X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FDwarfEHPrepare.cpp;h=0ebb5b0db70e1417ab13a5b355b18f2ec36e7716;hb=ab2e3e2d7074207e2a4bb15e2913fa83795bb1ca;hp=57f45ec199d480fea54bdc456fafe14f45a4cce0;hpb=9ccaf53ada99c63737547c0235baeb8454b04e80;p=oota-llvm.git diff --git a/lib/CodeGen/DwarfEHPrepare.cpp b/lib/CodeGen/DwarfEHPrepare.cpp index 57f45ec199d..0ebb5b0db70 100644 --- a/lib/CodeGen/DwarfEHPrepare.cpp +++ b/lib/CodeGen/DwarfEHPrepare.cpp @@ -25,19 +25,17 @@ #include "llvm/Support/CallSite.h" #include "llvm/Target/TargetLowering.h" #include "llvm/Transforms/Utils/BasicBlockUtils.h" -#include "llvm/Transforms/Utils/PromoteMemToReg.h" +#include "llvm/Transforms/Utils/SSAUpdater.h" using namespace llvm; STATISTIC(NumLandingPadsSplit, "Number of landing pads split"); STATISTIC(NumUnwindsLowered, "Number of unwind instructions lowered"); STATISTIC(NumExceptionValuesMoved, "Number of eh.exception calls moved"); -STATISTIC(NumStackTempsIntroduced, "Number of stack temporaries introduced"); namespace { class DwarfEHPrepare : public FunctionPass { const TargetMachine *TM; const TargetLowering *TLI; - bool CompileFast; // The eh.exception intrinsic. Function *ExceptionValueIntrinsic; @@ -45,7 +43,7 @@ namespace { // The eh.selector intrinsic. Function *SelectorIntrinsic; - // _Unwind_Resume_or_Rethrow call. + // _Unwind_Resume_or_Rethrow or _Unwind_SjLj_Resume call. Constant *URoR; // The EH language-specific catch-all type. @@ -54,9 +52,8 @@ namespace { // _Unwind_Resume or the target equivalent. Constant *RewindFunction; - // Dominator info is used when turning stack temporaries into registers. + // We both use and preserve dominator info. DominatorTree *DT; - DominanceFrontier *DF; // The function we are running on. Function *F; @@ -65,25 +62,11 @@ namespace { typedef SmallPtrSet BBSet; BBSet LandingPads; - // Stack temporary used to hold eh.exception values. - AllocaInst *ExceptionValueVar; - bool NormalizeLandingPads(); bool LowerUnwinds(); bool MoveExceptionValueCalls(); - bool FinishStackTemporaries(); - bool PromoteStackTemporaries(); Instruction *CreateExceptionValueCall(BasicBlock *BB); - Instruction *CreateValueLoad(BasicBlock *BB); - - /// CreateReadOfExceptionValue - Return the result of the eh.exception - /// intrinsic by calling the intrinsic if in a landing pad, or loading it - /// from the exception value variable otherwise. - Instruction *CreateReadOfExceptionValue(BasicBlock *BB) { - return LandingPads.count(BB) ? - CreateExceptionValueCall(BB) : CreateValueLoad(BB); - } /// CleanupSelectors - Any remaining eh.selector intrinsic calls which still /// use the "llvm.eh.catch.all.value" call need to convert to using its @@ -99,11 +82,11 @@ namespace { /// FindAllURoRInvokes - Find all URoR invokes in the function. void FindAllURoRInvokes(SmallPtrSet &URoRInvokes); - /// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow" - /// calls. The "unwind" part of these invokes jump to a landing pad within - /// the current function. This is a candidate to merge the selector - /// associated with the URoR invoke with the one from the URoR's landing - /// pad. + /// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow" or + /// "_Unwind_SjLj_Resume" calls. The "unwind" part of these invokes jump to + /// a landing pad within the current function. This is a candidate to merge + /// the selector associated with the URoR invoke with the one from the + /// URoR's landing pad. bool HandleURoRInvokes(); /// FindSelectorAndURoR - Find the eh.selector call and URoR call associated @@ -112,69 +95,21 @@ namespace { bool FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke, SmallPtrSet &SelCalls); - /// DoMem2RegPromotion - Take an alloca call and promote it from memory to a - /// register. - bool DoMem2RegPromotion(Value *V) { - AllocaInst *AI = dyn_cast(V); - if (!AI || !isAllocaPromotable(AI)) return false; - - // Turn the alloca into a register. - std::vector Allocas(1, AI); - PromoteMemToReg(Allocas, *DT, *DF); - return true; - } - - /// PromoteStoreInst - Perform Mem2Reg on a StoreInst. - bool PromoteStoreInst(StoreInst *SI) { - if (!SI || !DT || !DF) return false; - if (DoMem2RegPromotion(SI->getOperand(1))) - return true; - return false; - } - - /// PromoteEHPtrStore - Promote the storing of an EH pointer into a - /// register. This should get rid of the store and subsequent loads. - bool PromoteEHPtrStore(IntrinsicInst *II) { - if (!DT || !DF) return false; - - bool Changed = false; - StoreInst *SI; - - while (1) { - SI = 0; - for (Value::use_iterator - I = II->use_begin(), E = II->use_end(); I != E; ++I) { - SI = dyn_cast(*I); - if (SI) break; - } - - if (!PromoteStoreInst(SI)) - break; - - Changed = true; - } - - return Changed; - } - public: static char ID; // Pass identification, replacement for typeid. - DwarfEHPrepare(const TargetMachine *tm, bool fast) : + DwarfEHPrepare(const TargetMachine *tm) : FunctionPass(ID), TM(tm), TLI(TM->getTargetLowering()), - CompileFast(fast), ExceptionValueIntrinsic(0), SelectorIntrinsic(0), - URoR(0), EHCatchAllValue(0), RewindFunction(0) {} + URoR(0), EHCatchAllValue(0), RewindFunction(0) { + initializeDominatorTreePass(*PassRegistry::getPassRegistry()); + } virtual bool runOnFunction(Function &Fn); - // getAnalysisUsage - We need dominance frontiers for memory promotion. + // getAnalysisUsage - We need the dominator tree for handling URoR. virtual void getAnalysisUsage(AnalysisUsage &AU) const { - if (!CompileFast) - AU.addRequired(); + AU.addRequired(); AU.addPreserved(); - if (!CompileFast) - AU.addRequired(); - AU.addPreserved(); } const char *getPassName() const { @@ -186,8 +121,8 @@ namespace { char DwarfEHPrepare::ID = 0; -FunctionPass *llvm::createDwarfEHPass(const TargetMachine *tm, bool fast) { - return new DwarfEHPrepare(tm, fast); +FunctionPass *llvm::createDwarfEHPass(const TargetMachine *tm) { + return new DwarfEHPrepare(tm); } /// HasCatchAllInSelector - Return true if the intrinsic instruction has a @@ -268,7 +203,6 @@ DwarfEHPrepare::FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke, SmallPtrSet SeenPHIs; bool Changed = false; - restart: for (Value::use_iterator I = Inst->use_begin(), E = Inst->use_end(); I != E; ++I) { Instruction *II = dyn_cast(*I); @@ -282,11 +216,6 @@ DwarfEHPrepare::FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke, URoRInvoke = true; } else if (CastInst *CI = dyn_cast(II)) { Changed |= FindSelectorAndURoR(CI, URoRInvoke, SelCalls); - } else if (StoreInst *SI = dyn_cast(II)) { - if (!PromoteStoreInst(SI)) continue; - Changed = true; - SeenPHIs.clear(); - goto restart; // Uses may have changed, restart loop. } else if (PHINode *PN = dyn_cast(II)) { if (SeenPHIs.insert(PN)) // Don't process a PHI node more than once. @@ -297,10 +226,11 @@ DwarfEHPrepare::FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke, return Changed; } -/// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow" calls. The -/// "unwind" part of these invokes jump to a landing pad within the current -/// function. This is a candidate to merge the selector associated with the URoR -/// invoke with the one from the URoR's landing pad. +/// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow" or +/// "_Unwind_SjLj_Resume" calls. The "unwind" part of these invokes jump to a +/// landing pad within the current function. This is a candidate to merge the +/// selector associated with the URoR invoke with the one from the URoR's +/// landing pad. bool DwarfEHPrepare::HandleURoRInvokes() { if (!EHCatchAllValue) { EHCatchAllValue = @@ -318,13 +248,12 @@ bool DwarfEHPrepare::HandleURoRInvokes() { SmallPtrSet CatchAllSels; FindAllCleanupSelectors(Sels, CatchAllSels); - if (!DT) - // We require DominatorTree information. - return CleanupSelectors(CatchAllSels); - if (!URoR) { URoR = F->getParent()->getFunction("_Unwind_Resume_or_Rethrow"); - if (!URoR) return CleanupSelectors(CatchAllSels); + if (!URoR) { + URoR = F->getParent()->getFunction("_Unwind_SjLj_Resume"); + if (!URoR) return CleanupSelectors(CatchAllSels); + } } SmallPtrSet URoRInvokes; @@ -363,8 +292,6 @@ bool DwarfEHPrepare::HandleURoRInvokes() { IntrinsicInst *EHPtr = dyn_cast(*I); if (!EHPtr || EHPtr->getParent()->getParent() != F) continue; - Changed |= PromoteEHPtrStore(EHPtr); - bool URoRInvoke = false; SmallPtrSet SelCalls; Changed |= FindSelectorAndURoR(EHPtr, URoRInvoke, SelCalls); @@ -532,11 +459,8 @@ bool DwarfEHPrepare::NormalizeLandingPads() { // Add a fallthrough from NewBB to the original landing pad. BranchInst::Create(LPad, NewBB); - // Now update DominatorTree and DominanceFrontier analysis information. - if (DT) - DT->splitBlock(NewBB); - if (DF) - DF->splitBlock(NewBB); + // Now update DominatorTree analysis information. + DT->splitBlock(NewBB); // Remember the newly constructed landing pad. The original landing pad // LPad is no longer a landing pad now that all unwind edges have been @@ -586,7 +510,7 @@ bool DwarfEHPrepare::LowerUnwinds() { // Create the call... CallInst *CI = CallInst::Create(RewindFunction, - CreateReadOfExceptionValue(TI->getParent()), + CreateExceptionValueCall(TI->getParent()), "", TI); CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME)); // ...followed by an UnreachableInst. @@ -602,9 +526,11 @@ bool DwarfEHPrepare::LowerUnwinds() { } /// MoveExceptionValueCalls - Ensure that eh.exception is only ever called from -/// landing pads by replacing calls outside of landing pads with loads from a -/// stack temporary. Move eh.exception calls inside landing pads to the start -/// of the landing pad (optional, but may make things simpler for later passes). +/// landing pads by replacing calls outside of landing pads with direct use of +/// a register holding the appropriate value; this requires adding calls inside +/// all landing pads to initialize the register. Also, move eh.exception calls +/// inside landing pads to the start of the landing pad (optional, but may make +/// things simpler for later passes). bool DwarfEHPrepare::MoveExceptionValueCalls() { // If the eh.exception intrinsic is not declared in the module then there is // nothing to do. Speed up compilation by checking for this common case. @@ -614,61 +540,87 @@ bool DwarfEHPrepare::MoveExceptionValueCalls() { bool Changed = false; - for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) { - for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E;) - if (IntrinsicInst *CI = dyn_cast(II++)) - if (CI->getIntrinsicID() == Intrinsic::eh_exception) { - if (!CI->use_empty()) { - Value *ExceptionValue = CreateReadOfExceptionValue(BB); - if (CI == ExceptionValue) { - // The call was at the start of a landing pad - leave it alone. - assert(LandingPads.count(BB) && - "Created eh.exception call outside landing pad!"); - continue; - } - CI->replaceAllUsesWith(ExceptionValue); - } - CI->eraseFromParent(); - ++NumExceptionValuesMoved; - Changed = true; + // Move calls to eh.exception that are inside a landing pad to the start of + // the landing pad. + for (BBSet::const_iterator LI = LandingPads.begin(), LE = LandingPads.end(); + LI != LE; ++LI) { + BasicBlock *LP = *LI; + for (BasicBlock::iterator II = LP->getFirstNonPHIOrDbg(), IE = LP->end(); + II != IE;) + if (EHExceptionInst *EI = dyn_cast(II++)) { + // Found a call to eh.exception. + if (!EI->use_empty()) { + // If there is already a call to eh.exception at the start of the + // landing pad, then get hold of it; otherwise create such a call. + Value *CallAtStart = CreateExceptionValueCall(LP); + + // If the call was at the start of a landing pad then leave it alone. + if (EI == CallAtStart) + continue; + EI->replaceAllUsesWith(CallAtStart); } + EI->eraseFromParent(); + ++NumExceptionValuesMoved; + Changed = true; + } } - return Changed; -} - -/// FinishStackTemporaries - If we introduced a stack variable to hold the -/// exception value then initialize it in each landing pad. -bool DwarfEHPrepare::FinishStackTemporaries() { - if (!ExceptionValueVar) - // Nothing to do. - return false; + // Look for calls to eh.exception that are not in a landing pad. If one is + // found, then a register that holds the exception value will be created in + // each landing pad, and the SSAUpdater will be used to compute the values + // returned by eh.exception calls outside of landing pads. + SSAUpdater SSA; + + // Remember where we found the eh.exception call, to avoid rescanning earlier + // basic blocks which we already know contain no eh.exception calls. + bool FoundCallOutsideLandingPad = false; + Function::iterator BB = F->begin(); + for (Function::iterator BE = F->end(); BB != BE; ++BB) { + // Skip over landing pads. + if (LandingPads.count(BB)) + continue; - bool Changed = false; + for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end(); + II != IE; ++II) + if (isa(II)) { + SSA.Initialize(II->getType(), II->getName()); + FoundCallOutsideLandingPad = true; + break; + } - // Make sure that there is a store of the exception value at the start of - // each landing pad. - for (BBSet::iterator LI = LandingPads.begin(), LE = LandingPads.end(); - LI != LE; ++LI) { - Instruction *ExceptionValue = CreateReadOfExceptionValue(*LI); - Instruction *Store = new StoreInst(ExceptionValue, ExceptionValueVar); - Store->insertAfter(ExceptionValue); - Changed = true; + if (FoundCallOutsideLandingPad) + break; } - return Changed; -} + // If all calls to eh.exception are in landing pads then we are done. + if (!FoundCallOutsideLandingPad) + return Changed; -/// PromoteStackTemporaries - Turn any stack temporaries we introduced into -/// registers if possible. -bool DwarfEHPrepare::PromoteStackTemporaries() { - if (ExceptionValueVar && DT && DF && isAllocaPromotable(ExceptionValueVar)) { - // Turn the exception temporary into registers and phi nodes if possible. - std::vector Allocas(1, ExceptionValueVar); - PromoteMemToReg(Allocas, *DT, *DF); - return true; + // Add a call to eh.exception at the start of each landing pad, and tell the + // SSAUpdater that this is the value produced by the landing pad. + for (BBSet::iterator LI = LandingPads.begin(), LE = LandingPads.end(); + LI != LE; ++LI) + SSA.AddAvailableValue(*LI, CreateExceptionValueCall(*LI)); + + // Now turn all calls to eh.exception that are not in a landing pad into a use + // of the appropriate register. + for (Function::iterator BE = F->end(); BB != BE; ++BB) { + // Skip over landing pads. + if (LandingPads.count(BB)) + continue; + + for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end(); + II != IE;) + if (EHExceptionInst *EI = dyn_cast(II++)) { + // Found a call to eh.exception, replace it with the value from any + // upstream landing pad(s). + EI->replaceAllUsesWith(SSA.GetValueAtEndOfBlock(BB)); + EI->eraseFromParent(); + ++NumExceptionValuesMoved; + } } - return false; + + return true; } /// CreateExceptionValueCall - Insert a call to the eh.exception intrinsic at @@ -691,36 +643,11 @@ Instruction *DwarfEHPrepare::CreateExceptionValueCall(BasicBlock *BB) { return CallInst::Create(ExceptionValueIntrinsic, "eh.value.call", Start); } -/// CreateValueLoad - Insert a load of the exception value stack variable -/// (creating it if necessary) at the start of the basic block (unless -/// there already is a load, in which case the existing load is returned). -Instruction *DwarfEHPrepare::CreateValueLoad(BasicBlock *BB) { - Instruction *Start = BB->getFirstNonPHIOrDbg(); - // Is this a load of the exception temporary? - if (ExceptionValueVar) - if (LoadInst* LI = dyn_cast(Start)) - if (LI->getPointerOperand() == ExceptionValueVar) - // Reuse the existing load. - return Start; - - // Create the temporary if we didn't already. - if (!ExceptionValueVar) { - ExceptionValueVar = new AllocaInst(PointerType::getUnqual( - Type::getInt8Ty(BB->getContext())), "eh.value", F->begin()->begin()); - ++NumStackTempsIntroduced; - } - - // Load the value. - return new LoadInst(ExceptionValueVar, "eh.value.load", Start); -} - bool DwarfEHPrepare::runOnFunction(Function &Fn) { bool Changed = false; // Initialize internal state. - DT = getAnalysisIfAvailable(); - DF = getAnalysisIfAvailable(); - ExceptionValueVar = 0; + DT = &getAnalysis(); F = &Fn; // Ensure that only unwind edges end at landing pads (a landing pad is a @@ -735,13 +662,6 @@ bool DwarfEHPrepare::runOnFunction(Function &Fn) { // Move eh.exception calls to landing pads. Changed |= MoveExceptionValueCalls(); - // Initialize any stack temporaries we introduced. - Changed |= FinishStackTemporaries(); - - // Turn any stack temporaries into registers if possible. - if (!CompileFast) - Changed |= PromoteStackTemporaries(); - Changed |= HandleURoRInvokes(); LandingPads.clear();