| //===-- WinEHPrepare - Prepare exception handling for code generation ---===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This pass lowers LLVM IR exception handling into something closer to what the |
| // backend wants for functions using a personality function from a runtime |
| // provided by MSVC. Functions with other personality functions are left alone |
| // and may be prepared by other passes. In particular, all supported MSVC |
| // personality functions require cleanup code to be outlined, and the C++ |
| // personality requires catch handler code to be outlined. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/CodeGen/Passes.h" |
| #include "llvm/ADT/MapVector.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/ADT/SmallSet.h" |
| #include "llvm/ADT/SetVector.h" |
| #include "llvm/ADT/Triple.h" |
| #include "llvm/ADT/TinyPtrVector.h" |
| #include "llvm/Analysis/LibCallSemantics.h" |
| #include "llvm/Analysis/TargetLibraryInfo.h" |
| #include "llvm/CodeGen/WinEHFuncInfo.h" |
| #include "llvm/IR/Dominators.h" |
| #include "llvm/IR/Function.h" |
| #include "llvm/IR/IRBuilder.h" |
| #include "llvm/IR/Instructions.h" |
| #include "llvm/IR/IntrinsicInst.h" |
| #include "llvm/IR/Module.h" |
| #include "llvm/IR/PatternMatch.h" |
| #include "llvm/Pass.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 "llvm/Transforms/Utils/PromoteMemToReg.h" |
| #include <memory> |
| |
| using namespace llvm; |
| using namespace llvm::PatternMatch; |
| |
| #define DEBUG_TYPE "winehprepare" |
| |
| namespace { |
| |
| // 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<Value *, TinyPtrVector<AllocaInst *>> FrameVarInfoMap; |
| |
| // TinyPtrVector cannot hold nullptr, so we need our own sentinel that isn't |
| // quite null. |
| AllocaInst *getCatchObjectSentinel() { |
| return static_cast<AllocaInst *>(nullptr) + 1; |
| } |
| |
| typedef SmallSet<BasicBlock *, 4> VisitedBlockSet; |
| |
| class LandingPadActions; |
| 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) { |
| if (TM) |
| TheTriple = TM->getTargetTriple(); |
| } |
| |
| bool runOnFunction(Function &Fn) override; |
| |
| bool doFinalization(Module &M) override; |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override; |
| |
| const char *getPassName() const override { |
| return "Windows exception handling preparation"; |
| } |
| |
| private: |
| bool prepareExceptionHandlers(Function &F, |
| SmallVectorImpl<LandingPadInst *> &LPads); |
| void identifyEHBlocks(Function &F, SmallVectorImpl<LandingPadInst *> &LPads); |
| void promoteLandingPadValues(LandingPadInst *LPad); |
| void demoteValuesLiveAcrossHandlers(Function &F, |
| SmallVectorImpl<LandingPadInst *> &LPads); |
| void findSEHEHReturnPoints(Function &F, |
| SetVector<BasicBlock *> &EHReturnBlocks); |
| void findCXXEHReturnPoints(Function &F, |
| SetVector<BasicBlock *> &EHReturnBlocks); |
| void getPossibleReturnTargets(Function *ParentF, Function *HandlerF, |
| SetVector<BasicBlock*> &Targets); |
| void completeNestedLandingPad(Function *ParentFn, |
| LandingPadInst *OutlinedLPad, |
| const LandingPadInst *OriginalLPad, |
| FrameVarInfoMap &VarInfo); |
| Function *createHandlerFunc(Function *ParentFn, Type *RetTy, |
| const Twine &Name, Module *M, Value *&ParentFP); |
| bool outlineHandler(ActionHandler *Action, Function *SrcFn, |
| LandingPadInst *LPad, BasicBlock *StartBB, |
| FrameVarInfoMap &VarInfo); |
| void addStubInvokeToHandlerIfNeeded(Function *Handler); |
| |
| void mapLandingPadBlocks(LandingPadInst *LPad, LandingPadActions &Actions); |
| CatchHandler *findCatchHandler(BasicBlock *BB, BasicBlock *&NextBB, |
| VisitedBlockSet &VisitedBlocks); |
| void findCleanupHandlers(LandingPadActions &Actions, BasicBlock *StartBB, |
| BasicBlock *EndBB); |
| |
| void processSEHCatchHandler(CatchHandler *Handler, BasicBlock *StartBB); |
| |
| Triple TheTriple; |
| |
| // All fields are reset by runOnFunction. |
| DominatorTree *DT = nullptr; |
| const TargetLibraryInfo *LibInfo = nullptr; |
| EHPersonality Personality = EHPersonality::Unknown; |
| CatchHandlerMapTy CatchHandlerMap; |
| CleanupHandlerMapTy CleanupHandlerMap; |
| DenseMap<const LandingPadInst *, LandingPadMap> LPadMaps; |
| SmallPtrSet<BasicBlock *, 4> NormalBlocks; |
| SmallPtrSet<BasicBlock *, 4> EHBlocks; |
| SetVector<BasicBlock *> EHReturnBlocks; |
| |
| // This maps landing pad instructions found in outlined handlers to |
| // the landing pad instruction in the parent function from which they |
| // were cloned. The cloned/nested landing pad is used as the key |
| // because the landing pad may be cloned into multiple handlers. |
| // This map will be used to add the llvm.eh.actions call to the nested |
| // landing pads after all handlers have been outlined. |
| DenseMap<LandingPadInst *, const LandingPadInst *> NestedLPtoOriginalLP; |
| |
| // This maps blocks in the parent function which are destinations of |
| // catch handlers to cloned blocks in (other) outlined handlers. This |
| // handles the case where a nested landing pads has a catch handler that |
| // returns to a handler function rather than the parent function. |
| // The original block is used as the key here because there should only |
| // ever be one handler function from which the cloned block is not pruned. |
| // The original block will be pruned from the parent function after all |
| // handlers have been outlined. This map will be used to adjust the |
| // return instructions of handlers which return to the block that was |
| // outlined into a handler. This is done after all handlers have been |
| // outlined but before the outlined code is pruned from the parent function. |
| DenseMap<const BasicBlock *, BasicBlock *> LPadTargetBlocks; |
| |
| // Map from outlined handler to call to parent local address. Only used for |
| // 32-bit EH. |
| DenseMap<Function *, Value *> HandlerToParentFP; |
| |
| AllocaInst *SEHExceptionCodeSlot = nullptr; |
| }; |
| |
| class WinEHFrameVariableMaterializer : public ValueMaterializer { |
| public: |
| WinEHFrameVariableMaterializer(Function *OutlinedFn, Value *ParentFP, |
| FrameVarInfoMap &FrameVarInfo); |
| ~WinEHFrameVariableMaterializer() override {} |
| |
| Value *materializeValueFor(Value *V) override; |
| |
| void escapeCatchObject(Value *V); |
| |
| private: |
| FrameVarInfoMap &FrameVarInfo; |
| IRBuilder<> Builder; |
| }; |
| |
| class LandingPadMap { |
| public: |
| LandingPadMap() : OriginLPad(nullptr) {} |
| void mapLandingPad(const LandingPadInst *LPad); |
| |
| bool isInitialized() { return OriginLPad != nullptr; } |
| |
| bool isOriginLandingPadBlock(const BasicBlock *BB) const; |
| bool isLandingPadSpecificInst(const Instruction *Inst) const; |
| |
| void remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue, |
| Value *SelectorValue) const; |
| |
| private: |
| 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; |
| }; |
| |
| class WinEHCloningDirectorBase : public CloningDirector { |
| public: |
| WinEHCloningDirectorBase(Function *HandlerFn, Value *ParentFP, |
| FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap) |
| : Materializer(HandlerFn, ParentFP, VarInfo), |
| SelectorIDType(Type::getInt32Ty(HandlerFn->getContext())), |
| Int8PtrType(Type::getInt8PtrTy(HandlerFn->getContext())), |
| LPadMap(LPadMap), ParentFP(ParentFP) {} |
| |
| 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 handleIndirectBr(ValueToValueMapTy &VMap, |
| const IndirectBrInst *IBr, |
| 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; |
| virtual CloningAction handleCompare(ValueToValueMapTy &VMap, |
| const CmpInst *Compare, |
| BasicBlock *NewBB) = 0; |
| virtual CloningAction handleLandingPad(ValueToValueMapTy &VMap, |
| const LandingPadInst *LPad, |
| BasicBlock *NewBB) = 0; |
| |
| ValueMaterializer *getValueMaterializer() override { return &Materializer; } |
| |
| protected: |
| WinEHFrameVariableMaterializer Materializer; |
| Type *SelectorIDType; |
| Type *Int8PtrType; |
| LandingPadMap &LPadMap; |
| |
| /// The value representing the parent frame pointer. |
| Value *ParentFP; |
| }; |
| |
| class WinEHCatchDirector : public WinEHCloningDirectorBase { |
| public: |
| WinEHCatchDirector( |
| Function *CatchFn, Value *ParentFP, Value *Selector, |
| FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap, |
| DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPads, |
| DominatorTree *DT, SmallPtrSetImpl<BasicBlock *> &EHBlocks) |
| : WinEHCloningDirectorBase(CatchFn, ParentFP, VarInfo, LPadMap), |
| CurrentSelector(Selector->stripPointerCasts()), |
| ExceptionObjectVar(nullptr), NestedLPtoOriginalLP(NestedLPads), |
| DT(DT), EHBlocks(EHBlocks) {} |
| |
| 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 handleIndirectBr(ValueToValueMapTy &VMap, |
| const IndirectBrInst *IBr, |
| BasicBlock *NewBB) override; |
| CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke, |
| BasicBlock *NewBB) override; |
| CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume, |
| BasicBlock *NewBB) override; |
| CloningAction handleCompare(ValueToValueMapTy &VMap, const CmpInst *Compare, |
| BasicBlock *NewBB) override; |
| CloningAction handleLandingPad(ValueToValueMapTy &VMap, |
| const LandingPadInst *LPad, |
| BasicBlock *NewBB) override; |
| |
| Value *getExceptionVar() { return ExceptionObjectVar; } |
| TinyPtrVector<BasicBlock *> &getReturnTargets() { return ReturnTargets; } |
| |
| private: |
| Value *CurrentSelector; |
| |
| Value *ExceptionObjectVar; |
| TinyPtrVector<BasicBlock *> ReturnTargets; |
| |
| // This will be a reference to the field of the same name in the WinEHPrepare |
| // object which instantiates this WinEHCatchDirector object. |
| DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPtoOriginalLP; |
| DominatorTree *DT; |
| SmallPtrSetImpl<BasicBlock *> &EHBlocks; |
| }; |
| |
| class WinEHCleanupDirector : public WinEHCloningDirectorBase { |
| public: |
| WinEHCleanupDirector(Function *CleanupFn, Value *ParentFP, |
| FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap) |
| : WinEHCloningDirectorBase(CleanupFn, ParentFP, 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 handleIndirectBr(ValueToValueMapTy &VMap, |
| const IndirectBrInst *IBr, |
| BasicBlock *NewBB) override; |
| CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke, |
| BasicBlock *NewBB) override; |
| CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume, |
| BasicBlock *NewBB) override; |
| CloningAction handleCompare(ValueToValueMapTy &VMap, const CmpInst *Compare, |
| BasicBlock *NewBB) override; |
| CloningAction handleLandingPad(ValueToValueMapTy &VMap, |
| const LandingPadInst *LPad, |
| BasicBlock *NewBB) override; |
| }; |
| |
| 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 *> &actions() { return Actions; } |
| 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; |
| INITIALIZE_TM_PASS(WinEHPrepare, "winehprepare", "Prepare Windows exceptions", |
| false, false) |
| |
| FunctionPass *llvm::createWinEHPass(const TargetMachine *TM) { |
| return new WinEHPrepare(TM); |
| } |
| |
| bool WinEHPrepare::runOnFunction(Function &Fn) { |
| // No need to prepare outlined handlers. |
| if (Fn.hasFnAttribute("wineh-parent")) |
| return false; |
| |
| SmallVector<LandingPadInst *, 4> LPads; |
| SmallVector<ResumeInst *, 4> Resumes; |
| for (BasicBlock &BB : Fn) { |
| if (auto *LP = BB.getLandingPadInst()) |
| LPads.push_back(LP); |
| if (auto *Resume = dyn_cast<ResumeInst>(BB.getTerminator())) |
| Resumes.push_back(Resume); |
| } |
| |
| // No need to prepare functions that lack landing pads. |
| if (LPads.empty()) |
| return false; |
| |
| // Classify the personality to see what kind of preparation we need. |
| Personality = classifyEHPersonality(Fn.getPersonalityFn()); |
| |
| // Do nothing if this is not an MSVC personality. |
| if (!isMSVCEHPersonality(Personality)) |
| return false; |
| |
| DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree(); |
| LibInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(); |
| |
| // If there were any landing pads, prepareExceptionHandlers will make changes. |
| prepareExceptionHandlers(Fn, LPads); |
| return true; |
| } |
| |
| bool WinEHPrepare::doFinalization(Module &M) { return false; } |
| |
| void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const { |
| AU.addRequired<DominatorTreeWrapperPass>(); |
| AU.addRequired<TargetLibraryInfoWrapperPass>(); |
| } |
| |
| static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler, |
| Constant *&Selector, BasicBlock *&NextBB); |
| |
| // Finds blocks reachable from the starting set Worklist. Does not follow unwind |
| // edges or blocks listed in StopPoints. |
| static void findReachableBlocks(SmallPtrSetImpl<BasicBlock *> &ReachableBBs, |
| SetVector<BasicBlock *> &Worklist, |
| const SetVector<BasicBlock *> *StopPoints) { |
| while (!Worklist.empty()) { |
| BasicBlock *BB = Worklist.pop_back_val(); |
| |
| // Don't cross blocks that we should stop at. |
| if (StopPoints && StopPoints->count(BB)) |
| continue; |
| |
| if (!ReachableBBs.insert(BB).second) |
| continue; // Already visited. |
| |
| // Don't follow unwind edges of invokes. |
| if (auto *II = dyn_cast<InvokeInst>(BB->getTerminator())) { |
| Worklist.insert(II->getNormalDest()); |
| continue; |
| } |
| |
| // Otherwise, follow all successors. |
| Worklist.insert(succ_begin(BB), succ_end(BB)); |
| } |
| } |
| |
| // Attempt to find an instruction where a block can be split before |
| // a call to llvm.eh.begincatch and its operands. If the block |
| // begins with the begincatch call or one of its adjacent operands |
| // the block will not be split. |
| static Instruction *findBeginCatchSplitPoint(BasicBlock *BB, |
| IntrinsicInst *II) { |
| // If the begincatch call is already the first instruction in the block, |
| // don't split. |
| Instruction *FirstNonPHI = BB->getFirstNonPHI(); |
| if (II == FirstNonPHI) |
| return nullptr; |
| |
| // If either operand is in the same basic block as the instruction and |
| // isn't used by another instruction before the begincatch call, include it |
| // in the split block. |
| auto *Op0 = dyn_cast<Instruction>(II->getOperand(0)); |
| auto *Op1 = dyn_cast<Instruction>(II->getOperand(1)); |
| |
| Instruction *I = II->getPrevNode(); |
| Instruction *LastI = II; |
| |
| while (I == Op0 || I == Op1) { |
| // If the block begins with one of the operands and there are no other |
| // instructions between the operand and the begincatch call, don't split. |
| if (I == FirstNonPHI) |
| return nullptr; |
| |
| LastI = I; |
| I = I->getPrevNode(); |
| } |
| |
| // If there is at least one instruction in the block before the begincatch |
| // call and its operands, split the block at either the begincatch or |
| // its operand. |
| return LastI; |
| } |
| |
| /// Find all points where exceptional control rejoins normal control flow via |
| /// llvm.eh.endcatch. Add them to the normal bb reachability worklist. |
| void WinEHPrepare::findCXXEHReturnPoints( |
| Function &F, SetVector<BasicBlock *> &EHReturnBlocks) { |
| for (auto BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) { |
| BasicBlock *BB = BBI; |
| for (Instruction &I : *BB) { |
| if (match(&I, m_Intrinsic<Intrinsic::eh_begincatch>())) { |
| Instruction *SplitPt = |
| findBeginCatchSplitPoint(BB, cast<IntrinsicInst>(&I)); |
| if (SplitPt) { |
| // Split the block before the llvm.eh.begincatch call to allow |
| // cleanup and catch code to be distinguished later. |
| // Do not update BBI because we still need to process the |
| // portion of the block that we are splitting off. |
| SplitBlock(BB, SplitPt, DT); |
| break; |
| } |
| } |
| if (match(&I, m_Intrinsic<Intrinsic::eh_endcatch>())) { |
| // Split the block after the call to llvm.eh.endcatch if there is |
| // anything other than an unconditional branch, or if the successor |
| // starts with a phi. |
| auto *Br = dyn_cast<BranchInst>(I.getNextNode()); |
| if (!Br || !Br->isUnconditional() || |
| isa<PHINode>(Br->getSuccessor(0)->begin())) { |
| DEBUG(dbgs() << "splitting block " << BB->getName() |
| << " with llvm.eh.endcatch\n"); |
| BBI = SplitBlock(BB, I.getNextNode(), DT); |
| } |
| // The next BB is normal control flow. |
| EHReturnBlocks.insert(BB->getTerminator()->getSuccessor(0)); |
| break; |
| } |
| } |
| } |
| } |
| |
| static bool isCatchAllLandingPad(const BasicBlock *BB) { |
| const LandingPadInst *LP = BB->getLandingPadInst(); |
| if (!LP) |
| return false; |
| unsigned N = LP->getNumClauses(); |
| return (N > 0 && LP->isCatch(N - 1) && |
| isa<ConstantPointerNull>(LP->getClause(N - 1))); |
| } |
| |
| /// Find all points where exceptions control rejoins normal control flow via |
| /// selector dispatch. |
| void WinEHPrepare::findSEHEHReturnPoints( |
| Function &F, SetVector<BasicBlock *> &EHReturnBlocks) { |
| for (auto BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) { |
| BasicBlock *BB = BBI; |
| // If the landingpad is a catch-all, treat the whole lpad as if it is |
| // reachable from normal control flow. |
| // FIXME: This is imprecise. We need a better way of identifying where a |
| // catch-all starts and cleanups stop. As far as LLVM is concerned, there |
| // is no difference. |
| if (isCatchAllLandingPad(BB)) { |
| EHReturnBlocks.insert(BB); |
| continue; |
| } |
| |
| BasicBlock *CatchHandler; |
| BasicBlock *NextBB; |
| Constant *Selector; |
| if (isSelectorDispatch(BB, CatchHandler, Selector, NextBB)) { |
| // Split the edge if there are multiple predecessors. This creates a place |
| // where we can insert EH recovery code. |
| if (!CatchHandler->getSinglePredecessor()) { |
| DEBUG(dbgs() << "splitting EH return edge from " << BB->getName() |
| << " to " << CatchHandler->getName() << '\n'); |
| BBI = CatchHandler = SplitCriticalEdge( |
| BB, std::find(succ_begin(BB), succ_end(BB), CatchHandler)); |
| } |
| EHReturnBlocks.insert(CatchHandler); |
| } |
| } |
| } |
| |
| void WinEHPrepare::identifyEHBlocks(Function &F, |
| SmallVectorImpl<LandingPadInst *> &LPads) { |
| DEBUG(dbgs() << "Demoting values live across exception handlers in function " |
| << F.getName() << '\n'); |
| |
| // Build a set of all non-exceptional blocks and exceptional blocks. |
| // - Non-exceptional blocks are blocks reachable from the entry block while |
| // not following invoke unwind edges. |
| // - Exceptional blocks are blocks reachable from landingpads. Analysis does |
| // not follow llvm.eh.endcatch blocks, which mark a transition from |
| // exceptional to normal control. |
| |
| if (Personality == EHPersonality::MSVC_CXX) |
| findCXXEHReturnPoints(F, EHReturnBlocks); |
| else |
| findSEHEHReturnPoints(F, EHReturnBlocks); |
| |
| DEBUG({ |
| dbgs() << "identified the following blocks as EH return points:\n"; |
| for (BasicBlock *BB : EHReturnBlocks) |
| dbgs() << " " << BB->getName() << '\n'; |
| }); |
| |
| // Join points should not have phis at this point, unless they are a |
| // landingpad, in which case we will demote their phis later. |
| #ifndef NDEBUG |
| for (BasicBlock *BB : EHReturnBlocks) |
| assert((BB->isLandingPad() || !isa<PHINode>(BB->begin())) && |
| "non-lpad EH return block has phi"); |
| #endif |
| |
| // Normal blocks are the blocks reachable from the entry block and all EH |
| // return points. |
| SetVector<BasicBlock *> Worklist; |
| Worklist = EHReturnBlocks; |
| Worklist.insert(&F.getEntryBlock()); |
| findReachableBlocks(NormalBlocks, Worklist, nullptr); |
| DEBUG({ |
| dbgs() << "marked the following blocks as normal:\n"; |
| for (BasicBlock *BB : NormalBlocks) |
| dbgs() << " " << BB->getName() << '\n'; |
| }); |
| |
| // Exceptional blocks are the blocks reachable from landingpads that don't |
| // cross EH return points. |
| Worklist.clear(); |
| for (auto *LPI : LPads) |
| Worklist.insert(LPI->getParent()); |
| findReachableBlocks(EHBlocks, Worklist, &EHReturnBlocks); |
| DEBUG({ |
| dbgs() << "marked the following blocks as exceptional:\n"; |
| for (BasicBlock *BB : EHBlocks) |
| dbgs() << " " << BB->getName() << '\n'; |
| }); |
| |
| } |
| |
| /// Ensure that all values live into and out of exception handlers are stored |
| /// in memory. |
| /// FIXME: This falls down when values are defined in one handler and live into |
| /// another handler. For example, a cleanup defines a value used only by a |
| /// catch handler. |
| void WinEHPrepare::demoteValuesLiveAcrossHandlers( |
| Function &F, SmallVectorImpl<LandingPadInst *> &LPads) { |
| DEBUG(dbgs() << "Demoting values live across exception handlers in function " |
| << F.getName() << '\n'); |
| |
| // identifyEHBlocks() should have been called before this function. |
| assert(!NormalBlocks.empty()); |
| |
| // Try to avoid demoting EH pointer and selector values. They get in the way |
| // of our pattern matching. |
| SmallPtrSet<Instruction *, 10> EHVals; |
| for (BasicBlock &BB : F) { |
| LandingPadInst *LP = BB.getLandingPadInst(); |
| if (!LP) |
| continue; |
| EHVals.insert(LP); |
| for (User *U : LP->users()) { |
| auto *EI = dyn_cast<ExtractValueInst>(U); |
| if (!EI) |
| continue; |
| EHVals.insert(EI); |
| for (User *U2 : EI->users()) { |
| if (auto *PN = dyn_cast<PHINode>(U2)) |
| EHVals.insert(PN); |
| } |
| } |
| } |
| |
| SetVector<Argument *> ArgsToDemote; |
| SetVector<Instruction *> InstrsToDemote; |
| for (BasicBlock &BB : F) { |
| bool IsNormalBB = NormalBlocks.count(&BB); |
| bool IsEHBB = EHBlocks.count(&BB); |
| if (!IsNormalBB && !IsEHBB) |
| continue; // Blocks that are neither normal nor EH are unreachable. |
| for (Instruction &I : BB) { |
| for (Value *Op : I.operands()) { |
| // Don't demote static allocas, constants, and labels. |
| if (isa<Constant>(Op) || isa<BasicBlock>(Op) || isa<InlineAsm>(Op)) |
| continue; |
| auto *AI = dyn_cast<AllocaInst>(Op); |
| if (AI && AI->isStaticAlloca()) |
| continue; |
| |
| if (auto *Arg = dyn_cast<Argument>(Op)) { |
| if (IsEHBB) { |
| DEBUG(dbgs() << "Demoting argument " << *Arg |
| << " used by EH instr: " << I << "\n"); |
| ArgsToDemote.insert(Arg); |
| } |
| continue; |
| } |
| |
| // Don't demote EH values. |
| auto *OpI = cast<Instruction>(Op); |
| if (EHVals.count(OpI)) |
| continue; |
| |
| BasicBlock *OpBB = OpI->getParent(); |
| // If a value is produced and consumed in the same BB, we don't need to |
| // demote it. |
| if (OpBB == &BB) |
| continue; |
| bool IsOpNormalBB = NormalBlocks.count(OpBB); |
| bool IsOpEHBB = EHBlocks.count(OpBB); |
| if (IsNormalBB != IsOpNormalBB || IsEHBB != IsOpEHBB) { |
| DEBUG({ |
| dbgs() << "Demoting instruction live in-out from EH:\n"; |
| dbgs() << "Instr: " << *OpI << '\n'; |
| dbgs() << "User: " << I << '\n'; |
| }); |
| InstrsToDemote.insert(OpI); |
| } |
| } |
| } |
| } |
| |
| // Demote values live into and out of handlers. |
| // FIXME: This demotion is inefficient. We should insert spills at the point |
| // of definition, insert one reload in each handler that uses the value, and |
| // insert reloads in the BB used to rejoin normal control flow. |
| Instruction *AllocaInsertPt = F.getEntryBlock().getFirstInsertionPt(); |
| for (Instruction *I : InstrsToDemote) |
| DemoteRegToStack(*I, false, AllocaInsertPt); |
| |
| // Demote arguments separately, and only for uses in EH blocks. |
| for (Argument *Arg : ArgsToDemote) { |
| auto *Slot = new AllocaInst(Arg->getType(), nullptr, |
| Arg->getName() + ".reg2mem", AllocaInsertPt); |
| SmallVector<User *, 4> Users(Arg->user_begin(), Arg->user_end()); |
| for (User *U : Users) { |
| auto *I = dyn_cast<Instruction>(U); |
| if (I && EHBlocks.count(I->getParent())) { |
| auto *Reload = new LoadInst(Slot, Arg->getName() + ".reload", false, I); |
| U->replaceUsesOfWith(Arg, Reload); |
| } |
| } |
| new StoreInst(Arg, Slot, AllocaInsertPt); |
| } |
| |
| // Demote landingpad phis, as the landingpad will be removed from the machine |
| // CFG. |
| for (LandingPadInst *LPI : LPads) { |
| BasicBlock *BB = LPI->getParent(); |
| while (auto *Phi = dyn_cast<PHINode>(BB->begin())) |
| DemotePHIToStack(Phi, AllocaInsertPt); |
| } |
| |
| DEBUG(dbgs() << "Demoted " << InstrsToDemote.size() << " instructions and " |
| << ArgsToDemote.size() << " arguments for WinEHPrepare\n\n"); |
| } |
| |
| bool WinEHPrepare::prepareExceptionHandlers( |
| Function &F, SmallVectorImpl<LandingPadInst *> &LPads) { |
| // Don't run on functions that are already prepared. |
| for (LandingPadInst *LPad : LPads) { |
| BasicBlock *LPadBB = LPad->getParent(); |
| for (Instruction &Inst : *LPadBB) |
| if (match(&Inst, m_Intrinsic<Intrinsic::eh_actions>())) |
| return false; |
| } |
| |
| identifyEHBlocks(F, LPads); |
| demoteValuesLiveAcrossHandlers(F, 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; |
| |
| 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); |
| |
| if (isAsynchronousEHPersonality(Personality)) { |
| // FIXME: Switch the ehptr type to i32 and then switch this. |
| SEHExceptionCodeSlot = |
| new AllocaInst(Int8PtrType, nullptr, "seh_exception_code", |
| F.getEntryBlock().getFirstInsertionPt()); |
| } |
| |
| // In order to handle the case where one outlined catch handler returns |
| // to a block within another outlined catch handler that would otherwise |
| // be unreachable, we need to outline the nested landing pad before we |
| // outline the landing pad which encloses it. |
| if (!isAsynchronousEHPersonality(Personality)) |
| std::sort(LPads.begin(), LPads.end(), |
| [this](LandingPadInst *const &L, LandingPadInst *const &R) { |
| return DT->properlyDominates(R->getParent(), L->getParent()); |
| }); |
| |
| // This container stores the llvm.eh.recover and IndirectBr instructions |
| // that make up the body of each landing pad after it has been outlined. |
| // We need to defer the population of the target list for the indirectbr |
| // until all landing pads have been outlined so that we can handle the |
| // case of blocks in the target that are reached only from nested |
| // landing pads. |
| SmallVector<std::pair<CallInst*, IndirectBrInst *>, 4> LPadImpls; |
| |
| 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) { |
| if (match(&Inst, m_Intrinsic<Intrinsic::eh_actions>())) { |
| LPadHasActionList = true; |
| break; |
| } |
| } |
| |
| // If we've already outlined the handlers for this landingpad, |
| // there's nothing more to do here. |
| if (LPadHasActionList) |
| continue; |
| |
| // If either of the values in the aggregate returned by the landing pad is |
| // extracted and stored to memory, promote the stored value to a register. |
| promoteLandingPadValues(LPad); |
| |
| LandingPadActions Actions; |
| mapLandingPadBlocks(LPad, Actions); |
| |
| HandlersOutlined |= !Actions.actions().empty(); |
| 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); |
| continue; |
| } |
| } |
| |
| outlineHandler(Action, &F, LPad, StartBB, FrameVarInfo); |
| } |
| |
| // Split the block after the landingpad instruction so that it is just a |
| // call to llvm.eh.actions followed by indirectbr. |
| assert(!isa<PHINode>(LPadBB->begin()) && "lpad phi not removed"); |
| SplitBlock(LPadBB, LPad->getNextNode(), DT); |
| // Erase the branch inserted by the split so we can insert indirectbr. |
| LPadBB->getTerminator()->eraseFromParent(); |
| |
| // Replace all extracted values with undef and ultimately replace the |
| // landingpad with undef. |
| SmallVector<Instruction *, 4> SEHCodeUses; |
| SmallVector<Instruction *, 4> EHUndefs; |
| for (User *U : LPad->users()) { |
| auto *E = dyn_cast<ExtractValueInst>(U); |
| if (!E) |
| continue; |
| assert(E->getNumIndices() == 1 && |
| "Unexpected operation: extracting both landing pad values"); |
| unsigned Idx = *E->idx_begin(); |
| assert((Idx == 0 || Idx == 1) && "unexpected index"); |
| if (Idx == 0 && isAsynchronousEHPersonality(Personality)) |
| SEHCodeUses.push_back(E); |
| else |
| EHUndefs.push_back(E); |
| } |
| for (Instruction *E : EHUndefs) { |
| E->replaceAllUsesWith(UndefValue::get(E->getType())); |
| E->eraseFromParent(); |
| } |
| LPad->replaceAllUsesWith(UndefValue::get(LPad->getType())); |
| |
| // Rewrite uses of the exception pointer to loads of an alloca. |
| while (!SEHCodeUses.empty()) { |
| Instruction *E = SEHCodeUses.pop_back_val(); |
| SmallVector<Use *, 4> Uses; |
| for (Use &U : E->uses()) |
| Uses.push_back(&U); |
| for (Use *U : Uses) { |
| auto *I = cast<Instruction>(U->getUser()); |
| if (isa<ResumeInst>(I)) |
| continue; |
| if (auto *Phi = dyn_cast<PHINode>(I)) |
| SEHCodeUses.push_back(Phi); |
| else |
| U->set(new LoadInst(SEHExceptionCodeSlot, "sehcode", false, I)); |
| } |
| E->replaceAllUsesWith(UndefValue::get(E->getType())); |
| E->eraseFromParent(); |
| } |
| |
| // 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()); |
| // Find the frame escape index of the exception object alloca in the |
| // parent. |
| int FrameEscapeIdx = -1; |
| Value *EHObj = const_cast<Value *>(CatchAction->getExceptionVar()); |
| if (EHObj && !isa<ConstantPointerNull>(EHObj)) { |
| auto I = FrameVarInfo.find(EHObj); |
| assert(I != FrameVarInfo.end() && |
| "failed to map llvm.eh.begincatch var"); |
| FrameEscapeIdx = std::distance(FrameVarInfo.begin(), I); |
| } |
| ActionArgs.push_back(ConstantInt::get(Int32Type, FrameEscapeIdx)); |
| } else { |
| ActionArgs.push_back(ConstantInt::get(Int32Type, 0)); |
| } |
| ActionArgs.push_back(Action->getHandlerBlockOrFunc()); |
| } |
| CallInst *Recover = |
| CallInst::Create(ActionIntrin, ActionArgs, "recover", LPadBB); |
| |
| SetVector<BasicBlock *> ReturnTargets; |
| for (ActionHandler *Action : Actions) { |
| if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) { |
| const auto &CatchTargets = CatchAction->getReturnTargets(); |
| ReturnTargets.insert(CatchTargets.begin(), CatchTargets.end()); |
| } |
| } |
| IndirectBrInst *Branch = |
| IndirectBrInst::Create(Recover, ReturnTargets.size(), LPadBB); |
| for (BasicBlock *Target : ReturnTargets) |
| Branch->addDestination(Target); |
| |
| if (!isAsynchronousEHPersonality(Personality)) { |
| // C++ EH must repopulate the targets later to handle the case of |
| // targets that are reached indirectly through nested landing pads. |
| LPadImpls.push_back(std::make_pair(Recover, Branch)); |
| } |
| |
| } // End for each landingpad |
| |
| // If nothing got outlined, there is no more processing to be done. |
| if (!HandlersOutlined) |
| return false; |
| |
| // Replace any nested landing pad stubs with the correct action handler. |
| // This must be done before we remove unreachable blocks because it |
| // cleans up references to outlined blocks that will be deleted. |
| for (auto &LPadPair : NestedLPtoOriginalLP) |
| completeNestedLandingPad(&F, LPadPair.first, LPadPair.second, FrameVarInfo); |
| NestedLPtoOriginalLP.clear(); |
| |
| // Update the indirectbr instructions' target lists if necessary. |
| SetVector<BasicBlock*> CheckedTargets; |
| SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList; |
| for (auto &LPadImplPair : LPadImpls) { |
| IntrinsicInst *Recover = cast<IntrinsicInst>(LPadImplPair.first); |
| IndirectBrInst *Branch = LPadImplPair.second; |
| |
| // Get a list of handlers called by |
| parseEHActions(Recover, ActionList); |
| |
| // Add an indirect branch listing possible successors of the catch handlers. |
| SetVector<BasicBlock *> ReturnTargets; |
| for (const auto &Action : ActionList) { |
| if (auto *CA = dyn_cast<CatchHandler>(Action.get())) { |
| Function *Handler = cast<Function>(CA->getHandlerBlockOrFunc()); |
| getPossibleReturnTargets(&F, Handler, ReturnTargets); |
| } |
| } |
| ActionList.clear(); |
| // Clear any targets we already knew about. |
| for (unsigned int I = 0, E = Branch->getNumDestinations(); I < E; ++I) { |
| BasicBlock *KnownTarget = Branch->getDestination(I); |
| if (ReturnTargets.count(KnownTarget)) |
| ReturnTargets.remove(KnownTarget); |
| } |
| for (BasicBlock *Target : ReturnTargets) { |
| Branch->addDestination(Target); |
| // The target may be a block that we excepted to get pruned. |
| // If it is, it may contain a call to llvm.eh.endcatch. |
| if (CheckedTargets.insert(Target)) { |
| // Earlier preparations guarantee that all calls to llvm.eh.endcatch |
| // will be followed by an unconditional branch. |
| auto *Br = dyn_cast<BranchInst>(Target->getTerminator()); |
| if (Br && Br->isUnconditional() && |
| Br != Target->getFirstNonPHIOrDbgOrLifetime()) { |
| Instruction *Prev = Br->getPrevNode(); |
| if (match(cast<Value>(Prev), m_Intrinsic<Intrinsic::eh_endcatch>())) |
| Prev->eraseFromParent(); |
| } |
| } |
| } |
| } |
| LPadImpls.clear(); |
| |
| F.addFnAttr("wineh-parent", F.getName()); |
| |
| // Delete any blocks that were only used by handlers that were outlined above. |
| removeUnreachableBlocks(F); |
| |
| BasicBlock *Entry = &F.getEntryBlock(); |
| IRBuilder<> Builder(F.getParent()->getContext()); |
| Builder.SetInsertPoint(Entry->getFirstInsertionPt()); |
| |
| Function *FrameEscapeFn = |
| Intrinsic::getDeclaration(M, Intrinsic::localescape); |
| Function *RecoverFrameFn = |
| Intrinsic::getDeclaration(M, Intrinsic::localrecover); |
| SmallVector<Value *, 8> AllocasToEscape; |
| |
| // Scan the entry block for an existing call to llvm.localescape. We need to |
| // keep escaping those objects. |
| for (Instruction &I : F.front()) { |
| auto *II = dyn_cast<IntrinsicInst>(&I); |
| if (II && II->getIntrinsicID() == Intrinsic::localescape) { |
| auto Args = II->arg_operands(); |
| AllocasToEscape.append(Args.begin(), Args.end()); |
| II->eraseFromParent(); |
| break; |
| } |
| } |
| |
| // Finally, replace all of the temporary allocas for frame variables used in |
| // the outlined handlers with calls to llvm.localrecover. |
| for (auto &VarInfoEntry : FrameVarInfo) { |
| Value *ParentVal = VarInfoEntry.first; |
| TinyPtrVector<AllocaInst *> &Allocas = VarInfoEntry.second; |
| AllocaInst *ParentAlloca = cast<AllocaInst>(ParentVal); |
| |
| // FIXME: We should try to sink unescaped allocas from the parent frame into |
| // the child frame. If the alloca is escaped, we have to use the lifetime |
| // markers to ensure that the alloca is only live within the child frame. |
| |
| // 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) { |
| if (TempAlloca == getCatchObjectSentinel()) |
| continue; // Skip catch parameter sentinels. |
| Function *HandlerFn = TempAlloca->getParent()->getParent(); |
| llvm::Value *FP = HandlerToParentFP[HandlerFn]; |
| assert(FP); |
| |
| // FIXME: Sink this localrecover into the blocks where it is used. |
| Builder.SetInsertPoint(TempAlloca); |
| Builder.SetCurrentDebugLocation(TempAlloca->getDebugLoc()); |
| Value *RecoverArgs[] = { |
| Builder.CreateBitCast(&F, Int8PtrType, ""), FP, |
| llvm::ConstantInt::get(Int32Type, AllocasToEscape.size() - 1)}; |
| Instruction *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 = cast<Instruction>( |
| Builder.CreateBitCast(RecoveredAlloca, TempAlloca->getType())); |
| } |
| TempAlloca->replaceAllUsesWith(RecoveredAlloca); |
| TempAlloca->removeFromParent(); |
| RecoveredAlloca->takeName(TempAlloca); |
| delete TempAlloca; |
| } |
| } // End for each FrameVarInfo entry. |
| |
| // Insert 'call void (...)* @llvm.localescape(...)' at the end of the entry |
| // block. |
| Builder.SetInsertPoint(&F.getEntryBlock().back()); |
| Builder.CreateCall(FrameEscapeFn, AllocasToEscape); |
| |
| if (SEHExceptionCodeSlot) { |
| if (isAllocaPromotable(SEHExceptionCodeSlot)) { |
| SmallPtrSet<BasicBlock *, 4> UserBlocks; |
| for (User *U : SEHExceptionCodeSlot->users()) { |
| if (auto *Inst = dyn_cast<Instruction>(U)) |
| UserBlocks.insert(Inst->getParent()); |
| } |
| PromoteMemToReg(SEHExceptionCodeSlot, *DT); |
| // After the promotion, kill off dead instructions. |
| for (BasicBlock *BB : UserBlocks) |
| SimplifyInstructionsInBlock(BB, LibInfo); |
| } |
| } |
| |
| // Clean up the handler action maps we created for this function |
| DeleteContainerSeconds(CatchHandlerMap); |
| CatchHandlerMap.clear(); |
| DeleteContainerSeconds(CleanupHandlerMap); |
| CleanupHandlerMap.clear(); |
| HandlerToParentFP.clear(); |
| DT = nullptr; |
| LibInfo = nullptr; |
| SEHExceptionCodeSlot = nullptr; |
| EHBlocks.clear(); |
| NormalBlocks.clear(); |
| EHReturnBlocks.clear(); |
| |
| return HandlersOutlined; |
| } |
| |
| void WinEHPrepare::promoteLandingPadValues(LandingPadInst *LPad) { |
| // If the return values of the landing pad instruction are extracted and |
| // stored to memory, we want to promote the store locations to reg values. |
| SmallVector<AllocaInst *, 2> EHAllocas; |
| |
| // 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()) { |
| ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U); |
| if (!Extract) |
| continue; |
| |
| for (auto *EU : Extract->users()) { |
| if (auto *Store = dyn_cast<StoreInst>(EU)) { |
| auto *AV = cast<AllocaInst>(Store->getPointerOperand()); |
| EHAllocas.push_back(AV); |
| } |
| } |
| } |
| |
| // We can't do this without a dominator tree. |
| assert(DT); |
| |
| if (!EHAllocas.empty()) { |
| PromoteMemToReg(EHAllocas, *DT); |
| EHAllocas.clear(); |
| } |
| |
| // After promotion, some extracts may be trivially dead. Remove them. |
| SmallVector<Value *, 4> Users(LPad->user_begin(), LPad->user_end()); |
| for (auto *U : Users) |
| RecursivelyDeleteTriviallyDeadInstructions(U); |
| } |
| |
| void WinEHPrepare::getPossibleReturnTargets(Function *ParentF, |
| Function *HandlerF, |
| SetVector<BasicBlock*> &Targets) { |
| for (BasicBlock &BB : *HandlerF) { |
| // If the handler contains landing pads, check for any |
| // handlers that may return directly to a block in the |
| // parent function. |
| if (auto *LPI = BB.getLandingPadInst()) { |
| IntrinsicInst *Recover = cast<IntrinsicInst>(LPI->getNextNode()); |
| SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList; |
| parseEHActions(Recover, ActionList); |
| for (const auto &Action : ActionList) { |
| if (auto *CH = dyn_cast<CatchHandler>(Action.get())) { |
| Function *NestedF = cast<Function>(CH->getHandlerBlockOrFunc()); |
| getPossibleReturnTargets(ParentF, NestedF, Targets); |
| } |
| } |
| } |
| |
| auto *Ret = dyn_cast<ReturnInst>(BB.getTerminator()); |
| if (!Ret) |
| continue; |
| |
| // Handler functions must always return a block address. |
| BlockAddress *BA = cast<BlockAddress>(Ret->getReturnValue()); |
| |
| // If this is the handler for a nested landing pad, the |
| // return address may have been remapped to a block in the |
| // parent handler. We're not interested in those. |
| if (BA->getFunction() != ParentF) |
| continue; |
| |
| Targets.insert(BA->getBasicBlock()); |
| } |
| } |
| |
| void WinEHPrepare::completeNestedLandingPad(Function *ParentFn, |
| LandingPadInst *OutlinedLPad, |
| const LandingPadInst *OriginalLPad, |
| FrameVarInfoMap &FrameVarInfo) { |
| // Get the nested block and erase the unreachable instruction that was |
| // temporarily inserted as its terminator. |
| LLVMContext &Context = ParentFn->getContext(); |
| BasicBlock *OutlinedBB = OutlinedLPad->getParent(); |
| // If the nested landing pad was outlined before the landing pad that enclosed |
| // it, it will already be in outlined form. In that case, we just need to see |
| // if the returns and the enclosing branch instruction need to be updated. |
| IndirectBrInst *Branch = |
| dyn_cast<IndirectBrInst>(OutlinedBB->getTerminator()); |
| if (!Branch) { |
| // If the landing pad wasn't in outlined form, it should be a stub with |
| // an unreachable terminator. |
| assert(isa<UnreachableInst>(OutlinedBB->getTerminator())); |
| OutlinedBB->getTerminator()->eraseFromParent(); |
| // That should leave OutlinedLPad as the last instruction in its block. |
| assert(&OutlinedBB->back() == OutlinedLPad); |
| } |
| |
| // The original landing pad will have already had its action intrinsic |
| // built by the outlining loop. We need to clone that into the outlined |
| // location. It may also be necessary to add references to the exception |
| // variables to the outlined handler in which this landing pad is nested |
| // and remap return instructions in the nested handlers that should return |
| // to an address in the outlined handler. |
| Function *OutlinedHandlerFn = OutlinedBB->getParent(); |
| BasicBlock::const_iterator II = OriginalLPad; |
| ++II; |
| // The instruction after the landing pad should now be a call to eh.actions. |
| const Instruction *Recover = II; |
| const IntrinsicInst *EHActions = cast<IntrinsicInst>(Recover); |
| |
| // Remap the return target in the nested handler. |
| SmallVector<BlockAddress *, 4> ActionTargets; |
| SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList; |
| parseEHActions(EHActions, ActionList); |
| for (const auto &Action : ActionList) { |
| auto *Catch = dyn_cast<CatchHandler>(Action.get()); |
| if (!Catch) |
| continue; |
| // The dyn_cast to function here selects C++ catch handlers and skips |
| // SEH catch handlers. |
| auto *Handler = dyn_cast<Function>(Catch->getHandlerBlockOrFunc()); |
| if (!Handler) |
| continue; |
| // Visit all the return instructions, looking for places that return |
| // to a location within OutlinedHandlerFn. |
| for (BasicBlock &NestedHandlerBB : *Handler) { |
| auto *Ret = dyn_cast<ReturnInst>(NestedHandlerBB.getTerminator()); |
| if (!Ret) |
| continue; |
| |
| // Handler functions must always return a block address. |
| BlockAddress *BA = cast<BlockAddress>(Ret->getReturnValue()); |
| // The original target will have been in the main parent function, |
| // but if it is the address of a block that has been outlined, it |
| // should be a block that was outlined into OutlinedHandlerFn. |
| assert(BA->getFunction() == ParentFn); |
| |
| // Ignore targets that aren't part of an outlined handler function. |
| if (!LPadTargetBlocks.count(BA->getBasicBlock())) |
| continue; |
| |
| // If the return value is the address ofF a block that we |
| // previously outlined into the parent handler function, replace |
| // the return instruction and add the mapped target to the list |
| // of possible return addresses. |
| BasicBlock *MappedBB = LPadTargetBlocks[BA->getBasicBlock()]; |
| assert(MappedBB->getParent() == OutlinedHandlerFn); |
| BlockAddress *NewBA = BlockAddress::get(OutlinedHandlerFn, MappedBB); |
| Ret->eraseFromParent(); |
| ReturnInst::Create(Context, NewBA, &NestedHandlerBB); |
| ActionTargets.push_back(NewBA); |
| } |
| } |
| ActionList.clear(); |
| |
| if (Branch) { |
| // If the landing pad was already in outlined form, just update its targets. |
| for (unsigned int I = Branch->getNumDestinations(); I > 0; --I) |
| Branch->removeDestination(I); |
| // Add the previously collected action targets. |
| for (auto *Target : ActionTargets) |
| Branch->addDestination(Target->getBasicBlock()); |
| } else { |
| // If the landing pad was previously stubbed out, fill in its outlined form. |
| IntrinsicInst *NewEHActions = cast<IntrinsicInst>(EHActions->clone()); |
| OutlinedBB->getInstList().push_back(NewEHActions); |
| |
| // Insert an indirect branch into the outlined landing pad BB. |
| IndirectBrInst *IBr = IndirectBrInst::Create(NewEHActions, 0, OutlinedBB); |
| // Add the previously collected action targets. |
| for (auto *Target : ActionTargets) |
| IBr->addDestination(Target->getBasicBlock()); |
| } |
| } |
| |
| // 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; |
| } |
| |
| static bool isCatchBlock(BasicBlock *BB) { |
| for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end(); |
| II != IE; ++II) { |
| if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_begincatch>())) |
| return true; |
| } |
| return false; |
| } |
| |
| static BasicBlock *createStubLandingPad(Function *Handler) { |
| // FIXME: Finish this! |
| LLVMContext &Context = Handler->getContext(); |
| BasicBlock *StubBB = BasicBlock::Create(Context, "stub"); |
| Handler->getBasicBlockList().push_back(StubBB); |
| IRBuilder<> Builder(StubBB); |
| LandingPadInst *LPad = Builder.CreateLandingPad( |
| llvm::StructType::get(Type::getInt8PtrTy(Context), |
| Type::getInt32Ty(Context), nullptr), |
| 0); |
| // Insert a call to llvm.eh.actions so that we don't try to outline this lpad. |
| Function *ActionIntrin = |
| Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::eh_actions); |
| Builder.CreateCall(ActionIntrin, {}, "recover"); |
| LPad->setCleanup(true); |
| Builder.CreateUnreachable(); |
| return StubBB; |
| } |
| |
| // Cycles through the blocks in an outlined handler function looking for an |
| // invoke instruction and inserts an invoke of llvm.donothing with an empty |
| // landing pad if none is found. The code that generates the .xdata tables for |
| // the handler needs at least one landing pad to identify the parent function's |
| // personality. |
| void WinEHPrepare::addStubInvokeToHandlerIfNeeded(Function *Handler) { |
| ReturnInst *Ret = nullptr; |
| UnreachableInst *Unreached = nullptr; |
| for (BasicBlock &BB : *Handler) { |
| TerminatorInst *Terminator = BB.getTerminator(); |
| // If we find an invoke, there is nothing to be done. |
| auto *II = dyn_cast<InvokeInst>(Terminator); |
| if (II) |
| return; |
| // If we've already recorded a return instruction, keep looking for invokes. |
| if (!Ret) |
| Ret = dyn_cast<ReturnInst>(Terminator); |
| // If we haven't recorded an unreachable instruction, try this terminator. |
| if (!Unreached) |
| Unreached = dyn_cast<UnreachableInst>(Terminator); |
| } |
| |
| // If we got this far, the handler contains no invokes. We should have seen |
| // at least one return or unreachable instruction. We'll insert an invoke of |
| // llvm.donothing ahead of that instruction. |
| assert(Ret || Unreached); |
| TerminatorInst *Term; |
| if (Ret) |
| Term = Ret; |
| else |
| Term = Unreached; |
| BasicBlock *OldRetBB = Term->getParent(); |
| BasicBlock *NewRetBB = SplitBlock(OldRetBB, Term, DT); |
| // SplitBlock adds an unconditional branch instruction at the end of the |
| // parent block. We want to replace that with an invoke call, so we can |
| // erase it now. |
| OldRetBB->getTerminator()->eraseFromParent(); |
| BasicBlock *StubLandingPad = createStubLandingPad(Handler); |
| Function *F = |
| Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::donothing); |
| InvokeInst::Create(F, NewRetBB, StubLandingPad, None, "", OldRetBB); |
| } |
| |
| // FIXME: Consider sinking this into lib/Target/X86 somehow. TargetLowering |
| // usually doesn't build LLVM IR, so that's probably the wrong place. |
| Function *WinEHPrepare::createHandlerFunc(Function *ParentFn, Type *RetTy, |
| const Twine &Name, Module *M, |
| Value *&ParentFP) { |
| // x64 uses a two-argument prototype where the parent FP is the second |
| // argument. x86 uses no arguments, just the incoming EBP value. |
| LLVMContext &Context = M->getContext(); |
| Type *Int8PtrType = Type::getInt8PtrTy(Context); |
| FunctionType *FnType; |
| if (TheTriple.getArch() == Triple::x86_64) { |
| Type *ArgTys[2] = {Int8PtrType, Int8PtrType}; |
| FnType = FunctionType::get(RetTy, ArgTys, false); |
| } else { |
| FnType = FunctionType::get(RetTy, None, false); |
| } |
| |
| Function *Handler = |
| Function::Create(FnType, GlobalVariable::InternalLinkage, Name, M); |
| BasicBlock *Entry = BasicBlock::Create(Context, "entry"); |
| Handler->getBasicBlockList().push_front(Entry); |
| if (TheTriple.getArch() == Triple::x86_64) { |
| ParentFP = &(Handler->getArgumentList().back()); |
| } else { |
| assert(M); |
| Function *FrameAddressFn = |
| Intrinsic::getDeclaration(M, Intrinsic::frameaddress); |
| Function *RecoverFPFn = |
| Intrinsic::getDeclaration(M, Intrinsic::x86_seh_recoverfp); |
| IRBuilder<> Builder(&Handler->getEntryBlock()); |
| Value *EBP = |
| Builder.CreateCall(FrameAddressFn, {Builder.getInt32(1)}, "ebp"); |
| Value *ParentI8Fn = Builder.CreateBitCast(ParentFn, Int8PtrType); |
| ParentFP = Builder.CreateCall(RecoverFPFn, {ParentI8Fn, EBP}); |
| } |
| return Handler; |
| } |
| |
| bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn, |
| LandingPadInst *LPad, BasicBlock *StartBB, |
| FrameVarInfoMap &VarInfo) { |
| Module *M = SrcFn->getParent(); |
| LLVMContext &Context = M->getContext(); |
| Type *Int8PtrType = Type::getInt8PtrTy(Context); |
| |
| // Create a new function to receive the handler contents. |
| Value *ParentFP; |
| Function *Handler; |
| if (Action->getType() == Catch) { |
| Handler = createHandlerFunc(SrcFn, Int8PtrType, SrcFn->getName() + ".catch", M, |
| ParentFP); |
| } else { |
| Handler = createHandlerFunc(SrcFn, Type::getVoidTy(Context), |
| SrcFn->getName() + ".cleanup", M, ParentFP); |
| } |
| Handler->setPersonalityFn(SrcFn->getPersonalityFn()); |
| HandlerToParentFP[Handler] = ParentFP; |
| Handler->addFnAttr("wineh-parent", SrcFn->getName()); |
| BasicBlock *Entry = &Handler->getEntryBlock(); |
| |
| // Generate a standard prolog to setup the frame recovery structure. |
| IRBuilder<> Builder(Context); |
| Builder.SetInsertPoint(Entry); |
| Builder.SetCurrentDebugLocation(LPad->getDebugLoc()); |
| |
| std::unique_ptr<WinEHCloningDirectorBase> Director; |
| |
| ValueToValueMapTy VMap; |
| |
| 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, ParentFP, Sel, VarInfo, |
| LPadMap, NestedLPtoOriginalLP, DT, |
| EHBlocks)); |
| LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType), |
| ConstantInt::get(Type::getInt32Ty(Context), 1)); |
| } else { |
| Director.reset( |
| new WinEHCleanupDirector(Handler, ParentFP, VarInfo, LPadMap)); |
| LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType), |
| UndefValue::get(Type::getInt32Ty(Context))); |
| } |
| |
| SmallVector<ReturnInst *, 8> Returns; |
| 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; |
| } |
| |
| // The landing pad value may be used by PHI nodes. It will ultimately be |
| // eliminated, but we need it in the map for intermediate handling. |
| VMap[LPad] = UndefValue::get(LPad->getType()); |
| |
| // Skip over PHIs and, if applicable, landingpad instructions. |
| II = StartBB->getFirstInsertionPt(); |
| |
| CloneAndPruneIntoFromInst(Handler, SrcFn, II, VMap, |
| /*ModuleLevelChanges=*/false, Returns, "", |
| &OutlinedFunctionInfo, Director.get()); |
| |
| // Move all the instructions in the cloned "entry" block into our entry block. |
| // Depending on how the parent function was laid out, the block that will |
| // correspond to the outlined entry block may not be the first block in the |
| // list. We can recognize it, however, as the cloned block which has no |
| // predecessors. Any other block wouldn't have been cloned if it didn't |
| // have a predecessor which was also cloned. |
| Function::iterator ClonedIt = std::next(Function::iterator(Entry)); |
| while (!pred_empty(ClonedIt)) |
| ++ClonedIt; |
| BasicBlock *ClonedEntryBB = ClonedIt; |
| assert(ClonedEntryBB); |
| Entry->getInstList().splice(Entry->end(), ClonedEntryBB->getInstList()); |
| ClonedEntryBB->eraseFromParent(); |
| |
| // Make sure we can identify the handler's personality later. |
| addStubInvokeToHandlerIfNeeded(Handler); |
| |
| if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) { |
| WinEHCatchDirector *CatchDirector = |
| reinterpret_cast<WinEHCatchDirector *>(Director.get()); |
| CatchAction->setExceptionVar(CatchDirector->getExceptionVar()); |
| CatchAction->setReturnTargets(CatchDirector->getReturnTargets()); |
| |
| // Look for blocks that are not part of the landing pad that we just |
| // outlined but terminate with a call to llvm.eh.endcatch and a |
| // branch to a block that is in the handler we just outlined. |
| // These blocks will be part of a nested landing pad that intends to |
| // return to an address in this handler. This case is best handled |
| // after both landing pads have been outlined, so for now we'll just |
| // save the association of the blocks in LPadTargetBlocks. The |
| // return instructions which are created from these branches will be |
| // replaced after all landing pads have been outlined. |
| for (const auto MapEntry : VMap) { |
| // VMap maps all values and blocks that were just cloned, but dead |
| // blocks which were pruned will map to nullptr. |
| if (!isa<BasicBlock>(MapEntry.first) || MapEntry.second == nullptr) |
| continue; |
| const BasicBlock *MappedBB = cast<BasicBlock>(MapEntry.first); |
| for (auto *Pred : predecessors(const_cast<BasicBlock *>(MappedBB))) { |
| auto *Branch = dyn_cast<BranchInst>(Pred->getTerminator()); |
| if (!Branch || !Branch->isUnconditional() || Pred->size() <= 1) |
| continue; |
| BasicBlock::iterator II = const_cast<BranchInst *>(Branch); |
| --II; |
| if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_endcatch>())) { |
| // This would indicate that a nested landing pad wants to return |
| // to a block that is outlined into two different handlers. |
| assert(!LPadTargetBlocks.count(MappedBB)); |
| LPadTargetBlocks[MappedBB] = cast<BasicBlock>(MapEntry.second); |
| } |
| } |
| } |
| } // End if (CatchAction) |
| |
| Action->setHandlerBlockOrFunc(Handler); |
| |
| return true; |
| } |
| |
| /// 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 = SplitBlock(StartBB, StartBB->getFirstInsertionPt(), DT); |
| } |
| IRBuilder<> Builder(HandlerBB->getFirstInsertionPt()); |
| Function *EHCodeFn = Intrinsic::getDeclaration( |
| StartBB->getParent()->getParent(), Intrinsic::eh_exceptioncode); |
| Value *Code = Builder.CreateCall(EHCodeFn, {}, "sehcode"); |
| Code = Builder.CreateIntToPtr(Code, SEHExceptionCodeSlot->getAllocatedType()); |
| Builder.CreateStore(Code, SEHExceptionCodeSlot); |
| CatchAction->setHandlerBlockOrFunc(BlockAddress::get(HandlerBB)); |
| TinyPtrVector<BasicBlock *> Targets(HandlerBB); |
| CatchAction->setReturnTargets(Targets); |
| } |
| |
| 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 will have been promoted to reg values before |
| // this routine is called. |
| 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) { |
| ExtractedEHPtrs.push_back(Extract); |
| } else if (Idx == 1) { |
| ExtractedSelectors.push_back(Extract); |
| } |
| } |
| } |
| |
| bool LandingPadMap::isOriginLandingPadBlock(const BasicBlock *BB) const { |
| return BB->getLandingPadInst() == OriginLPad; |
| } |
| |
| 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; |
| } |
| return false; |
| } |
| |
| void LandingPadMap::remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue, |
| Value *SelectorValue) const { |
| // Remap all landing pad extract instructions to the specified values. |
| for (auto *Extract : ExtractedEHPtrs) |
| VMap[Extract] = EHPtrValue; |
| for (auto *Extract : ExtractedSelectors) |
| VMap[Extract] = SelectorValue; |
| } |
| |
| static bool isLocalAddressCall(const Value *V) { |
| return match(const_cast<Value *>(V), m_Intrinsic<Intrinsic::localaddress>()); |
| } |
| |
| 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; |
| |
| // Nested landing pads that have not already been outlined 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 *LPad = dyn_cast<LandingPadInst>(Inst)) { |
| return handleLandingPad(VMap, LPad, NewBB); |
| } |
| |
| // Nested landing pads that have already been outlined will be cloned in their |
| // outlined form, but we need to intercept the ibr instruction to filter out |
| // targets that do not return to the handler we are outlining. |
| if (auto *IBr = dyn_cast<IndirectBrInst>(Inst)) { |
| return handleIndirectBr(VMap, IBr, NewBB); |
| } |
| |
| 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 (auto *Cmp = dyn_cast<CmpInst>(Inst)) |
| return handleCompare(VMap, Cmp, 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); |
| |
| // When outlining llvm.localaddress(), remap that to the second argument, |
| // which is the FP of the parent. |
| if (isLocalAddressCall(Inst)) { |
| VMap[Inst] = ParentFP; |
| return CloningDirector::SkipInstruction; |
| } |
| |
| // Continue with the default cloning behavior. |
| return CloningDirector::CloneInstruction; |
| } |
| |
| CloningDirector::CloningAction WinEHCatchDirector::handleLandingPad( |
| ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) { |
| // If the instruction after the landing pad is a call to llvm.eh.actions |
| // the landing pad has already been outlined. In this case, we should |
| // clone it because it may return to a block in the handler we are |
| // outlining now that would otherwise be unreachable. The landing pads |
| // are sorted before outlining begins to enable this case to work |
| // properly. |
| const Instruction *NextI = LPad->getNextNode(); |
| if (match(NextI, m_Intrinsic<Intrinsic::eh_actions>())) |
| return CloningDirector::CloneInstruction; |
| |
| // If the landing pad hasn't been outlined yet, the landing pad we are |
| // outlining now does not dominate it and so it cannot return to a block |
| // in this handler. In that case, we can just insert a stub landing |
| // pad now and patch it up later. |
| Instruction *NewInst = LPad->clone(); |
| if (LPad->hasName()) |
| NewInst->setName(LPad->getName()); |
| // Save this correlation for later processing. |
| NestedLPtoOriginalLP[cast<LandingPadInst>(NewInst)] = LPad; |
| VMap[LPad] = NewInst; |
| BasicBlock::InstListType &InstList = NewBB->getInstList(); |
| InstList.push_back(NewInst); |
| InstList.push_back(new UnreachableInst(NewBB->getContext())); |
| return CloningDirector::StopCloningBB; |
| } |
| |
| 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(); |
| if (isa<ConstantPointerNull>(ExceptionObjectVar)) |
| return CloningDirector::SkipInstruction; |
| assert(cast<AllocaInst>(ExceptionObjectVar)->isStaticAlloca() && |
| "catch parameter is not static alloca"); |
| Materializer.escapeCatchObject(ExceptionObjectVar); |
| 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. However, a catch-all handler may call |
| // end catch from the original landing pad. If the call occurs in a nested |
| // landing pad block, we must skip it and continue so that the landing pad |
| // gets cloned. |
| auto *ParentBB = IntrinCall->getParent(); |
| if (ParentBB->isLandingPad() && !LPadMap.isOriginLandingPadBlock(ParentBB)) |
| return CloningDirector::SkipInstruction; |
| |
| // If an end catch occurs anywhere else we want to terminate the handler |
| // with a return to the code that follows the endcatch call. If the |
| // next instruction is not an unconditional branch, we need to split the |
| // block to provide a clear target for the return instruction. |
| BasicBlock *ContinueBB; |
| auto Next = std::next(BasicBlock::const_iterator(IntrinCall)); |
| const BranchInst *Branch = dyn_cast<BranchInst>(Next); |
| if (!Branch || !Branch->isUnconditional()) { |
| // We're interrupting the cloning process at this location, so the |
| // const_cast we're doing here will not cause a problem. |
| ContinueBB = SplitBlock(const_cast<BasicBlock *>(ParentBB), |
| const_cast<Instruction *>(cast<Instruction>(Next))); |
| } else { |
| ContinueBB = Branch->getSuccessor(0); |
| } |
| |
| ReturnInst::Create(NewBB->getContext(), BlockAddress::get(ContinueBB), NewBB); |
| ReturnTargets.push_back(ContinueBB); |
| |
| // 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::handleIndirectBr( |
| ValueToValueMapTy &VMap, |
| const IndirectBrInst *IBr, |
| BasicBlock *NewBB) { |
| // If this indirect branch is not part of a landing pad block, just clone it. |
| const BasicBlock *ParentBB = IBr->getParent(); |
| if (!ParentBB->isLandingPad()) |
| return CloningDirector::CloneInstruction; |
| |
| // If it is part of a landing pad, we want to filter out target blocks |
| // that are not part of the handler we are outlining. |
| const LandingPadInst *LPad = ParentBB->getLandingPadInst(); |
| |
| // Save this correlation for later processing. |
| NestedLPtoOriginalLP[cast<LandingPadInst>(VMap[LPad])] = LPad; |
| |
| // We should only get here for landing pads that have already been outlined. |
| assert(match(LPad->getNextNode(), m_Intrinsic<Intrinsic::eh_actions>())); |
| |
| // Copy the indirectbr, but only include targets that were previously |
| // identified as EH blocks and are dominated by the nested landing pad. |
| SetVector<const BasicBlock *> ReturnTargets; |
| for (int I = 0, E = IBr->getNumDestinations(); I < E; ++I) { |
| auto *TargetBB = IBr->getDestination(I); |
| if (EHBlocks.count(const_cast<BasicBlock*>(TargetBB)) && |
| DT->dominates(ParentBB, TargetBB)) { |
| DEBUG(dbgs() << " Adding destination " << TargetBB->getName() << "\n"); |
| ReturnTargets.insert(TargetBB); |
| } |
| } |
| IndirectBrInst *NewBranch = |
| IndirectBrInst::Create(const_cast<Value *>(IBr->getAddress()), |
| ReturnTargets.size(), NewBB); |
| for (auto *Target : ReturnTargets) |
| NewBranch->addDestination(const_cast<BasicBlock*>(Target)); |
| |
| // The operands and targets of the branch instruction are remapped later |
| // because it is a terminator. Tell the cloning code to clone the |
| // blocks we just added to the target list. |
| return CloningDirector::CloneSuccessors; |
| } |
| |
| 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 |
| WinEHCatchDirector::handleCompare(ValueToValueMapTy &VMap, |
| const CmpInst *Compare, BasicBlock *NewBB) { |
| const IntrinsicInst *IntrinCall = nullptr; |
| if (match(Compare->getOperand(0), m_Intrinsic<Intrinsic::eh_typeid_for>())) { |
| IntrinCall = dyn_cast<IntrinsicInst>(Compare->getOperand(0)); |
| } else if (match(Compare->getOperand(1), |
| m_Intrinsic<Intrinsic::eh_typeid_for>())) { |
| IntrinCall = dyn_cast<IntrinsicInst>(Compare->getOperand(1)); |
| } |
| if (IntrinCall) { |
| 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->stripPointerCasts()) { |
| VMap[Compare] = ConstantInt::get(SelectorIDType, 1); |
| } else { |
| VMap[Compare] = ConstantInt::get(SelectorIDType, 0); |
| } |
| return CloningDirector::SkipInstruction; |
| } |
| return CloningDirector::CloneInstruction; |
| } |
| |
| CloningDirector::CloningAction WinEHCleanupDirector::handleLandingPad( |
| ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) { |
| // The MS runtime will terminate the process if an exception occurs in a |
| // cleanup handler, so we shouldn't encounter landing pads in the actual |
| // cleanup code, but they may appear in catch blocks. Depending on where |
| // we started cloning we may see one, but it will get dropped during dead |
| // block pruning. |
| Instruction *NewInst = new UnreachableInst(NewBB->getContext()); |
| VMap[LPad] = NewInst; |
| BasicBlock::InstListType &InstList = NewBB->getInstList(); |
| InstList.push_back(NewInst); |
| return CloningDirector::StopCloningBB; |
| } |
| |
| CloningDirector::CloningAction WinEHCleanupDirector::handleBeginCatch( |
| ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) { |
| // Cleanup code may flow into catch blocks or the catch block may be part |
| // of a branch that will be optimized away. We'll insert a return |
| // instruction now, but it may be pruned before the cloning process is |
| // complete. |
| ReturnInst::Create(NewBB->getContext(), nullptr, NewBB); |
| return CloningDirector::StopCloningBB; |
| } |
| |
| CloningDirector::CloningAction WinEHCleanupDirector::handleEndCatch( |
| ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) { |
| // Cleanup handlers nested within catch handlers may begin with a call to |
| // eh.endcatch. We can just ignore that instruction. |
| return CloningDirector::SkipInstruction; |
| } |
| |
| 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::handleIndirectBr( |
| ValueToValueMapTy &VMap, |
| const IndirectBrInst *IBr, |
| BasicBlock *NewBB) { |
| // No special handling is required for cleanup cloning. |
| return CloningDirector::CloneInstruction; |
| } |
| |
| 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; |
| |
| // Remap the operands. |
| llvm::RemapInstruction(NewCall, VMap, RF_None, nullptr, &Materializer); |
| |
| // 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::CloneSuccessors; |
| } |
| |
| 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; |
| } |
| |
| CloningDirector::CloningAction |
| WinEHCleanupDirector::handleCompare(ValueToValueMapTy &VMap, |
| const CmpInst *Compare, BasicBlock *NewBB) { |
| if (match(Compare->getOperand(0), m_Intrinsic<Intrinsic::eh_typeid_for>()) || |
| match(Compare->getOperand(1), m_Intrinsic<Intrinsic::eh_typeid_for>())) { |
| VMap[Compare] = ConstantInt::get(SelectorIDType, 1); |
| return CloningDirector::SkipInstruction; |
| } |
| return CloningDirector::CloneInstruction; |
| } |
| |
| WinEHFrameVariableMaterializer::WinEHFrameVariableMaterializer( |
| Function *OutlinedFn, Value *ParentFP, FrameVarInfoMap &FrameVarInfo) |
| : FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) { |
| BasicBlock *EntryBB = &OutlinedFn->getEntryBlock(); |
| |
| // New allocas should be inserted in the entry block, but after the parent FP |
| // is established if it is an instruction. |
| Instruction *InsertPoint = EntryBB->getFirstInsertionPt(); |
| if (auto *FPInst = dyn_cast<Instruction>(ParentFP)) |
| InsertPoint = FPInst->getNextNode(); |
| Builder.SetInsertPoint(EntryBB, InsertPoint); |
| } |
| |
| Value *WinEHFrameVariableMaterializer::materializeValueFor(Value *V) { |
| // If we're asked to materialize a static alloca, we temporarily create an |
| // alloca in the outlined function and add this to the FrameVarInfo map. When |
| // all the outlining is complete, we'll replace these temporary allocas with |
| // calls to llvm.localrecover. |
| if (auto *AV = dyn_cast<AllocaInst>(V)) { |
| assert(AV->isStaticAlloca() && |
| "cannot materialize un-demoted dynamic alloca"); |
| AllocaInst *NewAlloca = dyn_cast<AllocaInst>(AV->clone()); |
| Builder.Insert(NewAlloca, AV->getName()); |
| FrameVarInfo[AV].push_back(NewAlloca); |
| return NewAlloca; |
| } |
| |
| if (isa<Instruction>(V) || isa<Argument>(V)) { |
| Function *Parent = isa<Instruction>(V) |
| ? cast<Instruction>(V)->getParent()->getParent() |
| : cast<Argument>(V)->getParent(); |
| errs() |
| << "Failed to demote instruction used in exception handler of function " |
| << GlobalValue::getRealLinkageName(Parent->getName()) << ":\n"; |
| errs() << " " << *V << '\n'; |
| report_fatal_error("WinEHPrepare failed to demote instruction"); |
| } |
| |
| // Don't materialize other values. |
| return nullptr; |
| } |
| |
| void WinEHFrameVariableMaterializer::escapeCatchObject(Value *V) { |
| // Catch parameter objects have to live in the parent frame. When we see a use |
| // of a catch parameter, add a sentinel to the multimap to indicate that it's |
| // used from another handler. This will prevent us from trying to sink the |
| // alloca into the handler and ensure that the catch parameter is present in |
| // the call to llvm.localescape. |
| FrameVarInfo[V].push_back(getCatchObjectSentinel()); |
| } |
| |
| // 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) { |
| findCleanupHandlers(Actions, BB, nullptr); |
| return; |
| } |
| |
| VisitedBlockSet VisitedBlocks; |
| |
| while (HandlersFound != NumClauses) { |
| BasicBlock *NextBB = nullptr; |
| |
| // Skip over filter clauses. |
| if (LPad->isFilter(HandlersFound)) { |
| ++HandlersFound; |
| continue; |
| } |
| |
| // See if the clause we're looking for is a catch-all. |
| // If so, the catch begins immediately. |
| Constant *ExpectedSelector = |
| LPad->getClause(HandlersFound)->stripPointerCasts(); |
| if (isa<ConstantPointerNull>(ExpectedSelector)) { |
| // The catch all must occur last. |
| assert(HandlersFound == NumClauses - 1); |
| |
| // There can be additional selector dispatches in the call chain that we |
| // need to ignore. |
| BasicBlock *CatchBlock = nullptr; |
| Constant *Selector; |
| while (BB && isSelectorDispatch(BB, CatchBlock, Selector, NextBB)) { |
| DEBUG(dbgs() << " Found extra catch dispatch in block " |
| << CatchBlock->getName() << "\n"); |
| BB = NextBB; |
| } |
| |
| // Add the catch handler to the action list. |
| CatchHandler *Action = nullptr; |
| if (CatchHandlerMap.count(BB) && CatchHandlerMap[BB] != nullptr) { |
| // If the CatchHandlerMap already has an entry for this BB, re-use it. |
| Action = CatchHandlerMap[BB]; |
| assert(Action->getSelector() == ExpectedSelector); |
| } else { |
| // We don't expect a selector dispatch, but there may be a call to |
| // llvm.eh.begincatch, which separates catch handling code from |
| // cleanup code in the same control flow. This call looks for the |
| // begincatch intrinsic. |
| Action = findCatchHandler(BB, NextBB, VisitedBlocks); |
| if (Action) { |
| // 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) |
| findCleanupHandlers(Actions, BB, BB); |
| } else { |
| // If an action was not found, it means that the control flows |
| // directly into the catch-all handler and there is no cleanup code. |
| // That's an expected situation and we must create a catch action. |
| // Since this is a catch-all handler, the selector won't actually |
| // appear in the code anywhere. ExpectedSelector here is the constant |
| // null ptr that we got from the landing pad instruction. |
| Action = new CatchHandler(BB, ExpectedSelector, 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); |
| assert(CatchAction); |
| |
| // See if there is any interesting code executed before the dispatch. |
| findCleanupHandlers(Actions, BB, CatchAction->getStartBlock()); |
| |
| // When the source program contains multiple nested try blocks the catch |
| // handlers can get strung together in such a way that we can encounter |
| // a dispatch for a selector that we've already had a handler for. |
| if (CatchAction->getSelector()->stripPointerCasts() == ExpectedSelector) { |
| ++HandlersFound; |
| |
| // Add the catch handler to the action list. |
| DEBUG(dbgs() << " Found catch dispatch in block " |
| << CatchAction->getStartBlock()->getName() << "\n"); |
| Actions.insertCatchHandler(CatchAction); |
| } else { |
| // Under some circumstances optimized IR will flow unconditionally into a |
| // handler block without checking the selector. This can only happen if |
| // the landing pad has a catch-all handler and the handler for the |
| // preceeding catch clause is identical to the catch-call handler |
| // (typically an empty catch). In this case, the handler must be shared |
| // by all remaining clauses. |
| if (isa<ConstantPointerNull>( |
| CatchAction->getSelector()->stripPointerCasts())) { |
| DEBUG(dbgs() << " Applying early catch-all handler in block " |
| << CatchAction->getStartBlock()->getName() |
| << " to all remaining clauses.\n"); |
| Actions.insertCatchHandler(CatchAction); |
| return; |
| } |
| |
| DEBUG(dbgs() << " Found extra 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. |
| findCleanupHandlers(Actions, BB, BB); |
| |
| // 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; |
| } |
| |
| // 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; |
| } |
| // If we encounter a block containing an llvm.eh.begincatch before we |
| // find a selector dispatch block, the handler is assumed to be |
| // reached unconditionally. This happens for catch-all blocks, but |
| // it can also happen for other catch handlers that have been combined |
| // with the catch-all handler during optimization. |
| if (isCatchBlock(BB)) { |
| PointerType *Int8PtrTy = Type::getInt8PtrTy(BB->getContext()); |
| Constant *NullSelector = ConstantPointerNull::get(Int8PtrTy); |
| CatchHandler *Action = new CatchHandler(BB, NullSelector, nullptr); |
| 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 findCleanupHandlers. |
| static void createCleanupHandler(LandingPadActions &Actions, |
| CleanupHandlerMapTy &CleanupHandlerMap, |
| BasicBlock *BB) { |
| CleanupHandler *Action = new CleanupHandler(BB); |
| CleanupHandlerMap[BB] = Action; |
| Actions.insertCleanupHandler(Action); |
| DEBUG(dbgs() << " Found cleanup code in block " |
| << Action->getStartBlock()->getName() << "\n"); |
| } |
| |
| static CallSite matchOutlinedFinallyCall(BasicBlock *BB, |
| Instruction *MaybeCall) { |
| // Look for finally blocks that Clang has already outlined for us. |
| // %fp = call i8* @llvm.localaddress() |
| // call void @"fin$parent"(iN 1, i8* %fp) |
| if (isLocalAddressCall(MaybeCall) && MaybeCall != BB->getTerminator()) |
| MaybeCall = MaybeCall->getNextNode(); |
| CallSite FinallyCall(MaybeCall); |
| if (!FinallyCall || FinallyCall.arg_size() != 2) |
| return CallSite(); |
| if (!match(FinallyCall.getArgument(0), m_SpecificInt(1))) |
| return CallSite(); |
| if (!isLocalAddressCall(FinallyCall.getArgument(1))) |
| return CallSite(); |
| return FinallyCall; |
| } |
| |
| static BasicBlock *followSingleUnconditionalBranches(BasicBlock *BB) { |
| // Skip single ubr blocks. |
| while (BB->getFirstNonPHIOrDbg() == BB->getTerminator()) { |
| auto *Br = dyn_cast<BranchInst>(BB->getTerminator()); |
| if (Br && Br->isUnconditional()) |
| BB = Br->getSuccessor(0); |
| else |
| return BB; |
| } |
| return BB; |
| } |
| |
| // 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. |
| // |
| void WinEHPrepare::findCleanupHandlers(LandingPadActions &Actions, |
| 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) { |
| BB = followSingleUnconditionalBranches(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]) { |
| Actions.insertCleanupHandler(Action); |
| DEBUG(dbgs() << " Found cleanup code in block " |
| << Action->getStartBlock()->getName() << "\n"); |
| // FIXME: This cleanup might chain into another, and we need to discover |
| // that. |
| return; |
| } 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 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. |
| BasicBlock *SuccBB = followSingleUnconditionalBranches(BB); |
| if (SuccBB == BB || SuccBB == EndBB) |
| return; |
| 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: |
| // %lpad.val1 = insertvalue { i8*, i32 } undef, i8* %exn, 0 |
| // %lpad.val2 = insertvalue { i8*, i32 } %lpad.val1, i32 %sel, 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 the resume value isn't a phi or landingpad value, it should be a |
| // series of insertions. Identify them so we can avoid them when scanning |
| // for cleanups. |
| if (!isa<PHINode>(ResumeVal) && !isa<LandingPadInst>(ResumeVal)) { |
| Insert2 = dyn_cast<InsertValueInst>(ResumeVal); |
| if (!Insert2) |
| return createCleanupHandler(Actions, CleanupHandlerMap, BB); |
| Insert1 = dyn_cast<InsertValueInst>(Insert2->getAggregateOperand()); |
| if (!Insert1) |
| return createCleanupHandler(Actions, 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(Actions, CleanupHandlerMap, BB); |
| } |
| } |
| return; |
| } |
| |
| BranchInst *Branch = dyn_cast<BranchInst>(Terminator); |
| if (Branch && Branch->isConditional()) { |
| // Look for the selector dispatch. |
| // %2 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIf to i8*)) |
| // %matches = icmp eq i32 %sel, %2 |
| // br i1 %matches, label %catch14, label %eh.resume |
| CmpInst *Compare = dyn_cast<CmpInst>(Branch->getCondition()); |
| if (!Compare || !Compare->isEquality()) |
| return createCleanupHandler(Actions, 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 (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>())) |
| continue; |
| return createCleanupHandler(Actions, CleanupHandlerMap, BB); |
| } |
| // The selector dispatch block should always terminate our search. |
| assert(BB == EndBB); |
| return; |
| } |
| |
| if (isAsynchronousEHPersonality(Personality)) { |
| // If this is a landingpad block, split the block at the first non-landing |
| // pad instruction. |
| Instruction *MaybeCall = BB->getFirstNonPHIOrDbg(); |
| if (LPadMap) { |
| while (MaybeCall != BB->getTerminator() && |
| LPadMap->isLandingPadSpecificInst(MaybeCall)) |
| MaybeCall = MaybeCall->getNextNode(); |
| } |
| |
| // Look for outlined finally calls on x64, since those happen to match the |
| // prototype provided by the runtime. |
| if (TheTriple.getArch() == Triple::x86_64) { |
| if (CallSite FinallyCall = matchOutlinedFinallyCall(BB, MaybeCall)) { |
| Function *Fin = FinallyCall.getCalledFunction(); |
| assert(Fin && "outlined finally call should be direct"); |
| auto *Action = new CleanupHandler(BB); |
| Action->setHandlerBlockOrFunc(Fin); |
| Actions.insertCleanupHandler(Action); |
| CleanupHandlerMap[BB] = Action; |
| DEBUG(dbgs() << " Found frontend-outlined finally call to " |
| << Fin->getName() << " in block " |
| << Action->getStartBlock()->getName() << "\n"); |
| |
| // Split the block if there were more interesting instructions and |
| // look for finally calls in the normal successor block. |
| BasicBlock *SuccBB = BB; |
| if (FinallyCall.getInstruction() != BB->getTerminator() && |
| FinallyCall.getInstruction()->getNextNode() != |
| BB->getTerminator()) { |
| SuccBB = |
| SplitBlock(BB, FinallyCall.getInstruction()->getNextNode(), DT); |
| } else { |
| if (FinallyCall.isInvoke()) { |
| SuccBB = cast<InvokeInst>(FinallyCall.getInstruction()) |
| ->getNormalDest(); |
| } else { |
| SuccBB = BB->getUniqueSuccessor(); |
| assert(SuccBB && |
| "splitOutlinedFinallyCalls didn't insert a branch"); |
| } |
| } |
| BB = SuccBB; |
| if (BB == EndBB) |
| return; |
| continue; |
| } |
| } |
| } |
| |
| // Anything else is either a catch block or interesting cleanup code. |
| for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end(); |
| II != IE; ++II) { |
| Instruction *Inst = II; |
| if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst)) |
| continue; |
| // Unconditional branches fall through to this loop. |
| if (Inst == Branch) |
| continue; |
| // If this is a catch block, there is no cleanup code to be found. |
| if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>())) |
| return; |
| // If this a nested landing pad, it may contain an endcatch call. |
| if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>())) |
| return; |
| // Anything else makes this interesting cleanup code. |
| return createCleanupHandler(Actions, CleanupHandlerMap, BB); |
| } |
| |
| // Only unconditional branches in empty blocks should get this far. |
| assert(Branch && Branch->isUnconditional()); |
| if (BB == EndBB) |
| return; |
| BB = Branch->getSuccessor(0); |
| } |
| } |
| |
| // This is a public function, declared in WinEHFuncInfo.h and is also |
| // referenced by WinEHNumbering in FunctionLoweringInfo.cpp. |
| void llvm::parseEHActions( |
| const IntrinsicInst *II, |
| SmallVectorImpl<std::unique_ptr<ActionHandler>> &Actions) { |
| assert(II->getIntrinsicID() == Intrinsic::eh_actions && |
| "attempted to parse non eh.actions intrinsic"); |
| for (unsigned I = 0, E = II->getNumArgOperands(); I != E;) { |
| uint64_t ActionKind = |
| cast<ConstantInt>(II->getArgOperand(I))->getZExtValue(); |
| if (ActionKind == /*catch=*/1) { |
| auto *Selector = cast<Constant>(II->getArgOperand(I + 1)); |
| ConstantInt *EHObjIndex = cast<ConstantInt>(II->getArgOperand(I + 2)); |
| int64_t EHObjIndexVal = EHObjIndex->getSExtValue(); |
| Constant *Handler = cast<Constant>(II->getArgOperand(I + 3)); |
| I += 4; |
| auto CH = make_unique<CatchHandler>(/*BB=*/nullptr, Selector, |
| /*NextBB=*/nullptr); |
| CH->setHandlerBlockOrFunc(Handler); |
| CH->setExceptionVarIndex(EHObjIndexVal); |
| Actions.push_back(std::move(CH)); |
| } else if (ActionKind == 0) { |
| Constant *Handler = cast<Constant>(II->getArgOperand(I + 1)); |
| I += 2; |
| auto CH = make_unique<CleanupHandler>(/*BB=*/nullptr); |
| CH->setHandlerBlockOrFunc(Handler); |
| Actions.push_back(std::move(CH)); |
| } else { |
| llvm_unreachable("Expected either a catch or cleanup handler!"); |
| } |
| } |
| std::reverse(Actions.begin(), Actions.end()); |
| } |
| |
| namespace { |
| struct WinEHNumbering { |
| WinEHNumbering(WinEHFuncInfo &FuncInfo) : FuncInfo(FuncInfo), |
| CurrentBaseState(-1), NextState(0) {} |
| |
| WinEHFuncInfo &FuncInfo; |
| int CurrentBaseState; |
| int NextState; |
| |
| SmallVector<std::unique_ptr<ActionHandler>, 4> HandlerStack; |
| SmallPtrSet<const Function *, 4> VisitedHandlers; |
| |
| int currentEHNumber() const { |
| return HandlerStack.empty() ? CurrentBaseState : HandlerStack.back()->getEHState(); |
| } |
| |
| void createUnwindMapEntry(int ToState, ActionHandler *AH); |
| void createTryBlockMapEntry(int TryLow, int TryHigh, |
| ArrayRef<CatchHandler *> Handlers); |
| void processCallSite(MutableArrayRef<std::unique_ptr<ActionHandler>> Actions, |
| ImmutableCallSite CS); |
| void popUnmatchedActions(int FirstMismatch); |
| void calculateStateNumbers(const Function &F); |
| void findActionRootLPads(const Function &F); |
| }; |
| } |
| |
| void WinEHNumbering::createUnwindMapEntry(int ToState, ActionHandler *AH) { |
| WinEHUnwindMapEntry UME; |
| UME.ToState = ToState; |
| if (auto *CH = dyn_cast_or_null<CleanupHandler>(AH)) |
| UME.Cleanup = cast<Function>(CH->getHandlerBlockOrFunc()); |
| else |
| UME.Cleanup = nullptr; |
| FuncInfo.UnwindMap.push_back(UME); |
| } |
| |
| void WinEHNumbering::createTryBlockMapEntry(int TryLow, int TryHigh, |
| ArrayRef<CatchHandler *> Handlers) { |
| // See if we already have an entry for this set of handlers. |
| // This is using iterators rather than a range-based for loop because |
| // if we find the entry we're looking for we'll need the iterator to erase it. |
| int NumHandlers = Handlers.size(); |
| auto I = FuncInfo.TryBlockMap.begin(); |
| auto E = FuncInfo.TryBlockMap.end(); |
| for ( ; I != E; ++I) { |
| auto &Entry = *I; |
| if (Entry.HandlerArray.size() != (size_t)NumHandlers) |
| continue; |
| int N; |
| for (N = 0; N < NumHandlers; ++N) { |
| if (Entry.HandlerArray[N].Handler != Handlers[N]->getHandlerBlockOrFunc()) |
| break; // breaks out of inner loop |
| } |
| // If all the handlers match, this is what we were looking for. |
| if (N == NumHandlers) { |
| break; |
| } |
| } |
| |
| // If we found an existing entry for this set of handlers, extend the range |
| // but move the entry to the end of the map vector. The order of entries |
| // in the map is critical to the way that the runtime finds handlers. |
| // FIXME: Depending on what has happened with block ordering, this may |
| // incorrectly combine entries that should remain separate. |
| if (I != E) { |
| // Copy the existing entry. |
| WinEHTryBlockMapEntry Entry = *I; |
| Entry.TryLow = std::min(TryLow, Entry.TryLow); |
| Entry.TryHigh = std::max(TryHigh, Entry.TryHigh); |
| assert(Entry.TryLow <= Entry.TryHigh); |
| // Erase the old entry and add this one to the back. |
| FuncInfo.TryBlockMap.erase(I); |
| FuncInfo.TryBlockMap.push_back(Entry); |
| return; |
| } |
| |
| // If we didn't find an entry, create a new one. |
| WinEHTryBlockMapEntry TBME; |
| TBME.TryLow = TryLow; |
| TBME.TryHigh = TryHigh; |
| assert(TBME.TryLow <= TBME.TryHigh); |
| for (CatchHandler *CH : Handlers) { |
| WinEHHandlerType HT; |
| if (CH->getSelector()->isNullValue()) { |
| HT.Adjectives = 0x40; |
| HT.TypeDescriptor = nullptr; |
| } else { |
| auto *GV = cast<GlobalVariable>(CH->getSelector()->stripPointerCasts()); |
| // Selectors are always pointers to GlobalVariables with 'struct' type. |
| // The struct has two fields, adjectives and a type descriptor. |
| auto *CS = cast<ConstantStruct>(GV->getInitializer()); |
| HT.Adjectives = |
| cast<ConstantInt>(CS->getAggregateElement(0U))->getZExtValue(); |
| HT.TypeDescriptor = |
| cast<GlobalVariable>(CS->getAggregateElement(1)->stripPointerCasts()); |
| } |
| HT.Handler = cast<Function>(CH->getHandlerBlockOrFunc()); |
| HT.CatchObjRecoverIdx = CH->getExceptionVarIndex(); |
| TBME.HandlerArray.push_back(HT); |
| } |
| FuncInfo.TryBlockMap.push_back(TBME); |
| } |
| |
| static void print_name(const Value *V) { |
| #ifndef NDEBUG |
| if (!V) { |
| DEBUG(dbgs() << "null"); |
| return; |
| } |
| |
| if (const auto *F = dyn_cast<Function>(V)) |
| DEBUG(dbgs() << F->getName()); |
| else |
| DEBUG(V->dump()); |
| #endif |
| } |
| |
| void WinEHNumbering::processCallSite( |
| MutableArrayRef<std::unique_ptr<ActionHandler>> Actions, |
| ImmutableCallSite CS) { |
| DEBUG(dbgs() << "processCallSite (EH state = " << currentEHNumber() |
| << ") for: "); |
| print_name(CS ? CS.getCalledValue() : nullptr); |
| DEBUG(dbgs() << '\n'); |
| |
| DEBUG(dbgs() << "HandlerStack: \n"); |
| for (int I = 0, E = HandlerStack.size(); I < E; ++I) { |
| DEBUG(dbgs() << " "); |
| print_name(HandlerStack[I]->getHandlerBlockOrFunc()); |
| DEBUG(dbgs() << '\n'); |
| } |
| DEBUG(dbgs() << "Actions: \n"); |
| for (int I = 0, E = Actions.size(); I < E; ++I) { |
| DEBUG(dbgs() << " "); |
| print_name(Actions[I]->getHandlerBlockOrFunc()); |
| DEBUG(dbgs() << '\n'); |
| } |
| int FirstMismatch = 0; |
| for (int E = std::min(HandlerStack.size(), Actions.size()); FirstMismatch < E; |
| ++FirstMismatch) { |
| if (HandlerStack[FirstMismatch]->getHandlerBlockOrFunc() != |
| Actions[FirstMismatch]->getHandlerBlockOrFunc()) |
| break; |
| } |
| |
| // Remove unmatched actions from the stack and process their EH states. |
| popUnmatchedActions(FirstMismatch); |
| |
| DEBUG(dbgs() << "Pushing actions for CallSite: "); |
| print_name(CS ? CS.getCalledValue() : nullptr); |
| DEBUG(dbgs() << '\n'); |
| |
| bool LastActionWasCatch = false; |
| const LandingPadInst *LastRootLPad = nullptr; |
| for (size_t I = FirstMismatch; I != Actions.size(); ++I) { |
| // We can reuse eh states when pushing two catches for the same invoke. |
| bool CurrActionIsCatch = isa<CatchHandler>(Actions[I].get()); |
| auto *Handler = cast<Function>(Actions[I]->getHandlerBlockOrFunc()); |
| // Various conditions can lead to a handler being popped from the |
| // stack and re-pushed later. That shouldn't create a new state. |
| // FIXME: Can code optimization lead to re-used handlers? |
| if (FuncInfo.HandlerEnclosedState.count(Handler)) { |
| // If we already assigned the state enclosed by this handler re-use it. |
| Actions[I]->setEHState(FuncInfo.HandlerEnclosedState[Handler]); |
| continue; |
| } |
| const LandingPadInst* RootLPad = FuncInfo.RootLPad[Handler]; |
| if (CurrActionIsCatch && LastActionWasCatch && RootLPad == LastRootLPad) { |
| DEBUG(dbgs() << "setEHState for handler to " << currentEHNumber() << "\n"); |
| Actions[I]->setEHState(currentEHNumber()); |
| } else { |
| DEBUG(dbgs() << "createUnwindMapEntry(" << currentEHNumber() << ", "); |
| print_name(Actions[I]->getHandlerBlockOrFunc()); |
| DEBUG(dbgs() << ") with EH state " << NextState << "\n"); |
| createUnwindMapEntry(currentEHNumber(), Actions[I].get()); |
| DEBUG(dbgs() << "setEHState for handler to " << NextState << "\n"); |
| Actions[I]->setEHState(NextState); |
| NextState++; |
| } |
| HandlerStack.push_back(std::move(Actions[I])); |
| LastActionWasCatch = CurrActionIsCatch; |
| LastRootLPad = RootLPad; |
| } |
| |
| // This is used to defer numbering states for a handler until after the |
| // last time it appears in an invoke action list. |
| if (CS.isInvoke()) { |
| for (int I = 0, E = HandlerStack.size(); I < E; ++I) { |
| auto *Handler = cast<Function>(HandlerStack[I]->getHandlerBlockOrFunc()); |
| if (FuncInfo.LastInvoke[Handler] != cast<InvokeInst>(CS.getInstruction())) |
| continue; |
| FuncInfo.LastInvokeVisited[Handler] = true; |
| DEBUG(dbgs() << "Last invoke of "); |
| print_name(Handler); |
| DEBUG(dbgs() << " has been visited.\n"); |
| } |
| } |
| |
| DEBUG(dbgs() << "In EHState " << currentEHNumber() << " for CallSite: "); |
| print_name(CS ? CS.getCalledValue() : nullptr); |
| DEBUG(dbgs() << '\n'); |
| } |
| |
| void WinEHNumbering::popUnmatchedActions(int FirstMismatch) { |
| // Don't recurse while we are looping over the handler stack. Instead, defer |
| // the numbering of the catch handlers until we are done popping. |
| SmallVector<CatchHandler *, 4> PoppedCatches; |
| for (int I = HandlerStack.size() - 1; I >= FirstMismatch; --I) { |
| std::unique_ptr<ActionHandler> Handler = HandlerStack.pop_back_val(); |
| if (isa<CatchHandler>(Handler.get())) |
| PoppedCatches.push_back(cast<CatchHandler>(Handler.release())); |
| } |
| |
| int TryHigh = NextState - 1; |
| int LastTryLowIdx = 0; |
| for (int I = 0, E = PoppedCatches.size(); I != E; ++I) { |
| CatchHandler *CH = PoppedCatches[I]; |
| DEBUG(dbgs() << "Popped handler with state " << CH->getEHState() << "\n"); |
| if (I + 1 == E || CH->getEHState() != PoppedCatches[I + 1]->getEHState()) { |
| int TryLow = CH->getEHState(); |
| auto Handlers = |
| makeArrayRef(&PoppedCatches[LastTryLowIdx], I - LastTryLowIdx + 1); |
| DEBUG(dbgs() << "createTryBlockMapEntry(" << TryLow << ", " << TryHigh); |
| for (size_t J = 0; J < Handlers.size(); ++J) { |
| DEBUG(dbgs() << ", "); |
| print_name(Handlers[J]->getHandlerBlockOrFunc()); |
| } |
| DEBUG(dbgs() << ")\n"); |
| createTryBlockMapEntry(TryLow, TryHigh, Handlers); |
| LastTryLowIdx = I + 1; |
| } |
| } |
| |
| for (CatchHandler *CH : PoppedCatches) { |
| if (auto *F = dyn_cast<Function>(CH->getHandlerBlockOrFunc())) { |
| if (FuncInfo.LastInvokeVisited[F]) { |
| DEBUG(dbgs() << "Assigning base state " << NextState << " to "); |
| print_name(F); |
| DEBUG(dbgs() << '\n'); |
| FuncInfo.HandlerBaseState[F] = NextState; |
| DEBUG(dbgs() << "createUnwindMapEntry(" << currentEHNumber() |
| << ", null)\n"); |
| createUnwindMapEntry(currentEHNumber(), nullptr); |
| ++NextState; |
| calculateStateNumbers(*F); |
| } |
| else { |
| DEBUG(dbgs() << "Deferring handling of "); |
| print_name(F); |
| DEBUG(dbgs() << " until last invoke visited.\n"); |
| } |
| } |
| delete CH; |
| } |
| } |
| |
| void WinEHNumbering::calculateStateNumbers(const Function &F) { |
| auto I = VisitedHandlers.insert(&F); |
| if (!I.second) |
| return; // We've already visited this handler, don't renumber it. |
| |
| int OldBaseState = CurrentBaseState; |
| if (FuncInfo.HandlerBaseState.count(&F)) { |
| CurrentBaseState = FuncInfo.HandlerBaseState[&F]; |
| } |
| |
| size_t SavedHandlerStackSize = HandlerStack.size(); |
| |
| DEBUG(dbgs() << "Calculating state numbers for: " << F.getName() << '\n'); |
| SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList; |
| for (const BasicBlock &BB : F) { |
| for (const Instruction &I : BB) { |
| const auto *CI = dyn_cast<CallInst>(&I); |
| if (!CI || CI->doesNotThrow()) |
| continue; |
| processCallSite(None, CI); |
| } |
| const auto *II = dyn_cast<InvokeInst>(BB.getTerminator()); |
| if (!II) |
| continue; |
| const LandingPadInst *LPI = II->getLandingPadInst(); |
| auto *ActionsCall = dyn_cast<IntrinsicInst>(LPI->getNextNode()); |
| if (!ActionsCall) |
| continue; |
| parseEHActions(ActionsCall, ActionList); |
| if (ActionList.empty()) |
| continue; |
| processCallSite(ActionList, II); |
| ActionList.clear(); |
| FuncInfo.LandingPadStateMap[LPI] = currentEHNumber(); |
| DEBUG(dbgs() << "Assigning state " << currentEHNumber() |
| << " to landing pad at " << LPI->getParent()->getName() |
| << '\n'); |
| } |
| |
| // Pop any actions that were pushed on the stack for this function. |
| popUnmatchedActions(SavedHandlerStackSize); |
| |
| DEBUG(dbgs() << "Assigning max state " << NextState - 1 |
| << " to " << F.getName() << '\n'); |
| FuncInfo.CatchHandlerMaxState[&F] = NextState - 1; |
| |
| CurrentBaseState = OldBaseState; |
| } |
| |
| // This function follows the same basic traversal as calculateStateNumbers |
| // but it is necessary to identify the root landing pad associated |
| // with each action before we start assigning state numbers. |
| void WinEHNumbering::findActionRootLPads(const Function &F) { |
| auto I = VisitedHandlers.insert(&F); |
| if (!I.second) |
| return; // We've already visited this handler, don't revisit it. |
| |
| SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList; |
| for (const BasicBlock &BB : F) { |
| const auto *II = dyn_cast<InvokeInst>(BB.getTerminator()); |
| if (!II) |
| continue; |
| const LandingPadInst *LPI = II->getLandingPadInst(); |
| auto *ActionsCall = dyn_cast<IntrinsicInst>(LPI->getNextNode()); |
| if (!ActionsCall) |
| continue; |
| |
| assert(ActionsCall->getIntrinsicID() == Intrinsic::eh_actions); |
| parseEHActions(ActionsCall, ActionList); |
| if (ActionList.empty()) |
| continue; |
| for (int I = 0, E = ActionList.size(); I < E; ++I) { |
| if (auto *Handler |
| = dyn_cast<Function>(ActionList[I]->getHandlerBlockOrFunc())) { |
| FuncInfo.LastInvoke[Handler] = II; |
| // Don't replace the root landing pad if we previously saw this |
| // handler in a different function. |
| if (FuncInfo.RootLPad.count(Handler) && |
| FuncInfo.RootLPad[Handler]->getParent()->getParent() != &F) |
| continue; |
| DEBUG(dbgs() << "Setting root lpad for "); |
| print_name(Handler); |
| DEBUG(dbgs() << " to " << LPI->getParent()->getName() << '\n'); |
| FuncInfo.RootLPad[Handler] = LPI; |
| } |
| } |
| // Walk the actions again and look for nested handlers. This has to |
| // happen after all of the actions have been processed in the current |
| // function. |
| for (int I = 0, E = ActionList.size(); I < E; ++I) |
| if (auto *Handler |
| = dyn_cast<Function>(ActionList[I]->getHandlerBlockOrFunc())) |
| findActionRootLPads(*Handler); |
| ActionList.clear(); |
| } |
| } |
| |
| void llvm::calculateWinCXXEHStateNumbers(const Function *ParentFn, |
| WinEHFuncInfo &FuncInfo) { |
| // Return if it's already been done. |
| if (!FuncInfo.LandingPadStateMap.empty()) |
| return; |
| |
| WinEHNumbering Num(FuncInfo); |
| Num.findActionRootLPads(*ParentFn); |
| // The VisitedHandlers list is used by both findActionRootLPads and |
| // calculateStateNumbers, but both functions need to visit all handlers. |
| Num.VisitedHandlers.clear(); |
| Num.calculateStateNumbers(*ParentFn); |
| // Pop everything on the handler stack. |
| // It may be necessary to call this more than once because a handler can |
| // be pushed on the stack as a result of clearing the stack. |
| while (!Num.HandlerStack.empty()) |
| Num.processCallSite(None, ImmutableCallSite()); |
| } |