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[Instrumentation] Add Call Graph Profile pass
This patch adds support for generating a call graph profile from Branch Frequency Info. The CGProfile module pass simply gets the block profile count for each BB and scans for call instructions. For each call instruction it adds an edge from the current function to the called function with the current BB block profile count as the weight. After scanning all the functions, it generates an appending module flag containing the data. The format looks like: !llvm.module.flags = !{!0} !0 = !{i32 5, !"CG Profile", !1} !1 = !{!2, !3, !4} ; List of edges !2 = !{void ()* @A, void ()* @b, i64 32} ; Edge from a to b with a weight of 32 !3 = !{void (i1)* @freq, void ()* @A, i64 11} !4 = !{void (i1)* @freq, void ()* @b, i64 20} Differential Revision: https://reviews.llvm.org/D48105 llvm-svn: 335306
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//===-- CGProfile.cpp -----------------------------------------------------===// | ||
// | ||
// The LLVM Compiler Infrastructure | ||
// | ||
// This file is distributed under the University of Illinois Open Source | ||
// License. See LICENSE.TXT for details. | ||
// | ||
//===----------------------------------------------------------------------===// | ||
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#include "llvm/ADT/MapVector.h" | ||
#include "llvm/Analysis/BlockFrequencyInfo.h" | ||
#include "llvm/Analysis/BranchProbabilityInfo.h" | ||
#include "llvm/IR/Constants.h" | ||
#include "llvm/IR/Instructions.h" | ||
#include "llvm/IR/MDBuilder.h" | ||
#include "llvm/IR/PassManager.h" | ||
#include "llvm/Transforms/Instrumentation.h" | ||
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#include <array> | ||
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using namespace llvm; | ||
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class CGProfilePass : public ModulePass { | ||
public: | ||
static char ID; | ||
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CGProfilePass() : ModulePass(ID) { | ||
initializeCGProfilePassPass(*PassRegistry::getPassRegistry()); | ||
} | ||
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StringRef getPassName() const override { return "CGProfilePass"; } | ||
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private: | ||
bool runOnModule(Module &M) override; | ||
bool addModuleFlags( | ||
Module &M, | ||
MapVector<std::pair<Function *, Function *>, uint64_t> &Counts) const; | ||
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void getAnalysisUsage(AnalysisUsage &AU) const override { | ||
AU.addRequired<BlockFrequencyInfoWrapperPass>(); | ||
AU.addRequired<BranchProbabilityInfoWrapperPass>(); | ||
} | ||
}; | ||
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bool CGProfilePass::runOnModule(Module &M) { | ||
if (skipModule(M)) | ||
return false; | ||
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MapVector<std::pair<Function *, Function *>, uint64_t> Counts; | ||
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for (auto &F : M) { | ||
if (F.isDeclaration()) | ||
continue; | ||
getAnalysis<BranchProbabilityInfoWrapperPass>(F).getBPI(); | ||
auto &BFI = getAnalysis<BlockFrequencyInfoWrapperPass>(F).getBFI(); | ||
for (const auto &BB : F) { | ||
Optional<uint64_t> BBCount = BFI.getBlockProfileCount(&BB); | ||
if (!BBCount) | ||
continue; | ||
for (const auto &I : BB) { | ||
auto *CI = dyn_cast<CallInst>(&I); | ||
if (!CI) | ||
continue; | ||
Function *CalledF = CI->getCalledFunction(); | ||
if (!CalledF || CalledF->isIntrinsic()) | ||
continue; | ||
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uint64_t &Count = Counts[std::make_pair(&F, CalledF)]; | ||
Count = SaturatingAdd(Count, *BBCount); | ||
} | ||
} | ||
} | ||
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return addModuleFlags(M, Counts); | ||
} | ||
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bool CGProfilePass::addModuleFlags( | ||
Module &M, | ||
MapVector<std::pair<Function *, Function *>, uint64_t> &Counts) const { | ||
if (Counts.empty()) | ||
return false; | ||
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LLVMContext &Context = M.getContext(); | ||
MDBuilder MDB(Context); | ||
std::vector<Metadata *> Nodes; | ||
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for (auto E : Counts) { | ||
SmallVector<Metadata *, 3> Vals; | ||
Vals.push_back(ValueAsMetadata::get(E.first.first)); | ||
Vals.push_back(ValueAsMetadata::get(E.first.second)); | ||
Vals.push_back(MDB.createConstant( | ||
ConstantInt::get(Type::getInt64Ty(Context), E.second))); | ||
Nodes.push_back(MDNode::get(Context, Vals)); | ||
} | ||
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M.addModuleFlag(Module::Append, "CG Profile", MDNode::get(Context, Nodes)); | ||
return true; | ||
} | ||
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char CGProfilePass::ID = 0; | ||
INITIALIZE_PASS_BEGIN(CGProfilePass, "cg-profile", | ||
"Generate profile information from the call graph.", | ||
false, false) | ||
INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass) | ||
INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfoWrapperPass) | ||
INITIALIZE_PASS_END(CGProfilePass, "cg-profile", | ||
"Generate profile information from the call graph.", false, | ||
false) | ||
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ModulePass *llvm::createCGProfilePass() { return new CGProfilePass(); } |
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; RUN: opt < %s -cg-profile -S | FileCheck %s | ||
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declare void @b() | ||
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define void @a() !prof !1 { | ||
call void @b() | ||
ret void | ||
} | ||
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define void @freq(i1 %cond) !prof !1 { | ||
br i1 %cond, label %A, label %B, !prof !2 | ||
A: | ||
call void @a(); | ||
ret void | ||
B: | ||
call void @b(); | ||
ret void | ||
} | ||
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!1 = !{!"function_entry_count", i64 32} | ||
!2 = !{!"branch_weights", i32 5, i32 10} | ||
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; CHECK: !llvm.module.flags = !{![[cgprof:[0-9]+]]} | ||
; CHECK: ![[cgprof]] = !{i32 5, !"CG Profile", ![[prof:[0-9]+]]} | ||
; CHECK: ![[prof]] = !{![[e0:[0-9]+]], ![[e1:[0-9]+]], ![[e2:[0-9]+]]} | ||
; CHECK: ![[e0]] = !{void ()* @a, void ()* @b, i64 32} | ||
; CHECK: ![[e1]] = !{void (i1)* @freq, void ()* @a, i64 11} | ||
; CHECK: ![[e2]] = !{void (i1)* @freq, void ()* @b, i64 20} |
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; RUN: llc -filetype=asm %s -o - -mtriple x86_64-pc-linux-gnu | FileCheck %s | ||
; RUN: llc -filetype=obj %s -o %t -mtriple x86_64-pc-linux-gnu | ||
; RUN: llvm-readobj -elf-cg-profile %t | FileCheck %s --check-prefix=OBJ | ||
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declare void @b() | ||
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define void @a() { | ||
call void @b() | ||
ret void | ||
} | ||
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define void @freq(i1 %cond) { | ||
br i1 %cond, label %A, label %B | ||
A: | ||
call void @a(); | ||
ret void | ||
B: | ||
call void @b(); | ||
ret void | ||
} | ||
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!llvm.module.flags = !{!0} | ||
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!0 = !{i32 5, !"CG Profile", !1} | ||
!1 = !{!2, !3, !4} | ||
!2 = !{void ()* @a, void ()* @b, i64 32} | ||
!3 = !{void (i1)* @freq, void ()* @a, i64 11} | ||
!4 = !{void (i1)* @freq, void ()* @b, i64 20} | ||
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; CHECK: .cg_profile a, b, 32 | ||
; CHECK: .cg_profile freq, a, 11 | ||
; CHECK: .cg_profile freq, b, 20 | ||
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; OBJ: CGProfile [ | ||
; OBJ: CGProfileEntry { | ||
; OBJ: From: a | ||
; OBJ: To: b | ||
; OBJ: Weight: 32 | ||
; OBJ: } | ||
; OBJ: CGProfileEntry { | ||
; OBJ: From: freq | ||
; OBJ: To: a | ||
; OBJ: Weight: 11 | ||
; OBJ: } | ||
; OBJ: CGProfileEntry { | ||
; OBJ: From: freq | ||
; OBJ: To: b | ||
; OBJ: Weight: 20 | ||
; OBJ: } | ||
; OBJ:] |
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; RUN: not llvm-as < %s -o /dev/null 2>&1 | FileCheck %s | ||
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declare void @b() | ||
declare void @a() | ||
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!llvm.module.flags = !{!0} | ||
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!0 = !{i32 5, !"CG Profile", !1} | ||
!1 = !{!2, !"", !3, !4, !5, !6, !7, !8} | ||
!2 = !{void ()* @a, void ()* @b, i64 32} | ||
!3 = !{void ()* @a, void ()* @b} | ||
!4 = !{void ()* @a, void ()* @b, i64 32, i64 32} | ||
!5 = !{!"a", void ()* @b, i64 32} | ||
!6 = !{void ()* @a, !"b", i64 32} | ||
!7 = !{void ()* @a, void ()* @b, !""} | ||
!8 = !{void ()* @a, void ()* @b, null} | ||
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; CHECK: expected a MDNode triple | ||
; CHECK: !"" | ||
; CHECK: expected a MDNode triple | ||
; CHECK: !3 = !{void ()* @a, void ()* @b} | ||
; CHECK: expected a MDNode triple | ||
; CHECK: !4 = !{void ()* @a, void ()* @b, i64 32, i64 32} | ||
; CHECK: expected a Function | ||
; CHECK: !"a" | ||
; CHECK: expected a Function | ||
; CHECK: !"b" | ||
; CHECK: expected an integer constant | ||
; CHECK: !"" | ||
; CHECK: expected an integer constant |