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/TargetTransformInfo.h"
  14 #include "llvm/IR/CallSite.h"
  15 #include "llvm/IR/Constants.h"
  16 #include "llvm/IR/Instructions.h"
  17 #include "llvm/IR/MDBuilder.h"
  18 #include "llvm/IR/PassManager.h"
  19 #include "llvm/ProfileData/InstrProf.h"
  20 #include "llvm/Transforms/Instrumentation.h"
  21
  22 #include <array>
  23
  24 using namespace llvm;
  25
  26 PreservedAnalyses CGProfilePass::run(Module &M, ModuleAnalysisManager &MAM) {
  27   MapVector<std::pair<Function *, Function *>, uint64_t> Counts;
  28   FunctionAnalysisManager &FAM =
  29       MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
  30   InstrProfSymtab Symtab;
  31   auto UpdateCounts = [&](TargetTransformInfo &TTI, Function *F,
  32                           Function *CalledF, uint64_t NewCount) {
  33     if (!CalledF || !TTI.isLoweredToCall(CalledF))
  34       return;
  35     uint64_t &Count = Counts[std::make_pair(F, CalledF)];
  36     Count = SaturatingAdd(Count, NewCount);
  37   };
  38   // Ignore error here.  Indirect calls are ignored if this fails.
  39   (void)(bool)Symtab.create(M);
  40   for (auto &F : M) {
  41     if (F.isDeclaration())
  42       continue;
  43     auto &BFI = FAM.getResult<BlockFrequencyAnalysis>(F);
  44     if (BFI.getEntryFreq() == 0)
  45       continue;
  46     TargetTransformInfo &TTI = FAM.getResult<TargetIRAnalysis>(F);
  47     for (auto &BB : F) {
  48       Optional<uint64_t> BBCount = BFI.getBlockProfileCount(&BB);
  49       if (!BBCount)
  50         continue;
  51       for (auto &I : BB) {
  52         CallSite CS(&I);
  53         if (!CS)
  54           continue;
  55         if (CS.isIndirectCall()) {
  56           InstrProfValueData ValueData[8];
  57           uint32_t ActualNumValueData;
  58           uint64_t TotalC;
  59           if (!getValueProfDataFromInst(*CS.getInstruction(),
  60                                         IPVK_IndirectCallTarget, 8, ValueData,
  61                                         ActualNumValueData, TotalC))
  62             continue;
  63           for (const auto &VD :
  64                ArrayRef<InstrProfValueData>(ValueData, ActualNumValueData)) {
  65             UpdateCounts(TTI, &F, Symtab.getFunction(VD.Value), VD.Count);
  66           }
  67           continue;
  68         }
  69         UpdateCounts(TTI, &F, CS.getCalledFunction(), *BBCount);
  70       }
  71     }
  72   }
  73
  74   addModuleFlags(M, Counts);
  75
  76   return PreservedAnalyses::all();
  77 }
  78
  79 void CGProfilePass::addModuleFlags(
  80     Module &M,
  81     MapVector<std::pair<Function *, Function *>, uint64_t> &Counts) const {
  82   if (Counts.empty())
  83     return;
  84
  85   LLVMContext &Context = M.getContext();
  86   MDBuilder MDB(Context);
  87   std::vector<Metadata *> Nodes;
  88
  89   for (auto E : Counts) {
  90     Metadata *Vals[] = {ValueAsMetadata::get(E.first.first),
  91                         ValueAsMetadata::get(E.first.second),
  92                         MDB.createConstant(ConstantInt::get(
  93                             Type::getInt64Ty(Context), E.second))};
  94     Nodes.push_back(MDNode::get(Context, Vals));
  95   }
  96
  97   M.addModuleFlag(Module::Append, "CG Profile", MDNode::get(Context, Nodes));
  98 }