llvm-project/llvm/lib/Target/Target.cpp

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//===-- Target.cpp --------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
2010-10-08 04:05:18 +08:00
// This file implements the common infrastructure (including C bindings) for
// libLLVMTarget.a, which implements target information.
//
//===----------------------------------------------------------------------===//
#include "llvm-c/Target.h"
#include "llvm-c/Initialization.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Value.h"
#include "llvm/InitializePasses.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include <cstring>
using namespace llvm;
[PM] Rework how the TargetLibraryInfo pass integrates with the new pass manager to support the actual uses of it. =] When I ported instcombine to the new pass manager I discover that it didn't work because TLI wasn't available in the right places. This is a somewhat surprising and/or subtle aspect of the new pass manager design that came up before but I think is useful to be reminded of: While the new pass manager *allows* a function pass to query a module analysis, it requires that the module analysis is already run and cached prior to the function pass manager starting up, possibly with a 'require<foo>' style utility in the pass pipeline. This is an intentional hurdle because using a module analysis from a function pass *requires* that the module analysis is run prior to entering the function pass manager. Otherwise the other functions in the module could be in who-knows-what state, etc. A somewhat surprising consequence of this design decision (at least to me) is that you have to design a function pass that leverages a module analysis to do so as an optional feature. Even if that means your function pass does no work in the absence of the module analysis, you have to handle that possibility and remain conservatively correct. This is a natural consequence of things being able to invalidate the module analysis and us being unable to re-run it. And it's a generally good thing because it lets us reorder passes arbitrarily without breaking correctness, etc. This ends up causing problems in one case. What if we have a module analysis that is *definitionally* impossible to invalidate. In the places this might come up, the analysis is usually also definitionally trivial to run even while other transformation passes run on the module, regardless of the state of anything. And so, it follows that it is natural to have a hard requirement on such analyses from a function pass. It turns out, that TargetLibraryInfo is just such an analysis, and InstCombine has a hard requirement on it. The approach I've taken here is to produce an analysis that models this flexibility by making it both a module and a function analysis. This exposes the fact that it is in fact safe to compute at any point. We can even make it a valid CGSCC analysis at some point if that is useful. However, we don't want to have a copy of the actual target library info state for each function! This state is specific to the triple. The somewhat direct and blunt approach here is to turn TLI into a pimpl, with the state and mutators in the implementation class and the query routines primarily in the wrapper. Then the analysis can lazily construct and cache the implementations, keyed on the triple, and on-demand produce wrappers of them for each function. One minor annoyance is that we will end up with a wrapper for each function in the module. While this is a bit wasteful (one pointer per function) it seems tolerable. And it has the advantage of ensuring that we pay the absolute minimum synchronization cost to access this information should we end up with a nice parallel function pass manager in the future. We could look into trying to mark when analysis results are especially cheap to recompute and more eagerly GC-ing the cached results, or we could look at supporting a variant of analyses whose results are specifically *not* cached and expected to just be used and discarded by the consumer. Either way, these seem like incremental enhancements that should happen when we start profiling the memory and CPU usage of the new pass manager and not before. The other minor annoyance is that if we end up using the TLI in both a module pass and a function pass, those will be produced by two separate analyses, and thus will point to separate copies of the implementation state. While a minor issue, I dislike this and would like to find a way to cleanly allow a single analysis instance to be used across multiple IR unit managers. But I don't have a good solution to this today, and I don't want to hold up all of the work waiting to come up with one. This too seems like a reasonable thing to incrementally improve later. llvm-svn: 226981
2015-01-24 10:06:09 +08:00
inline TargetLibraryInfoImpl *unwrap(LLVMTargetLibraryInfoRef P) {
return reinterpret_cast<TargetLibraryInfoImpl*>(P);
}
[PM] Rework how the TargetLibraryInfo pass integrates with the new pass manager to support the actual uses of it. =] When I ported instcombine to the new pass manager I discover that it didn't work because TLI wasn't available in the right places. This is a somewhat surprising and/or subtle aspect of the new pass manager design that came up before but I think is useful to be reminded of: While the new pass manager *allows* a function pass to query a module analysis, it requires that the module analysis is already run and cached prior to the function pass manager starting up, possibly with a 'require<foo>' style utility in the pass pipeline. This is an intentional hurdle because using a module analysis from a function pass *requires* that the module analysis is run prior to entering the function pass manager. Otherwise the other functions in the module could be in who-knows-what state, etc. A somewhat surprising consequence of this design decision (at least to me) is that you have to design a function pass that leverages a module analysis to do so as an optional feature. Even if that means your function pass does no work in the absence of the module analysis, you have to handle that possibility and remain conservatively correct. This is a natural consequence of things being able to invalidate the module analysis and us being unable to re-run it. And it's a generally good thing because it lets us reorder passes arbitrarily without breaking correctness, etc. This ends up causing problems in one case. What if we have a module analysis that is *definitionally* impossible to invalidate. In the places this might come up, the analysis is usually also definitionally trivial to run even while other transformation passes run on the module, regardless of the state of anything. And so, it follows that it is natural to have a hard requirement on such analyses from a function pass. It turns out, that TargetLibraryInfo is just such an analysis, and InstCombine has a hard requirement on it. The approach I've taken here is to produce an analysis that models this flexibility by making it both a module and a function analysis. This exposes the fact that it is in fact safe to compute at any point. We can even make it a valid CGSCC analysis at some point if that is useful. However, we don't want to have a copy of the actual target library info state for each function! This state is specific to the triple. The somewhat direct and blunt approach here is to turn TLI into a pimpl, with the state and mutators in the implementation class and the query routines primarily in the wrapper. Then the analysis can lazily construct and cache the implementations, keyed on the triple, and on-demand produce wrappers of them for each function. One minor annoyance is that we will end up with a wrapper for each function in the module. While this is a bit wasteful (one pointer per function) it seems tolerable. And it has the advantage of ensuring that we pay the absolute minimum synchronization cost to access this information should we end up with a nice parallel function pass manager in the future. We could look into trying to mark when analysis results are especially cheap to recompute and more eagerly GC-ing the cached results, or we could look at supporting a variant of analyses whose results are specifically *not* cached and expected to just be used and discarded by the consumer. Either way, these seem like incremental enhancements that should happen when we start profiling the memory and CPU usage of the new pass manager and not before. The other minor annoyance is that if we end up using the TLI in both a module pass and a function pass, those will be produced by two separate analyses, and thus will point to separate copies of the implementation state. While a minor issue, I dislike this and would like to find a way to cleanly allow a single analysis instance to be used across multiple IR unit managers. But I don't have a good solution to this today, and I don't want to hold up all of the work waiting to come up with one. This too seems like a reasonable thing to incrementally improve later. llvm-svn: 226981
2015-01-24 10:06:09 +08:00
inline LLVMTargetLibraryInfoRef wrap(const TargetLibraryInfoImpl *P) {
TargetLibraryInfoImpl *X = const_cast<TargetLibraryInfoImpl*>(P);
return reinterpret_cast<LLVMTargetLibraryInfoRef>(X);
}
void llvm::initializeTarget(PassRegistry &Registry) {
initializeTargetLibraryInfoWrapperPassPass(Registry);
[PM] Change the core design of the TTI analysis to use a polymorphic type erased interface and a single analysis pass rather than an extremely complex analysis group. The end result is that the TTI analysis can contain a type erased implementation that supports the polymorphic TTI interface. We can build one from a target-specific implementation or from a dummy one in the IR. I've also factored all of the code into "mix-in"-able base classes, including CRTP base classes to facilitate calling back up to the most specialized form when delegating horizontally across the surface. These aren't as clean as I would like and I'm planning to work on cleaning some of this up, but I wanted to start by putting into the right form. There are a number of reasons for this change, and this particular design. The first and foremost reason is that an analysis group is complete overkill, and the chaining delegation strategy was so opaque, confusing, and high overhead that TTI was suffering greatly for it. Several of the TTI functions had failed to be implemented in all places because of the chaining-based delegation making there be no checking of this. A few other functions were implemented with incorrect delegation. The message to me was very clear working on this -- the delegation and analysis group structure was too confusing to be useful here. The other reason of course is that this is *much* more natural fit for the new pass manager. This will lay the ground work for a type-erased per-function info object that can look up the correct subtarget and even cache it. Yet another benefit is that this will significantly simplify the interaction of the pass managers and the TargetMachine. See the future work below. The downside of this change is that it is very, very verbose. I'm going to work to improve that, but it is somewhat an implementation necessity in C++ to do type erasure. =/ I discussed this design really extensively with Eric and Hal prior to going down this path, and afterward showed them the result. No one was really thrilled with it, but there doesn't seem to be a substantially better alternative. Using a base class and virtual method dispatch would make the code much shorter, but as discussed in the update to the programmer's manual and elsewhere, a polymorphic interface feels like the more principled approach even if this is perhaps the least compelling example of it. ;] Ultimately, there is still a lot more to be done here, but this was the huge chunk that I couldn't really split things out of because this was the interface change to TTI. I've tried to minimize all the other parts of this. The follow up work should include at least: 1) Improving the TargetMachine interface by having it directly return a TTI object. Because we have a non-pass object with value semantics and an internal type erasure mechanism, we can narrow the interface of the TargetMachine to *just* do what we need: build and return a TTI object that we can then insert into the pass pipeline. 2) Make the TTI object be fully specialized for a particular function. This will include splitting off a minimal form of it which is sufficient for the inliner and the old pass manager. 3) Add a new pass manager analysis which produces TTI objects from the target machine for each function. This may actually be done as part of #2 in order to use the new analysis to implement #2. 4) Work on narrowing the API between TTI and the targets so that it is easier to understand and less verbose to type erase. 5) Work on narrowing the API between TTI and its clients so that it is easier to understand and less verbose to forward. 6) Try to improve the CRTP-based delegation. I feel like this code is just a bit messy and exacerbating the complexity of implementing the TTI in each target. Many thanks to Eric and Hal for their help here. I ended up blocked on this somewhat more abruptly than I expected, and so I appreciate getting it sorted out very quickly. Differential Revision: http://reviews.llvm.org/D7293 llvm-svn: 227669
2015-01-31 11:43:40 +08:00
initializeTargetTransformInfoWrapperPassPass(Registry);
}
void LLVMInitializeTarget(LLVMPassRegistryRef R) {
initializeTarget(*unwrap(R));
}
LLVMTargetDataRef LLVMGetModuleDataLayout(LLVMModuleRef M) {
return wrap(&unwrap(M)->getDataLayout());
}
void LLVMSetModuleDataLayout(LLVMModuleRef M, LLVMTargetDataRef DL) {
unwrap(M)->setDataLayout(*unwrap(DL));
}
LLVMTargetDataRef LLVMCreateTargetData(const char *StringRep) {
return wrap(new DataLayout(StringRep));
}
void LLVMDisposeTargetData(LLVMTargetDataRef TD) {
delete unwrap(TD);
}
void LLVMAddTargetLibraryInfo(LLVMTargetLibraryInfoRef TLI,
LLVMPassManagerRef PM) {
unwrap(PM)->add(new TargetLibraryInfoWrapperPass(*unwrap(TLI)));
}
char *LLVMCopyStringRepOfTargetData(LLVMTargetDataRef TD) {
std::string StringRep = unwrap(TD)->getStringRepresentation();
return strdup(StringRep.c_str());
}
LLVMByteOrdering LLVMByteOrder(LLVMTargetDataRef TD) {
return unwrap(TD)->isLittleEndian() ? LLVMLittleEndian : LLVMBigEndian;
}
unsigned LLVMPointerSize(LLVMTargetDataRef TD) {
return unwrap(TD)->getPointerSize(0);
}
unsigned LLVMPointerSizeForAS(LLVMTargetDataRef TD, unsigned AS) {
return unwrap(TD)->getPointerSize(AS);
}
LLVMTypeRef LLVMIntPtrType(LLVMTargetDataRef TD) {
Revert the series of commits starting with r166578 which introduced the getIntPtrType support for multiple address spaces via a pointer type, and also introduced a crasher bug in the constant folder reported in PR14233. These commits also contained several problems that should really be addressed before they are re-committed. I have avoided reverting various cleanups to the DataLayout APIs that are reasonable to have moving forward in order to reduce the amount of churn, and minimize the number of commits that were reverted. I've also manually updated merge conflicts and manually arranged for the getIntPtrType function to stay in DataLayout and to be defined in a plausible way after this revert. Thanks to Duncan for working through this exact strategy with me, and Nick Lewycky for tracking down the really annoying crasher this triggered. (Test case to follow in its own commit.) After discussing with Duncan extensively, and based on a note from Micah, I'm going to continue to back out some more of the more problematic patches in this series in order to ensure we go into the LLVM 3.2 branch with a reasonable story here. I'll send a note to llvmdev explaining what's going on and why. Summary of reverted revisions: r166634: Fix a compiler warning with an unused variable. r166607: Add some cleanup to the DataLayout changes requested by Chandler. r166596: Revert "Back out r166591, not sure why this made it through since I cancelled the command. Bleh, sorry about this! r166591: Delete a directory that wasn't supposed to be checked in yet. r166578: Add in support for getIntPtrType to get the pointer type based on the address space. llvm-svn: 167221
2012-11-01 16:07:29 +08:00
return wrap(unwrap(TD)->getIntPtrType(getGlobalContext()));
}
LLVMTypeRef LLVMIntPtrTypeForAS(LLVMTargetDataRef TD, unsigned AS) {
return wrap(unwrap(TD)->getIntPtrType(getGlobalContext(), AS));
}
LLVMTypeRef LLVMIntPtrTypeInContext(LLVMContextRef C, LLVMTargetDataRef TD) {
return wrap(unwrap(TD)->getIntPtrType(*unwrap(C)));
}
LLVMTypeRef LLVMIntPtrTypeForASInContext(LLVMContextRef C, LLVMTargetDataRef TD, unsigned AS) {
return wrap(unwrap(TD)->getIntPtrType(*unwrap(C), AS));
}
unsigned long long LLVMSizeOfTypeInBits(LLVMTargetDataRef TD, LLVMTypeRef Ty) {
return unwrap(TD)->getTypeSizeInBits(unwrap(Ty));
}
unsigned long long LLVMStoreSizeOfType(LLVMTargetDataRef TD, LLVMTypeRef Ty) {
return unwrap(TD)->getTypeStoreSize(unwrap(Ty));
}
unsigned long long LLVMABISizeOfType(LLVMTargetDataRef TD, LLVMTypeRef Ty) {
return unwrap(TD)->getTypeAllocSize(unwrap(Ty));
}
unsigned LLVMABIAlignmentOfType(LLVMTargetDataRef TD, LLVMTypeRef Ty) {
return unwrap(TD)->getABITypeAlignment(unwrap(Ty));
}
unsigned LLVMCallFrameAlignmentOfType(LLVMTargetDataRef TD, LLVMTypeRef Ty) {
return unwrap(TD)->getABITypeAlignment(unwrap(Ty));
}
unsigned LLVMPreferredAlignmentOfType(LLVMTargetDataRef TD, LLVMTypeRef Ty) {
return unwrap(TD)->getPrefTypeAlignment(unwrap(Ty));
}
unsigned LLVMPreferredAlignmentOfGlobal(LLVMTargetDataRef TD,
LLVMValueRef GlobalVar) {
return unwrap(TD)->getPreferredAlignment(unwrap<GlobalVariable>(GlobalVar));
}
unsigned LLVMElementAtOffset(LLVMTargetDataRef TD, LLVMTypeRef StructTy,
unsigned long long Offset) {
StructType *STy = unwrap<StructType>(StructTy);
return unwrap(TD)->getStructLayout(STy)->getElementContainingOffset(Offset);
}
unsigned long long LLVMOffsetOfElement(LLVMTargetDataRef TD, LLVMTypeRef StructTy,
unsigned Element) {
StructType *STy = unwrap<StructType>(StructTy);
return unwrap(TD)->getStructLayout(STy)->getElementOffset(Element);
}