From: Xinliang David Li Date: Tue, 5 Dec 2017 17:19:41 +0000 (+0000) Subject: [PGO] detect infinite loop and form MST properly X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9a320d928477b9ab9670179391152797a6ccde9a;p=llvm [PGO] detect infinite loop and form MST properly Differential Revision: http://reviews.llvm.org/D40702 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@319794 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/lib/Transforms/Instrumentation/CFGMST.h b/lib/Transforms/Instrumentation/CFGMST.h index 16e2e6b4e73..a1c2670c659 100644 --- a/lib/Transforms/Instrumentation/CFGMST.h +++ b/lib/Transforms/Instrumentation/CFGMST.h @@ -20,6 +20,7 @@ #include "llvm/Analysis/BlockFrequencyInfo.h" #include "llvm/Analysis/BranchProbabilityInfo.h" #include "llvm/Analysis/CFG.h" +#include "llvm/Analysis/LoopInfo.h" #include "llvm/Support/BranchProbability.h" #include "llvm/Support/Debug.h" #include "llvm/Support/raw_ostream.h" @@ -136,6 +137,21 @@ public: << " w = " << BBWeight << "\n"); } } + // check if there is any infinite loop. If yes, add a fake edge from + // the header block to the fake node: + for (auto *L : *LI) { + SmallVector ExitingBlocks; + L->getExitingBlocks(ExitingBlocks); + if (!ExitingBlocks.empty()) + continue; + auto *HB = L->getHeader(); + if (!HB) + continue; + addEdge(HB, nullptr, UINT64_MAX); + DEBUG(dbgs() << " Edge: from infinite loop header " + << HB->getName() << " to exit" + << " w = " << UINT64_MAX << "\n"); + } } // Sort CFG edges based on its weight. @@ -212,11 +228,13 @@ public: BranchProbabilityInfo *BPI; BlockFrequencyInfo *BFI; + LoopInfo *LI; public: CFGMST(Function &Func, BranchProbabilityInfo *BPI_ = nullptr, - BlockFrequencyInfo *BFI_ = nullptr) - : F(Func), BPI(BPI_), BFI(BFI_) { + BlockFrequencyInfo *BFI_ = nullptr, + LoopInfo *LI_ = nullptr) + : F(Func), BPI(BPI_), BFI(BFI_), LI(LI_) { buildEdges(); sortEdgesByWeight(); computeMinimumSpanningTree(); diff --git a/lib/Transforms/Instrumentation/PGOInstrumentation.cpp b/lib/Transforms/Instrumentation/PGOInstrumentation.cpp index 47278e19283..16ecb4a2415 100644 --- a/lib/Transforms/Instrumentation/PGOInstrumentation.cpp +++ b/lib/Transforms/Instrumentation/PGOInstrumentation.cpp @@ -390,6 +390,7 @@ private: void getAnalysisUsage(AnalysisUsage &AU) const override { AU.addRequired(); + AU.addRequired(); } }; @@ -415,6 +416,7 @@ private: void getAnalysisUsage(AnalysisUsage &AU) const override { AU.addRequired(); + AU.addRequired(); } }; @@ -426,6 +428,7 @@ INITIALIZE_PASS_BEGIN(PGOInstrumentationGenLegacyPass, "pgo-instr-gen", "PGO instrumentation.", false, false) INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass) INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfoWrapperPass) +INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass) INITIALIZE_PASS_END(PGOInstrumentationGenLegacyPass, "pgo-instr-gen", "PGO instrumentation.", false, false) @@ -439,6 +442,7 @@ INITIALIZE_PASS_BEGIN(PGOInstrumentationUseLegacyPass, "pgo-instr-use", "Read PGO instrumentation profile.", false, false) INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass) INITIALIZE_PASS_DEPENDENCY(BranchProbabilityInfoWrapperPass) +INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass) INITIALIZE_PASS_END(PGOInstrumentationUseLegacyPass, "pgo-instr-use", "Read PGO instrumentation profile.", false, false) @@ -530,9 +534,9 @@ public: Function &Func, std::unordered_multimap &ComdatMembers, bool CreateGlobalVar = false, BranchProbabilityInfo *BPI = nullptr, - BlockFrequencyInfo *BFI = nullptr) + BlockFrequencyInfo *BFI = nullptr, LoopInfo *LI = nullptr) : F(Func), ComdatMembers(ComdatMembers), ValueSites(IPVK_Last + 1), - SIVisitor(Func), MIVisitor(Func), MST(F, BPI, BFI) { + SIVisitor(Func), MIVisitor(Func), MST(F, BPI, BFI, LI) { // This should be done before CFG hash computation. SIVisitor.countSelects(Func); MIVisitor.countMemIntrinsics(Func); @@ -715,9 +719,10 @@ BasicBlock *FuncPGOInstrumentation::getInstrBB(Edge *E) { // Critical edges will be split. static void instrumentOneFunc( Function &F, Module *M, BranchProbabilityInfo *BPI, BlockFrequencyInfo *BFI, + LoopInfo *LI, std::unordered_multimap &ComdatMembers) { FuncPGOInstrumentation FuncInfo(F, ComdatMembers, true, BPI, - BFI); + BFI, LI); unsigned NumCounters = FuncInfo.getNumCounters(); uint32_t I = 0; @@ -844,9 +849,10 @@ public: PGOUseFunc(Function &Func, Module *Modu, std::unordered_multimap &ComdatMembers, BranchProbabilityInfo *BPI = nullptr, - BlockFrequencyInfo *BFIin = nullptr) + BlockFrequencyInfo *BFIin = nullptr, + LoopInfo *LI = nullptr) : F(Func), M(Modu), BFI(BFIin), - FuncInfo(Func, ComdatMembers, false, BPI, BFIin), + FuncInfo(Func, ComdatMembers, false, BPI, BFIin, LI), FreqAttr(FFA_Normal) {} // Read counts for the instrumented BB from profile. @@ -1379,7 +1385,8 @@ static void collectComdatMembers( static bool InstrumentAllFunctions( Module &M, function_ref LookupBPI, - function_ref LookupBFI) { + function_ref LookupBFI, + function_ref LookupLI) { createIRLevelProfileFlagVariable(M); std::unordered_multimap ComdatMembers; collectComdatMembers(M, ComdatMembers); @@ -1389,7 +1396,8 @@ static bool InstrumentAllFunctions( continue; auto *BPI = LookupBPI(F); auto *BFI = LookupBFI(F); - instrumentOneFunc(F, &M, BPI, BFI, ComdatMembers); + auto *LI = LookupLI(F); + instrumentOneFunc(F, &M, BPI, BFI, LI, ComdatMembers); } return true; } @@ -1404,7 +1412,10 @@ bool PGOInstrumentationGenLegacyPass::runOnModule(Module &M) { auto LookupBFI = [this](Function &F) { return &this->getAnalysis(F).getBFI(); }; - return InstrumentAllFunctions(M, LookupBPI, LookupBFI); + auto LookupLI = [this](Function &F) { + return &this->getAnalysis(F).getLoopInfo(); + }; + return InstrumentAllFunctions(M, LookupBPI, LookupBFI, LookupLI); } PreservedAnalyses PGOInstrumentationGen::run(Module &M, @@ -1418,7 +1429,11 @@ PreservedAnalyses PGOInstrumentationGen::run(Module &M, return &FAM.getResult(F); }; - if (!InstrumentAllFunctions(M, LookupBPI, LookupBFI)) + auto LookupLI = [&FAM](Function &F) { + return &FAM.getResult(F); + }; + + if (!InstrumentAllFunctions(M, LookupBPI, LookupBFI, LookupLI)) return PreservedAnalyses::all(); return PreservedAnalyses::none(); @@ -1427,7 +1442,8 @@ PreservedAnalyses PGOInstrumentationGen::run(Module &M, static bool annotateAllFunctions( Module &M, StringRef ProfileFileName, function_ref LookupBPI, - function_ref LookupBFI) { + function_ref LookupBFI, + function_ref LookupLI) { DEBUG(dbgs() << "Read in profile counters: "); auto &Ctx = M.getContext(); // Read the counter array from file. @@ -1463,7 +1479,8 @@ static bool annotateAllFunctions( continue; auto *BPI = LookupBPI(F); auto *BFI = LookupBFI(F); - PGOUseFunc Func(F, &M, ComdatMembers, BPI, BFI); + auto *LI = LookupLI(F); + PGOUseFunc Func(F, &M, ComdatMembers, BPI, BFI, LI); if (!Func.readCounters(PGOReader.get())) continue; Func.populateCounters(); @@ -1539,7 +1556,11 @@ PreservedAnalyses PGOInstrumentationUse::run(Module &M, return &FAM.getResult(F); }; - if (!annotateAllFunctions(M, ProfileFileName, LookupBPI, LookupBFI)) + auto LookupLI = [&FAM](Function &F) { + return &FAM.getResult(F); + }; + + if (!annotateAllFunctions(M, ProfileFileName, LookupBPI, LookupBFI, LookupLI)) return PreservedAnalyses::all(); return PreservedAnalyses::none(); @@ -1555,8 +1576,11 @@ bool PGOInstrumentationUseLegacyPass::runOnModule(Module &M) { auto LookupBFI = [this](Function &F) { return &this->getAnalysis(F).getBFI(); }; + auto LookupLI = [this](Function &F) { + return &this->getAnalysis(F).getLoopInfo(); + }; - return annotateAllFunctions(M, ProfileFileName, LookupBPI, LookupBFI); + return annotateAllFunctions(M, ProfileFileName, LookupBPI, LookupBFI, LookupLI); } static std::string getSimpleNodeName(const BasicBlock *Node) { diff --git a/test/Transforms/PGOProfile/infinite_loop_gen.ll b/test/Transforms/PGOProfile/infinite_loop_gen.ll new file mode 100644 index 00000000000..f200fc3857a --- /dev/null +++ b/test/Transforms/PGOProfile/infinite_loop_gen.ll @@ -0,0 +1,18 @@ +; RUN: opt < %s -pgo-instr-gen -S -o - | FileCheck %s + +define void @foo() { +entry: + br label %while.body +; CHECK: llvm.instrprof.increment + + while.body: ; preds = %entry, %while.body +; CHECK: llvm.instrprof.increment + call void (...) @bar() #2 + br label %while.body +} + +declare void @bar(...) + + +attributes #0 = { nounwind } +