1 //===-- CGProfile.cpp -----------------------------------------------------===//
2 //
3 //                      The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "llvm/Transforms/Instrumentation/CGProfile.h"
11 
12 #include "llvm/ADT/MapVector.h"
13 #include "llvm/Analysis/BlockFrequencyInfo.h"
14 #include "llvm/Analysis/TargetTransformInfo.h"
15 #include "llvm/IR/CallSite.h"
16 #include "llvm/IR/Constants.h"
17 #include "llvm/IR/Instructions.h"
18 #include "llvm/IR/MDBuilder.h"
19 #include "llvm/IR/PassManager.h"
20 #include "llvm/ProfileData/InstrProf.h"
21 #include "llvm/Transforms/Instrumentation.h"
22 
23 #include <array>
24 
25 using namespace llvm;
26 
27 PreservedAnalyses CGProfilePass::run(Module &M, ModuleAnalysisManager &MAM) {
28   MapVector<std::pair<Function *, Function *>, uint64_t> Counts;
29   FunctionAnalysisManager &FAM =
30       MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
31   InstrProfSymtab Symtab;
32   auto UpdateCounts = [&](TargetTransformInfo &TTI, Function *F,
33                           Function *CalledF, uint64_t NewCount) {
34     if (!CalledF || !TTI.isLoweredToCall(CalledF))
35       return;
36     uint64_t &Count = Counts[std::make_pair(F, CalledF)];
37     Count = SaturatingAdd(Count, NewCount);
38   };
39   // Ignore error here.  Indirect calls are ignored if this fails.
40   (void)(bool)Symtab.create(M);
41   for (auto &F : M) {
42     if (F.isDeclaration())
43       continue;
44     auto &BFI = FAM.getResult<BlockFrequencyAnalysis>(F);
45     if (BFI.getEntryFreq() == 0)
46       continue;
47     TargetTransformInfo &TTI = FAM.getResult<TargetIRAnalysis>(F);
48     for (auto &BB : F) {
49       Optional<uint64_t> BBCount = BFI.getBlockProfileCount(&BB);
50       if (!BBCount)
51         continue;
52       for (auto &I : BB) {
53         CallSite CS(&I);
54         if (!CS)
55           continue;
56         if (CS.isIndirectCall()) {
57           InstrProfValueData ValueData[8];
58           uint32_t ActualNumValueData;
59           uint64_t TotalC;
60           if (!getValueProfDataFromInst(*CS.getInstruction(),
61                                         IPVK_IndirectCallTarget, 8, ValueData,
62                                         ActualNumValueData, TotalC))
63             continue;
64           for (const auto &VD :
65                ArrayRef<InstrProfValueData>(ValueData, ActualNumValueData)) {
66             UpdateCounts(TTI, &F, Symtab.getFunction(VD.Value), VD.Count);
67           }
68           continue;
69         }
70         UpdateCounts(TTI, &F, CS.getCalledFunction(), *BBCount);
71       }
72     }
73   }
74 
75   addModuleFlags(M, Counts);
76 
77   return PreservedAnalyses::all();
78 }
79 
80 void CGProfilePass::addModuleFlags(
81     Module &M,
82     MapVector<std::pair<Function *, Function *>, uint64_t> &Counts) const {
83   if (Counts.empty())
84     return;
85 
86   LLVMContext &Context = M.getContext();
87   MDBuilder MDB(Context);
88   std::vector<Metadata *> Nodes;
89 
90   for (auto E : Counts) {
91     Metadata *Vals[] = {ValueAsMetadata::get(E.first.first),
92                         ValueAsMetadata::get(E.first.second),
93                         MDB.createConstant(ConstantInt::get(
94                             Type::getInt64Ty(Context), E.second))};
95     Nodes.push_back(MDNode::get(Context, Vals));
96   }
97 
98   M.addModuleFlag(Module::Append, "CG Profile", MDNode::get(Context, Nodes));
99 }
100