[llvm] r220345 - LTO: respect command-line options that disable vectorization.
Alexey Volkov
avolkov.intel at gmail.com
Mon Oct 27 13:43:39 PDT 2014
Hi Arnold,
Unfortunately this change doesn't fix the problem.
I still see messages "LV: Not vectorizing: No #pragma vectorize enable." in
debug log.
2014-10-27 1:07 GMT+03:00 Arnold Schwaighofer <aschwaighofer at apple.com>:
>
> r220652 restored the old behavior (defaulting to vectorization) while
> allowing to disable lto vectorization.
>
>
>
>
> 'disable-lto-vectorization' allows to disable lto vectorization if so
> desired.
>
>
>
>
> Alexey could you let me know whether your testcase works again?
>
>
>
>
> Thanks,
>
> Arnold
>
> On 10/24/14, JF Bastien wrote:
> > Yes, cl::opt<bool> defaults to false when there's no init. Changing
> the default will affect non-LTO too. This may be the right thing to do, but
> isn't my call. Turning it on only for LTO sounds better IMO, but
> I'm not sure what you're suggesting: I think there shouldn't be
> a vectorization flags that are different for LTO and for non-LTO.
> >
> > On Fri, Oct 24, 2014 at 8:57 AM, Arnold Schwaighofer <
> aschwaighofer at apple.com <aschwaighofer at apple.com>> wrote:
> >
> > > JF are you sure that “LoopVectorize” is set to true by default by the
> PassManager instance of libLTO?
> > >
> >
> > >
> > >
> >
> > > The reason why I forced these parameters to true is that this is not
> the case if I remember correctly.
> > >
> >
> > >
> > >
> >
> > > We wanted the default for libLTO to be with vectorization.
> > >
> >
> > >
> > >
> >
> > > PassManager.cpp:
> > >
> >
> > >
> > >
> >
> > > static cl::opt<bool>
> > >
> >
> > > RunLoopVectorization("vectorize-loops", cl::Hidden,
> > >
> >
> > > cl::desc("Run the Loop vectorization passes"));
> > >
> >
> > >
> > >
> >
> > > PassManagerBuilder::PassManagerBuilder() {
> > >
> >
> > > OptLevel = 2;
> > >
> >
> > > SizeLevel = 0;
> > >
> >
> > > LibraryInfo = nullptr;
> > >
> >
> > > Inliner = nullptr;
> > >
> >
> > > DisableTailCalls = false;
> > >
> >
> > > DisableUnitAtATime = false;
> > >
> >
> > > DisableUnrollLoops = false;
> > >
> >
> > > BBVectorize = RunBBVectorization;
> > >
> >
> > > SLPVectorize = RunSLPVectorization;
> > >
> >
> > > LoopVectorize = RunLoopVectorization;
> > >
> >
> > > RerollLoops = RunLoopRerolling;
> > >
> >
> > > LoadCombine = RunLoadCombine;
> > >
> >
> > > DisableGVNLoadPRE = false;
> > >
> >
> > > VerifyInput = false;
> > >
> >
> > > VerifyOutput = false;
> > >
> >
> > > StripDebug = false;
> > >
> >
> > > MergeFunctions = false;
> > >
> >
> > > }
> > >
> >
> > >
> > >
> >
> > > LTOCodeGenerator.cpp:
> > >
> >
> > >
> > >
> >
> > > /// Optimize merged modules using various IPO passes
> > >
> >
> > > bool LTOCodeGenerator::generateObjectFile(raw_ostream &out,
> > >
> >
> > > bool DisableOpt,
> > >
> >
> > > bool DisableInline,
> > >
> >
> > > bool DisableGVNLoadPRE,
> > >
> >
> > > std::string &errMsg) {
> > >
> >
> > > if (!this->determineTarget(errMsg))
> > >
> >
> > > return false;
> > >
> >
> > >
> > >
> >
> > > Module *mergedModule = IRLinker.getModule();
> > >
> >
> > >
> > >
> >
> > > // Mark which symbols can not be internalized
> > >
> >
> > > this->applyScopeRestrictions();
> > >
> >
> > >
> > >
> >
> > > // Instantiate the pass manager to organize the passes.
> > >
> >
> > > PassManager passes;
> > >
> >
> > >
> > >
> >
> > > // Add an appropriate DataLayout instance for this module...
> > >
> >
> > >
> mergedModule->setDataLayout(TargetMach->getSubtargetImpl()->getDataLayout());
> > >
> >
> > >
> > >
> >
> > > Triple TargetTriple(TargetMach->getTargetTriple());
> > >
> >
> > > PassManagerBuilder PMB;
> > >
> >
> > > PMB.DisableGVNLoadPRE = DisableGVNLoadPRE;
> > >
> >
> > > if (!DisableInline)
> > >
> >
> > > PMB.Inliner = createFunctionInliningPass();
> > >
> >
> > > PMB.LibraryInfo = new TargetLibraryInfo(TargetTriple);
> > >
> >
> > > if (DisableOpt)
> > >
> >
> > > PMB.OptLevel = 0;
> > >
> >
> > > PMB.VerifyInput = true;
> > >
> >
> > > PMB.VerifyOutput = true;
> > >
> >
> > >
> > >
> >
> > > PMB.populateLTOPassManager(passes, TargetMach);
> > >
> >
> > >
> > >
> >
> > >
> > >
> >
> > >
> > >
> >
> > > I think cl::opt<bool> defaults to false and your commit effectively
> disabled vectorization during LTO. We can recover this by changing the
> default cl::opt flags 'vectorize-loops’ and 'vectorize-slp' to
> true. If that does not work (because we make assumption somewhere about the
> default being false) we can follow the example of “DisableGVNLoadPRE” in
> LTOCodeGenerator.cpp and a a flag to disable Vectorization during LTO and
> pass that to the PassManager created in generateObjectFile.
> > >
> >
> > >
> > >
> >
> > > PMB.LoopVectorize = !DisableLTOVectorization;
> > >
> >
> > >
> > >
> >
> > >
> > >
> >
> > > Thanks,
> > >
> >
> > > Arnold
> > >
> >
> > >
> > >
> >
> > > > DisableUnrollLoops
> > >
> >
> > > > On Oct 24, 2014, at 5:27 AM, Alexey Volkov <avolkov.intel at gmail.com
> <avolkov.intel at gmail.com>> wrote:
> > >
> >
> > > >
> > >
> >
> > > > Hi JF,
> > >
> >
> > > >
> > >
> >
> > > > After your commit I saw a performance regression because of disabled
> Loop Vectorizer:
> > >
> >
> > > > LV: Not vectorizing: No #pragma vectorize enable.
> > >
> >
> > > > It is really strange since I used -Ofast -flto clang's options
> to build an application.
> > >
> >
> > > > Before this change loop was successfully vectorized by Loop
> Vectorizer.
> > >
> >
> > > >
> > >
> >
> > > > Thanks, Alexey.
> > >
> >
> > > >
> > >
> >
> > > > 2014-10-22 3:18 GMT+04:00 JF Bastien <jfb at google.com <jfb at google.com
> >>:
> > >
> >
> > > > Author: jfb
> > >
> >
> > > > Date: Tue Oct 21 18:18:21 2014
> > >
> >
> > > > New Revision: 220345
> > >
> >
> > > >
> > >
> >
> > > > URL: http://llvm.org/viewvc/llvm-project?rev=220345&view=rev
> > >
> >
> > > > Log:
> > >
> >
> > > > LTO: respect command-line options that disable vectorization.
> > >
> >
> > > >
> > >
> >
> > > > Summary: Patches 202051 and 208013 added calls to LTO's
> PassManager which unconditionally add LoopVectorizePass and
> SLPVectorizerPass instead of following the logic in
> PassManagerBuilder::populateModulePassManager and honoring the
> -vectorize-loops -run-slp-after-loop-vectorization flags.
> > >
> >
> > > >
> > >
> >
> > > > Reviewers: nadav, aschwaighofer, yijiang
> > >
> >
> > > >
> > >
> >
> > > > Subscribers: llvm-commits
> > >
> >
> > > >
> > >
> >
> > > > Differential Revision: http://reviews.llvm.org/D5884
> > >
> >
> > > >
> > >
> >
> > > > Modified:
> > >
> >
> > > > llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
> > >
> >
> > > >
> > >
> >
> > > > Modified: llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
> > >
> >
> > > > URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp?rev=220345&r1=220344&r2=220345&view=diff
> > >
> >
> > > >
> ==============================================================================
> > >
> >
> > > > --- llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp (original)
> > >
> >
> > > > +++ llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp Tue Oct 21
> 18:18:21 2014
> > >
> >
> > > > @@ -440,10 +440,12 @@ void PassManagerBuilder::addLTOOptimizat
> > >
> >
> > > > // More loops are countable; try to optimize them.
> > >
> >
> > > > PM.add(createIndVarSimplifyPass());
> > >
> >
> > > > PM.add(createLoopDeletionPass());
> > >
> >
> > > > - PM.add(createLoopVectorizePass(true, true));
> > >
> >
> > > > + PM.add(createLoopVectorizePass(DisableUnrollLoops,
> LoopVectorize));
> > >
> >
> > > >
> > >
> >
> > > > // More scalar chains could be vectorized due to more alias
> information
> > >
> >
> > > > - PM.add(createSLPVectorizerPass()); // Vectorize parallel scalar
> chains.
> > >
> >
> > > > + if (RunSLPAfterLoopVectorization)
> > >
> >
> > > > + if (SLPVectorize)
> > >
> >
> > > > + PM.add(createSLPVectorizerPass()); // Vectorize parallel
> scalar chains.
> > >
> >
> > > >
> > >
> >
> > > > // After vectorization, assume intrinsics may tell us more about
> pointer
> > >
> >
> > > > // alignments.
> > >
> >
> > > >
> > >
> >
> > > >
> > >
> >
> > > > _______________________________________________
> > >
> >
> > > > llvm-commits mailing list
> > >
> >
> > > > llvm-commits at cs.uiuc.edu <llvm-commits at cs.uiuc.edu>
> > >
> >
> > > > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> > >
> >
> > > >
> > >
> >
> > > >
> > >
> >
> > > >
> > >
> >
> > > > --
> > >
> >
> > > > Alexey Volkov
> > >
> >
> > > > Intel Corporation
> > >
> >
> > > > _______________________________________________
> > >
> >
> > > > llvm-commits mailing list
> > >
> >
> > > > llvm-commits at cs.uiuc.edu <llvm-commits at cs.uiuc.edu>
> > >
> >
> > > > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> > >
> >
> > >
> > >
> >
> > >
> > >
> > >
> >
> >
> >
> >
> >
>
--
Alexey Volkov
Intel Corporation
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