llvm/lib/Transforms/Instrumentation/PGOForceFunctionAttrs.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/Transforms/Instrumentation/PGOForceFunctionAttrs.h"
  10 #include "llvm/Analysis/BlockFrequencyInfo.h"
  11 #include "llvm/Analysis/ProfileSummaryInfo.h"
  12 #include "llvm/IR/Module.h"
  13 #include "llvm/IR/PassManager.h"
  14 #include "llvm/Support/ErrorHandling.h"
  15
  16 using namespace llvm;
  17
  18 static bool shouldRunOnFunction(Function &F, ProfileSummaryInfo &PSI,
  19                                 FunctionAnalysisManager &FAM) {
  20   if (F.isDeclaration())
  21     return false;
  22   // Respect existing attributes.
  23   if (F.hasOptNone() || F.hasOptSize() || F.hasMinSize())
  24     return false;
  25   if (F.hasFnAttribute(Attribute::Cold))
  26     return true;
  27   if (!PSI.hasProfileSummary())
  28     return false;
  29   BlockFrequencyInfo &BFI = FAM.getResult<BlockFrequencyAnalysis>(F);
  30   return PSI.isFunctionColdInCallGraph(&F, BFI);
  31 }
  32
  33 PreservedAnalyses PGOForceFunctionAttrsPass::run(Module &M,
  34                                                  ModuleAnalysisManager &AM) {
  35   if (ColdType == PGOOptions::ColdFuncOpt::Default)
  36     return PreservedAnalyses::all();
  37   ProfileSummaryInfo &PSI = AM.getResult<ProfileSummaryAnalysis>(M);
  38   FunctionAnalysisManager &FAM =
  39       AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
  40   bool MadeChange = false;
  41   for (Function &F : M) {
  42     if (!shouldRunOnFunction(F, PSI, FAM))
  43       continue;
  44     switch (ColdType) {
  45     case PGOOptions::ColdFuncOpt::Default:
  46       llvm_unreachable("bailed out for default above");
  47       break;
  48     case PGOOptions::ColdFuncOpt::OptSize:
  49       F.addFnAttr(Attribute::OptimizeForSize);
  50       break;
  51     case PGOOptions::ColdFuncOpt::MinSize:
  52       F.addFnAttr(Attribute::MinSize);
  53       break;
  54     case PGOOptions::ColdFuncOpt::OptNone:
  55       // alwaysinline is incompatible with optnone.
  56       if (F.hasFnAttribute(Attribute::AlwaysInline))
  57         continue;
  58       F.addFnAttr(Attribute::OptimizeNone);
  59       F.addFnAttr(Attribute::NoInline);
  60       break;
  61     }
  62     MadeChange = true;
  63   }
  64   return MadeChange ? PreservedAnalyses::none() : PreservedAnalyses::all();
  65 }