, {&BN});
[LCG] Teach the ref edge removal to handle a ref edge that is trivial due to a call cycle. This actually crashed the ref removal before. I've added a unittest that covers this kind of interesting graph structure and mutation. llvm-svn: 290645
2016-12-28 10:24:58 +08:00
EXPECT_EQ(0u, NewRCs.size());
EXPECT_EQ(&RC, CG.lookupRefSCC(AN));
EXPECT_EQ(&RC, CG.lookupRefSCC(BN));
EXPECT_EQ(&RC, CG.lookupRefSCC(CN));
EXPECT_EQ(&C, CG.lookupSCC(AN));
EXPECT_EQ(&C, CG.lookupSCC(BN));
EXPECT_EQ(&C, CG.lookupSCC(CN));
J = CG.postorder_ref_scc_begin();
EXPECT_EQ(I, J);
EXPECT_EQ(&RC, &*J);
EXPECT_EQ(E, std::next(J));
}
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
TEST(LazyCallGraphTest, InternalCallEdgeToRef) {
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
LLVMContext Context;
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// A nice fully connected (including self-edges) SCC (and RefSCC)
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
std::unique_ptr<Module> M = parseAssembly(Context, "define void @a() {\n"
"entry:\n"
" call void @a()\n"
" call void @b()\n"
" call void @c()\n"
" ret void\n"
"}\n"
"define void @b() {\n"
"entry:\n"
" call void @a()\n"
" call void @b()\n"
" call void @c()\n"
" ret void\n"
"}\n"
"define void @c() {\n"
"entry:\n"
" call void @a()\n"
" call void @b()\n"
" call void @c()\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Add the first round of mutation support to the lazy call graph. This implements the core functionality necessary to remove an edge from the call graph and correctly update both the basic graph and the SCC structure. As part of that it has to run a tiny (in number of nodes) Tarjan-style DFS walk of an SCC being mutated to compute newly formed SCCs, etc. This is *very rough* and a WIP. I have a bunch of FIXMEs for code cleanup that will reduce the boilerplate in this change substantially. I also have a bunch of simplifications to various parts of both algorithms that I want to make, but first I'd like to have a more holistic picture. Ideally, I'd also like more testing. I'll probably add quite a few more unit tests as I go here to cover the various different aspects and corner cases of removing edges from the graph. Still, this is, so far, successfully updating the SCC graph in-place without disrupting the identity established for the existing SCCs even when we do challenging things like delete the critical edge that made an SCC cycle at all and have to reform things as a tree of smaller SCCs. Getting this to work is really critical for the new pass manager as it is going to associate significant state with the SCC instance and needs it to be stable. That is also the motivation behind the return of the newly formed SCCs. Eventually, I'll wire this all the way up to the public API so that the pass manager can use it to correctly re-enqueue newly formed SCCs into a fresh postorder traversal. llvm-svn: 206968
2014-04-23 19:03:03 +08:00
// Force the graph to be fully expanded.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
auto I = CG.postorder_ref_scc_begin();
LazyCallGraph::RefSCC &RC = *I++;
EXPECT_EQ(CG.postorder_ref_scc_end(), I);
[LCG] Add the first round of mutation support to the lazy call graph. This implements the core functionality necessary to remove an edge from the call graph and correctly update both the basic graph and the SCC structure. As part of that it has to run a tiny (in number of nodes) Tarjan-style DFS walk of an SCC being mutated to compute newly formed SCCs, etc. This is *very rough* and a WIP. I have a bunch of FIXMEs for code cleanup that will reduce the boilerplate in this change substantially. I also have a bunch of simplifications to various parts of both algorithms that I want to make, but first I'd like to have a more holistic picture. Ideally, I'd also like more testing. I'll probably add quite a few more unit tests as I go here to cover the various different aspects and corner cases of removing edges from the graph. Still, this is, so far, successfully updating the SCC graph in-place without disrupting the identity established for the existing SCCs even when we do challenging things like delete the critical edge that made an SCC cycle at all and have to reform things as a tree of smaller SCCs. Getting this to work is really critical for the new pass manager as it is going to associate significant state with the SCC instance and needs it to be stable. That is also the motivation behind the return of the newly formed SCCs. Eventually, I'll wire this all the way up to the public API so that the pass manager can use it to correctly re-enqueue newly formed SCCs into a fresh postorder traversal. llvm-svn: 206968
2014-04-23 19:03:03 +08:00
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(1, RC.size());
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
LazyCallGraph::SCC &AC = *RC.begin();
[LCG] Add the first round of mutation support to the lazy call graph. This implements the core functionality necessary to remove an edge from the call graph and correctly update both the basic graph and the SCC structure. As part of that it has to run a tiny (in number of nodes) Tarjan-style DFS walk of an SCC being mutated to compute newly formed SCCs, etc. This is *very rough* and a WIP. I have a bunch of FIXMEs for code cleanup that will reduce the boilerplate in this change substantially. I also have a bunch of simplifications to various parts of both algorithms that I want to make, but first I'd like to have a more holistic picture. Ideally, I'd also like more testing. I'll probably add quite a few more unit tests as I go here to cover the various different aspects and corner cases of removing edges from the graph. Still, this is, so far, successfully updating the SCC graph in-place without disrupting the identity established for the existing SCCs even when we do challenging things like delete the critical edge that made an SCC cycle at all and have to reform things as a tree of smaller SCCs. Getting this to work is really critical for the new pass manager as it is going to associate significant state with the SCC instance and needs it to be stable. That is also the motivation behind the return of the newly formed SCCs. Eventually, I'll wire this all the way up to the public API so that the pass manager can use it to correctly re-enqueue newly formed SCCs into a fresh postorder traversal. llvm-svn: 206968
2014-04-23 19:03:03 +08:00
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
LazyCallGraph::Node &AN = *CG.lookup(lookupFunction(*M, "a"));
LazyCallGraph::Node &BN = *CG.lookup(lookupFunction(*M, "b"));
LazyCallGraph::Node &CN = *CG.lookup(lookupFunction(*M, "c"));
EXPECT_EQ(&AC, CG.lookupSCC(AN));
EXPECT_EQ(&AC, CG.lookupSCC(BN));
EXPECT_EQ(&AC, CG.lookupSCC(CN));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Remove the call edge from b -> a to a ref edge, which should leave the
// 3 functions still in a single connected component because of a -> b ->
// c -> a.
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
auto NewCs = RC.switchInternalEdgeToRef(BN, AN);
EXPECT_EQ(NewCs.begin(), NewCs.end());
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(1, RC.size());
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
EXPECT_EQ(&AC, CG.lookupSCC(AN));
EXPECT_EQ(&AC, CG.lookupSCC(BN));
EXPECT_EQ(&AC, CG.lookupSCC(CN));
[LCG] Add the first round of mutation support to the lazy call graph. This implements the core functionality necessary to remove an edge from the call graph and correctly update both the basic graph and the SCC structure. As part of that it has to run a tiny (in number of nodes) Tarjan-style DFS walk of an SCC being mutated to compute newly formed SCCs, etc. This is *very rough* and a WIP. I have a bunch of FIXMEs for code cleanup that will reduce the boilerplate in this change substantially. I also have a bunch of simplifications to various parts of both algorithms that I want to make, but first I'd like to have a more holistic picture. Ideally, I'd also like more testing. I'll probably add quite a few more unit tests as I go here to cover the various different aspects and corner cases of removing edges from the graph. Still, this is, so far, successfully updating the SCC graph in-place without disrupting the identity established for the existing SCCs even when we do challenging things like delete the critical edge that made an SCC cycle at all and have to reform things as a tree of smaller SCCs. Getting this to work is really critical for the new pass manager as it is going to associate significant state with the SCC instance and needs it to be stable. That is also the motivation behind the return of the newly formed SCCs. Eventually, I'll wire this all the way up to the public API so that the pass manager can use it to correctly re-enqueue newly formed SCCs into a fresh postorder traversal. llvm-svn: 206968
2014-04-23 19:03:03 +08:00
// Remove the edge from c -> a, which should leave 'a' in the original SCC
// and form a new SCC for 'b' and 'c'.
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
NewCs = RC.switchInternalEdgeToRef(CN, AN);
EXPECT_EQ(1, std::distance(NewCs.begin(), NewCs.end()));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(2, RC.size());
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
EXPECT_EQ(&AC, CG.lookupSCC(AN));
LazyCallGraph::SCC &BC = *CG.lookupSCC(BN);
EXPECT_NE(&BC, &AC);
EXPECT_EQ(&BC, CG.lookupSCC(CN));
auto J = RC.find(AC);
EXPECT_EQ(&AC, &*J);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
--J;
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
EXPECT_EQ(&BC, &*J);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(RC.begin(), J);
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
EXPECT_EQ(J, NewCs.begin());
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Remove the edge from c -> b, which should leave 'b' in the original SCC
// and form a new SCC for 'c'. It shouldn't change 'a's SCC.
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
NewCs = RC.switchInternalEdgeToRef(CN, BN);
EXPECT_EQ(1, std::distance(NewCs.begin(), NewCs.end()));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(3, RC.size());
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
EXPECT_EQ(&AC, CG.lookupSCC(AN));
EXPECT_EQ(&BC, CG.lookupSCC(BN));
LazyCallGraph::SCC &CC = *CG.lookupSCC(CN);
EXPECT_NE(&CC, &AC);
EXPECT_NE(&CC, &BC);
J = RC.find(AC);
EXPECT_EQ(&AC, &*J);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
--J;
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
EXPECT_EQ(&BC, &*J);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
--J;
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
EXPECT_EQ(&CC, &*J);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(RC.begin(), J);
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
EXPECT_EQ(J, NewCs.begin());
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
}
TEST(LazyCallGraphTest, InternalRefEdgeToCall) {
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
LLVMContext Context;
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Basic tests for making a ref edge a call. This hits the basics of the
// process only.
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
std::unique_ptr<Module> M =
parseAssembly(Context, "define void @a() {\n"
"entry:\n"
" call void @b()\n"
" call void @c()\n"
" store void()* @d, void()** undef\n"
" ret void\n"
"}\n"
"define void @b() {\n"
"entry:\n"
" store void()* @c, void()** undef\n"
" call void @d()\n"
" ret void\n"
"}\n"
"define void @c() {\n"
"entry:\n"
" store void()* @b, void()** undef\n"
" call void @d()\n"
" ret void\n"
"}\n"
"define void @d() {\n"
"entry:\n"
" store void()* @a, void()** undef\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Force the graph to be fully expanded.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
auto I = CG.postorder_ref_scc_begin();
LazyCallGraph::RefSCC &RC = *I++;
EXPECT_EQ(CG.postorder_ref_scc_end(), I);
LazyCallGraph::Node &A = *CG.lookup(lookupFunction(*M, "a"));
LazyCallGraph::Node &B = *CG.lookup(lookupFunction(*M, "b"));
LazyCallGraph::Node &C = *CG.lookup(lookupFunction(*M, "c"));
LazyCallGraph::Node &D = *CG.lookup(lookupFunction(*M, "d"));
LazyCallGraph::SCC &AC = *CG.lookupSCC(A);
LazyCallGraph::SCC &BC = *CG.lookupSCC(B);
LazyCallGraph::SCC &CC = *CG.lookupSCC(C);
LazyCallGraph::SCC &DC = *CG.lookupSCC(D);
// Check the initial post-order. Note that B and C could be flipped here (and
// in our mutation) without changing the nature of this test.
ASSERT_EQ(4, RC.size());
EXPECT_EQ(&DC, &RC[0]);
EXPECT_EQ(&BC, &RC[1]);
EXPECT_EQ(&CC, &RC[2]);
EXPECT_EQ(&AC, &RC[3]);
// Switch the ref edge from A -> D to a call edge. This should have no
// effect as it is already in postorder and no new cycles are formed.
[PM] Fix a nasty bug in the new PM where we failed to properly invalidation of analyses when merging SCCs. While I've added a bunch of testing of this, it takes something much more like the inliner to really trigger this as you need to have partially-analyzed SCCs with updates at just the right time. So I've added a direct test for this using the inliner and verifying the domtree. Without the changes here, this test ends up finding a stale dominator tree. However, to handle this properly, we need to invalidate analyses *before* merging the SCCs. After talking to Philip and Sanjoy about this they convinced me this was the right approach. To do this, we need a callback mechanism when merging SCCs so we can observe the cycle that will be merged before the merge happens. This API update ended up being surprisingly easy. With this commit, the new PM passes the test-suite again. It hadn't since MemorySSA was enabled for EarlyCSE as that also will find this bug very quickly. llvm-svn: 307498
2017-07-09 21:45:11 +08:00
EXPECT_FALSE(RC.switchInternalEdgeToCall(A, D));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
ASSERT_EQ(4, RC.size());
EXPECT_EQ(&DC, &RC[0]);
EXPECT_EQ(&BC, &RC[1]);
EXPECT_EQ(&CC, &RC[2]);
EXPECT_EQ(&AC, &RC[3]);
// Switch B -> C to a call edge. This doesn't form any new cycles but does
// require reordering the SCCs.
[PM] Fix a nasty bug in the new PM where we failed to properly invalidation of analyses when merging SCCs. While I've added a bunch of testing of this, it takes something much more like the inliner to really trigger this as you need to have partially-analyzed SCCs with updates at just the right time. So I've added a direct test for this using the inliner and verifying the domtree. Without the changes here, this test ends up finding a stale dominator tree. However, to handle this properly, we need to invalidate analyses *before* merging the SCCs. After talking to Philip and Sanjoy about this they convinced me this was the right approach. To do this, we need a callback mechanism when merging SCCs so we can observe the cycle that will be merged before the merge happens. This API update ended up being surprisingly easy. With this commit, the new PM passes the test-suite again. It hadn't since MemorySSA was enabled for EarlyCSE as that also will find this bug very quickly. llvm-svn: 307498
2017-07-09 21:45:11 +08:00
EXPECT_FALSE(RC.switchInternalEdgeToCall(B, C));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
ASSERT_EQ(4, RC.size());
EXPECT_EQ(&DC, &RC[0]);
EXPECT_EQ(&CC, &RC[1]);
EXPECT_EQ(&BC, &RC[2]);
EXPECT_EQ(&AC, &RC[3]);
// Switch C -> B to a call edge. This forms a cycle and forces merging SCCs.
[PM] Fix a nasty bug in the new PM where we failed to properly invalidation of analyses when merging SCCs. While I've added a bunch of testing of this, it takes something much more like the inliner to really trigger this as you need to have partially-analyzed SCCs with updates at just the right time. So I've added a direct test for this using the inliner and verifying the domtree. Without the changes here, this test ends up finding a stale dominator tree. However, to handle this properly, we need to invalidate analyses *before* merging the SCCs. After talking to Philip and Sanjoy about this they convinced me this was the right approach. To do this, we need a callback mechanism when merging SCCs so we can observe the cycle that will be merged before the merge happens. This API update ended up being surprisingly easy. With this commit, the new PM passes the test-suite again. It hadn't since MemorySSA was enabled for EarlyCSE as that also will find this bug very quickly. llvm-svn: 307498
2017-07-09 21:45:11 +08:00
EXPECT_TRUE(RC.switchInternalEdgeToCall(C, B, [&](ArrayRef<LazyCallGraph::SCC *> MergedCs) {
ASSERT_EQ(1u, MergedCs.size());
EXPECT_EQ(&CC, MergedCs[0]);
}));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
ASSERT_EQ(3, RC.size());
EXPECT_EQ(&DC, &RC[0]);
EXPECT_EQ(&BC, &RC[1]);
EXPECT_EQ(&AC, &RC[2]);
EXPECT_EQ(2, BC.size());
EXPECT_EQ(&BC, CG.lookupSCC(B));
EXPECT_EQ(&BC, CG.lookupSCC(C));
}
TEST(LazyCallGraphTest, InternalRefEdgeToCallNoCycleInterleaved) {
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
LLVMContext Context;
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Test for having a post-order prior to changing a ref edge to a call edge
// with SCCs connecting to the source and connecting to the target, but not
// connecting to both, interleaved between the source and target. This
// ensures we correctly partition the range rather than simply moving one or
// the other.
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
std::unique_ptr<Module> M =
parseAssembly(Context, "define void @a() {\n"
"entry:\n"
" call void @b1()\n"
" call void @c1()\n"
" ret void\n"
"}\n"
"define void @b1() {\n"
"entry:\n"
" call void @c1()\n"
" call void @b2()\n"
" ret void\n"
"}\n"
"define void @c1() {\n"
"entry:\n"
" call void @b2()\n"
" call void @c2()\n"
" ret void\n"
"}\n"
"define void @b2() {\n"
"entry:\n"
" call void @c2()\n"
" call void @b3()\n"
" ret void\n"
"}\n"
"define void @c2() {\n"
"entry:\n"
" call void @b3()\n"
" call void @c3()\n"
" ret void\n"
"}\n"
"define void @b3() {\n"
"entry:\n"
" call void @c3()\n"
" call void @d()\n"
" ret void\n"
"}\n"
"define void @c3() {\n"
"entry:\n"
" store void()* @b1, void()** undef\n"
" call void @d()\n"
" ret void\n"
"}\n"
"define void @d() {\n"
"entry:\n"
" store void()* @a, void()** undef\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Force the graph to be fully expanded.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
auto I = CG.postorder_ref_scc_begin();
LazyCallGraph::RefSCC &RC = *I++;
EXPECT_EQ(CG.postorder_ref_scc_end(), I);
LazyCallGraph::Node &A = *CG.lookup(lookupFunction(*M, "a"));
LazyCallGraph::Node &B1 = *CG.lookup(lookupFunction(*M, "b1"));
LazyCallGraph::Node &B2 = *CG.lookup(lookupFunction(*M, "b2"));
LazyCallGraph::Node &B3 = *CG.lookup(lookupFunction(*M, "b3"));
LazyCallGraph::Node &C1 = *CG.lookup(lookupFunction(*M, "c1"));
LazyCallGraph::Node &C2 = *CG.lookup(lookupFunction(*M, "c2"));
LazyCallGraph::Node &C3 = *CG.lookup(lookupFunction(*M, "c3"));
LazyCallGraph::Node &D = *CG.lookup(lookupFunction(*M, "d"));
LazyCallGraph::SCC &AC = *CG.lookupSCC(A);
LazyCallGraph::SCC &B1C = *CG.lookupSCC(B1);
LazyCallGraph::SCC &B2C = *CG.lookupSCC(B2);
LazyCallGraph::SCC &B3C = *CG.lookupSCC(B3);
LazyCallGraph::SCC &C1C = *CG.lookupSCC(C1);
LazyCallGraph::SCC &C2C = *CG.lookupSCC(C2);
LazyCallGraph::SCC &C3C = *CG.lookupSCC(C3);
LazyCallGraph::SCC &DC = *CG.lookupSCC(D);
// Several call edges are initially present to force a particual post-order.
// Remove them now, leaving an interleaved post-order pattern.
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
RC.switchTrivialInternalEdgeToRef(B3, C3);
RC.switchTrivialInternalEdgeToRef(C2, B3);
RC.switchTrivialInternalEdgeToRef(B2, C2);
RC.switchTrivialInternalEdgeToRef(C1, B2);
RC.switchTrivialInternalEdgeToRef(B1, C1);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Check the initial post-order. We ensure this order with the extra edges
// that are nuked above.
ASSERT_EQ(8, RC.size());
EXPECT_EQ(&DC, &RC[0]);
EXPECT_EQ(&C3C, &RC[1]);
EXPECT_EQ(&B3C, &RC[2]);
EXPECT_EQ(&C2C, &RC[3]);
EXPECT_EQ(&B2C, &RC[4]);
EXPECT_EQ(&C1C, &RC[5]);
EXPECT_EQ(&B1C, &RC[6]);
EXPECT_EQ(&AC, &RC[7]);
// Switch C3 -> B1 to a call edge. This doesn't form any new cycles but does
// require reordering the SCCs in the face of tricky internal node
// structures.
[PM] Fix a nasty bug in the new PM where we failed to properly invalidation of analyses when merging SCCs. While I've added a bunch of testing of this, it takes something much more like the inliner to really trigger this as you need to have partially-analyzed SCCs with updates at just the right time. So I've added a direct test for this using the inliner and verifying the domtree. Without the changes here, this test ends up finding a stale dominator tree. However, to handle this properly, we need to invalidate analyses *before* merging the SCCs. After talking to Philip and Sanjoy about this they convinced me this was the right approach. To do this, we need a callback mechanism when merging SCCs so we can observe the cycle that will be merged before the merge happens. This API update ended up being surprisingly easy. With this commit, the new PM passes the test-suite again. It hadn't since MemorySSA was enabled for EarlyCSE as that also will find this bug very quickly. llvm-svn: 307498
2017-07-09 21:45:11 +08:00
EXPECT_FALSE(RC.switchInternalEdgeToCall(C3, B1));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
ASSERT_EQ(8, RC.size());
EXPECT_EQ(&DC, &RC[0]);
EXPECT_EQ(&B3C, &RC[1]);
EXPECT_EQ(&B2C, &RC[2]);
EXPECT_EQ(&B1C, &RC[3]);
EXPECT_EQ(&C3C, &RC[4]);
EXPECT_EQ(&C2C, &RC[5]);
EXPECT_EQ(&C1C, &RC[6]);
EXPECT_EQ(&AC, &RC[7]);
}
TEST(LazyCallGraphTest, InternalRefEdgeToCallBothPartitionAndMerge) {
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
LLVMContext Context;
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Test for having a postorder where between the source and target are all
// three kinds of other SCCs:
// 1) One connected to the target only that have to be shifted below the
// source.
// 2) One connected to the source only that have to be shifted below the
// target.
// 3) One connected to both source and target that has to remain and get
// merged away.
//
// To achieve this we construct a heavily connected graph to force
// a particular post-order. Then we remove the forcing edges and connect
// a cycle.
//
// Diagram for the graph we want on the left and the graph we use to force
// the ordering on the right. Edges ponit down or right.
//
// A | A |
// / \ | / \ |
// B E | B \ |
// |\ | | |\ | |
// | D | | C-D-E |
// | \| | | \| |
// C F | \ F |
// \ / | \ / |
// G | G |
//
// And we form a cycle by connecting F to B.
Remove every uses of getGlobalContext() in LLVM (but the C API) At the same time, fixes InstructionsTest::CastInst unittest: yes you can leave the IR in an invalid state and exit when you don't destroy the context (like the global one), no longer now. This is the first part of http://reviews.llvm.org/D19094 From: Mehdi Amini <mehdi.amini@apple.com> llvm-svn: 266379
2016-04-15 05:59:01 +08:00
std::unique_ptr<Module> M =
parseAssembly(Context, "define void @a() {\n"
"entry:\n"
" call void @b()\n"
" call void @e()\n"
" ret void\n"
"}\n"
"define void @b() {\n"
"entry:\n"
" call void @c()\n"
" call void @d()\n"
" ret void\n"
"}\n"
"define void @c() {\n"
"entry:\n"
" call void @d()\n"
" call void @g()\n"
" ret void\n"
"}\n"
"define void @d() {\n"
"entry:\n"
" call void @e()\n"
" call void @f()\n"
" ret void\n"
"}\n"
"define void @e() {\n"
"entry:\n"
" call void @f()\n"
" ret void\n"
"}\n"
"define void @f() {\n"
"entry:\n"
" store void()* @b, void()** undef\n"
" call void @g()\n"
" ret void\n"
"}\n"
"define void @g() {\n"
"entry:\n"
" store void()* @a, void()** undef\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Force the graph to be fully expanded.
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
auto I = CG.postorder_ref_scc_begin();
LazyCallGraph::RefSCC &RC = *I++;
EXPECT_EQ(CG.postorder_ref_scc_end(), I);
LazyCallGraph::Node &A = *CG.lookup(lookupFunction(*M, "a"));
LazyCallGraph::Node &B = *CG.lookup(lookupFunction(*M, "b"));
LazyCallGraph::Node &C = *CG.lookup(lookupFunction(*M, "c"));
LazyCallGraph::Node &D = *CG.lookup(lookupFunction(*M, "d"));
LazyCallGraph::Node &E = *CG.lookup(lookupFunction(*M, "e"));
LazyCallGraph::Node &F = *CG.lookup(lookupFunction(*M, "f"));
LazyCallGraph::Node &G = *CG.lookup(lookupFunction(*M, "g"));
LazyCallGraph::SCC &AC = *CG.lookupSCC(A);
LazyCallGraph::SCC &BC = *CG.lookupSCC(B);
LazyCallGraph::SCC &CC = *CG.lookupSCC(C);
LazyCallGraph::SCC &DC = *CG.lookupSCC(D);
LazyCallGraph::SCC &EC = *CG.lookupSCC(E);
LazyCallGraph::SCC &FC = *CG.lookupSCC(F);
LazyCallGraph::SCC &GC = *CG.lookupSCC(G);
// Remove the extra edges that were used to force a particular post-order.
[PM] Teach the CGSCC's CG update utility to more carefully invalidate analyses when we're about to break apart an SCC. We can't wait until after breaking apart the SCC to invalidate things: 1) Which SCC do we then invalidate? All of them? 2) Even if we invalidate all of them, a newly created SCC may not have a proxy that will convey the invalidation to functions! Previously we only invalidated one of the SCCs and too late. This led to stale analyses remaining in the cache. And because the caching strategy actually works, they would get used and chaos would ensue. Doing invalidation early is somewhat pessimizing though if we *know* that the SCC structure won't change. So it turns out that the design to make the mutation API force the caller to know the *kind* of mutation in advance was indeed 100% correct and we didn't do enough of it. So this change also splits two cases of switching a call edge to a ref edge into two separate APIs so that callers can clearly test for this and take the easy path without invalidating when appropriate. This is particularly important in this case as we expect most inlines to be between functions in separate SCCs and so the common case is that we don't have to so aggressively invalidate analyses. The LCG API change in turn needed some basic cleanups and better testing in its unittest. No interesting functionality changed there other than more coverage of the returned sequence of SCCs. While this seems like an obvious improvement over the current state, I'd like to revisit the core concept of invalidating within the CG-update layer at all. I'm wondering if we would be better served forcing the callers to handle the invalidation beforehand in the cases that they can handle it. An interesting example is when we want to teach the inliner to *update and preserve* analyses. But we can cross that bridge when we get there. With this patch, the new pass manager an build all of the LLVM test suite at -O3 and everything passes. =D I haven't bootstrapped yet and I'm sure there are still plenty of bugs, but this gives a nice baseline so I'm going to increasingly focus on fleshing out the missing functionality, especially the bits that are just turned off right now in order to let us establish this baseline. llvm-svn: 290664
2016-12-28 18:34:50 +08:00
RC.switchTrivialInternalEdgeToRef(C, D);
RC.switchTrivialInternalEdgeToRef(D, E);
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
// Check the initial post-order. We ensure this order with the extra edges
// that are nuked above.
ASSERT_EQ(7, RC.size());
EXPECT_EQ(&GC, &RC[0]);
EXPECT_EQ(&FC, &RC[1]);
EXPECT_EQ(&EC, &RC[2]);
EXPECT_EQ(&DC, &RC[3]);
EXPECT_EQ(&CC, &RC[4]);
EXPECT_EQ(&BC, &RC[5]);
EXPECT_EQ(&AC, &RC[6]);
// Switch F -> B to a call edge. This merges B, D, and F into a single SCC,
// and has to place the C and E SCCs on either side of it:
// A A |
// / \ / \ |
// B E | E |
// |\ | \ / |
// | D | -> B |
// | \| / \ |
// C F C | |
// \ / \ / |
// G G |
[PM] Fix a nasty bug in the new PM where we failed to properly invalidation of analyses when merging SCCs. While I've added a bunch of testing of this, it takes something much more like the inliner to really trigger this as you need to have partially-analyzed SCCs with updates at just the right time. So I've added a direct test for this using the inliner and verifying the domtree. Without the changes here, this test ends up finding a stale dominator tree. However, to handle this properly, we need to invalidate analyses *before* merging the SCCs. After talking to Philip and Sanjoy about this they convinced me this was the right approach. To do this, we need a callback mechanism when merging SCCs so we can observe the cycle that will be merged before the merge happens. This API update ended up being surprisingly easy. With this commit, the new PM passes the test-suite again. It hadn't since MemorySSA was enabled for EarlyCSE as that also will find this bug very quickly. llvm-svn: 307498
2017-07-09 21:45:11 +08:00
EXPECT_TRUE(RC.switchInternalEdgeToCall(
F, B, [&](ArrayRef<LazyCallGraph::SCC *> MergedCs) {
ASSERT_EQ(2u, MergedCs.size());
EXPECT_EQ(&FC, MergedCs[0]);
EXPECT_EQ(&DC, MergedCs[1]);
}));
[LCG] Construct an actual call graph with call-edge SCCs nested inside reference-edge SCCs. This essentially builds a more normal call graph as a subgraph of the "reference graph" that was the old model. This allows both to exist and the different use cases to use the aspect which addresses their needs. Specifically, the pass manager and other *ordering* constrained logic can use the reference graph to achieve conservative order of visit, while analyses reasoning about attributes and other properties derived from reachability can reason about the direct call graph. Note that this isn't necessarily complete: it doesn't model edges to declarations or indirect calls. Those can be found by scanning the instructions of the function if desirable, and in fact every user currently does this in order to handle things like calls to instrinsics. If useful, we could consider caching this information in the call graph to save the instruction scans, but currently that doesn't seem to be important. An important realization for why the representation chosen here works is that the call graph is a formal subset of the reference graph and thus both can live within the same data structure. All SCCs of the call graph are necessarily contained within an SCC of the reference graph, etc. The design is to build 'RefSCC's to model SCCs of the reference graph, and then within them more literal SCCs for the call graph. The formation of actual call edge SCCs is not done lazily, unlike reference edge 'RefSCC's. Instead, once a reference SCC is formed, it directly builds the call SCCs within it and stores them in a post-order sequence. This is used to provide a consistent platform for mutation and update of the graph. The post-order also allows for very efficient updates in common cases by bounding the number of nodes (and thus edges) considered. There is considerable common code that I'm still looking for the best way to factor out between the various DFS implementations here. So far, my attempts have made the code harder to read and understand despite reducing the duplication, which seems a poor tradeoff. I've not given up on figuring out the right way to do this, but I wanted to wait until I at least had the system working and tested to continue attempting to factor it differently. This also requires introducing several new algorithms in order to handle all of the incremental update scenarios for the more complex structure involving two edge colorings. I've tried to comment the algorithms sufficiently to make it clear how this is expected to work, but they may still need more extensive documentation. I know that there are some changes which are not strictly necessarily coupled here. The process of developing this started out with a very focused set of changes for the new structure of the graph and algorithms, but subsequent changes to bring the APIs and code into consistent and understandable patterns also ended up touching on other aspects. There was no good way to separate these out without causing *massive* merge conflicts. Ultimately, to a large degree this is a rewrite of most of the core algorithms in the LCG class and so I don't think it really matters much. Many thanks to the careful review by Sanjoy Das! Differential Revision: http://reviews.llvm.org/D16802 llvm-svn: 261040
2016-02-17 08:18:16 +08:00
EXPECT_EQ(3, BC.size());
// And make sure the postorder was updated.
ASSERT_EQ(5, RC.size());
EXPECT_EQ(&GC, &RC[0]);
EXPECT_EQ(&CC, &RC[1]);
EXPECT_EQ(&BC, &RC[2]);
EXPECT_EQ(&EC, &RC[3]);
EXPECT_EQ(&AC, &RC[4]);
[LCG] Add the first round of mutation support to the lazy call graph. This implements the core functionality necessary to remove an edge from the call graph and correctly update both the basic graph and the SCC structure. As part of that it has to run a tiny (in number of nodes) Tarjan-style DFS walk of an SCC being mutated to compute newly formed SCCs, etc. This is *very rough* and a WIP. I have a bunch of FIXMEs for code cleanup that will reduce the boilerplate in this change substantially. I also have a bunch of simplifications to various parts of both algorithms that I want to make, but first I'd like to have a more holistic picture. Ideally, I'd also like more testing. I'll probably add quite a few more unit tests as I go here to cover the various different aspects and corner cases of removing edges from the graph. Still, this is, so far, successfully updating the SCC graph in-place without disrupting the identity established for the existing SCCs even when we do challenging things like delete the critical edge that made an SCC cycle at all and have to reform things as a tree of smaller SCCs. Getting this to work is really critical for the new pass manager as it is going to associate significant state with the SCC instance and needs it to be stable. That is also the motivation behind the return of the newly formed SCCs. Eventually, I'll wire this all the way up to the public API so that the pass manager can use it to correctly re-enqueue newly formed SCCs into a fresh postorder traversal. llvm-svn: 206968
2014-04-23 19:03:03 +08:00
}
[LCG] Teach the LazyCallGraph to handle visiting the blockaddress constant expression and to correctly form function reference edges through them without crashing because one of the operands (the `BasicBlock` isn't actually a constant despite being an operand of a constant). llvm-svn: 290581
2016-12-27 13:00:45 +08:00
// Test for IR containing constants using blockaddress constant expressions.
// These are truly unique constructs: constant expressions with non-constant
// operands.
TEST(LazyCallGraphTest, HandleBlockAddress) {
LLVMContext Context;
std::unique_ptr<Module> M =
parseAssembly(Context, "define void @f() {\n"
"entry:\n"
" ret void\n"
"bb:\n"
" unreachable\n"
"}\n"
"define void @g(i8** %ptr) {\n"
"entry:\n"
" store i8* blockaddress(@f, %bb), i8** %ptr\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[LCG] Teach the LazyCallGraph to handle visiting the blockaddress constant expression and to correctly form function reference edges through them without crashing because one of the operands (the `BasicBlock` isn't actually a constant despite being an operand of a constant). llvm-svn: 290581
2016-12-27 13:00:45 +08:00
[PM/LCG] Remove the lazy RefSCC formation from the LazyCallGraph during iteration. The lazy formation of RefSCCs isn't really the most important part of the laziness here -- that has to do with walking the functions themselves -- and isn't essential to maintain. Originally, there were incremental update algorithms that relied on updates happening predominantly near the most recent RefSCC formed, but those have been replaced with ones that have much tighter general case bounds at this point. We do still perform asserts that only scale well due to this incrementality, but those are easy to place behind EXPENSIVE_CHECKS. Removing this simplifies the entire analysis by having a single up-front step that builds all of the RefSCCs in a direct Tarjan walk. We can even easily replace this with other or better algorithms at will and with much less confusion now that there is no iterator-based incremental logic involved. This removes a lot of complexity from LCG. Another advantage of moving in this direction is that it simplifies testing the system substantially as we no longer have to worry about observing and mutating the graph half-way through the RefSCC formation. We still need a somewhat special iterator for RefSCCs because we want the iterator to remain stable in the face of graph updates. However, this now merely involves relative indexing to the current RefSCC's position in the sequence which isn't too hard. Differential Revision: https://reviews.llvm.org/D29381 llvm-svn: 294227
2017-02-07 03:38:06 +08:00
CG.buildRefSCCs();
[LCG] Teach the LazyCallGraph to handle visiting the blockaddress constant expression and to correctly form function reference edges through them without crashing because one of the operands (the `BasicBlock` isn't actually a constant despite being an operand of a constant). llvm-svn: 290581
2016-12-27 13:00:45 +08:00
auto I = CG.postorder_ref_scc_begin();
LazyCallGraph::RefSCC &FRC = *I++;
LazyCallGraph::RefSCC &GRC = *I++;
EXPECT_EQ(CG.postorder_ref_scc_end(), I);
LazyCallGraph::Node &F = *CG.lookup(lookupFunction(*M, "f"));
LazyCallGraph::Node &G = *CG.lookup(lookupFunction(*M, "g"));
EXPECT_EQ(&FRC, CG.lookupRefSCC(F));
EXPECT_EQ(&GRC, CG.lookupRefSCC(G));
EXPECT_TRUE(GRC.isParentOf(FRC));
}
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
TEST(LazyCallGraphTest, ReplaceNodeFunction) {
LLVMContext Context;
// A graph with several different kinds of edges pointing at a particular
// function.
std::unique_ptr<Module> M =
parseAssembly(Context,
"define void @a(i8** %ptr) {\n"
"entry:\n"
" store i8* bitcast (void(i8**)* @d to i8*), i8** %ptr\n"
" ret void\n"
"}\n"
"define void @b(i8** %ptr) {\n"
"entry:\n"
" store i8* bitcast (void(i8**)* @d to i8*), i8** %ptr\n"
" store i8* bitcast (void(i8**)* @d to i8*), i8** %ptr\n"
" call void @d(i8** %ptr)"
" ret void\n"
"}\n"
"define void @c(i8** %ptr) {\n"
"entry:\n"
" call void @d(i8** %ptr)"
" call void @d(i8** %ptr)"
" store i8* bitcast (void(i8**)* @d to i8*), i8** %ptr\n"
" ret void\n"
"}\n"
"define void @d(i8** %ptr) {\n"
"entry:\n"
" store i8* bitcast (void(i8**)* @b to i8*), i8** %ptr\n"
" call void @c(i8** %ptr)"
" call void @d(i8** %ptr)"
" store i8* bitcast (void(i8**)* @d to i8*), i8** %ptr\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
// Force the graph to be fully expanded.
CG.buildRefSCCs();
auto I = CG.postorder_ref_scc_begin();
LazyCallGraph::RefSCC &RC1 = *I++;
LazyCallGraph::RefSCC &RC2 = *I++;
EXPECT_EQ(CG.postorder_ref_scc_end(), I);
Fix signed/unsigned comparison warnings llvm-svn: 297561
2017-03-11 21:02:31 +08:00
ASSERT_EQ(2, RC1.size());
[PM/LCG] Teach the LazyCallGraph how to replace a function without disturbing the graph or having to update edges. This is motivated by porting argument promotion to the new pass manager. Because of how LLVM IR Function objects work, in order to change their signature a new object needs to be created. This is efficient and straight forward in the IR but previously was very hard to implement in LCG. We could easily replace the function a node in the graph represents. The challenging part is how to handle updating the edges in the graph. LCG previously used an edge to a raw function to represent a node that had not yet been scanned for calls and references. This was the core of its laziness. However, that model causes this kind of update to be very hard: 1) The keys to lookup an edge need to be `Function*`s that would all need to be updated when we update the node. 2) There will be some unknown number of edges that haven't transitioned from `Function*` edges to `Node*` edges. All of this complexity isn't necessary. Instead, we can always build a node around any function, always pointing edges at it and always using it as the key to lookup an edge. To maintain the laziness, we need to sink the *edges* of a node into a secondary object and explicitly model transitioning a node from empty to populated by scanning the function. This design seems much cleaner in a number of ways, but importantly there is now exactly *one* place where the `Function*` has to be updated! Some other cleanups that fall out of this include having something to model the *entry* edges more accurately. Rather than hand rolling parts of the node in the graph itself, we have an explicit `EdgeSequence` object that gives us exactly the functionality needed. We also have a consistent place to define the edge iterators and can use them for both the entry edges and the internal edges of the graph. The API used to model the separation between a node and its edges is intentionally very thin as most clients are expected to deal with nodes that have populated edges. We model this exactly as an optional does with an additional method to populate the edges when that is a reasonable thing for a client to do. This is based on API design suggestions from Richard Smith and David Blaikie, credit goes to them for helping pick how to model this without it being either too explicit or too implicit. The patch is somewhat noisy due to shifting around iterator types and new syntax for walking the edges of a node, but most of the functionality change is in the `Edge`, `EdgeSequence`, and `Node` types. Differential Revision: https://reviews.llvm.org/D29577 llvm-svn: 294653
2017-02-10 07:24:13 +08:00
LazyCallGraph::SCC &C1 = RC1[0];
LazyCallGraph::SCC &C2 = RC1[1];
LazyCallGraph::Node &AN = *CG.lookup(lookupFunction(*M, "a"));
LazyCallGraph::Node &BN = *CG.lookup(lookupFunction(*M, "b"));
LazyCallGraph::Node &CN = *CG.lookup(lookupFunction(*M, "c"));
LazyCallGraph::Node &DN = *CG.lookup(lookupFunction(*M, "d"));
EXPECT_EQ(&C1, CG.lookupSCC(DN));
EXPECT_EQ(&C1, CG.lookupSCC(CN));
EXPECT_EQ(&C2, CG.lookupSCC(BN));
EXPECT_EQ(&RC1, CG.lookupRefSCC(DN));
EXPECT_EQ(&RC1, CG.lookupRefSCC(CN));
EXPECT_EQ(&RC1, CG.lookupRefSCC(BN));
EXPECT_EQ(&RC2, CG.lookupRefSCC(AN));
// Now we need to build a new function 'e' with the same signature as 'd'.
Function &D = DN.getFunction();
Function &E = *Function::Create(D.getFunctionType(), D.getLinkage(), "e");
D.getParent()->getFunctionList().insert(D.getIterator(), &E);
// Change each use of 'd' to use 'e'. This is particularly easy as they have
// the same type.
D.replaceAllUsesWith(&E);
// Splice the body of the old function into the new one.
E.getBasicBlockList().splice(E.begin(), D.getBasicBlockList());
// And fix up the one argument.
D.arg_begin()->replaceAllUsesWith(&*E.arg_begin());
E.arg_begin()->takeName(&*D.arg_begin());
// Now replace the function in the graph.
RC1.replaceNodeFunction(DN, E);
EXPECT_EQ(&E, &DN.getFunction());
EXPECT_EQ(&DN, &(*CN)[DN].getNode());
EXPECT_EQ(&DN, &(*BN)[DN].getNode());
}
[PM/LCG] Teach LCG to support spurious reference edges. Somewhat amazingly, this only requires teaching it to clean them up when deleting a dead function from the graph. And we already have exactly the necessary data structures to do that in the parent RefSCCs. This allows ArgPromote to work in a much simpler way be merely letting reference edges linger in the graph after the causing IR is deleted. We will clean up these edges when we run any function pass over the IR, but don't remove them eagerly. This avoids all of the quadratic update issues both in the current pass manager and in my previous attempt with the new pass manager. Differential Revision: https://reviews.llvm.org/D29579 llvm-svn: 294663
2017-02-10 07:30:14 +08:00
TEST(LazyCallGraphTest, RemoveFunctionWithSpurriousRef) {
LLVMContext Context;
// A graph with a couple of RefSCCs.
std::unique_ptr<Module> M =
parseAssembly(Context,
"define void @a(i8** %ptr) {\n"
"entry:\n"
" store i8* bitcast (void(i8**)* @d to i8*), i8** %ptr\n"
" ret void\n"
"}\n"
"define void @b(i8** %ptr) {\n"
"entry:\n"
" store i8* bitcast (void(i8**)* @c to i8*), i8** %ptr\n"
" ret void\n"
"}\n"
"define void @c(i8** %ptr) {\n"
"entry:\n"
" call void @d(i8** %ptr)"
" ret void\n"
"}\n"
"define void @d(i8** %ptr) {\n"
"entry:\n"
" call void @c(i8** %ptr)"
" store i8* bitcast (void(i8**)* @b to i8*), i8** %ptr\n"
" ret void\n"
"}\n"
"define void @dead() {\n"
"entry:\n"
" ret void\n"
"}\n");
[PM/LCG] Teach the LazyCallGraph to maintain reference edges from every function to every defined function known to LLVM as a library function. LLVM can introduce calls to these functions either by replacing other library calls or by recognizing patterns (such as memset_pattern or vector math patterns) and replacing those with calls. When these library functions are actually defined in the module, we need to have reference edges to them initially so that we visit them during the CGSCC walk in the right order and can effectively rebuild the call graph afterward. This was discovered when building code with Fortify enabled as that is a common case of both inline definitions of library calls and simplifications of code into calling them. This can in extreme cases of LTO-ing with libc introduce *many* more reference edges. I discussed a bunch of different options with folks but all of them are unsatisfying. They either make the graph operations substantially more complex even when there are *no* defined libfuncs, or they introduce some other complexity into the callgraph. So this patch goes with the simplest possible solution of actual synthetic reference edges. If this proves to be a memory problem, I'm happy to implement one of the clever techniques to save memory here. llvm-svn: 308088
2017-07-15 16:08:19 +08:00
LazyCallGraph CG = buildCG(*M);
[PM/LCG] Teach LCG to support spurious reference edges. Somewhat amazingly, this only requires teaching it to clean them up when deleting a dead function from the graph. And we already have exactly the necessary data structures to do that in the parent RefSCCs. This allows ArgPromote to work in a much simpler way be merely letting reference edges linger in the graph after the causing IR is deleted. We will clean up these edges when we run any function pass over the IR, but don't remove them eagerly. This avoids all of the quadratic update issues both in the current pass manager and in my previous attempt with the new pass manager. Differential Revision: https://reviews.llvm.org/D29579 llvm-svn: 294663
2017-02-10 07:30:14 +08:00
// Insert spurious ref edges.
LazyCallGraph::Node &AN = CG.get(lookupFunction(*M, "a"));
LazyCallGraph::Node &BN = CG.get(lookupFunction(*M, "b"));
LazyCallGraph::Node &CN = CG.get(lookupFunction(*M, "c"));
LazyCallGraph::Node &DN = CG.get(lookupFunction(*M, "d"));
LazyCallGraph::Node &DeadN = CG.get(lookupFunction(*M, "dead"));
AN.populate();
BN.populate();
CN.populate();
DN.populate();
DeadN.populate();
CG.insertEdge(AN, DeadN, LazyCallGraph::Edge::Ref);
CG.insertEdge(BN, DeadN, LazyCallGraph::Edge::Ref);
CG.insertEdge(CN, DeadN, LazyCallGraph::Edge::Ref);
CG.insertEdge(DN, DeadN, LazyCallGraph::Edge::Ref);
// Force the graph to be fully expanded.
CG.buildRefSCCs();
auto I = CG.postorder_ref_scc_begin();
LazyCallGraph::RefSCC &DeadRC = *I++;
LazyCallGraph::RefSCC &RC1 = *I++;
LazyCallGraph::RefSCC &RC2 = *I++;
EXPECT_EQ(CG.postorder_ref_scc_end(), I);
Fix signed/unsigned comparison warnings llvm-svn: 297561
2017-03-11 21:02:31 +08:00
ASSERT_EQ(2, RC1.size());
[PM/LCG] Teach LCG to support spurious reference edges. Somewhat amazingly, this only requires teaching it to clean them up when deleting a dead function from the graph. And we already have exactly the necessary data structures to do that in the parent RefSCCs. This allows ArgPromote to work in a much simpler way be merely letting reference edges linger in the graph after the causing IR is deleted. We will clean up these edges when we run any function pass over the IR, but don't remove them eagerly. This avoids all of the quadratic update issues both in the current pass manager and in my previous attempt with the new pass manager. Differential Revision: https://reviews.llvm.org/D29579 llvm-svn: 294663
2017-02-10 07:30:14 +08:00
LazyCallGraph::SCC &C1 = RC1[0];
LazyCallGraph::SCC &C2 = RC1[1];
EXPECT_EQ(&DeadRC, CG.lookupRefSCC(DeadN));
EXPECT_EQ(&C1, CG.lookupSCC(DN));
EXPECT_EQ(&C1, CG.lookupSCC(CN));
EXPECT_EQ(&C2, CG.lookupSCC(BN));
EXPECT_EQ(&RC1, CG.lookupRefSCC(DN));
EXPECT_EQ(&RC1, CG.lookupRefSCC(CN));
EXPECT_EQ(&RC1, CG.lookupRefSCC(BN));
EXPECT_EQ(&RC2, CG.lookupRefSCC(AN));
// Now delete 'dead'. There are no uses of this function but there are
// spurious references.
CG.removeDeadFunction(DeadN.getFunction());
// The only observable change should be that the RefSCC is gone from the
// postorder sequence.
I = CG.postorder_ref_scc_begin();
EXPECT_EQ(&RC1, &*I++);
EXPECT_EQ(&RC2, &*I++);
EXPECT_EQ(CG.postorder_ref_scc_end(), I);
}
[LCG] Add a unittest for the LazyCallGraph. I had a weak moment and resisted this for too long. Just with the basic testing here I was able to exercise the analysis in more detail and sift out both type signature bugs in the API and a bug in the DFS numbering. All of these are fixed here as well. The unittests will be much more important for the mutation support where it is necessary to craft minimal mutations and then inspect the state of the graph. There is just no way to do that with a standard FileCheck test. However, unittesting these kinds of analyses is really quite easy, especially as they're designed with the new pass manager where there is essentially no infrastructure required to rig up the core logic and exercise it at an API level. As a minor aside about the DFS numbering bug, the DFS numbering used in LCG is a bit unusual. Rather than numbering from 0, we number from 1, and use 0 as the sentinel "unvisited" state. Other implementations often use '-1' for this, but I find it easier to deal with 0 and it shouldn't make any real difference provided someone doesn't write silly bugs like forgetting to actually initialize the DFS numbering. Oops. ;] llvm-svn: 206954
2014-04-23 16:08:49 +08:00
}