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Diffstat (limited to 'contrib/llvm/lib/CodeGen/WinEHPrepare.cpp')
| -rw-r--r-- | contrib/llvm/lib/CodeGen/WinEHPrepare.cpp | 2856 |
1 files changed, 2856 insertions, 0 deletions
diff --git a/contrib/llvm/lib/CodeGen/WinEHPrepare.cpp b/contrib/llvm/lib/CodeGen/WinEHPrepare.cpp new file mode 100644 index 0000000..c2b3d84 --- /dev/null +++ b/contrib/llvm/lib/CodeGen/WinEHPrepare.cpp @@ -0,0 +1,2856 @@ +//===-- 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/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 = Triple(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(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, Value *PersonalityFn); + + 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; + 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 llvm.frameaddress(1). 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(LPads.back()->getPersonalityFn()); + + // Do nothing if this is not an MSVC personality. + if (!isMSVCEHPersonality(Personality)) + return false; + + DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree(); + + // 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>(); +} + +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 is a phi node. Returning from EH to a phi node + // is just as impossible as having a phi after an indirectbr. + if (isa<PHINode>(CatchHandler->begin())) { + 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()); + + 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; + } + + auto *OpI = cast<Instruction>(Op); + 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. + for (Instruction *E : SEHCodeUses) { + 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; + LoadInst *LI; + if (auto *Phi = dyn_cast<PHINode>(I)) + LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false, + Phi->getIncomingBlock(*U)); + else + LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false, I); + U->set(LI); + } + 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::frameescape); + Function *RecoverFrameFn = + Intrinsic::getDeclaration(M, Intrinsic::framerecover); + SmallVector<Value *, 8> AllocasToEscape; + + // Scan the entry block for an existing call to llvm.frameescape. We need to + // keep escaping those objects. + for (Instruction &I : F.front()) { + auto *II = dyn_cast<IntrinsicInst>(&I); + if (II && II->getIntrinsicID() == Intrinsic::frameescape) { + 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.framerecover. + 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 framerecover 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.frameescape(...)' at the end of the entry + // block. + Builder.SetInsertPoint(&F.getEntryBlock().back()); + Builder.CreateCall(FrameEscapeFn, AllocasToEscape); + + if (SEHExceptionCodeSlot) { + if (SEHExceptionCodeSlot->hasNUses(0)) + SEHExceptionCodeSlot->eraseFromParent(); + else if (isAllocaPromotable(SEHExceptionCodeSlot)) + PromoteMemToReg(SEHExceptionCodeSlot, *DT); + } + + // Clean up the handler action maps we created for this function + DeleteContainerSeconds(CatchHandlerMap); + CatchHandlerMap.clear(); + DeleteContainerSeconds(CleanupHandlerMap); + CleanupHandlerMap.clear(); + HandlerToParentFP.clear(); + DT = 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; + assert(match(Recover, m_Intrinsic<Intrinsic::eh_actions>())); + 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, + Value *PersonalityFn) { + // 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), + PersonalityFn, 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, + Value *PersonalityFn) { + 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, PersonalityFn); + 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(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(); + FunctionType *FnType; + if (TheTriple.getArch() == Triple::x86_64) { + Type *Int8PtrType = Type::getInt8PtrTy(Context); + 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); + Value *Args[1] = {ConstantInt::get(Type::getInt32Ty(Context), 1)}; + ParentFP = CallInst::Create(FrameAddressFn, Args, "parent_fp", + &Handler->getEntryBlock()); + } + 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(Int8PtrType, SrcFn->getName() + ".catch", M, + ParentFP); + } else { + Handler = createHandlerFunc(Type::getVoidTy(Context), + SrcFn->getName() + ".cleanup", M, ParentFP); + } + 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, LPad->getPersonalityFn()); + + 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 isFrameAddressCall(const Value *V) { + return match(const_cast<Value *>(V), + m_Intrinsic<Intrinsic::frameaddress>(m_SpecificInt(0))); +} + +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.frameaddress(i32 0), remap that to the second argument, + // which is the FP of the parent. + if (isFrameAddressCall(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.framerecover. + 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.frameescape. + 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.frameaddress(i32 0) + // call void @"fin$parent"(iN 1, i8* %fp) + if (isFrameAddressCall(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 (!isFrameAddressCall(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 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. + 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) { + 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; + assert(ActionsCall->getIntrinsicID() == Intrinsic::eh_actions); + 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()); +} |
