llvm/lib/Transforms/Instrumentation/CGProfile.cpp

   1 //===-- CGProfile.cpp -----------------------------------------------------===//
   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/CGProfile.h"
  10
  11 #include "llvm/ADT/MapVector.h"
  12 #include "llvm/Analysis/BlockFrequencyInfo.h"
  13 #include "llvm/Analysis/LazyBlockFrequencyInfo.h"
  14 #include "llvm/Analysis/TargetTransformInfo.h"
  15 #include "llvm/IR/Constants.h"
  16 #include "llvm/IR/MDBuilder.h"
  17 #include "llvm/IR/Module.h"
  18 #include "llvm/IR/PassManager.h"
  19 #include "llvm/ProfileData/InstrProf.h"
  20 #include "llvm/Transforms/Utils/Instrumentation.h"
  21 #include <optional>
  22
  23 using namespace llvm;
  24
  25 static bool
  26 addModuleFlags(Module &M,
  27                MapVector<std::pair<Function *, Function *>, uint64_t> &Counts) {
  28   if (Counts.empty())
  29     return false;
  30
  31   LLVMContext &Context = M.getContext();
  32   MDBuilder MDB(Context);
  33   std::vector<Metadata *> Nodes;
  34
  35   for (auto E : Counts) {
  36     Metadata *Vals[] = {ValueAsMetadata::get(E.first.first),
  37                         ValueAsMetadata::get(E.first.second),
  38                         MDB.createConstant(ConstantInt::get(
  39                             Type::getInt64Ty(Context), E.second))};
  40     Nodes.push_back(MDNode::get(Context, Vals));
  41   }
  42
  43   M.addModuleFlag(Module::Append, "CG Profile",
  44                   MDTuple::getDistinct(Context, Nodes));
  45   return true;
  46 }
  47
  48 static bool runCGProfilePass(Module &M, FunctionAnalysisManager &FAM,
  49                              bool InLTO) {
  50   MapVector<std::pair<Function *, Function *>, uint64_t> Counts;
  51   InstrProfSymtab Symtab;
  52   auto UpdateCounts = [&](TargetTransformInfo &TTI, Function *F,
  53                           Function *CalledF, uint64_t NewCount) {
  54     if (NewCount == 0)
  55       return;
  56     if (!CalledF || !TTI.isLoweredToCall(CalledF) ||
  57         CalledF->hasDLLImportStorageClass())
  58       return;
  59     uint64_t &Count = Counts[std::make_pair(F, CalledF)];
  60     Count = SaturatingAdd(Count, NewCount);
  61   };
  62   // Ignore error here.  Indirect calls are ignored if this fails.
  63   (void)(bool)Symtab.create(M, InLTO);
  64   for (auto &F : M) {
  65     // Avoid extra cost of running passes for BFI when the function doesn't have
  66     // entry count.
  67     if (F.isDeclaration() || !F.getEntryCount())
  68       continue;
  69     auto &BFI = FAM.getResult<BlockFrequencyAnalysis>(F);
  70     if (BFI.getEntryFreq() == BlockFrequency(0))
  71       continue;
  72     TargetTransformInfo &TTI = FAM.getResult<TargetIRAnalysis>(F);
  73     for (auto &BB : F) {
  74       std::optional<uint64_t> BBCount = BFI.getBlockProfileCount(&BB);
  75       if (!BBCount)
  76         continue;
  77       for (auto &I : BB) {
  78         CallBase *CB = dyn_cast<CallBase>(&I);
  79         if (!CB)
  80           continue;
  81         if (CB->isIndirectCall()) {
  82           uint64_t TotalC;
  83           auto ValueData =
  84               getValueProfDataFromInst(*CB, IPVK_IndirectCallTarget, 8, TotalC);
  85           for (const auto &VD : ValueData)
  86             UpdateCounts(TTI, &F, Symtab.getFunction(VD.Value), VD.Count);
  87           continue;
  88         }
  89         UpdateCounts(TTI, &F, CB->getCalledFunction(), *BBCount);
  90       }
  91     }
  92   }
  93
  94   return addModuleFlags(M, Counts);
  95 }
  96
  97 PreservedAnalyses CGProfilePass::run(Module &M, ModuleAnalysisManager &MAM) {
  98   FunctionAnalysisManager &FAM =
  99       MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
 100   runCGProfilePass(M, FAM, InLTO);
 101
 102   return PreservedAnalyses::all();
 103 }