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/InitializePasses.h"
19 #include "llvm/ProfileData/InstrProf.h"
20 #include "llvm/Transforms/Instrumentation.h"
21 #include <optional>
22
23 using namespace llvm;
24
25 static bool
addModuleFlags(Module & M,MapVector<std::pair<Function *,Function * >,uint64_t> & Counts)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
runCGProfilePass(Module & M,function_ref<BlockFrequencyInfo & (Function &)> GetBFI,function_ref<TargetTransformInfo & (Function &)> GetTTI,bool LazyBFI)48 static bool runCGProfilePass(
49 Module &M, function_ref<BlockFrequencyInfo &(Function &)> GetBFI,
50 function_ref<TargetTransformInfo &(Function &)> GetTTI, bool LazyBFI) {
51 MapVector<std::pair<Function *, Function *>, uint64_t> Counts;
52 InstrProfSymtab Symtab;
53 auto UpdateCounts = [&](TargetTransformInfo &TTI, Function *F,
54 Function *CalledF, uint64_t NewCount) {
55 if (NewCount == 0)
56 return;
57 if (!CalledF || !TTI.isLoweredToCall(CalledF) ||
58 CalledF->hasDLLImportStorageClass())
59 return;
60 uint64_t &Count = Counts[std::make_pair(F, CalledF)];
61 Count = SaturatingAdd(Count, NewCount);
62 };
63 // Ignore error here. Indirect calls are ignored if this fails.
64 (void)(bool) Symtab.create(M);
65 for (auto &F : M) {
66 // Avoid extra cost of running passes for BFI when the function doesn't have
67 // entry count. Since LazyBlockFrequencyInfoPass only exists in LPM, check
68 // if using LazyBlockFrequencyInfoPass.
69 // TODO: Remove LazyBFI when LazyBlockFrequencyInfoPass is available in NPM.
70 if (F.isDeclaration() || (LazyBFI && !F.getEntryCount()))
71 continue;
72 auto &BFI = GetBFI(F);
73 if (BFI.getEntryFreq() == 0)
74 continue;
75 TargetTransformInfo &TTI = GetTTI(F);
76 for (auto &BB : F) {
77 std::optional<uint64_t> BBCount = BFI.getBlockProfileCount(&BB);
78 if (!BBCount)
79 continue;
80 for (auto &I : BB) {
81 CallBase *CB = dyn_cast<CallBase>(&I);
82 if (!CB)
83 continue;
84 if (CB->isIndirectCall()) {
85 InstrProfValueData ValueData[8];
86 uint32_t ActualNumValueData;
87 uint64_t TotalC;
88 if (!getValueProfDataFromInst(*CB, IPVK_IndirectCallTarget, 8,
89 ValueData, ActualNumValueData, TotalC))
90 continue;
91 for (const auto &VD :
92 ArrayRef<InstrProfValueData>(ValueData, ActualNumValueData)) {
93 UpdateCounts(TTI, &F, Symtab.getFunction(VD.Value), VD.Count);
94 }
95 continue;
96 }
97 UpdateCounts(TTI, &F, CB->getCalledFunction(), *BBCount);
98 }
99 }
100 }
101
102 return addModuleFlags(M, Counts);
103 }
104
run(Module & M,ModuleAnalysisManager & MAM)105 PreservedAnalyses CGProfilePass::run(Module &M, ModuleAnalysisManager &MAM) {
106 FunctionAnalysisManager &FAM =
107 MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
108 auto GetBFI = [&FAM](Function &F) -> BlockFrequencyInfo & {
109 return FAM.getResult<BlockFrequencyAnalysis>(F);
110 };
111 auto GetTTI = [&FAM](Function &F) -> TargetTransformInfo & {
112 return FAM.getResult<TargetIRAnalysis>(F);
113 };
114
115 runCGProfilePass(M, GetBFI, GetTTI, false);
116
117 return PreservedAnalyses::all();
118 }
119