93cdd1b5cf
The performance of cold functions shouldn't matter too much, so if we care about binary sizes, add an option to mark cold functions as optsize/minsize for binary size, or optnone for compile times [1]. Clang patch will be in a future patch. This is intended to replace `shouldOptimizeForSize(Function&, ...)`. We've seen multiple cases where calls to this expensive function, if not careful, can blow up compile times. I will clean up users of that function in a followup patch. Initial version: https://reviews.llvm.org/D149800 [1] https://discourse.llvm.org/t/rfc-new-feature-proposal-de-optimizing-cold-functions-using-pgo-info/56388
62 lines
2.2 KiB
C++
62 lines
2.2 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Instrumentation/PGOForceFunctionAttrs.h"
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#include "llvm/Analysis/BlockFrequencyInfo.h"
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#include "llvm/Analysis/ProfileSummaryInfo.h"
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#include "llvm/IR/PassManager.h"
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#include "llvm/Support/ErrorHandling.h"
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using namespace llvm;
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static bool shouldRunOnFunction(Function &F, ProfileSummaryInfo &PSI,
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FunctionAnalysisManager &FAM) {
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if (F.isDeclaration())
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return false;
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// Respect existing attributes.
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if (F.hasOptNone() || F.hasOptSize() || F.hasMinSize())
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return false;
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if (F.hasFnAttribute(Attribute::Cold))
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return true;
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if (!PSI.hasProfileSummary())
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return false;
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BlockFrequencyInfo &BFI = FAM.getResult<BlockFrequencyAnalysis>(F);
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return PSI.isFunctionColdInCallGraph(&F, BFI);
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}
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PreservedAnalyses PGOForceFunctionAttrsPass::run(Module &M,
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ModuleAnalysisManager &AM) {
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if (ColdType == PGOOptions::ColdFuncOpt::Default)
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return PreservedAnalyses::all();
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ProfileSummaryInfo &PSI = AM.getResult<ProfileSummaryAnalysis>(M);
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FunctionAnalysisManager &FAM =
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AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
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bool MadeChange = false;
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for (Function &F : M) {
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if (!shouldRunOnFunction(F, PSI, FAM))
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continue;
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MadeChange = true;
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switch (ColdType) {
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case PGOOptions::ColdFuncOpt::Default:
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llvm_unreachable("bailed out for default above");
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break;
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case PGOOptions::ColdFuncOpt::OptSize:
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F.addFnAttr(Attribute::OptimizeForSize);
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break;
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case PGOOptions::ColdFuncOpt::MinSize:
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F.addFnAttr(Attribute::MinSize);
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break;
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case PGOOptions::ColdFuncOpt::OptNone:
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F.addFnAttr(Attribute::OptimizeNone);
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F.addFnAttr(Attribute::NoInline);
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break;
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}
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}
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return MadeChange ? PreservedAnalyses::none() : PreservedAnalyses::all();
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}
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