diff options
Diffstat (limited to 'lib/CodeGen/WinEHPrepare.cpp')
| -rw-r--r-- | lib/CodeGen/WinEHPrepare.cpp | 1629 |
1 files changed, 1244 insertions, 385 deletions
diff --git a/lib/CodeGen/WinEHPrepare.cpp b/lib/CodeGen/WinEHPrepare.cpp index 6f712a9..ab0f96e 100644 --- a/lib/CodeGen/WinEHPrepare.cpp +++ b/lib/CodeGen/WinEHPrepare.cpp @@ -16,6 +16,8 @@ #include "llvm/CodeGen/Passes.h" #include "llvm/ADT/MapVector.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/SmallSet.h" #include "llvm/ADT/TinyPtrVector.h" #include "llvm/Analysis/LibCallSemantics.h" #include "llvm/IR/Function.h" @@ -25,6 +27,10 @@ #include "llvm/IR/Module.h" #include "llvm/IR/PatternMatch.h" #include "llvm/Pass.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Transforms/Utils/BasicBlockUtils.h" #include "llvm/Transforms/Utils/Cloning.h" #include "llvm/Transforms/Utils/Local.h" #include <memory> @@ -36,25 +42,31 @@ using namespace llvm::PatternMatch; namespace { -struct HandlerAllocas { - TinyPtrVector<AllocaInst *> Allocas; - int ParentFrameAllocationIndex; -}; - // This map is used to model frame variable usage during outlining, to // construct a structure type to hold the frame variables in a frame // allocation block, and to remap the frame variable allocas (including // spill locations as needed) to GEPs that get the variable from the // frame allocation structure. -typedef MapVector<AllocaInst *, HandlerAllocas> FrameVarInfoMap; +typedef MapVector<Value *, TinyPtrVector<AllocaInst *>> FrameVarInfoMap; -class WinEHPrepare : public FunctionPass { - std::unique_ptr<FunctionPass> DwarfPrepare; +typedef SmallSet<BasicBlock *, 4> VisitedBlockSet; + +enum ActionType { Catch, Cleanup }; + +class LandingPadActions; +class ActionHandler; +class CatchHandler; +class CleanupHandler; +class LandingPadMap; +typedef DenseMap<const BasicBlock *, CatchHandler *> CatchHandlerMapTy; +typedef DenseMap<const BasicBlock *, CleanupHandler *> CleanupHandlerMapTy; + +class WinEHPrepare : public FunctionPass { public: static char ID; // Pass identification, replacement for typeid. WinEHPrepare(const TargetMachine *TM = nullptr) - : FunctionPass(ID), DwarfPrepare(createDwarfEHPass(TM)) {} + : FunctionPass(ID) {} bool runOnFunction(Function &Fn) override; @@ -67,11 +79,24 @@ public: } private: - bool prepareCPPEHHandlers(Function &F, - SmallVectorImpl<LandingPadInst *> &LPads); - bool outlineCatchHandler(Function *SrcFn, Constant *SelectorType, - LandingPadInst *LPad, CallInst *&EHAlloc, - AllocaInst *&EHObjPtr, FrameVarInfoMap &VarInfo); + bool prepareExceptionHandlers(Function &F, + SmallVectorImpl<LandingPadInst *> &LPads); + bool outlineHandler(ActionHandler *Action, Function *SrcFn, + LandingPadInst *LPad, BasicBlock *StartBB, + FrameVarInfoMap &VarInfo); + + void mapLandingPadBlocks(LandingPadInst *LPad, LandingPadActions &Actions); + CatchHandler *findCatchHandler(BasicBlock *BB, BasicBlock *&NextBB, + VisitedBlockSet &VisitedBlocks); + CleanupHandler *findCleanupHandler(BasicBlock *StartBB, BasicBlock *EndBB); + + void processSEHCatchHandler(CatchHandler *Handler, BasicBlock *StartBB); + + // All fields are reset by runOnFunction. + EHPersonality Personality; + CatchHandlerMapTy CatchHandlerMap; + CleanupHandlerMapTy CleanupHandlerMap; + DenseMap<const LandingPadInst *, LandingPadMap> LPadMaps; }; class WinEHFrameVariableMaterializer : public ValueMaterializer { @@ -87,34 +112,218 @@ private: IRBuilder<> Builder; }; -class WinEHCatchDirector : public CloningDirector { +class LandingPadMap { +public: + LandingPadMap() : OriginLPad(nullptr) {} + void mapLandingPad(const LandingPadInst *LPad); + + bool isInitialized() { return OriginLPad != nullptr; } + + bool mapIfEHPtrLoad(const LoadInst *Load) { + return mapIfEHLoad(Load, EHPtrStores, EHPtrStoreAddrs); + } + bool mapIfSelectorLoad(const LoadInst *Load) { + return mapIfEHLoad(Load, SelectorStores, SelectorStoreAddrs); + } + + bool isLandingPadSpecificInst(const Instruction *Inst) const; + + void remapSelector(ValueToValueMapTy &VMap, Value *MappedValue) const; + +private: + bool mapIfEHLoad(const LoadInst *Load, + SmallVectorImpl<const StoreInst *> &Stores, + SmallVectorImpl<const Value *> &StoreAddrs); + + const LandingPadInst *OriginLPad; + // We will normally only see one of each of these instructions, but + // if more than one occurs for some reason we can handle that. + TinyPtrVector<const ExtractValueInst *> ExtractedEHPtrs; + TinyPtrVector<const ExtractValueInst *> ExtractedSelectors; + + // In optimized code, there will typically be at most one instance of + // each of the following, but in unoptimized IR it is not uncommon + // for the values to be stored, loaded and then stored again. In that + // case we will create a second entry for each store and store address. + SmallVector<const StoreInst *, 2> EHPtrStores; + SmallVector<const StoreInst *, 2> SelectorStores; + SmallVector<const Value *, 2> EHPtrStoreAddrs; + SmallVector<const Value *, 2> SelectorStoreAddrs; +}; + +class WinEHCloningDirectorBase : public CloningDirector { public: - WinEHCatchDirector(LandingPadInst *LPI, Function *CatchFn, Value *Selector, - Value *EHObj, FrameVarInfoMap &VarInfo) - : LPI(LPI), CurrentSelector(Selector->stripPointerCasts()), EHObj(EHObj), - Materializer(CatchFn, VarInfo), - SelectorIDType(Type::getInt32Ty(LPI->getContext())), - Int8PtrType(Type::getInt8PtrTy(LPI->getContext())) {} + WinEHCloningDirectorBase(Function *HandlerFn, + FrameVarInfoMap &VarInfo, + LandingPadMap &LPadMap) + : Materializer(HandlerFn, VarInfo), + SelectorIDType(Type::getInt32Ty(HandlerFn->getContext())), + Int8PtrType(Type::getInt8PtrTy(HandlerFn->getContext())), + LPadMap(LPadMap) {} CloningAction handleInstruction(ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) override; + virtual CloningAction handleBeginCatch(ValueToValueMapTy &VMap, + const Instruction *Inst, + BasicBlock *NewBB) = 0; + virtual CloningAction handleEndCatch(ValueToValueMapTy &VMap, + const Instruction *Inst, + BasicBlock *NewBB) = 0; + virtual CloningAction handleTypeIdFor(ValueToValueMapTy &VMap, + const Instruction *Inst, + BasicBlock *NewBB) = 0; + virtual CloningAction handleInvoke(ValueToValueMapTy &VMap, + const InvokeInst *Invoke, + BasicBlock *NewBB) = 0; + virtual CloningAction handleResume(ValueToValueMapTy &VMap, + const ResumeInst *Resume, + BasicBlock *NewBB) = 0; + ValueMaterializer *getValueMaterializer() override { return &Materializer; } -private: - LandingPadInst *LPI; - Value *CurrentSelector; - Value *EHObj; +protected: WinEHFrameVariableMaterializer Materializer; Type *SelectorIDType; Type *Int8PtrType; + LandingPadMap &LPadMap; +}; + +class WinEHCatchDirector : public WinEHCloningDirectorBase { +public: + WinEHCatchDirector(Function *CatchFn, Value *Selector, + FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap) + : WinEHCloningDirectorBase(CatchFn, VarInfo, LPadMap), + CurrentSelector(Selector->stripPointerCasts()), + ExceptionObjectVar(nullptr) {} + + CloningAction handleBeginCatch(ValueToValueMapTy &VMap, + const Instruction *Inst, + BasicBlock *NewBB) override; + CloningAction handleEndCatch(ValueToValueMapTy &VMap, const Instruction *Inst, + BasicBlock *NewBB) override; + CloningAction handleTypeIdFor(ValueToValueMapTy &VMap, + const Instruction *Inst, + BasicBlock *NewBB) override; + CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke, + BasicBlock *NewBB) override; + CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume, + BasicBlock *NewBB) override; + + const Value *getExceptionVar() { return ExceptionObjectVar; } + TinyPtrVector<BasicBlock *> &getReturnTargets() { return ReturnTargets; } + +private: + Value *CurrentSelector; - const Value *ExtractedEHPtr; - const Value *ExtractedSelector; - const Value *EHPtrStoreAddr; - const Value *SelectorStoreAddr; + const Value *ExceptionObjectVar; + TinyPtrVector<BasicBlock *> ReturnTargets; }; + +class WinEHCleanupDirector : public WinEHCloningDirectorBase { +public: + WinEHCleanupDirector(Function *CleanupFn, + FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap) + : WinEHCloningDirectorBase(CleanupFn, VarInfo, LPadMap) {} + + CloningAction handleBeginCatch(ValueToValueMapTy &VMap, + const Instruction *Inst, + BasicBlock *NewBB) override; + CloningAction handleEndCatch(ValueToValueMapTy &VMap, const Instruction *Inst, + BasicBlock *NewBB) override; + CloningAction handleTypeIdFor(ValueToValueMapTy &VMap, + const Instruction *Inst, + BasicBlock *NewBB) override; + CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke, + BasicBlock *NewBB) override; + CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume, + BasicBlock *NewBB) override; +}; + +class ActionHandler { +public: + ActionHandler(BasicBlock *BB, ActionType Type) + : StartBB(BB), Type(Type), HandlerBlockOrFunc(nullptr) {} + + ActionType getType() const { return Type; } + BasicBlock *getStartBlock() const { return StartBB; } + + bool hasBeenProcessed() { return HandlerBlockOrFunc != nullptr; } + + void setHandlerBlockOrFunc(Constant *F) { HandlerBlockOrFunc = F; } + Constant *getHandlerBlockOrFunc() { return HandlerBlockOrFunc; } + +private: + BasicBlock *StartBB; + ActionType Type; + + // Can be either a BlockAddress or a Function depending on the EH personality. + Constant *HandlerBlockOrFunc; +}; + +class CatchHandler : public ActionHandler { +public: + CatchHandler(BasicBlock *BB, Constant *Selector, BasicBlock *NextBB) + : ActionHandler(BB, ActionType::Catch), Selector(Selector), + NextBB(NextBB), ExceptionObjectVar(nullptr) {} + + // Method for support type inquiry through isa, cast, and dyn_cast: + static inline bool classof(const ActionHandler *H) { + return H->getType() == ActionType::Catch; + } + + Constant *getSelector() const { return Selector; } + BasicBlock *getNextBB() const { return NextBB; } + + const Value *getExceptionVar() { return ExceptionObjectVar; } + TinyPtrVector<BasicBlock *> &getReturnTargets() { return ReturnTargets; } + + void setExceptionVar(const Value *Val) { ExceptionObjectVar = Val; } + void setReturnTargets(TinyPtrVector<BasicBlock *> &Targets) { + ReturnTargets = Targets; + } + +private: + Constant *Selector; + BasicBlock *NextBB; + const Value *ExceptionObjectVar; + TinyPtrVector<BasicBlock *> ReturnTargets; +}; + +class CleanupHandler : public ActionHandler { +public: + CleanupHandler(BasicBlock *BB) : ActionHandler(BB, ActionType::Cleanup) {} + + // Method for support type inquiry through isa, cast, and dyn_cast: + static inline bool classof(const ActionHandler *H) { + return H->getType() == ActionType::Cleanup; + } +}; + +class LandingPadActions { +public: + LandingPadActions() : HasCleanupHandlers(false) {} + + void insertCatchHandler(CatchHandler *Action) { Actions.push_back(Action); } + void insertCleanupHandler(CleanupHandler *Action) { + Actions.push_back(Action); + HasCleanupHandlers = true; + } + + bool includesCleanup() const { return HasCleanupHandlers; } + + SmallVectorImpl<ActionHandler *>::iterator begin() { return Actions.begin(); } + SmallVectorImpl<ActionHandler *>::iterator end() { return Actions.end(); } + +private: + // Note that this class does not own the ActionHandler objects in this vector. + // The ActionHandlers are owned by the CatchHandlerMap and CleanupHandlerMap + // in the WinEHPrepare class. + SmallVector<ActionHandler *, 4> Actions; + bool HasCleanupHandlers; +}; + } // end anonymous namespace char WinEHPrepare::ID = 0; @@ -125,10 +334,10 @@ FunctionPass *llvm::createWinEHPass(const TargetMachine *TM) { return new WinEHPrepare(TM); } -static bool isMSVCPersonality(EHPersonality Pers) { - return Pers == EHPersonality::MSVC_Win64SEH || - Pers == EHPersonality::MSVC_CXX; -} +// FIXME: Remove this once the backend can handle the prepared IR. +static cl::opt<bool> +SEHPrepare("sehprepare", cl::Hidden, + cl::desc("Prepare functions with SEH personalities")); bool WinEHPrepare::runOnFunction(Function &Fn) { SmallVector<LandingPadInst *, 4> LPads; @@ -145,60 +354,67 @@ bool WinEHPrepare::runOnFunction(Function &Fn) { return false; // Classify the personality to see what kind of preparation we need. - EHPersonality Pers = classifyEHPersonality(LPads.back()->getPersonalityFn()); - - // Delegate through to the DWARF pass if this is unrecognized. - if (!isMSVCPersonality(Pers)) - return DwarfPrepare->runOnFunction(Fn); + Personality = classifyEHPersonality(LPads.back()->getPersonalityFn()); - // FIXME: This only returns true if the C++ EH handlers were outlined. - // When that code is complete, it should always return whatever - // prepareCPPEHHandlers returns. - if (Pers == EHPersonality::MSVC_CXX && prepareCPPEHHandlers(Fn, LPads)) - return true; - - // FIXME: SEH Cleanups are unimplemented. Replace them with unreachable. - if (Resumes.empty()) + // Do nothing if this is not an MSVC personality. + if (!isMSVCEHPersonality(Personality)) return false; - for (ResumeInst *Resume : Resumes) { - IRBuilder<>(Resume).CreateUnreachable(); - Resume->eraseFromParent(); + if (isAsynchronousEHPersonality(Personality) && !SEHPrepare) { + // Replace all resume instructions with unreachable. + // FIXME: Remove this once the backend can handle the prepared IR. + for (ResumeInst *Resume : Resumes) { + IRBuilder<>(Resume).CreateUnreachable(); + Resume->eraseFromParent(); + } + return true; } + // If there were any landing pads, prepareExceptionHandlers will make changes. + prepareExceptionHandlers(Fn, LPads); return true; } bool WinEHPrepare::doFinalization(Module &M) { - return DwarfPrepare->doFinalization(M); + return false; } -void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const { - DwarfPrepare->getAnalysisUsage(AU); -} +void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {} -bool WinEHPrepare::prepareCPPEHHandlers( +bool WinEHPrepare::prepareExceptionHandlers( Function &F, SmallVectorImpl<LandingPadInst *> &LPads) { // These containers are used to re-map frame variables that are used in // outlined catch and cleanup handlers. They will be populated as the // handlers are outlined. FrameVarInfoMap FrameVarInfo; - SmallVector<CallInst *, 4> HandlerAllocs; - SmallVector<AllocaInst *, 4> HandlerEHObjPtrs; bool HandlersOutlined = false; + Module *M = F.getParent(); + LLVMContext &Context = M->getContext(); + + // Create a new function to receive the handler contents. + PointerType *Int8PtrType = Type::getInt8PtrTy(Context); + Type *Int32Type = Type::getInt32Ty(Context); + Function *ActionIntrin = Intrinsic::getDeclaration(M, Intrinsic::eh_actions); + for (LandingPadInst *LPad : LPads) { // Look for evidence that this landingpad has already been processed. bool LPadHasActionList = false; BasicBlock *LPadBB = LPad->getParent(); - for (Instruction &Inst : LPadBB->getInstList()) { - // FIXME: Make this an intrinsic. - if (auto *Call = dyn_cast<CallInst>(&Inst)) - if (Call->getCalledFunction()->getName() == "llvm.eh.actions") { + for (Instruction &Inst : *LPadBB) { + if (auto *IntrinCall = dyn_cast<IntrinsicInst>(&Inst)) { + if (IntrinCall->getIntrinsicID() == Intrinsic::eh_actions) { LPadHasActionList = true; break; } + } + // FIXME: This is here to help with the development of nested landing pad + // outlining. It should be removed when that is finished. + if (isa<UnreachableInst>(Inst)) { + LPadHasActionList = true; + break; + } } // If we've already outlined the handlers for this landingpad, @@ -206,177 +422,244 @@ bool WinEHPrepare::prepareCPPEHHandlers( if (LPadHasActionList) continue; - for (unsigned Idx = 0, NumClauses = LPad->getNumClauses(); Idx < NumClauses; - ++Idx) { - if (LPad->isCatch(Idx)) { - // Create a new instance of the handler data structure in the - // HandlerData vector. - CallInst *EHAlloc = nullptr; - AllocaInst *EHObjPtr = nullptr; - bool Outlined = outlineCatchHandler(&F, LPad->getClause(Idx), LPad, - EHAlloc, EHObjPtr, FrameVarInfo); - if (Outlined) { + LandingPadActions Actions; + mapLandingPadBlocks(LPad, Actions); + + for (ActionHandler *Action : Actions) { + if (Action->hasBeenProcessed()) + continue; + BasicBlock *StartBB = Action->getStartBlock(); + + // SEH doesn't do any outlining for catches. Instead, pass the handler + // basic block addr to llvm.eh.actions and list the block as a return + // target. + if (isAsynchronousEHPersonality(Personality)) { + if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) { + processSEHCatchHandler(CatchAction, StartBB); HandlersOutlined = true; - // These values must be resolved after all handlers have been - // outlined. - if (EHAlloc) - HandlerAllocs.push_back(EHAlloc); - if (EHObjPtr) - HandlerEHObjPtrs.push_back(EHObjPtr); + continue; } - } // End if (isCatch) - } // End for each clause - } // End for each landingpad + } + + if (outlineHandler(Action, &F, LPad, StartBB, FrameVarInfo)) { + HandlersOutlined = true; + } + } // End for each Action + + // FIXME: We need a guard against partially outlined functions. + if (!HandlersOutlined) + continue; + + // Replace the landing pad with a new llvm.eh.action based landing pad. + BasicBlock *NewLPadBB = BasicBlock::Create(Context, "lpad", &F, LPadBB); + assert(!isa<PHINode>(LPadBB->begin())); + Instruction *NewLPad = LPad->clone(); + NewLPadBB->getInstList().push_back(NewLPad); + while (!pred_empty(LPadBB)) { + auto *pred = *pred_begin(LPadBB); + InvokeInst *Invoke = cast<InvokeInst>(pred->getTerminator()); + Invoke->setUnwindDest(NewLPadBB); + } + + // Replace uses of the old lpad in phis with this block and delete the old + // block. + LPadBB->replaceSuccessorsPhiUsesWith(NewLPadBB); + LPadBB->getTerminator()->eraseFromParent(); + new UnreachableInst(LPadBB->getContext(), LPadBB); + + // Add a call to describe the actions for this landing pad. + std::vector<Value *> ActionArgs; + for (ActionHandler *Action : Actions) { + // Action codes from docs are: 0 cleanup, 1 catch. + if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) { + ActionArgs.push_back(ConstantInt::get(Int32Type, 1)); + ActionArgs.push_back(CatchAction->getSelector()); + Value *EHObj = const_cast<Value *>(CatchAction->getExceptionVar()); + if (EHObj) + ActionArgs.push_back(EHObj); + else + ActionArgs.push_back(ConstantPointerNull::get(Int8PtrType)); + } else { + ActionArgs.push_back(ConstantInt::get(Int32Type, 0)); + } + ActionArgs.push_back(Action->getHandlerBlockOrFunc()); + } + CallInst *Recover = + CallInst::Create(ActionIntrin, ActionArgs, "recover", NewLPadBB); + + // Add an indirect branch listing possible successors of the catch handlers. + IndirectBrInst *Branch = IndirectBrInst::Create(Recover, 0, NewLPadBB); + for (ActionHandler *Action : Actions) { + if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) { + for (auto *Target : CatchAction->getReturnTargets()) { + Branch->addDestination(Target); + } + } + } + } // End for each landingpad // If nothing got outlined, there is no more processing to be done. if (!HandlersOutlined) return false; - // FIXME: We will replace the landingpad bodies with llvm.eh.actions - // calls and indirect branches here and then delete blocks - // which are no longer reachable. That will get rid of the - // handlers that we have outlined. There is code below - // that looks for allocas with no uses in the parent function. - // That will only happen after the pruning is implemented. - - // Remap the frame variables. - SmallVector<Type *, 2> StructTys; - StructTys.push_back(Type::getInt32Ty(F.getContext())); // EH state - StructTys.push_back(Type::getInt8PtrTy(F.getContext())); // EH object - - // Start the index at two since we always have the above fields at 0 and 1. - int Idx = 2; - - // FIXME: Sort the FrameVarInfo vector by the ParentAlloca size and alignment - // and add padding as necessary to provide the proper alignment. - - // Map the alloca instructions to the corresponding index in the - // frame allocation structure. If any alloca is used only in a single - // handler and is not used in the parent frame after outlining, it will - // be assigned an index of -1, meaning the handler can keep its - // "temporary" alloca and the original alloca can be erased from the - // parent function. If we later encounter this alloca in a second - // handler, we will assign it a place in the frame allocation structure - // at that time. Since the instruction replacement doesn't happen until - // all the entries in the HandlerData have been processed this isn't a - // problem. - for (auto &VarInfoEntry : FrameVarInfo) { - AllocaInst *ParentAlloca = VarInfoEntry.first; - HandlerAllocas &AllocaInfo = VarInfoEntry.second; - - // If the instruction still has uses in the parent function or if it is - // referenced by more than one handler, add it to the frame allocation - // structure. - if (ParentAlloca->getNumUses() != 0 || AllocaInfo.Allocas.size() > 1) { - Type *VarTy = ParentAlloca->getAllocatedType(); - StructTys.push_back(VarTy); - AllocaInfo.ParentFrameAllocationIndex = Idx++; - } else { - // If the variable is not used in the parent frame and it is only used - // in one handler, the alloca can be removed from the parent frame - // and the handler will keep its "temporary" alloca to define the value. - // An element index of -1 is used to indicate this condition. - AllocaInfo.ParentFrameAllocationIndex = -1; - } - } + // Delete any blocks that were only used by handlers that were outlined above. + removeUnreachableBlocks(F); - // Having filled the StructTys vector and assigned an index to each element, - // we can now create the structure. - StructType *EHDataStructTy = StructType::create( - F.getContext(), StructTys, "struct." + F.getName().str() + ".ehdata"); - IRBuilder<> Builder(F.getParent()->getContext()); - - // Create a frame allocation. - Module *M = F.getParent(); - LLVMContext &Context = M->getContext(); BasicBlock *Entry = &F.getEntryBlock(); + IRBuilder<> Builder(F.getParent()->getContext()); Builder.SetInsertPoint(Entry->getFirstInsertionPt()); - Function *FrameAllocFn = - Intrinsic::getDeclaration(M, Intrinsic::frameallocate); - uint64_t EHAllocSize = M->getDataLayout()->getTypeAllocSize(EHDataStructTy); - Value *FrameAllocArgs[] = { - ConstantInt::get(Type::getInt32Ty(Context), EHAllocSize)}; - CallInst *FrameAlloc = - Builder.CreateCall(FrameAllocFn, FrameAllocArgs, "frame.alloc"); - - Value *FrameEHData = Builder.CreateBitCast( - FrameAlloc, EHDataStructTy->getPointerTo(), "eh.data"); - - // Now visit each handler that is using the structure and bitcast its EHAlloc - // value to be a pointer to the frame alloc structure. - DenseMap<Function *, Value *> EHDataMap; - for (CallInst *EHAlloc : HandlerAllocs) { - // The EHAlloc has no uses at this time, so we need to just insert the - // cast before the next instruction. There is always a next instruction. - BasicBlock::iterator II = EHAlloc; - ++II; - Builder.SetInsertPoint(cast<Instruction>(II)); - Value *EHData = Builder.CreateBitCast( - EHAlloc, EHDataStructTy->getPointerTo(), "eh.data"); - EHDataMap[EHAlloc->getParent()->getParent()] = EHData; - } - // Next, replace the place-holder EHObjPtr allocas with GEP instructions - // that pull the EHObjPtr from the frame alloc structure - for (AllocaInst *EHObjPtr : HandlerEHObjPtrs) { - Value *EHData = EHDataMap[EHObjPtr->getParent()->getParent()]; - Builder.SetInsertPoint(EHObjPtr); - Value *ElementPtr = Builder.CreateConstInBoundsGEP2_32(EHData, 0, 1); - EHObjPtr->replaceAllUsesWith(ElementPtr); - EHObjPtr->removeFromParent(); - ElementPtr->takeName(EHObjPtr); - delete EHObjPtr; - } + Function *FrameEscapeFn = + Intrinsic::getDeclaration(M, Intrinsic::frameescape); + Function *RecoverFrameFn = + Intrinsic::getDeclaration(M, Intrinsic::framerecover); // Finally, replace all of the temporary allocas for frame variables used in - // the outlined handlers and the original frame allocas with GEP instructions - // that get the equivalent pointer from the frame allocation struct. + // the outlined handlers with calls to llvm.framerecover. + BasicBlock::iterator II = Entry->getFirstInsertionPt(); + Instruction *AllocaInsertPt = II; + SmallVector<Value *, 8> AllocasToEscape; for (auto &VarInfoEntry : FrameVarInfo) { - AllocaInst *ParentAlloca = VarInfoEntry.first; - HandlerAllocas &AllocaInfo = VarInfoEntry.second; - int Idx = AllocaInfo.ParentFrameAllocationIndex; - - // If we have an index of -1 for this instruction, it means it isn't used - // outside of this handler. In that case, we just keep the "temporary" - // alloca in the handler and erase the original alloca from the parent. - if (Idx == -1) { + Value *ParentVal = VarInfoEntry.first; + TinyPtrVector<AllocaInst *> &Allocas = VarInfoEntry.second; + + // If the mapped value isn't already an alloca, we need to spill it if it + // is a computed value or copy it if it is an argument. + AllocaInst *ParentAlloca = dyn_cast<AllocaInst>(ParentVal); + if (!ParentAlloca) { + if (auto *Arg = dyn_cast<Argument>(ParentVal)) { + // Lower this argument to a copy and then demote that to the stack. + // We can't just use the argument location because the handler needs + // it to be in the frame allocation block. + // Use 'select i8 true, %arg, undef' to simulate a 'no-op' instruction. + Value *TrueValue = ConstantInt::getTrue(Context); + Value *UndefValue = UndefValue::get(Arg->getType()); + Instruction *SI = + SelectInst::Create(TrueValue, Arg, UndefValue, + Arg->getName() + ".tmp", AllocaInsertPt); + Arg->replaceAllUsesWith(SI); + // Reset the select operand, because it was clobbered by the RAUW above. + SI->setOperand(1, Arg); + ParentAlloca = DemoteRegToStack(*SI, true, SI); + } else if (auto *PN = dyn_cast<PHINode>(ParentVal)) { + ParentAlloca = DemotePHIToStack(PN, AllocaInsertPt); + } else { + Instruction *ParentInst = cast<Instruction>(ParentVal); + // FIXME: This is a work-around to temporarily handle the case where an + // instruction that is only used in handlers is not sunk. + // Without uses, DemoteRegToStack would just eliminate the value. + // This will fail if ParentInst is an invoke. + if (ParentInst->getNumUses() == 0) { + BasicBlock::iterator InsertPt = ParentInst; + ++InsertPt; + ParentAlloca = + new AllocaInst(ParentInst->getType(), nullptr, + ParentInst->getName() + ".reg2mem", InsertPt); + new StoreInst(ParentInst, ParentAlloca, InsertPt); + } else { + ParentAlloca = DemoteRegToStack(*ParentInst, true, ParentInst); + } + } + } + + // If the parent alloca is no longer used and only one of the handlers used + // it, erase the parent and leave the copy in the outlined handler. + if (ParentAlloca->getNumUses() == 0 && Allocas.size() == 1) { ParentAlloca->eraseFromParent(); - } else { - // Otherwise, we replace the parent alloca and all outlined allocas - // which map to it with GEP instructions. - - // First replace the original alloca. - Builder.SetInsertPoint(ParentAlloca); - Builder.SetCurrentDebugLocation(ParentAlloca->getDebugLoc()); - Value *ElementPtr = - Builder.CreateConstInBoundsGEP2_32(FrameEHData, 0, Idx); - ParentAlloca->replaceAllUsesWith(ElementPtr); - ParentAlloca->removeFromParent(); - ElementPtr->takeName(ParentAlloca); - delete ParentAlloca; - - // Next replace all outlined allocas that are mapped to it. - for (AllocaInst *TempAlloca : AllocaInfo.Allocas) { - Value *EHData = EHDataMap[TempAlloca->getParent()->getParent()]; - // FIXME: Sink this GEP into the blocks where it is used. - Builder.SetInsertPoint(TempAlloca); - Builder.SetCurrentDebugLocation(TempAlloca->getDebugLoc()); - ElementPtr = Builder.CreateConstInBoundsGEP2_32(EHData, 0, Idx); - TempAlloca->replaceAllUsesWith(ElementPtr); - TempAlloca->removeFromParent(); - ElementPtr->takeName(TempAlloca); - delete TempAlloca; + continue; + } + + // Add this alloca to the list of things to escape. + AllocasToEscape.push_back(ParentAlloca); + + // Next replace all outlined allocas that are mapped to it. + for (AllocaInst *TempAlloca : Allocas) { + Function *HandlerFn = TempAlloca->getParent()->getParent(); + // FIXME: Sink this GEP into the blocks where it is used. + Builder.SetInsertPoint(TempAlloca); + Builder.SetCurrentDebugLocation(TempAlloca->getDebugLoc()); + Value *RecoverArgs[] = { + Builder.CreateBitCast(&F, Int8PtrType, ""), + &(HandlerFn->getArgumentList().back()), + llvm::ConstantInt::get(Int32Type, AllocasToEscape.size() - 1)}; + Value *RecoveredAlloca = Builder.CreateCall(RecoverFrameFn, RecoverArgs); + // Add a pointer bitcast if the alloca wasn't an i8. + if (RecoveredAlloca->getType() != TempAlloca->getType()) { + RecoveredAlloca->setName(Twine(TempAlloca->getName()) + ".i8"); + RecoveredAlloca = + Builder.CreateBitCast(RecoveredAlloca, TempAlloca->getType()); } - } // end else of if (Idx == -1) - } // End for each FrameVarInfo entry. + TempAlloca->replaceAllUsesWith(RecoveredAlloca); + TempAlloca->removeFromParent(); + RecoveredAlloca->takeName(TempAlloca); + delete TempAlloca; + } + } // End for each FrameVarInfo entry. + + // Insert 'call void (...)* @llvm.frameescape(...)' at the end of the entry + // block. + Builder.SetInsertPoint(&F.getEntryBlock().back()); + Builder.CreateCall(FrameEscapeFn, AllocasToEscape); + + // Insert an alloca for the EH state in the entry block. On x86, we will also + // insert stores to update the EH state, but on other ISAs, the runtime does + // it for us. + // FIXME: This record is different on x86. + Type *UnwindHelpTy = Type::getInt64Ty(Context); + AllocaInst *UnwindHelp = + new AllocaInst(UnwindHelpTy, "unwindhelp", &F.getEntryBlock().front()); + Builder.CreateStore(llvm::ConstantInt::get(UnwindHelpTy, -2), UnwindHelp); + Function *UnwindHelpFn = + Intrinsic::getDeclaration(M, Intrinsic::eh_unwindhelp); + Builder.CreateCall(UnwindHelpFn, + Builder.CreateBitCast(UnwindHelp, Int8PtrType)); + + // Clean up the handler action maps we created for this function + DeleteContainerSeconds(CatchHandlerMap); + CatchHandlerMap.clear(); + DeleteContainerSeconds(CleanupHandlerMap); + CleanupHandlerMap.clear(); return HandlersOutlined; } -bool WinEHPrepare::outlineCatchHandler(Function *SrcFn, Constant *SelectorType, - LandingPadInst *LPad, CallInst *&EHAlloc, - AllocaInst *&EHObjPtr, - FrameVarInfoMap &VarInfo) { +// This function examines a block to determine whether the block ends with a +// conditional branch to a catch handler based on a selector comparison. +// This function is used both by the WinEHPrepare::findSelectorComparison() and +// WinEHCleanupDirector::handleTypeIdFor(). +static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler, + Constant *&Selector, BasicBlock *&NextBB) { + ICmpInst::Predicate Pred; + BasicBlock *TBB, *FBB; + Value *LHS, *RHS; + + if (!match(BB->getTerminator(), + m_Br(m_ICmp(Pred, m_Value(LHS), m_Value(RHS)), TBB, FBB))) + return false; + + if (!match(LHS, + m_Intrinsic<Intrinsic::eh_typeid_for>(m_Constant(Selector))) && + !match(RHS, m_Intrinsic<Intrinsic::eh_typeid_for>(m_Constant(Selector)))) + return false; + + if (Pred == CmpInst::ICMP_EQ) { + CatchHandler = TBB; + NextBB = FBB; + return true; + } + + if (Pred == CmpInst::ICMP_NE) { + CatchHandler = FBB; + NextBB = TBB; + return true; + } + + return false; +} + +bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn, + LandingPadInst *LPad, BasicBlock *StartBB, + FrameVarInfoMap &VarInfo) { Module *M = SrcFn->getParent(); LLVMContext &Context = M->getContext(); @@ -385,133 +668,241 @@ bool WinEHPrepare::outlineCatchHandler(Function *SrcFn, Constant *SelectorType, std::vector<Type *> ArgTys; ArgTys.push_back(Int8PtrType); ArgTys.push_back(Int8PtrType); - FunctionType *FnType = FunctionType::get(Int8PtrType, ArgTys, false); - Function *CatchHandler = Function::Create( - FnType, GlobalVariable::ExternalLinkage, SrcFn->getName() + ".catch", M); + Function *Handler; + if (Action->getType() == Catch) { + FunctionType *FnType = FunctionType::get(Int8PtrType, ArgTys, false); + Handler = Function::Create(FnType, GlobalVariable::InternalLinkage, + SrcFn->getName() + ".catch", M); + } else { + FunctionType *FnType = + FunctionType::get(Type::getVoidTy(Context), ArgTys, false); + Handler = Function::Create(FnType, GlobalVariable::InternalLinkage, + SrcFn->getName() + ".cleanup", M); + } // Generate a standard prolog to setup the frame recovery structure. IRBuilder<> Builder(Context); - BasicBlock *Entry = BasicBlock::Create(Context, "catch.entry"); - CatchHandler->getBasicBlockList().push_front(Entry); + BasicBlock *Entry = BasicBlock::Create(Context, "entry"); + Handler->getBasicBlockList().push_front(Entry); Builder.SetInsertPoint(Entry); Builder.SetCurrentDebugLocation(LPad->getDebugLoc()); - // The outlined handler will be called with the parent's frame pointer as - // its second argument. To enable the handler to access variables from - // the parent frame, we use that pointer to get locate a special block - // of memory that was allocated using llvm.eh.allocateframe for this - // purpose. During the outlining process we will determine which frame - // variables are used in handlers and create a structure that maps these - // variables into the frame allocation block. - // - // The frame allocation block also contains an exception state variable - // used by the runtime and a pointer to the exception object pointer - // which will be filled in by the runtime for use in the handler. - Function *RecoverFrameFn = - Intrinsic::getDeclaration(M, Intrinsic::framerecover); - Value *RecoverArgs[] = {Builder.CreateBitCast(SrcFn, Int8PtrType, ""), - &(CatchHandler->getArgumentList().back())}; - EHAlloc = Builder.CreateCall(RecoverFrameFn, RecoverArgs, "eh.alloc"); - - // This alloca is only temporary. We'll be replacing it once we know all the - // frame variables that need to go in the frame allocation structure. - EHObjPtr = Builder.CreateAlloca(Int8PtrType, 0, "eh.obj.ptr"); - - // This will give us a raw pointer to the exception object, which - // corresponds to the formal parameter of the catch statement. If the - // handler uses this object, we will generate code during the outlining - // process to cast the pointer to the appropriate type and deference it - // as necessary. The un-outlined landing pad code represents the - // exception object as the result of the llvm.eh.begincatch call. - Value *EHObj = Builder.CreateLoad(EHObjPtr, false, "eh.obj"); + std::unique_ptr<WinEHCloningDirectorBase> Director; ValueToValueMapTy VMap; - // FIXME: Map other values referenced in the filter handler. - - WinEHCatchDirector Director(LPad, CatchHandler, SelectorType, EHObj, VarInfo); + LandingPadMap &LPadMap = LPadMaps[LPad]; + if (!LPadMap.isInitialized()) + LPadMap.mapLandingPad(LPad); + if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) { + Constant *Sel = CatchAction->getSelector(); + Director.reset(new WinEHCatchDirector(Handler, Sel, VarInfo, LPadMap)); + LPadMap.remapSelector(VMap, ConstantInt::get(Type::getInt32Ty(Context), 1)); + } else { + Director.reset(new WinEHCleanupDirector(Handler, VarInfo, LPadMap)); + } SmallVector<ReturnInst *, 8> Returns; - ClonedCodeInfo InlinedFunctionInfo; + ClonedCodeInfo OutlinedFunctionInfo; + + // If the start block contains PHI nodes, we need to map them. + BasicBlock::iterator II = StartBB->begin(); + while (auto *PN = dyn_cast<PHINode>(II)) { + bool Mapped = false; + // Look for PHI values that we have already mapped (such as the selector). + for (Value *Val : PN->incoming_values()) { + if (VMap.count(Val)) { + VMap[PN] = VMap[Val]; + Mapped = true; + } + } + // If we didn't find a match for this value, map it as an undef. + if (!Mapped) { + VMap[PN] = UndefValue::get(PN->getType()); + } + ++II; + } - BasicBlock::iterator II = LPad; + // Skip over PHIs and, if applicable, landingpad instructions. + II = StartBB->getFirstInsertionPt(); - CloneAndPruneIntoFromInst(CatchHandler, SrcFn, ++II, VMap, + CloneAndPruneIntoFromInst(Handler, SrcFn, II, VMap, /*ModuleLevelChanges=*/false, Returns, "", - &InlinedFunctionInfo, - SrcFn->getParent()->getDataLayout(), &Director); + &OutlinedFunctionInfo, Director.get()); // Move all the instructions in the first cloned block into our entry block. BasicBlock *FirstClonedBB = std::next(Function::iterator(Entry)); Entry->getInstList().splice(Entry->end(), FirstClonedBB->getInstList()); FirstClonedBB->eraseFromParent(); + if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) { + WinEHCatchDirector *CatchDirector = + reinterpret_cast<WinEHCatchDirector *>(Director.get()); + CatchAction->setExceptionVar(CatchDirector->getExceptionVar()); + CatchAction->setReturnTargets(CatchDirector->getReturnTargets()); + } + + Action->setHandlerBlockOrFunc(Handler); + return true; } -CloningDirector::CloningAction WinEHCatchDirector::handleInstruction( - ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) { - // Intercept instructions which extract values from the landing pad aggregate. - if (auto *Extract = dyn_cast<ExtractValueInst>(Inst)) { - if (Extract->getAggregateOperand() == LPI) { - assert(Extract->getNumIndices() == 1 && - "Unexpected operation: extracting both landing pad values"); - assert((*(Extract->idx_begin()) == 0 || *(Extract->idx_begin()) == 1) && - "Unexpected operation: extracting an unknown landing pad element"); - - if (*(Extract->idx_begin()) == 0) { - // Element 0 doesn't directly corresponds to anything in the WinEH - // scheme. - // It will be stored to a memory location, then later loaded and finally - // the loaded value will be used as the argument to an - // llvm.eh.begincatch - // call. We're tracking it here so that we can skip the store and load. - ExtractedEHPtr = Inst; - } else { - // Element 1 corresponds to the filter selector. We'll map it to 1 for - // matching purposes, but it will also probably be stored to memory and - // reloaded, so we need to track the instuction so that we can map the - // loaded value too. - VMap[Inst] = ConstantInt::get(SelectorIDType, 1); - ExtractedSelector = Inst; - } - - // Tell the caller not to clone this instruction. - return CloningDirector::SkipInstruction; - } - // Other extract value instructions just get cloned. - return CloningDirector::CloneInstruction; +/// This BB must end in a selector dispatch. All we need to do is pass the +/// handler block to llvm.eh.actions and list it as a possible indirectbr +/// target. +void WinEHPrepare::processSEHCatchHandler(CatchHandler *CatchAction, + BasicBlock *StartBB) { + BasicBlock *HandlerBB; + BasicBlock *NextBB; + Constant *Selector; + bool Res = isSelectorDispatch(StartBB, HandlerBB, Selector, NextBB); + if (Res) { + // If this was EH dispatch, this must be a conditional branch to the handler + // block. + // FIXME: Handle instructions in the dispatch block. Currently we drop them, + // leading to crashes if some optimization hoists stuff here. + assert(CatchAction->getSelector() && HandlerBB && + "expected catch EH dispatch"); + } else { + // This must be a catch-all. Split the block after the landingpad. + assert(CatchAction->getSelector()->isNullValue() && "expected catch-all"); + HandlerBB = + StartBB->splitBasicBlock(StartBB->getFirstInsertionPt(), "catch.all"); } + CatchAction->setHandlerBlockOrFunc(BlockAddress::get(HandlerBB)); + TinyPtrVector<BasicBlock *> Targets(HandlerBB); + CatchAction->setReturnTargets(Targets); +} - if (auto *Store = dyn_cast<StoreInst>(Inst)) { - // Look for and suppress stores of the extracted landingpad values. - const Value *StoredValue = Store->getValueOperand(); - if (StoredValue == ExtractedEHPtr) { - EHPtrStoreAddr = Store->getPointerOperand(); - return CloningDirector::SkipInstruction; +void LandingPadMap::mapLandingPad(const LandingPadInst *LPad) { + // Each instance of this class should only ever be used to map a single + // landing pad. + assert(OriginLPad == nullptr || OriginLPad == LPad); + + // If the landing pad has already been mapped, there's nothing more to do. + if (OriginLPad == LPad) + return; + + OriginLPad = LPad; + + // The landingpad instruction returns an aggregate value. Typically, its + // value will be passed to a pair of extract value instructions and the + // results of those extracts are often passed to store instructions. + // In unoptimized code the stored value will often be loaded and then stored + // again. + for (auto *U : LPad->users()) { + const ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U); + if (!Extract) + continue; + assert(Extract->getNumIndices() == 1 && + "Unexpected operation: extracting both landing pad values"); + unsigned int Idx = *(Extract->idx_begin()); + assert((Idx == 0 || Idx == 1) && + "Unexpected operation: extracting an unknown landing pad element"); + if (Idx == 0) { + // Element 0 doesn't directly corresponds to anything in the WinEH + // scheme. + // It will be stored to a memory location, then later loaded and finally + // the loaded value will be used as the argument to an + // llvm.eh.begincatch + // call. We're tracking it here so that we can skip the store and load. + ExtractedEHPtrs.push_back(Extract); + } else if (Idx == 1) { + // Element 1 corresponds to the filter selector. We'll map it to 1 for + // matching purposes, but it will also probably be stored to memory and + // reloaded, so we need to track the instuction so that we can map the + // loaded value too. + ExtractedSelectors.push_back(Extract); } - if (StoredValue == ExtractedSelector) { - SelectorStoreAddr = Store->getPointerOperand(); - return CloningDirector::SkipInstruction; + + // Look for stores of the extracted values. + for (auto *EU : Extract->users()) { + if (auto *Store = dyn_cast<StoreInst>(EU)) { + if (Idx == 1) { + SelectorStores.push_back(Store); + SelectorStoreAddrs.push_back(Store->getPointerOperand()); + } else { + EHPtrStores.push_back(Store); + EHPtrStoreAddrs.push_back(Store->getPointerOperand()); + } + } } + } +} - // Any other store just gets cloned. - return CloningDirector::CloneInstruction; +bool LandingPadMap::isLandingPadSpecificInst(const Instruction *Inst) const { + if (Inst == OriginLPad) + return true; + for (auto *Extract : ExtractedEHPtrs) { + if (Inst == Extract) + return true; + } + for (auto *Extract : ExtractedSelectors) { + if (Inst == Extract) + return true; + } + for (auto *Store : EHPtrStores) { + if (Inst == Store) + return true; + } + for (auto *Store : SelectorStores) { + if (Inst == Store) + return true; + } + + return false; +} + +void LandingPadMap::remapSelector(ValueToValueMapTy &VMap, + Value *MappedValue) const { + // Remap all selector extract instructions to the specified value. + for (auto *Extract : ExtractedSelectors) + VMap[Extract] = MappedValue; +} + +bool LandingPadMap::mapIfEHLoad(const LoadInst *Load, + SmallVectorImpl<const StoreInst *> &Stores, + SmallVectorImpl<const Value *> &StoreAddrs) { + // This makes the assumption that a store we've previously seen dominates + // this load instruction. That might seem like a rather huge assumption, + // but given the way that landingpads are constructed its fairly safe. + // FIXME: Add debug/assert code that verifies this. + const Value *LoadAddr = Load->getPointerOperand(); + for (auto *StoreAddr : StoreAddrs) { + if (LoadAddr == StoreAddr) { + // Handle the common debug scenario where this loaded value is stored + // to a different location. + for (auto *U : Load->users()) { + if (auto *Store = dyn_cast<StoreInst>(U)) { + Stores.push_back(Store); + StoreAddrs.push_back(Store->getPointerOperand()); + } + } + return true; + } } + return false; +} + +CloningDirector::CloningAction WinEHCloningDirectorBase::handleInstruction( + ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) { + // If this is one of the boilerplate landing pad instructions, skip it. + // The instruction will have already been remapped in VMap. + if (LPadMap.isLandingPadSpecificInst(Inst)) + return CloningDirector::SkipInstruction; if (auto *Load = dyn_cast<LoadInst>(Inst)) { // Look for loads of (previously suppressed) landingpad values. - // The EHPtr load can be ignored (it should only be used as - // an argument to llvm.eh.begincatch), but the selector value - // needs to be mapped to a constant value of 1 to be used to - // simplify the branching to always flow to the current handler. - const Value *LoadAddr = Load->getPointerOperand(); - if (LoadAddr == EHPtrStoreAddr) { - VMap[Inst] = UndefValue::get(Int8PtrType); + // The EHPtr load can be mapped to an undef value as it should only be used + // as an argument to llvm.eh.begincatch, but the selector value needs to be + // mapped to a constant value of 1. This value will be used to simplify the + // branching to always flow to the current handler. + if (LPadMap.mapIfSelectorLoad(Load)) { + VMap[Inst] = ConstantInt::get(SelectorIDType, 1); return CloningDirector::SkipInstruction; } - if (LoadAddr == SelectorStoreAddr) { - VMap[Inst] = ConstantInt::get(SelectorIDType, 1); + if (LPadMap.mapIfEHPtrLoad(Load)) { + VMap[Inst] = UndefValue::get(Int8PtrType); return CloningDirector::SkipInstruction; } @@ -519,108 +910,576 @@ CloningDirector::CloningAction WinEHCatchDirector::handleInstruction( return CloningDirector::CloneInstruction; } - if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>())) { - // The argument to the call is some form of the first element of the - // landingpad aggregate value, but that doesn't matter. It isn't used - // here. - // The return value of this instruction, however, is used to access the - // EH object pointer. We have generated an instruction to get that value - // from the EH alloc block, so we can just map to that here. - VMap[Inst] = EHObj; - return CloningDirector::SkipInstruction; - } - if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>())) { - auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst); - // It might be interesting to track whether or not we are inside a catch - // function, but that might make the algorithm more brittle than it needs - // to be. - - // The end catch call can occur in one of two places: either in a - // landingpad - // block that is part of the catch handlers exception mechanism, or at the - // end of the catch block. If it occurs in a landing pad, we must skip it - // and continue so that the landing pad gets cloned. - // FIXME: This case isn't fully supported yet and shouldn't turn up in any - // of the test cases until it is. - if (IntrinCall->getParent()->isLandingPad()) - return CloningDirector::SkipInstruction; - - // If an end catch occurs anywhere else the next instruction should be an - // unconditional branch instruction that we want to replace with a return - // to the the address of the branch target. - const BasicBlock *EndCatchBB = IntrinCall->getParent(); - const TerminatorInst *Terminator = EndCatchBB->getTerminator(); - const BranchInst *Branch = dyn_cast<BranchInst>(Terminator); - assert(Branch && Branch->isUnconditional()); - assert(std::next(BasicBlock::const_iterator(IntrinCall)) == - BasicBlock::const_iterator(Branch)); - - ReturnInst::Create(NewBB->getContext(), - BlockAddress::get(Branch->getSuccessor(0)), NewBB); - - // We just added a terminator to the cloned block. - // Tell the caller to stop processing the current basic block so that - // the branch instruction will be skipped. + // Nested landing pads will be cloned as stubs, with just the + // landingpad instruction and an unreachable instruction. When + // all landingpads have been outlined, we'll replace this with the + // llvm.eh.actions call and indirect branch created when the + // landing pad was outlined. + if (auto *NestedLPad = dyn_cast<LandingPadInst>(Inst)) { + Instruction *NewInst = NestedLPad->clone(); + if (NestedLPad->hasName()) + NewInst->setName(NestedLPad->getName()); + // FIXME: Store this mapping somewhere else also. + VMap[NestedLPad] = NewInst; + BasicBlock::InstListType &InstList = NewBB->getInstList(); + InstList.push_back(NewInst); + InstList.push_back(new UnreachableInst(NewBB->getContext())); return CloningDirector::StopCloningBB; } - if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>())) { - auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst); - Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts(); - // This causes a replacement that will collapse the landing pad CFG based - // on the filter function we intend to match. - if (Selector == CurrentSelector) - VMap[Inst] = ConstantInt::get(SelectorIDType, 1); - else - VMap[Inst] = ConstantInt::get(SelectorIDType, 0); - // Tell the caller not to clone this instruction. - return CloningDirector::SkipInstruction; - } + + if (auto *Invoke = dyn_cast<InvokeInst>(Inst)) + return handleInvoke(VMap, Invoke, NewBB); + + if (auto *Resume = dyn_cast<ResumeInst>(Inst)) + return handleResume(VMap, Resume, NewBB); + + if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>())) + return handleBeginCatch(VMap, Inst, NewBB); + if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>())) + return handleEndCatch(VMap, Inst, NewBB); + if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>())) + return handleTypeIdFor(VMap, Inst, NewBB); // Continue with the default cloning behavior. return CloningDirector::CloneInstruction; } +CloningDirector::CloningAction WinEHCatchDirector::handleBeginCatch( + ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) { + // The argument to the call is some form of the first element of the + // landingpad aggregate value, but that doesn't matter. It isn't used + // here. + // The second argument is an outparameter where the exception object will be + // stored. Typically the exception object is a scalar, but it can be an + // aggregate when catching by value. + // FIXME: Leave something behind to indicate where the exception object lives + // for this handler. Should it be part of llvm.eh.actions? + assert(ExceptionObjectVar == nullptr && "Multiple calls to " + "llvm.eh.begincatch found while " + "outlining catch handler."); + ExceptionObjectVar = Inst->getOperand(1)->stripPointerCasts(); + return CloningDirector::SkipInstruction; +} + +CloningDirector::CloningAction +WinEHCatchDirector::handleEndCatch(ValueToValueMapTy &VMap, + const Instruction *Inst, BasicBlock *NewBB) { + auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst); + // It might be interesting to track whether or not we are inside a catch + // function, but that might make the algorithm more brittle than it needs + // to be. + + // The end catch call can occur in one of two places: either in a + // landingpad block that is part of the catch handlers exception mechanism, + // or at the end of the catch block. If it occurs in a landing pad, we must + // skip it and continue so that the landing pad gets cloned. + // FIXME: This case isn't fully supported yet and shouldn't turn up in any + // of the test cases until it is. + if (IntrinCall->getParent()->isLandingPad()) + return CloningDirector::SkipInstruction; + + // If an end catch occurs anywhere else the next instruction should be an + // unconditional branch instruction that we want to replace with a return + // to the the address of the branch target. + const BasicBlock *EndCatchBB = IntrinCall->getParent(); + const TerminatorInst *Terminator = EndCatchBB->getTerminator(); + const BranchInst *Branch = dyn_cast<BranchInst>(Terminator); + assert(Branch && Branch->isUnconditional()); + assert(std::next(BasicBlock::const_iterator(IntrinCall)) == + BasicBlock::const_iterator(Branch)); + + BasicBlock *ContinueLabel = Branch->getSuccessor(0); + ReturnInst::Create(NewBB->getContext(), BlockAddress::get(ContinueLabel), + NewBB); + ReturnTargets.push_back(ContinueLabel); + + // We just added a terminator to the cloned block. + // Tell the caller to stop processing the current basic block so that + // the branch instruction will be skipped. + return CloningDirector::StopCloningBB; +} + +CloningDirector::CloningAction WinEHCatchDirector::handleTypeIdFor( + ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) { + auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst); + Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts(); + // This causes a replacement that will collapse the landing pad CFG based + // on the filter function we intend to match. + if (Selector == CurrentSelector) + VMap[Inst] = ConstantInt::get(SelectorIDType, 1); + else + VMap[Inst] = ConstantInt::get(SelectorIDType, 0); + // Tell the caller not to clone this instruction. + return CloningDirector::SkipInstruction; +} + +CloningDirector::CloningAction +WinEHCatchDirector::handleInvoke(ValueToValueMapTy &VMap, + const InvokeInst *Invoke, BasicBlock *NewBB) { + return CloningDirector::CloneInstruction; +} + +CloningDirector::CloningAction +WinEHCatchDirector::handleResume(ValueToValueMapTy &VMap, + const ResumeInst *Resume, BasicBlock *NewBB) { + // Resume instructions shouldn't be reachable from catch handlers. + // We still need to handle it, but it will be pruned. + BasicBlock::InstListType &InstList = NewBB->getInstList(); + InstList.push_back(new UnreachableInst(NewBB->getContext())); + return CloningDirector::StopCloningBB; +} + +CloningDirector::CloningAction WinEHCleanupDirector::handleBeginCatch( + ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) { + // Catch blocks within cleanup handlers will always be unreachable. + // We'll insert an unreachable instruction now, but it will be pruned + // before the cloning process is complete. + BasicBlock::InstListType &InstList = NewBB->getInstList(); + InstList.push_back(new UnreachableInst(NewBB->getContext())); + return CloningDirector::StopCloningBB; +} + +CloningDirector::CloningAction WinEHCleanupDirector::handleEndCatch( + ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) { + // Catch blocks within cleanup handlers will always be unreachable. + // We'll insert an unreachable instruction now, but it will be pruned + // before the cloning process is complete. + BasicBlock::InstListType &InstList = NewBB->getInstList(); + InstList.push_back(new UnreachableInst(NewBB->getContext())); + return CloningDirector::StopCloningBB; +} + +CloningDirector::CloningAction WinEHCleanupDirector::handleTypeIdFor( + ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) { + // If we encounter a selector comparison while cloning a cleanup handler, + // we want to stop cloning immediately. Anything after the dispatch + // will be outlined into a different handler. + BasicBlock *CatchHandler; + Constant *Selector; + BasicBlock *NextBB; + if (isSelectorDispatch(const_cast<BasicBlock *>(Inst->getParent()), + CatchHandler, Selector, NextBB)) { + ReturnInst::Create(NewBB->getContext(), nullptr, NewBB); + return CloningDirector::StopCloningBB; + } + // If eg.typeid.for is called for any other reason, it can be ignored. + VMap[Inst] = ConstantInt::get(SelectorIDType, 0); + return CloningDirector::SkipInstruction; +} + +CloningDirector::CloningAction WinEHCleanupDirector::handleInvoke( + ValueToValueMapTy &VMap, const InvokeInst *Invoke, BasicBlock *NewBB) { + // All invokes in cleanup handlers can be replaced with calls. + SmallVector<Value *, 16> CallArgs(Invoke->op_begin(), Invoke->op_end() - 3); + // Insert a normal call instruction... + CallInst *NewCall = + CallInst::Create(const_cast<Value *>(Invoke->getCalledValue()), CallArgs, + Invoke->getName(), NewBB); + NewCall->setCallingConv(Invoke->getCallingConv()); + NewCall->setAttributes(Invoke->getAttributes()); + NewCall->setDebugLoc(Invoke->getDebugLoc()); + VMap[Invoke] = NewCall; + + // Insert an unconditional branch to the normal destination. + BranchInst::Create(Invoke->getNormalDest(), NewBB); + + // The unwind destination won't be cloned into the new function, so + // we don't need to clean up its phi nodes. + + // We just added a terminator to the cloned block. + // Tell the caller to stop processing the current basic block. + return CloningDirector::StopCloningBB; +} + +CloningDirector::CloningAction WinEHCleanupDirector::handleResume( + ValueToValueMapTy &VMap, const ResumeInst *Resume, BasicBlock *NewBB) { + ReturnInst::Create(NewBB->getContext(), nullptr, NewBB); + + // We just added a terminator to the cloned block. + // Tell the caller to stop processing the current basic block so that + // the branch instruction will be skipped. + return CloningDirector::StopCloningBB; +} + WinEHFrameVariableMaterializer::WinEHFrameVariableMaterializer( Function *OutlinedFn, FrameVarInfoMap &FrameVarInfo) : FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) { Builder.SetInsertPoint(&OutlinedFn->getEntryBlock()); - // FIXME: Do something with the FrameVarMapped so that it is shared across the - // function. } Value *WinEHFrameVariableMaterializer::materializeValueFor(Value *V) { - // If we're asked to materialize an alloca variable, we temporarily - // create a matching alloca in the outlined function. When all the - // outlining is complete, we'll collect these into a structure and - // replace these temporary allocas with GEPs referencing the frame - // allocation block. + // If we're asked to materialize a value that is an instruction, we + // temporarily create an alloca in the outlined function and add this + // to the FrameVarInfo map. When all the outlining is complete, we'll + // collect these into a structure, spilling non-alloca values in the + // parent frame as necessary, and replace these temporary allocas with + // GEPs referencing the frame allocation block. + + // If the value is an alloca, the mapping is direct. if (auto *AV = dyn_cast<AllocaInst>(V)) { - AllocaInst *NewAlloca = Builder.CreateAlloca( - AV->getAllocatedType(), AV->getArraySize(), AV->getName()); - FrameVarInfo[AV].Allocas.push_back(NewAlloca); + AllocaInst *NewAlloca = dyn_cast<AllocaInst>(AV->clone()); + Builder.Insert(NewAlloca, AV->getName()); + FrameVarInfo[AV].push_back(NewAlloca); return NewAlloca; } -// FIXME: Do PHI nodes need special handling? + // For other types of instructions or arguments, we need an alloca based on + // the value's type and a load of the alloca. The alloca will be replaced + // by a GEP, but the load will stay. In the parent function, the value will + // be spilled to a location in the frame allocation block. + if (isa<Instruction>(V) || isa<Argument>(V)) { + AllocaInst *NewAlloca = + Builder.CreateAlloca(V->getType(), nullptr, "eh.temp.alloca"); + FrameVarInfo[V].push_back(NewAlloca); + LoadInst *NewLoad = Builder.CreateLoad(NewAlloca, V->getName() + ".reload"); + return NewLoad; + } -// FIXME: Are there other cases we can handle better? GEP, ExtractValue, etc. + // Don't materialize other values. + return nullptr; +} -// FIXME: This doesn't work during cloning because it finds an instruction -// in the use list that isn't yet part of a basic block. -#if 0 - // If we're asked to remap some other instruction, we'll need to - // spill it to an alloca variable in the parent function and add a - // temporary alloca in the outlined function to be processed as - // described above. - Instruction *Inst = dyn_cast<Instruction>(V); - if (Inst) { - AllocaInst *Spill = DemoteRegToStack(*Inst, true); - AllocaInst *NewAlloca = Builder.CreateAlloca(Spill->getAllocatedType(), - Spill->getArraySize()); - FrameVarMap[AV] = NewAlloca; - return NewAlloca; +// This function maps the catch and cleanup handlers that are reachable from the +// specified landing pad. The landing pad sequence will have this basic shape: +// +// <cleanup handler> +// <selector comparison> +// <catch handler> +// <cleanup handler> +// <selector comparison> +// <catch handler> +// <cleanup handler> +// ... +// +// Any of the cleanup slots may be absent. The cleanup slots may be occupied by +// any arbitrary control flow, but all paths through the cleanup code must +// eventually reach the next selector comparison and no path can skip to a +// different selector comparisons, though some paths may terminate abnormally. +// Therefore, we will use a depth first search from the start of any given +// cleanup block and stop searching when we find the next selector comparison. +// +// If the landingpad instruction does not have a catch clause, we will assume +// that any instructions other than selector comparisons and catch handlers can +// be ignored. In practice, these will only be the boilerplate instructions. +// +// The catch handlers may also have any control structure, but we are only +// interested in the start of the catch handlers, so we don't need to actually +// follow the flow of the catch handlers. The start of the catch handlers can +// be located from the compare instructions, but they can be skipped in the +// flow by following the contrary branch. +void WinEHPrepare::mapLandingPadBlocks(LandingPadInst *LPad, + LandingPadActions &Actions) { + unsigned int NumClauses = LPad->getNumClauses(); + unsigned int HandlersFound = 0; + BasicBlock *BB = LPad->getParent(); + + DEBUG(dbgs() << "Mapping landing pad: " << BB->getName() << "\n"); + + if (NumClauses == 0) { + // This landing pad contains only cleanup code. + CleanupHandler *Action = new CleanupHandler(BB); + CleanupHandlerMap[BB] = Action; + Actions.insertCleanupHandler(Action); + DEBUG(dbgs() << " Assuming cleanup code in block " << BB->getName() + << "\n"); + assert(LPad->isCleanup()); + return; + } + + VisitedBlockSet VisitedBlocks; + + while (HandlersFound != NumClauses) { + BasicBlock *NextBB = nullptr; + + // See if the clause we're looking for is a catch-all. + // If so, the catch begins immediately. + if (isa<ConstantPointerNull>(LPad->getClause(HandlersFound))) { + // The catch all must occur last. + assert(HandlersFound == NumClauses - 1); + + // For C++ EH, check if there is any interesting cleanup code before we + // begin the catch. This is important because cleanups cannot rethrow + // exceptions but code called from catches can. For SEH, it isn't + // important if some finally code before a catch-all is executed out of + // line or after recovering from the exception. + if (Personality == EHPersonality::MSVC_CXX) { + if (auto *CleanupAction = findCleanupHandler(BB, BB)) { + // Add a cleanup entry to the list + Actions.insertCleanupHandler(CleanupAction); + DEBUG(dbgs() << " Found cleanup code in block " + << CleanupAction->getStartBlock()->getName() << "\n"); + } + } + + // Add the catch handler to the action list. + CatchHandler *Action = + new CatchHandler(BB, LPad->getClause(HandlersFound), nullptr); + CatchHandlerMap[BB] = Action; + Actions.insertCatchHandler(Action); + DEBUG(dbgs() << " Catch all handler at block " << BB->getName() << "\n"); + ++HandlersFound; + + // Once we reach a catch-all, don't expect to hit a resume instruction. + BB = nullptr; + break; + } + + CatchHandler *CatchAction = findCatchHandler(BB, NextBB, VisitedBlocks); + // See if there is any interesting code executed before the dispatch. + if (auto *CleanupAction = + findCleanupHandler(BB, CatchAction->getStartBlock())) { + // Add a cleanup entry to the list + Actions.insertCleanupHandler(CleanupAction); + DEBUG(dbgs() << " Found cleanup code in block " + << CleanupAction->getStartBlock()->getName() << "\n"); + } + + assert(CatchAction); + ++HandlersFound; + + // Add the catch handler to the action list. + Actions.insertCatchHandler(CatchAction); + DEBUG(dbgs() << " Found catch dispatch in block " + << CatchAction->getStartBlock()->getName() << "\n"); + + // Move on to the block after the catch handler. + BB = NextBB; + } + + // If we didn't wind up in a catch-all, see if there is any interesting code + // executed before the resume. + if (auto *CleanupAction = findCleanupHandler(BB, BB)) { + // Add a cleanup entry to the list + Actions.insertCleanupHandler(CleanupAction); + DEBUG(dbgs() << " Found cleanup code in block " + << CleanupAction->getStartBlock()->getName() << "\n"); + } + + // It's possible that some optimization moved code into a landingpad that + // wasn't + // previously being used for cleanup. If that happens, we need to execute + // that + // extra code from a cleanup handler. + if (Actions.includesCleanup() && !LPad->isCleanup()) + LPad->setCleanup(true); +} + +// This function searches starting with the input block for the next +// block that terminates with a branch whose condition is based on a selector +// comparison. This may be the input block. See the mapLandingPadBlocks +// comments for a discussion of control flow assumptions. +// +CatchHandler *WinEHPrepare::findCatchHandler(BasicBlock *BB, + BasicBlock *&NextBB, + VisitedBlockSet &VisitedBlocks) { + // See if we've already found a catch handler use it. + // Call count() first to avoid creating a null entry for blocks + // we haven't seen before. + if (CatchHandlerMap.count(BB) && CatchHandlerMap[BB] != nullptr) { + CatchHandler *Action = cast<CatchHandler>(CatchHandlerMap[BB]); + NextBB = Action->getNextBB(); + return Action; } -#endif + // VisitedBlocks applies only to the current search. We still + // need to consider blocks that we've visited while mapping other + // landing pads. + VisitedBlocks.insert(BB); + + BasicBlock *CatchBlock = nullptr; + Constant *Selector = nullptr; + + // If this is the first time we've visited this block from any landing pad + // look to see if it is a selector dispatch block. + if (!CatchHandlerMap.count(BB)) { + if (isSelectorDispatch(BB, CatchBlock, Selector, NextBB)) { + CatchHandler *Action = new CatchHandler(BB, Selector, NextBB); + CatchHandlerMap[BB] = Action; + return Action; + } + } + + // Visit each successor, looking for the dispatch. + // FIXME: We expect to find the dispatch quickly, so this will probably + // work better as a breadth first search. + for (BasicBlock *Succ : successors(BB)) { + if (VisitedBlocks.count(Succ)) + continue; + + CatchHandler *Action = findCatchHandler(Succ, NextBB, VisitedBlocks); + if (Action) + return Action; + } + return nullptr; +} + +// These are helper functions to combine repeated code from findCleanupHandler. +static CleanupHandler *createCleanupHandler(CleanupHandlerMapTy &CleanupHandlerMap, + BasicBlock *BB) { + CleanupHandler *Action = new CleanupHandler(BB); + CleanupHandlerMap[BB] = Action; + return Action; +} + +// This function searches starting with the input block for the next block that +// contains code that is not part of a catch handler and would not be eliminated +// during handler outlining. +// +CleanupHandler *WinEHPrepare::findCleanupHandler(BasicBlock *StartBB, + BasicBlock *EndBB) { + // Here we will skip over the following: + // + // landing pad prolog: + // + // Unconditional branches + // + // Selector dispatch + // + // Resume pattern + // + // Anything else marks the start of an interesting block + + BasicBlock *BB = StartBB; + // Anything other than an unconditional branch will kick us out of this loop + // one way or another. + while (BB) { + // If we've already scanned this block, don't scan it again. If it is + // a cleanup block, there will be an action in the CleanupHandlerMap. + // If we've scanned it and it is not a cleanup block, there will be a + // nullptr in the CleanupHandlerMap. If we have not scanned it, there will + // be no entry in the CleanupHandlerMap. We must call count() first to + // avoid creating a null entry for blocks we haven't scanned. + if (CleanupHandlerMap.count(BB)) { + if (auto *Action = CleanupHandlerMap[BB]) { + return cast<CleanupHandler>(Action); + } else { + // Here we handle the case where the cleanup handler map contains a + // value for this block but the value is a nullptr. This means that + // we have previously analyzed the block and determined that it did + // not contain any cleanup code. Based on the earlier analysis, we + // know the the block must end in either an unconditional branch, a + // resume or a conditional branch that is predicated on a comparison + // with a selector. Either the resume or the selector dispatch + // would terminate the search for cleanup code, so the unconditional + // branch is the only case for which we might need to continue + // searching. + if (BB == EndBB) + return nullptr; + BasicBlock *SuccBB; + if (!match(BB->getTerminator(), m_UnconditionalBr(SuccBB))) + return nullptr; + BB = SuccBB; + continue; + } + } + + // Create an entry in the cleanup handler map for this block. Initially + // we create an entry that says this isn't a cleanup block. If we find + // cleanup code, the caller will replace this entry. + CleanupHandlerMap[BB] = nullptr; + + TerminatorInst *Terminator = BB->getTerminator(); + + // Landing pad blocks have extra instructions we need to accept. + LandingPadMap *LPadMap = nullptr; + if (BB->isLandingPad()) { + LandingPadInst *LPad = BB->getLandingPadInst(); + LPadMap = &LPadMaps[LPad]; + if (!LPadMap->isInitialized()) + LPadMap->mapLandingPad(LPad); + } + + // Look for the bare resume pattern: + // %exn2 = load i8** %exn.slot + // %sel2 = load i32* %ehselector.slot + // %lpad.val1 = insertvalue { i8*, i32 } undef, i8* %exn2, 0 + // %lpad.val2 = insertvalue { i8*, i32 } %lpad.val1, i32 %sel2, 1 + // resume { i8*, i32 } %lpad.val2 + if (auto *Resume = dyn_cast<ResumeInst>(Terminator)) { + InsertValueInst *Insert1 = nullptr; + InsertValueInst *Insert2 = nullptr; + Value *ResumeVal = Resume->getOperand(0); + // If there is only one landingpad, we may use the lpad directly with no + // insertions. + if (isa<LandingPadInst>(ResumeVal)) + return nullptr; + if (!isa<PHINode>(ResumeVal)) { + Insert2 = dyn_cast<InsertValueInst>(ResumeVal); + if (!Insert2) + return createCleanupHandler(CleanupHandlerMap, BB); + Insert1 = dyn_cast<InsertValueInst>(Insert2->getAggregateOperand()); + if (!Insert1) + return createCleanupHandler(CleanupHandlerMap, BB); + } + for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end(); + II != IE; ++II) { + Instruction *Inst = II; + if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst)) + continue; + if (Inst == Insert1 || Inst == Insert2 || Inst == Resume) + continue; + if (!Inst->hasOneUse() || + (Inst->user_back() != Insert1 && Inst->user_back() != Insert2)) { + return createCleanupHandler(CleanupHandlerMap, BB); + } + } + return nullptr; + } + + BranchInst *Branch = dyn_cast<BranchInst>(Terminator); + if (Branch) { + if (Branch->isConditional()) { + // Look for the selector dispatch. + // %sel = load i32* %ehselector.slot + // %2 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIf to i8*)) + // %matches = icmp eq i32 %sel12, %2 + // br i1 %matches, label %catch14, label %eh.resume + CmpInst *Compare = dyn_cast<CmpInst>(Branch->getCondition()); + if (!Compare || !Compare->isEquality()) + return createCleanupHandler(CleanupHandlerMap, BB); + for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), + IE = BB->end(); + II != IE; ++II) { + Instruction *Inst = II; + if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst)) + continue; + if (Inst == Compare || Inst == Branch) + continue; + if (!Inst->hasOneUse() || (Inst->user_back() != Compare)) + return createCleanupHandler(CleanupHandlerMap, BB); + if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>())) + continue; + if (!isa<LoadInst>(Inst)) + return createCleanupHandler(CleanupHandlerMap, BB); + } + // The selector dispatch block should always terminate our search. + assert(BB == EndBB); + return nullptr; + } else { + // Look for empty blocks with unconditional branches. + for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), + IE = BB->end(); + II != IE; ++II) { + Instruction *Inst = II; + if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst)) + continue; + if (Inst == Branch) + continue; + if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>())) + continue; + // Anything else makes this interesting cleanup code. + return createCleanupHandler(CleanupHandlerMap, BB); + } + if (BB == EndBB) + return nullptr; + // The branch was unconditional. + BB = Branch->getSuccessor(0); + continue; + } // End else of if branch was conditional + } // End if Branch + + // Anything else makes this interesting cleanup code. + return createCleanupHandler(CleanupHandlerMap, BB); + } return nullptr; } |