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[SamplePGO] More pipeline changes when flattened profile used in ThinLTO postlink 

Summary:
Follow on to D54819/r351476.

We also don't need to perform extra InstCombine pass when we aren't
loading the sample profile in the ThinLTO backend because we have a
flattened sample profile.

Additionally, for consistency and clarity, when we aren't reloading the
sample profile, perform ICP in the same location as non-sample PGO
backends. To this end I have moved the ICP invocation for non-SamplePGO
ThinLTO down into buildModuleSimplificationPipeline (partly addresses
the FIXME where we were previously setting this up).

Reviewers: wmi

Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D57705

llvm-svn: 353135
This commit is contained in:
Teresa Johnson 2019-02-05 04:09:19 +00:00
parent a9354b2f33
commit b0bf530fb5
2 changed files with 34 additions and 22 deletions
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52
llvm/lib/Passes/PassBuilder.cpp
View File

@ -589,6 +589,32 @@ PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
bool DebugLogging) {
ModulePassManager MPM(DebugLogging);
bool HasSampleProfile = PGOOpt && !PGOOpt->SampleProfileFile.empty();
// In ThinLTO mode, when flattened profile is used, all the available
// profile information will be annotated in PreLink phase so there is
// no need to load the profile again in PostLink.
bool LoadSampleProfile =
HasSampleProfile &&
!(FlattenedProfileUsed && Phase == ThinLTOPhase::PostLink);
// During the ThinLTO backend phase we perform early indirect call promotion
// here, before globalopt. Otherwise imported available_externally functions
// look unreferenced and are removed. If we are going to load the sample
// profile then defer until later.
// TODO: See if we can move later and consolidate with the location where
// we perform ICP when we are loading a sample profile.
// TODO: We pass HasSampleProfile (whether there was a sample profile file
// passed to the compile) to the SamplePGO flag of ICP. This is used to
// determine whether the new direct calls are annotated with prof metadata.
// Ideally this should be determined from whether the IR is annotated with
// sample profile, and not whether the a sample profile was provided on the
// command line. E.g. for flattened profiles where we will not be reloading
// the sample profile in the ThinLTO backend, we ideally shouldn't have to
// provide the sample profile file.
if (Phase == ThinLTOPhase::PostLink && !LoadSampleProfile)
MPM.addPass(PGOIndirectCallPromotion(true /* InLTO */, HasSampleProfile));
// Do basic inference of function attributes from known properties of system
// libraries and other oracles.
MPM.addPass(InferFunctionAttrsPass());
@ -609,21 +635,16 @@ PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
// More details about SamplePGO design can be found in:
// https://research.google.com/pubs/pub45290.html
// FIXME: revisit how SampleProfileLoad/Inliner/ICP is structured.
if (PGOOpt && !PGOOpt->SampleProfileFile.empty() &&
Phase == ThinLTOPhase::PostLink)
if (LoadSampleProfile)
EarlyFPM.addPass(InstCombinePass());
MPM.addPass(createModuleToFunctionPassAdaptor(std::move(EarlyFPM)));
if (PGOOpt && !PGOOpt->SampleProfileFile.empty()) {
if (LoadSampleProfile) {
// Annotate sample profile right after early FPM to ensure freshness of
// the debug info.
// In ThinLTO mode, when flattened profile is used, all the available
// profile information will be annotated in PreLink phase so there is
// no need to load the profile again in PostLink.
if (!(FlattenedProfileUsed && Phase == ThinLTOPhase::PostLink))
MPM.addPass(SampleProfileLoaderPass(PGOOpt->SampleProfileFile,
PGOOpt->ProfileRemappingFile,
Phase == ThinLTOPhase::PreLink));
MPM.addPass(SampleProfileLoaderPass(PGOOpt->SampleProfileFile,
PGOOpt->ProfileRemappingFile,
Phase == ThinLTOPhase::PreLink));
// Do not invoke ICP in the ThinLTOPrelink phase as it makes it hard
// for the profile annotation to be accurate in the ThinLTO backend.
if (Phase != ThinLTOPhase::PreLink)
@ -632,7 +653,7 @@ PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
// imported available_externally functions look unreferenced and are
// removed.
MPM.addPass(PGOIndirectCallPromotion(Phase == ThinLTOPhase::PostLink,
true));
true /* SamplePGO */));
}
// Interprocedural constant propagation now that basic cleanup has occurred
@ -990,15 +1011,6 @@ ModulePassManager PassBuilder::buildThinLTODefaultPipeline(
// Force any function attributes we want the rest of the pipeline to observe.
MPM.addPass(ForceFunctionAttrsPass());
// During the ThinLTO backend phase we perform early indirect call promotion
// here, before globalopt. Otherwise imported available_externally functions
// look unreferenced and are removed.
// FIXME: move this into buildModuleSimplificationPipeline to merge the logic
// with SamplePGO.
if (!PGOOpt || PGOOpt->SampleProfileFile.empty())
MPM.addPass(PGOIndirectCallPromotion(true /* InLTO */,
false /* SamplePGO */));
// Add the core simplification pipeline.
MPM.addPass(buildModuleSimplificationPipeline(Level, ThinLTOPhase::PostLink,
DebugLogging));

4
llvm/test/Other/new-pm-thinlto-defaults.ll
View File

@ -55,13 +55,13 @@
; CHECK-EP-PIPELINE-START-NEXT: Running pass: NoOpModulePass
; CHECK-DIS-NEXT: Running pass: ModuleToFunctionPassAdaptor<{{.*}}AddDiscriminatorsPass{{.*}}>
; CHECK-DIS-NEXT: Running analysis: InnerAnalysisManagerProxy
; CHECK-O-NEXT: Running pass: PassManager<{{.*}}Module{{.*}}>
; CHECK-O-NEXT: Starting llvm::Module pass manager run.
; CHECK-POSTLINK-O-NEXT: Running pass: PGOIndirectCallPromotion
; CHECK-POSTLINK-O-NEXT: Running analysis: ProfileSummaryAnalysis
; CHECK-POSTLINK-O-NEXT: Running analysis: InnerAnalysisManagerProxy
; CHECK-POSTLINK-O-NEXT: Running analysis: OptimizationRemarkEmitterAnalysis
; CHECK-POSTLINK-O-NEXT: Running analysis: PassInstrumentationAnalysis
; CHECK-O-NEXT: Running pass: PassManager<{{.*}}Module{{.*}}>
; CHECK-O-NEXT: Starting llvm::Module pass manager run.
; CHECK-O-NEXT: Running pass: InferFunctionAttrsPass
; CHECK-O-NEXT: Running analysis: TargetLibraryAnalysis
; CHECK-O-NEXT: Running pass: ModuleToFunctionPassAdaptor<{{.*}}PassManager{{.*}}>