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
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(
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 
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