X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FDwarfEHPrepare.cpp;h=e019dfbc8f7db0a666ae1581f8ac08121d17b8ac;hb=f606a6ed992d5e4e2877419b51e2a9b540b5e3f0;hp=76d084877d2fe8b59cd5e121f18435c5aee59f71;hpb=d04a8d4b33ff316ca4cf961e06c9e312eff8e64f;p=oota-llvm.git diff --git a/lib/CodeGen/DwarfEHPrepare.cpp b/lib/CodeGen/DwarfEHPrepare.cpp index 76d084877d2..e019dfbc8f7 100644 --- a/lib/CodeGen/DwarfEHPrepare.cpp +++ b/lib/CodeGen/DwarfEHPrepare.cpp @@ -12,57 +12,86 @@ // //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "dwarfehprepare" #include "llvm/CodeGen/Passes.h" +#include "llvm/ADT/BitVector.h" #include "llvm/ADT/Statistic.h" -#include "llvm/Analysis/Dominators.h" -#include "llvm/Function.h" -#include "llvm/Instructions.h" -#include "llvm/IntrinsicInst.h" -#include "llvm/MC/MCAsmInfo.h" -#include "llvm/Module.h" +#include "llvm/Analysis/CFG.h" +#include "llvm/Analysis/LibCallSemantics.h" +#include "llvm/Analysis/TargetTransformInfo.h" +#include "llvm/IR/Dominators.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/Module.h" #include "llvm/Pass.h" -#include "llvm/Support/CallSite.h" #include "llvm/Target/TargetLowering.h" -#include "llvm/Transforms/Utils/BasicBlockUtils.h" -#include "llvm/Transforms/Utils/SSAUpdater.h" +#include "llvm/Target/TargetSubtargetInfo.h" +#include "llvm/Transforms/Utils/Local.h" using namespace llvm; +#define DEBUG_TYPE "dwarfehprepare" + STATISTIC(NumResumesLowered, "Number of resume calls lowered"); namespace { class DwarfEHPrepare : public FunctionPass { const TargetMachine *TM; - const TargetLowering *TLI; // RewindFunction - _Unwind_Resume or the target equivalent. Constant *RewindFunction; + DominatorTree *DT; + const TargetLowering *TLI; + bool InsertUnwindResumeCalls(Function &Fn); Value *GetExceptionObject(ResumeInst *RI); + size_t + pruneUnreachableResumes(Function &Fn, + SmallVectorImpl &Resumes, + SmallVectorImpl &CleanupLPads); public: static char ID; // Pass identification, replacement for typeid. - DwarfEHPrepare(const TargetMachine *tm) : - FunctionPass(ID), TM(tm), TLI(TM->getTargetLowering()), - RewindFunction(0) { - initializeDominatorTreePass(*PassRegistry::getPassRegistry()); - } - virtual bool runOnFunction(Function &Fn); + // INITIALIZE_TM_PASS requires a default constructor, but it isn't used in + // practice. + DwarfEHPrepare() + : FunctionPass(ID), TM(nullptr), RewindFunction(nullptr), DT(nullptr), + TLI(nullptr) {} + + DwarfEHPrepare(const TargetMachine *TM) + : FunctionPass(ID), TM(TM), RewindFunction(nullptr), DT(nullptr), + TLI(nullptr) {} - virtual void getAnalysisUsage(AnalysisUsage &AU) const { } + bool runOnFunction(Function &Fn) override; - const char *getPassName() const { + bool doFinalization(Module &M) override { + RewindFunction = nullptr; + return false; + } + + void getAnalysisUsage(AnalysisUsage &AU) const override; + + const char *getPassName() const override { return "Exception handling preparation"; } }; } // end anonymous namespace char DwarfEHPrepare::ID = 0; +INITIALIZE_TM_PASS_BEGIN(DwarfEHPrepare, "dwarfehprepare", + "Prepare DWARF exceptions", false, false) +INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) +INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass) +INITIALIZE_TM_PASS_END(DwarfEHPrepare, "dwarfehprepare", + "Prepare DWARF exceptions", false, false) -FunctionPass *llvm::createDwarfEHPass(const TargetMachine *tm) { - return new DwarfEHPrepare(tm); +FunctionPass *llvm::createDwarfEHPass(const TargetMachine *TM) { + return new DwarfEHPrepare(TM); +} + +void DwarfEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const { + AU.addRequired(); + AU.addRequired(); } /// GetExceptionObject - Return the exception object from the value passed into @@ -70,10 +99,10 @@ FunctionPass *llvm::createDwarfEHPass(const TargetMachine *tm) { /// instructions, including the 'resume' instruction. Value *DwarfEHPrepare::GetExceptionObject(ResumeInst *RI) { Value *V = RI->getOperand(0); - Value *ExnObj = 0; + Value *ExnObj = nullptr; InsertValueInst *SelIVI = dyn_cast(V); - LoadInst *SelLoad = 0; - InsertValueInst *ExcIVI = 0; + LoadInst *SelLoad = nullptr; + InsertValueInst *ExcIVI = nullptr; bool EraseIVIs = false; if (SelIVI) { @@ -94,36 +123,88 @@ Value *DwarfEHPrepare::GetExceptionObject(ResumeInst *RI) { RI->eraseFromParent(); if (EraseIVIs) { - if (SelIVI->getNumUses() == 0) + if (SelIVI->use_empty()) SelIVI->eraseFromParent(); - if (ExcIVI->getNumUses() == 0) + if (ExcIVI->use_empty()) ExcIVI->eraseFromParent(); - if (SelLoad && SelLoad->getNumUses() == 0) + if (SelLoad && SelLoad->use_empty()) SelLoad->eraseFromParent(); } return ExnObj; } +/// Replace resumes that are not reachable from a cleanup landing pad with +/// unreachable and then simplify those blocks. +size_t DwarfEHPrepare::pruneUnreachableResumes( + Function &Fn, SmallVectorImpl &Resumes, + SmallVectorImpl &CleanupLPads) { + BitVector ResumeReachable(Resumes.size()); + size_t ResumeIndex = 0; + for (auto *RI : Resumes) { + for (auto *LP : CleanupLPads) { + if (isPotentiallyReachable(LP, RI, DT)) { + ResumeReachable.set(ResumeIndex); + break; + } + } + ++ResumeIndex; + } + + // If everything is reachable, there is no change. + if (ResumeReachable.all()) + return Resumes.size(); + + const TargetTransformInfo &TTI = + getAnalysis().getTTI(Fn); + LLVMContext &Ctx = Fn.getContext(); + + // Otherwise, insert unreachable instructions and call simplifycfg. + size_t ResumesLeft = 0; + for (size_t I = 0, E = Resumes.size(); I < E; ++I) { + ResumeInst *RI = Resumes[I]; + if (ResumeReachable[I]) { + Resumes[ResumesLeft++] = RI; + } else { + BasicBlock *BB = RI->getParent(); + new UnreachableInst(Ctx, RI); + RI->eraseFromParent(); + SimplifyCFG(BB, TTI, 1); + } + } + Resumes.resize(ResumesLeft); + return ResumesLeft; +} + /// InsertUnwindResumeCalls - Convert the ResumeInsts that are still present /// into calls to the appropriate _Unwind_Resume function. bool DwarfEHPrepare::InsertUnwindResumeCalls(Function &Fn) { - bool UsesNewEH = false; SmallVector Resumes; - for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) { - TerminatorInst *TI = I->getTerminator(); - if (ResumeInst *RI = dyn_cast(TI)) + SmallVector CleanupLPads; + for (BasicBlock &BB : Fn) { + if (auto *RI = dyn_cast(BB.getTerminator())) Resumes.push_back(RI); - else if (InvokeInst *II = dyn_cast(TI)) - UsesNewEH = II->getUnwindDest()->isLandingPad(); + if (auto *LP = BB.getLandingPadInst()) + if (LP->isCleanup()) + CleanupLPads.push_back(LP); } if (Resumes.empty()) - return UsesNewEH; + return false; + + // Check the personality, don't do anything if it's for MSVC. + EHPersonality Pers = classifyEHPersonality(Fn.getPersonalityFn()); + if (isMSVCEHPersonality(Pers)) + return false; + + LLVMContext &Ctx = Fn.getContext(); + + size_t ResumesLeft = pruneUnreachableResumes(Fn, Resumes, CleanupLPads); + if (ResumesLeft == 0) + return true; // We pruned them all. // Find the rewind function if we didn't already. if (!RewindFunction) { - LLVMContext &Ctx = Resumes[0]->getContext(); FunctionType *FTy = FunctionType::get(Type::getVoidTy(Ctx), Type::getInt8PtrTy(Ctx), false); const char *RewindName = TLI->getLibcallName(RTLIB::UNWIND_RESUME); @@ -131,10 +212,7 @@ bool DwarfEHPrepare::InsertUnwindResumeCalls(Function &Fn) { } // Create the basic block where the _Unwind_Resume call will live. - LLVMContext &Ctx = Fn.getContext(); - unsigned ResumesSize = Resumes.size(); - - if (ResumesSize == 1) { + if (ResumesLeft == 1) { // Instead of creating a new BB and PHI node, just append the call to // _Unwind_Resume to the end of the single resume block. ResumeInst *RI = Resumes.front(); @@ -151,14 +229,12 @@ bool DwarfEHPrepare::InsertUnwindResumeCalls(Function &Fn) { } BasicBlock *UnwindBB = BasicBlock::Create(Ctx, "unwind_resume", &Fn); - PHINode *PN = PHINode::Create(Type::getInt8PtrTy(Ctx), ResumesSize, + PHINode *PN = PHINode::Create(Type::getInt8PtrTy(Ctx), ResumesLeft, "exn.obj", UnwindBB); // Extract the exception object from the ResumeInst and add it to the PHI node // that feeds the _Unwind_Resume call. - for (SmallVectorImpl::iterator - I = Resumes.begin(), E = Resumes.end(); I != E; ++I) { - ResumeInst *RI = *I; + for (ResumeInst *RI : Resumes) { BasicBlock *Parent = RI->getParent(); BranchInst::Create(UnwindBB, Parent); @@ -178,6 +254,11 @@ bool DwarfEHPrepare::InsertUnwindResumeCalls(Function &Fn) { } bool DwarfEHPrepare::runOnFunction(Function &Fn) { + assert(TM && "DWARF EH preparation requires a target machine"); + DT = &getAnalysis().getDomTree(); + TLI = TM->getSubtargetImpl(Fn)->getTargetLowering(); bool Changed = InsertUnwindResumeCalls(Fn); + DT = nullptr; + TLI = nullptr; return Changed; }