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
22 using namespace llvm;
23
24 static bool
addModuleFlags(Module & M,MapVector<std::pair<Function *,Function * >,uint64_t> & Counts)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
runCGProfilePass(Module & M,function_ref<BlockFrequencyInfo & (Function &)> GetBFI,function_ref<TargetTransformInfo & (Function &)> GetTTI,bool LazyBFI)47 static bool runCGProfilePass(
48 Module &M, function_ref<BlockFrequencyInfo &(Function &)> GetBFI,
49 function_ref<TargetTransformInfo &(Function &)> GetTTI, bool LazyBFI) {
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);
64 for (auto &F : M) {
65 // Avoid extra cost of running passes for BFI when the function doesn't have
66 // entry count. Since LazyBlockFrequencyInfoPass only exists in LPM, check
67 // if using LazyBlockFrequencyInfoPass.
68 // TODO: Remove LazyBFI when LazyBlockFrequencyInfoPass is available in NPM.
69 if (F.isDeclaration() || (LazyBFI && !F.getEntryCount()))
70 continue;
71 auto &BFI = GetBFI(F);
72 if (BFI.getEntryFreq() == 0)
73 continue;
74 TargetTransformInfo &TTI = GetTTI(F);
75 for (auto &BB : F) {
76 Optional<uint64_t> BBCount = BFI.getBlockProfileCount(&BB);
77 if (!BBCount)
78 continue;
79 for (auto &I : BB) {
80 CallBase *CB = dyn_cast<CallBase>(&I);
81 if (!CB)
82 continue;
83 if (CB->isIndirectCall()) {
84 InstrProfValueData ValueData[8];
85 uint32_t ActualNumValueData;
86 uint64_t TotalC;
87 if (!getValueProfDataFromInst(*CB, IPVK_IndirectCallTarget, 8,
88 ValueData, ActualNumValueData, TotalC))
89 continue;
90 for (const auto &VD :
91 ArrayRef<InstrProfValueData>(ValueData, ActualNumValueData)) {
92 UpdateCounts(TTI, &F, Symtab.getFunction(VD.Value), VD.Count);
93 }
94 continue;
95 }
96 UpdateCounts(TTI, &F, CB->getCalledFunction(), *BBCount);
97 }
98 }
99 }
100
101 return addModuleFlags(M, Counts);
102 }
103
run(Module & M,ModuleAnalysisManager & MAM)104 PreservedAnalyses CGProfilePass::run(Module &M, ModuleAnalysisManager &MAM) {
105 FunctionAnalysisManager &FAM =
106 MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
107 auto GetBFI = [&FAM](Function &F) -> BlockFrequencyInfo & {
108 return FAM.getResult<BlockFrequencyAnalysis>(F);
109 };
110 auto GetTTI = [&FAM](Function &F) -> TargetTransformInfo & {
111 return FAM.getResult<TargetIRAnalysis>(F);
112 };
113
114 runCGProfilePass(M, GetBFI, GetTTI, false);
115
116 return PreservedAnalyses::all();
117 }
118