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/PassManager.h"
18 #include "llvm/ProfileData/InstrProf.h"
19 #include "llvm/Transforms/Instrumentation.h"
20 #include <optional>
21 
22 using namespace llvm;
23 
24 static bool
25 addModuleFlags(Module &M,
26                MapVector<std::pair<Function *, Function *>, uint64_t> &Counts) {
27   if (Counts.empty())
28     return false;
29 
30   LLVMContext &Context = M.getContext();
31   MDBuilder MDB(Context);
32   std::vector<Metadata *> Nodes;
33 
34   for (auto E : Counts) {
35     Metadata *Vals[] = {ValueAsMetadata::get(E.first.first),
36                         ValueAsMetadata::get(E.first.second),
37                         MDB.createConstant(ConstantInt::get(
38                             Type::getInt64Ty(Context), E.second))};
39     Nodes.push_back(MDNode::get(Context, Vals));
40   }
41 
42   M.addModuleFlag(Module::Append, "CG Profile",
43                   MDTuple::getDistinct(Context, Nodes));
44   return true;
45 }
46 
47 static bool runCGProfilePass(Module &M, FunctionAnalysisManager &FAM,
48                              bool InLTO) {
49   MapVector<std::pair<Function *, Function *>, uint64_t> Counts;
50   InstrProfSymtab Symtab;
51   auto UpdateCounts = [&](TargetTransformInfo &TTI, Function *F,
52                           Function *CalledF, uint64_t NewCount) {
53     if (NewCount == 0)
54       return;
55     if (!CalledF || !TTI.isLoweredToCall(CalledF) ||
56         CalledF->hasDLLImportStorageClass())
57       return;
58     uint64_t &Count = Counts[std::make_pair(F, CalledF)];
59     Count = SaturatingAdd(Count, NewCount);
60   };
61   // Ignore error here.  Indirect calls are ignored if this fails.
62   (void)(bool)Symtab.create(M, InLTO);
63   for (auto &F : M) {
64     // Avoid extra cost of running passes for BFI when the function doesn't have
65     // entry count.
66     if (F.isDeclaration() || !F.getEntryCount())
67       continue;
68     auto &BFI = FAM.getResult<BlockFrequencyAnalysis>(F);
69     if (BFI.getEntryFreq() == BlockFrequency(0))
70       continue;
71     TargetTransformInfo &TTI = FAM.getResult<TargetIRAnalysis>(F);
72     for (auto &BB : F) {
73       std::optional<uint64_t> BBCount = BFI.getBlockProfileCount(&BB);
74       if (!BBCount)
75         continue;
76       for (auto &I : BB) {
77         CallBase *CB = dyn_cast<CallBase>(&I);
78         if (!CB)
79           continue;
80         if (CB->isIndirectCall()) {
81           InstrProfValueData ValueData[8];
82           uint32_t ActualNumValueData;
83           uint64_t TotalC;
84           if (!getValueProfDataFromInst(*CB, IPVK_IndirectCallTarget, 8,
85                                         ValueData, ActualNumValueData, TotalC))
86             continue;
87           for (const auto &VD :
88                ArrayRef<InstrProfValueData>(ValueData, ActualNumValueData)) {
89             UpdateCounts(TTI, &F, Symtab.getFunction(VD.Value), VD.Count);
90           }
91           continue;
92         }
93         UpdateCounts(TTI, &F, CB->getCalledFunction(), *BBCount);
94       }
95     }
96   }
97 
98   return addModuleFlags(M, Counts);
99 }
100 
101 PreservedAnalyses CGProfilePass::run(Module &M, ModuleAnalysisManager &MAM) {
102   FunctionAnalysisManager &FAM =
103       MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
104   runCGProfilePass(M, FAM, InLTO);
105 
106   return PreservedAnalyses::all();
107 }
108