Currently, this pass only focuses on *trivial* loop unswitching. At that
reduced problem it remains significantly better than the current loop
unswitch:
- Old pass is worse than cubic complexity. New pass is (I think) linear.
- New pass is much simpler in its design by focusing on full unswitching. (See
below for details on this).
- New pass doesn't carry state for thresholds between pass iterations.
- New pass doesn't carry state for correctness (both miscompile and
infloop) between pass iterations.
- New pass produces substantially better code after unswitching.
- New pass can handle more trivial unswitch cases.
- New pass doesn't recompute the dominator tree for the entire function
and instead incrementally updates it.
I've ported all of the trivial unswitching test cases from the old pass
to the new one to make sure that major functionality isn't lost in the
process. For several of the test cases I've worked to improve the
precision and rigor of the CHECKs, but for many I've just updated them
to handle the new IR produced.
My initial motivation was the fact that the old pass carried state in
very unreliable ways between pass iterations, and these mechansims were
incompatible with the new pass manager. However, I discovered many more
improvements to make along the way.
This pass makes two very significant assumptions that enable most of these
improvements:
1) Focus on *full* unswitching -- that is, completely removing whatever
control flow construct is being unswitched from the loop. In the case
of trivial unswitching, this means removing the trivial (exiting)
edge. In non-trivial unswitching, this means removing the branch or
switch itself. This is in opposition to *partial* unswitching where
some part of the unswitched control flow remains in the loop. Partial
unswitching only really applies to switches and to folded branches.
These are very similar to full unrolling and partial unrolling. The
full form is an effective canonicalization, the partial form needs
a complex cost model, cannot be iterated, isn't canonicalizing, and
should be a separate pass that runs very late (much like unrolling).
2) Leverage LLVM's Loop machinery to the fullest. The original unswitch
dates from a time when a great deal of LLVM's loop infrastructure was
missing, ineffective, and/or unreliable. As a consequence, a lot of
complexity was added which we no longer need.
With these two overarching principles, I think we can build a fast and
effective unswitcher that fits in well in the new PM and in the
canonicalization pipeline. Some of the remaining functionality around
partial unswitching may not be relevant today (not many test cases or
benchmarks I can find) but if they are I'd like to add support for them
as a separate layer that runs very late in the pipeline.
Purely to make reviewing and introducing this code more manageable, I've
split this into first a trivial-unswitch-only pass and in the next patch
I'll add support for full non-trivial unswitching against a *fixed*
threshold, exactly like full unrolling. I even plan to re-use the
unrolling thresholds, as these are incredibly similar cost tradeoffs:
we're cloning a loop body in order to end up with simplified control
flow. We should only do that when the total growth is reasonably small.
One of the biggest changes with this pass compared to the previous one
is that previously, each individual trivial exiting edge from a switch
was unswitched separately as a branch. Now, we unswitch the entire
switch at once, with cases going to the various destinations. This lets
us unswitch multiple exiting edges in a single operation and also avoids
numerous extremely bad behaviors, where we would introduce 1000s of
branches to test for thousands of possible values, all of which would
take the exact same exit path bypassing the loop. Now we will use
a switch with 1000s of cases that can be efficiently lowered into
a jumptable. This avoids relying on somehow forming a switch out of the
branches or getting horrible code if that fails for any reason.
Another significant change is that this pass actively updates the CFG
based on unswitching. For trivial unswitching, this is actually very
easy because of the definition of loop simplified form. Doing this makes
the code coming out of loop unswitch dramatically more friendly. We
still should run loop-simplifycfg (at the least) after this to clean up,
but it will have to do a lot less work.
Finally, this pass makes much fewer attempts to simplify instructions
based on the unswitch. Something like loop-instsimplify, instcombine, or
GVN can be used to do increasingly powerful simplifications based on the
now dominating predicate. The old simplifications are things that
something like loop-instsimplify should get today or a very, very basic
loop-instcombine could get. Keeping that logic separate is a big
simplifying technique.
Most of the code in this pass that isn't in the old one has to do with
achieving specific goals:
- Updating the dominator tree as we go
- Unswitching all cases in a switch in a single step.
I think it is still shorter than just the trivial unswitching code in
the old pass despite having this functionality.
Differential Revision: https://reviews.llvm.org/D32409
llvm-svn: 301576
Just calling dropAllReferences leaves pointers to the ConstantExpr
behind, so we would eventually crash with a null pointer dereference.
Differential Revision: https://reviews.llvm.org/D32551
llvm-svn: 301575
Summary:
Misc improvements to debug output. Fix a couple typos and also dump the
value profile before we make any profitability checks.
Reviewers: davidxl
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32607
llvm-svn: 301574
Clang warns that a profile is out-of-date if it can't find a profile
record for any function in a TU. This warning became noisy after llvm
started allowing dead-stripping of instrumented functions.
To fix this, this patch changes the existing profile out-of-date warning
(-Wprofile-instr-out-of-date) so that it only complains about mismatched
data. Further, it introduces a new, off-by-default warning about missing
function data (-Wprofile-instr-missing).
Differential Revision: https://reviews.llvm.org/D28867
llvm-svn: 301570
Generate the better include paths. Instead of #include <llvm_header.h> doxygen
produces #include "llvm/Folder/llvm_header.h"
Patch by Yuka Takahashi (D32342)!
llvm-svn: 301569
Summary:
The type of the target frame index is intptr, not the type of the value we're
going to store into it. Without this change we crash in the attached test case
when trying to type-legalize a TargetFrameIndex.
Patchpoint lowering types the target frame index as intptr as well.
Reviewers: reames, bogner, arsenm
Subscribers: arsenm, mcrosier, llvm-commits
Differential Revision: https://reviews.llvm.org/D32256
llvm-svn: 301566
The UnknownPragmaHandlers added by DoPrintPreprocessedInput conflict with the
real PragmaHandlers from clang::Parser because they try to handle the same
#pragma directives. This makes it impossible to use a Preprocessor (that was
previously passed to DoPrintPreprocessedInput), as an Preprocessor for a
clang::Parser instance which is what we currently do in cling.
This patch removes the added UnknownPragmaHandler to avoid conflicts these
conflicts and leave the PragmaHandlers of the Preprocessors in a the same state
as before calling DoPrintPreprocessedInput.
Patch by Raphael Isemann (D32486)!
llvm-svn: 301563
libraries are properly unloaded when llvm_shutdown is called.
Summary:
This was mostly affecting usage of the JIT, where storing the library handles in
a set made iteration unordered/undefined. This lead to disagreement between the
JIT and native code as to what the address and implementation of particularly on
Windows with stdlib functions:
JIT: putenv_s("TEST", "VALUE") // called msvcrt.dll, putenv_s
JIT: getenv("TEST") -> "VALUE" // called msvcrt.dll, getenv
Native: getenv("TEST") -> NULL // called ucrt.dll, getenv
Also fixed is the issue of DynamicLibrary::getPermanentLibrary(0,0) on Windows
not giving priority to the process' symbols as it did on Unix.
Reviewers: chapuni, v.g.vassilev, lhames
Reviewed By: lhames
Subscribers: danalbert, srhines, mgorny, vsk, llvm-commits
Differential Revision: https://reviews.llvm.org/D30107
llvm-svn: 301562
This updates the regular expression used to match host/port pairs for the gdb-remote command to also match IPv6 addresses.
The IPv6 address matcher is very generic and does not really check for structural validity of the address. It turns out that IPv6 addresses are very complicated.
llvm-svn: 301559
Polly comes in two library flavors: One loadable module to use the
LLVM framework -load mechanism, and another one that host applications
can link to. These have very different requirements for Polly's
own dependencies.
The loadable module assumes that all its LLVM dependencies are already
available in the address space of the host application, and is not allowed
to bring in its own copy of any LLVM library (including the NVPTX
backend in case of Polly-ACC).
The non-module library is intended to be linked to using
target_link_libraries. CMake would then resolve all of its dependencies,
including NVPTX and ensure that only a single instance of each library
will be used.
Differential Revision: https://reviews.llvm.org/D32442
llvm-svn: 301558
Previously parsing of these were all grouped together into a
single master class that could parse any type of debug info
fragment.
With writing forthcoming, the complexity of each individual
fragment is enough to warrant them having their own classes so
that reading and writing of each fragment type can be grouped
together, but isolated from the code for reading and writing
other fragment types.
In doing so, I found a place where parsing code was duplicated
for the FileChecksums fragment, across llvm-readobj and the
CodeView library, and one of the implementations had a bug.
Now that the codepaths are merged, the bug is resolved.
Differential Revision: https://reviews.llvm.org/D32547
llvm-svn: 301557
We have a lot of very similarly named classes related to
dealing with module debug info. This patch has NFC, it just
renames some classes to be more descriptive (albeit slightly
more to type). The mapping from old to new class names is as
follows:
Old | New
ModInfo | DbiModuleDescriptor
ModuleSubstream | ModuleDebugFragment
ModStream | ModuleDebugStream
With the corresponding Builder classes renamed accordingly.
Differential Revision: https://reviews.llvm.org/D32506
llvm-svn: 301555
This patch abstracts the generation of Config.h and creates a dummy project entry point to allow generation of LLDB's Config header without performing a full CMake configuration.
This will enable the Xcode project to generate LLDB's Config header.
llvm-svn: 301553
Author: milena.vujosevic.janicic
Reviewers: sdardis
The code implements size reduction pass for MicroMIPS.
Load and store instructions are examined and transformed, if possible.
lw32 instruction is transformed into 16-bit instruction lwsp
sw32 instruction is transformed into 16-bit instruction swsp
Arithmetic instrcutions are examined and transformed, if possible.
addu32 instruction is transformed into 16-bit instruction addu16
subu32 instruction is transformed into 16-bit instruction subu16
Differential Revision: https://reviews.llvm.org/D15144
llvm-svn: 301540
Summary:
Previously, clang-format would accidentally parse an async function
declaration as a function expression, and thus not insert an unwrapped
line for async functions, causing subsequent functions to run into the
function:
async function f() {
x();
} function g() { ...
With this change, async functions get parsed as top level function
declarations and get their own unwrapped line context.
Reviewers: djasper
Subscribers: klimek, cfe-commits
Differential Revision: https://reviews.llvm.org/D32590
llvm-svn: 301538
before r301492, we could specify "*:1234" as an address to lldb-server
and it would interpret that as "any". I am not sure that's a good idea,
but we have usages of that in the test suite, and without this the
remote test suite fails.
I'm adding that back, as it does not seem it was an intended side-effect
of that change, but I am open to removing it in the future, after
discussion and test suite fixup.
llvm-svn: 301534
In getCmpSelInstrCost(), CondTy may actually be scalar while ValTy is a
vector when LoopVectorizer is the caller. Therefore the assert that CondTy
must be a vector type if ValTy is was wrong and is now removed.
Review: Ulrich Weigand
llvm-svn: 301533
for iOS < 9 and OS X < 10.11 X86 targets
This commit adds a new error that disallows methods that have parameters/return
values with a vector type for some older X86 targets. This diagnostic is
needed because objc_msgSend doesn't support SIMD vector registers/return values
on X86 in iOS < 9 and OS X < 10.11. Note that we don't necessarily know if the
vector argument/return value will use a SIMD register, so instead we chose to
be conservative and prohibit all vector types.
rdar://21662309
Differential Revision: https://reviews.llvm.org/D28670
llvm-svn: 301532
Fix a crash when trying to extend a value passed as a sign- or
zero-extended stack parameter. The cause of the crash was that we were
setting the size of the loaded value to 32 bits, and then tyring to
extend again to 32 bits.
This patch addresses the issue by also introducing a G_TRUNC after the
load. This will leave the unused bits to their original values set by
the caller, while being consistent about the types. For values that are
not extended, we just use a smaller load.
llvm-svn: 301531
It is useful to output size of ranges when address ranges
section of .gdb_index is dumped.
It helps to compare outputs produced by different linkers,
for example. In that case address ranges can look very different,
when they are the same at fact. Difference comes from different
low address because of different address of .text.
Differential revision: https://reviews.llvm.org/D32492
llvm-svn: 301527
George Rokos