X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FWinEHPrepare.cpp;h=d04d93f11e4120f959677fb13a96a0e2a99fc996;hb=933d2bd39159e0e9ee5ebf150dcac1865628609d;hp=35b944ea309cb4b6169a1aba4a7cd1d8e0b1bd8f;hpb=5e708e26db256c46ca369270b5494ba11a79e4ad;p=oota-llvm.git diff --git a/lib/CodeGen/WinEHPrepare.cpp b/lib/CodeGen/WinEHPrepare.cpp index 35b944ea309..d04d93f11e4 100644 --- a/lib/CodeGen/WinEHPrepare.cpp +++ b/lib/CodeGen/WinEHPrepare.cpp @@ -8,9 +8,11 @@ //===----------------------------------------------------------------------===// // // This pass lowers LLVM IR exception handling into something closer to what the -// backend wants. It snifs the personality function to see which kind of -// preparation is necessary. If the personality function uses the Itanium LSDA, -// this pass delegates to the DWARF EH preparation pass. +// 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. // //===----------------------------------------------------------------------===// @@ -18,8 +20,11 @@ #include "llvm/ADT/MapVector.h" #include "llvm/ADT/STLExtras.h" #include "llvm/ADT/SmallSet.h" +#include "llvm/ADT/SetVector.h" +#include "llvm/ADT/Triple.h" #include "llvm/ADT/TinyPtrVector.h" #include "llvm/Analysis/LibCallSemantics.h" +#include "llvm/Analysis/TargetLibraryInfo.h" #include "llvm/CodeGen/WinEHFuncInfo.h" #include "llvm/IR/Dominators.h" #include "llvm/IR/Function.h" @@ -29,7 +34,6 @@ #include "llvm/IR/Module.h" #include "llvm/IR/PatternMatch.h" #include "llvm/Pass.h" -#include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include "llvm/Support/raw_ostream.h" #include "llvm/Transforms/Utils/BasicBlockUtils.h" @@ -70,7 +74,10 @@ class WinEHPrepare : public FunctionPass { public: static char ID; // Pass identification, replacement for typeid. WinEHPrepare(const TargetMachine *TM = nullptr) - : FunctionPass(ID), DT(nullptr) {} + : FunctionPass(ID) { + if (TM) + TheTriple = Triple(TM->getTargetTriple()); + } bool runOnFunction(Function &Fn) override; @@ -85,15 +92,26 @@ public: private: bool prepareExceptionHandlers(Function &F, SmallVectorImpl &LPads); + void identifyEHBlocks(Function &F, SmallVectorImpl &LPads); void promoteLandingPadValues(LandingPadInst *LPad); + void demoteValuesLiveAcrossHandlers(Function &F, + SmallVectorImpl &LPads); + void findSEHEHReturnPoints(Function &F, + SetVector &EHReturnBlocks); + void findCXXEHReturnPoints(Function &F, + SetVector &EHReturnBlocks); + void getPossibleReturnTargets(Function *ParentF, Function *HandlerF, + SetVector &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 addStubInvokeToHandlerIfNeeded(Function *Handler); void mapLandingPadBlocks(LandingPadInst *LPad, LandingPadActions &Actions); CatchHandler *findCatchHandler(BasicBlock *BB, BasicBlock *&NextBB, @@ -103,12 +121,18 @@ private: void processSEHCatchHandler(CatchHandler *Handler, BasicBlock *StartBB); + Triple TheTriple; + // All fields are reset by runOnFunction. - DominatorTree *DT; - EHPersonality Personality; + DominatorTree *DT = nullptr; + const TargetLibraryInfo *LibInfo = nullptr; + EHPersonality Personality = EHPersonality::Unknown; CatchHandlerMapTy CatchHandlerMap; CleanupHandlerMapTy CleanupHandlerMap; DenseMap LPadMaps; + SmallPtrSet NormalBlocks; + SmallPtrSet EHBlocks; + SetVector EHReturnBlocks; // This maps landing pad instructions found in outlined handlers to // the landing pad instruction in the parent function from which they @@ -130,11 +154,17 @@ private: // 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 LPadTargetBlocks; + + // Map from outlined handler to call to llvm.frameaddress(1). Only used for + // 32-bit EH. + DenseMap HandlerToParentFP; + + AllocaInst *SEHExceptionCodeSlot = nullptr; }; class WinEHFrameVariableMaterializer : public ValueMaterializer { public: - WinEHFrameVariableMaterializer(Function *OutlinedFn, + WinEHFrameVariableMaterializer(Function *OutlinedFn, Value *ParentFP, FrameVarInfoMap &FrameVarInfo); ~WinEHFrameVariableMaterializer() override {} @@ -170,12 +200,12 @@ private: class WinEHCloningDirectorBase : public CloningDirector { public: - WinEHCloningDirectorBase(Function *HandlerFn, FrameVarInfoMap &VarInfo, - LandingPadMap &LPadMap) - : Materializer(HandlerFn, VarInfo), + 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) {} + LPadMap(LPadMap), ParentFP(ParentFP) {} CloningAction handleInstruction(ValueToValueMapTy &VMap, const Instruction *Inst, @@ -190,12 +220,18 @@ public: 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; @@ -207,17 +243,22 @@ protected: Type *SelectorIDType; Type *Int8PtrType; LandingPadMap &LPadMap; + + /// The value representing the parent frame pointer. + Value *ParentFP; }; class WinEHCatchDirector : public WinEHCloningDirectorBase { public: WinEHCatchDirector( - Function *CatchFn, Value *Selector, FrameVarInfoMap &VarInfo, - LandingPadMap &LPadMap, - DenseMap &NestedLPads) - : WinEHCloningDirectorBase(CatchFn, VarInfo, LPadMap), + Function *CatchFn, Value *ParentFP, Value *Selector, + FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap, + DenseMap &NestedLPads, + DominatorTree *DT, SmallPtrSetImpl &EHBlocks) + : WinEHCloningDirectorBase(CatchFn, ParentFP, VarInfo, LPadMap), CurrentSelector(Selector->stripPointerCasts()), - ExceptionObjectVar(nullptr), NestedLPtoOriginalLP(NestedLPads) {} + ExceptionObjectVar(nullptr), NestedLPtoOriginalLP(NestedLPads), + DT(DT), EHBlocks(EHBlocks) {} CloningAction handleBeginCatch(ValueToValueMapTy &VMap, const Instruction *Inst, @@ -227,10 +268,15 @@ public: 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; @@ -247,13 +293,16 @@ private: // This will be a reference to the field of the same name in the WinEHPrepare // object which instantiates this WinEHCatchDirector object. DenseMap &NestedLPtoOriginalLP; + DominatorTree *DT; + SmallPtrSetImpl &EHBlocks; }; class WinEHCleanupDirector : public WinEHCloningDirectorBase { public: - WinEHCleanupDirector(Function *CleanupFn, FrameVarInfoMap &VarInfo, - LandingPadMap &LPadMap) - : WinEHCloningDirectorBase(CleanupFn, VarInfo, LPadMap) {} + WinEHCleanupDirector(Function *CleanupFn, Value *ParentFP, + FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap) + : WinEHCloningDirectorBase(CleanupFn, ParentFP, VarInfo, + LPadMap) {} CloningAction handleBeginCatch(ValueToValueMapTy &VMap, const Instruction *Inst, @@ -263,10 +312,15 @@ public: 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; @@ -306,12 +360,11 @@ FunctionPass *llvm::createWinEHPass(const TargetMachine *TM) { return new WinEHPrepare(TM); } -// FIXME: Remove this once the backend can handle the prepared IR. -static cl::opt - SEHPrepare("sehprepare", cl::Hidden, - cl::desc("Prepare functions with SEH personalities")); - bool WinEHPrepare::runOnFunction(Function &Fn) { + // No need to prepare outlined handlers. + if (Fn.hasFnAttribute("wineh-parent")) + return false; + SmallVector LPads; SmallVector Resumes; for (BasicBlock &BB : Fn) { @@ -326,23 +379,14 @@ bool WinEHPrepare::runOnFunction(Function &Fn) { return false; // Classify the personality to see what kind of preparation we need. - Personality = classifyEHPersonality(LPads.back()->getPersonalityFn()); + Personality = classifyEHPersonality(Fn.getPersonalityFn()); // Do nothing if this is not an MSVC personality. if (!isMSVCEHPersonality(Personality)) return false; DT = &getAnalysis().getDomTree(); - - if (isAsynchronousEHPersonality(Personality) && !SEHPrepare) { - // Replace all resume instructions with unreachable. - // FIXME: Remove this once the backend can handle the prepared IR. - for (ResumeInst *Resume : Resumes) { - IRBuilder<>(Resume).CreateUnreachable(); - Resume->eraseFromParent(); - } - return true; - } + LibInfo = &getAnalysis().getTLI(); // If there were any landing pads, prepareExceptionHandlers will make changes. prepareExceptionHandlers(Fn, LPads); @@ -353,10 +397,318 @@ bool WinEHPrepare::doFinalization(Module &M) { return false; } void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const { AU.addRequired(); + AU.addRequired(); +} + +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 &ReachableBBs, + SetVector &Worklist, + const SetVector *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(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(II->getOperand(0)); + auto *Op1 = dyn_cast(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 &EHReturnBlocks) { + for (auto BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) { + BasicBlock *BB = BBI; + for (Instruction &I : *BB) { + if (match(&I, m_Intrinsic())) { + Instruction *SplitPt = + findBeginCatchSplitPoint(BB, cast(&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())) { + // 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(I.getNextNode()); + if (!Br || !Br->isUnconditional() || + isa(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(LP->getClause(N - 1))); +} + +/// Find all points where exceptions control rejoins normal control flow via +/// selector dispatch. +void WinEHPrepare::findSEHEHReturnPoints( + Function &F, SetVector &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(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 &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(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 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 &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 ArgsToDemote; + SetVector 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(Op) || isa(Op) || isa(Op)) + continue; + auto *AI = dyn_cast(Op); + if (AI && AI->isStaticAlloca()) + continue; + + if (auto *Arg = dyn_cast(Op)) { + if (IsEHBB) { + DEBUG(dbgs() << "Demoting argument " << *Arg + << " used by EH instr: " << I << "\n"); + ArgsToDemote.insert(Arg); + } + continue; + } + + auto *OpI = cast(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 Users(Arg->user_begin(), Arg->user_end()); + for (User *U : Users) { + auto *I = dyn_cast(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(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 &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())) + 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. @@ -372,20 +724,37 @@ bool WinEHPrepare::prepareExceptionHandlers( 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, 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 (auto *IntrinCall = dyn_cast(&Inst)) { - if (IntrinCall->getIntrinsicID() == Intrinsic::eh_actions) { - LPadHasActionList = true; - break; - } - } - // FIXME: This is here to help with the development of nested landing pad - // outlining. It should be removed when that is finished. - if (isa(Inst)) { + if (match(&Inst, m_Intrinsic())) { LPadHasActionList = true; break; } @@ -422,36 +791,57 @@ bool WinEHPrepare::prepareExceptionHandlers( outlineHandler(Action, &F, LPad, StartBB, FrameVarInfo); } - // Replace the landing pad with a new llvm.eh.action based landing pad. - BasicBlock *NewLPadBB = BasicBlock::Create(Context, "lpad", &F, LPadBB); - assert(!isa(LPadBB->begin())); - auto *NewLPad = cast(LPad->clone()); - NewLPadBB->getInstList().push_back(NewLPad); - while (!pred_empty(LPadBB)) { - auto *pred = *pred_begin(LPadBB); - InvokeInst *Invoke = cast(pred->getTerminator()); - Invoke->setUnwindDest(NewLPadBB); - } + // Split the block after the landingpad instruction so that it is just a + // call to llvm.eh.actions followed by indirectbr. + assert(!isa(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(); - // If anyone is still using the old landingpad value, just give them undef - // instead. The eh pointer and selector values are not real. + // Replace all extracted values with undef and ultimately replace the + // landingpad with undef. + SmallVector SEHCodeUses; + SmallVector EHUndefs; + for (User *U : LPad->users()) { + auto *E = dyn_cast(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())); - // Replace the mapping of any nested landing pad that previously mapped - // to this landing pad with a referenced to the cloned version. - for (auto &LPadPair : NestedLPtoOriginalLP) { - const LandingPadInst *OriginalLPad = LPadPair.second; - if (OriginalLPad == LPad) { - LPadPair.second = NewLPad; + // Rewrite uses of the exception pointer to loads of an alloca. + for (Instruction *E : SEHCodeUses) { + SmallVector Uses; + for (Use &U : E->uses()) + Uses.push_back(&U); + for (Use *U : Uses) { + auto *I = cast(U->getUser()); + if (isa(I)) + continue; + LoadInst *LI; + if (auto *Phi = dyn_cast(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(); } - // Replace uses of the old lpad in phis with this block and delete the old - // block. - LPadBB->replaceSuccessorsPhiUsesWith(NewLPadBB); - LPadBB->getTerminator()->eraseFromParent(); - new UnreachableInst(LPadBB->getContext(), LPadBB); - // Add a call to describe the actions for this landing pad. std::vector ActionArgs; for (ActionHandler *Action : Actions) { @@ -476,17 +866,26 @@ bool WinEHPrepare::prepareExceptionHandlers( ActionArgs.push_back(Action->getHandlerBlockOrFunc()); } CallInst *Recover = - CallInst::Create(ActionIntrin, ActionArgs, "recover", NewLPadBB); + CallInst::Create(ActionIntrin, ActionArgs, "recover", LPadBB); - // Add an indirect branch listing possible successors of the catch handlers. - IndirectBrInst *Branch = IndirectBrInst::Create(Recover, 0, NewLPadBB); + SetVector ReturnTargets; for (ActionHandler *Action : Actions) { if (auto *CatchAction = dyn_cast(Action)) { - for (auto *Target : CatchAction->getReturnTargets()) { - Branch->addDestination(Target); - } + 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. @@ -500,6 +899,50 @@ bool WinEHPrepare::prepareExceptionHandlers( completeNestedLandingPad(&F, LPadPair.first, LPadPair.second, FrameVarInfo); NestedLPtoOriginalLP.clear(); + // Update the indirectbr instructions' target lists if necessary. + SetVector CheckedTargets; + SmallVector, 4> ActionList; + for (auto &LPadImplPair : LPadImpls) { + IntrinsicInst *Recover = cast(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 ReturnTargets; + for (const auto &Action : ActionList) { + if (auto *CA = dyn_cast(Action.get())) { + Function *Handler = cast(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(Target->getTerminator()); + if (Br && Br->isUnconditional() && + Br != Target->getFirstNonPHIOrDbgOrLifetime()) { + Instruction *Prev = Br->getPrevNode(); + if (match(cast(Prev), m_Intrinsic())) + Prev->eraseFromParent(); + } + } + } + } + LPadImpls.clear(); + F.addFnAttr("wineh-parent", F.getName()); // Delete any blocks that were only used by handlers that were outlined above. @@ -513,55 +956,26 @@ bool WinEHPrepare::prepareExceptionHandlers( Intrinsic::getDeclaration(M, Intrinsic::frameescape); Function *RecoverFrameFn = Intrinsic::getDeclaration(M, Intrinsic::framerecover); + SmallVector 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(&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. - BasicBlock::iterator II = Entry->getFirstInsertionPt(); - Instruction *AllocaInsertPt = II; - SmallVector AllocasToEscape; for (auto &VarInfoEntry : FrameVarInfo) { Value *ParentVal = VarInfoEntry.first; TinyPtrVector &Allocas = VarInfoEntry.second; - - // If the mapped value isn't already an alloca, we need to spill it if it - // is a computed value or copy it if it is an argument. - AllocaInst *ParentAlloca = dyn_cast(ParentVal); - if (!ParentAlloca) { - if (auto *Arg = dyn_cast(ParentVal)) { - // Lower this argument to a copy and then demote that to the stack. - // We can't just use the argument location because the handler needs - // it to be in the frame allocation block. - // Use 'select i8 true, %arg, undef' to simulate a 'no-op' instruction. - Value *TrueValue = ConstantInt::getTrue(Context); - Value *UndefValue = UndefValue::get(Arg->getType()); - Instruction *SI = - SelectInst::Create(TrueValue, Arg, UndefValue, - Arg->getName() + ".tmp", AllocaInsertPt); - Arg->replaceAllUsesWith(SI); - // Reset the select operand, because it was clobbered by the RAUW above. - SI->setOperand(1, Arg); - ParentAlloca = DemoteRegToStack(*SI, true, SI); - } else if (auto *PN = dyn_cast(ParentVal)) { - ParentAlloca = DemotePHIToStack(PN, AllocaInsertPt); - } else { - Instruction *ParentInst = cast(ParentVal); - // FIXME: This is a work-around to temporarily handle the case where an - // instruction that is only used in handlers is not sunk. - // Without uses, DemoteRegToStack would just eliminate the value. - // This will fail if ParentInst is an invoke. - if (ParentInst->getNumUses() == 0) { - BasicBlock::iterator InsertPt = ParentInst; - ++InsertPt; - ParentAlloca = - new AllocaInst(ParentInst->getType(), nullptr, - ParentInst->getName() + ".reg2mem", - AllocaInsertPt); - new StoreInst(ParentInst, ParentAlloca, InsertPt); - } else { - ParentAlloca = DemoteRegToStack(*ParentInst, true, AllocaInsertPt); - } - } - } + AllocaInst *ParentAlloca = cast(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 @@ -575,19 +989,23 @@ bool WinEHPrepare::prepareExceptionHandlers( if (TempAlloca == getCatchObjectSentinel()) continue; // Skip catch parameter sentinels. Function *HandlerFn = TempAlloca->getParent()->getParent(); - // FIXME: Sink this GEP into the blocks where it is used. + 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, ""), - &(HandlerFn->getArgumentList().back()), + Builder.CreateBitCast(&F, Int8PtrType, ""), FP, llvm::ConstantInt::get(Int32Type, AllocasToEscape.size() - 1)}; - Value *RecoveredAlloca = Builder.CreateCall(RecoverFrameFn, RecoverArgs); + 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 = - Builder.CreateBitCast(RecoveredAlloca, TempAlloca->getType()); + RecoveredAlloca = cast( + Builder.CreateBitCast(RecoveredAlloca, TempAlloca->getType())); } TempAlloca->replaceAllUsesWith(RecoveredAlloca); TempAlloca->removeFromParent(); @@ -601,11 +1019,32 @@ bool WinEHPrepare::prepareExceptionHandlers( Builder.SetInsertPoint(&F.getEntryBlock().back()); Builder.CreateCall(FrameEscapeFn, AllocasToEscape); + if (SEHExceptionCodeSlot) { + if (isAllocaPromotable(SEHExceptionCodeSlot)) { + SmallPtrSet UserBlocks; + for (User *U : SEHExceptionCodeSlot->users()) { + if (auto *Inst = dyn_cast(U)) + UserBlocks.insert(Inst->getParent()); + } + PromoteMemToReg(SEHExceptionCodeSlot, *DT); + // After the promotion, kill off dead instructions. + for (BasicBlock *BB : UserBlocks) + SimplifyInstructionsInBlock(BB, LibInfo); + } + } + // Clean up the handler action maps we created for this function DeleteContainerSeconds(CatchHandlerMap); CatchHandlerMap.clear(); DeleteContainerSeconds(CleanupHandlerMap); CleanupHandlerMap.clear(); + HandlerToParentFP.clear(); + DT = nullptr; + LibInfo = nullptr; + SEHExceptionCodeSlot = nullptr; + EHBlocks.clear(); + NormalBlocks.clear(); + EHReturnBlocks.clear(); return HandlersOutlined; } @@ -647,6 +1086,42 @@ void WinEHPrepare::promoteLandingPadValues(LandingPadInst *LPad) { RecursivelyDeleteTriviallyDeadInstructions(U); } +void WinEHPrepare::getPossibleReturnTargets(Function *ParentF, + Function *HandlerF, + SetVector &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(LPI->getNextNode()); + SmallVector, 4> ActionList; + parseEHActions(Recover, ActionList); + for (const auto &Action : ActionList) { + if (auto *CH = dyn_cast(Action.get())) { + Function *NestedF = cast(CH->getHandlerBlockOrFunc()); + getPossibleReturnTargets(ParentF, NestedF, Targets); + } + } + } + + auto *Ret = dyn_cast(BB.getTerminator()); + if (!Ret) + continue; + + // Handler functions must always return a block address. + BlockAddress *BA = cast(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, @@ -655,10 +1130,19 @@ void WinEHPrepare::completeNestedLandingPad(Function *ParentFn, // temporarily inserted as its terminator. LLVMContext &Context = ParentFn->getContext(); BasicBlock *OutlinedBB = OutlinedLPad->getParent(); - assert(isa(OutlinedBB->getTerminator())); - OutlinedBB->getTerminator()->eraseFromParent(); - // That should leave OutlinedLPad as the last instruction in its block. - assert(&OutlinedBB->back() == OutlinedLPad); + // 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(OutlinedBB->getTerminator()); + if (!Branch) { + // If the landing pad wasn't in outlined form, it should be a stub with + // an unreachable terminator. + assert(isa(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 @@ -671,16 +1155,14 @@ void WinEHPrepare::completeNestedLandingPad(Function *ParentFn, ++II; // The instruction after the landing pad should now be a call to eh.actions. const Instruction *Recover = II; - assert(match(Recover, m_Intrinsic())); - IntrinsicInst *EHActions = cast(Recover->clone()); + const IntrinsicInst *EHActions = cast(Recover); - // Remap the exception variables into the outlined function. - WinEHFrameVariableMaterializer Materializer(OutlinedHandlerFn, FrameVarInfo); + // Remap the return target in the nested handler. SmallVector ActionTargets; - SmallVector ActionList; + SmallVector, 4> ActionList; parseEHActions(EHActions, ActionList); - for (auto *Action : ActionList) { - auto *Catch = dyn_cast(Action); + for (const auto &Action : ActionList) { + auto *Catch = dyn_cast(Action.get()); if (!Catch) continue; // The dyn_cast to function here selects C++ catch handlers and skips @@ -702,7 +1184,7 @@ void WinEHPrepare::completeNestedLandingPad(Function *ParentFn, // should be a block that was outlined into OutlinedHandlerFn. assert(BA->getFunction() == ParentFn); - // Ignore targets that aren't part of OutlinedHandlerFn. + // Ignore targets that aren't part of an outlined handler function. if (!LPadTargetBlocks.count(BA->getBasicBlock())) continue; @@ -718,15 +1200,26 @@ void WinEHPrepare::completeNestedLandingPad(Function *ParentFn, ActionTargets.push_back(NewBA); } } - DeleteContainerPointers(ActionList); ActionList.clear(); - OutlinedBB->getInstList().push_back(EHActions); - // Insert an indirect branch into the outlined landing pad BB. - IndirectBrInst *IBr = IndirectBrInst::Create(EHActions, 0, OutlinedBB); - // Add the previously collected action targets. - for (auto *Target : ActionTargets) - IBr->addDestination(Target->getBasicBlock()); + 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(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 @@ -763,8 +1256,16 @@ static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler, return false; } -static BasicBlock *createStubLandingPad(Function *Handler, - Value *PersonalityFn) { +static bool isCatchBlock(BasicBlock *BB) { + for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end(); + II != IE; ++II) { + if (match(cast(II), m_Intrinsic())) + return true; + } + return false; +} + +static BasicBlock *createStubLandingPad(Function *Handler) { // FIXME: Finish this! LLVMContext &Context = Handler->getContext(); BasicBlock *StubBB = BasicBlock::Create(Context, "stub"); @@ -773,7 +1274,11 @@ static BasicBlock *createStubLandingPad(Function *Handler, LandingPadInst *LPad = Builder.CreateLandingPad( llvm::StructType::get(Type::getInt8PtrTy(Context), Type::getInt32Ty(Context), nullptr), - PersonalityFn, 0); + 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; @@ -784,9 +1289,9 @@ static BasicBlock *createStubLandingPad(Function *Handler, // 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) { +void WinEHPrepare::addStubInvokeToHandlerIfNeeded(Function *Handler) { ReturnInst *Ret = nullptr; + UnreachableInst *Unreached = nullptr; for (BasicBlock &BB : *Handler) { TerminatorInst *Terminator = BB.getTerminator(); // If we find an invoke, there is nothing to be done. @@ -794,57 +1299,91 @@ void WinEHPrepare::addStubInvokeToHandlerIfNeeded(Function *Handler, if (II) return; // If we've already recorded a return instruction, keep looking for invokes. - if (Ret) - continue; - // If we haven't recorded a return instruction yet, try this terminator. - Ret = dyn_cast(Terminator); + if (!Ret) + Ret = dyn_cast(Terminator); + // If we haven't recorded an unreachable instruction, try this terminator. + if (!Unreached) + Unreached = dyn_cast(Terminator); } // If we got this far, the handler contains no invokes. We should have seen - // at least one return. We'll insert an invoke of llvm.donothing ahead of - // that return. - assert(Ret); - BasicBlock *OldRetBB = Ret->getParent(); - BasicBlock *NewRetBB = SplitBlock(OldRetBB, Ret); + // 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); + BasicBlock *StubLandingPad = createStubLandingPad(Handler); Function *F = Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::donothing); InvokeInst::Create(F, NewRetBB, StubLandingPad, None, "", OldRetBB); } +// FIXME: Consider sinking this into lib/Target/X86 somehow. TargetLowering +// usually doesn't build LLVM IR, so that's probably the wrong place. +Function *WinEHPrepare::createHandlerFunc(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. - Type *Int8PtrType = Type::getInt8PtrTy(Context); - std::vector ArgTys; - ArgTys.push_back(Int8PtrType); - ArgTys.push_back(Int8PtrType); + Value *ParentFP; Function *Handler; if (Action->getType() == Catch) { - FunctionType *FnType = FunctionType::get(Int8PtrType, ArgTys, false); - Handler = Function::Create(FnType, GlobalVariable::InternalLinkage, - SrcFn->getName() + ".catch", M); + Handler = createHandlerFunc(Int8PtrType, SrcFn->getName() + ".catch", M, + ParentFP); } else { - FunctionType *FnType = - FunctionType::get(Type::getVoidTy(Context), ArgTys, false); - Handler = Function::Create(FnType, GlobalVariable::InternalLinkage, - SrcFn->getName() + ".cleanup", M); + Handler = createHandlerFunc(Type::getVoidTy(Context), + SrcFn->getName() + ".cleanup", M, ParentFP); } - + Handler->setPersonalityFn(SrcFn->getPersonalityFn()); + HandlerToParentFP[Handler] = ParentFP; Handler->addFnAttr("wineh-parent", SrcFn->getName()); + BasicBlock *Entry = &Handler->getEntryBlock(); // Generate a standard prolog to setup the frame recovery structure. IRBuilder<> Builder(Context); - BasicBlock *Entry = BasicBlock::Create(Context, "entry"); - Handler->getBasicBlockList().push_front(Entry); Builder.SetInsertPoint(Entry); Builder.SetCurrentDebugLocation(LPad->getDebugLoc()); @@ -857,12 +1396,14 @@ bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn, LPadMap.mapLandingPad(LPad); if (auto *CatchAction = dyn_cast(Action)) { Constant *Sel = CatchAction->getSelector(); - Director.reset(new WinEHCatchDirector(Handler, Sel, VarInfo, LPadMap, - NestedLPtoOriginalLP)); + 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, VarInfo, LPadMap)); + Director.reset( + new WinEHCleanupDirector(Handler, ParentFP, VarInfo, LPadMap)); LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType), UndefValue::get(Type::getInt32Ty(Context))); } @@ -888,6 +1429,10 @@ bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn, ++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(); @@ -895,13 +1440,22 @@ bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn, /*ModuleLevelChanges=*/false, Returns, "", &OutlinedFunctionInfo, Director.get()); - // Move all the instructions in the first cloned block into our entry block. - BasicBlock *FirstClonedBB = std::next(Function::iterator(Entry)); - Entry->getInstList().splice(Entry->end(), FirstClonedBB->getInstList()); - FirstClonedBB->eraseFromParent(); + // 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()); + addStubInvokeToHandlerIfNeeded(Handler); if (auto *CatchAction = dyn_cast(Action)) { WinEHCatchDirector *CatchDirector = @@ -964,9 +1518,14 @@ void WinEHPrepare::processSEHCatchHandler(CatchHandler *CatchAction, } else { // This must be a catch-all. Split the block after the landingpad. assert(CatchAction->getSelector()->isNullValue() && "expected catch-all"); - HandlerBB = - StartBB->splitBasicBlock(StartBB->getFirstInsertionPt(), "catch.all"); + 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 Targets(HandlerBB); CatchAction->setReturnTargets(Targets); @@ -1031,6 +1590,11 @@ void LandingPadMap::remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue, VMap[Extract] = SelectorValue; } +static bool isFrameAddressCall(const Value *V) { + return match(const_cast(V), + m_Intrinsic(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. @@ -1038,21 +1602,31 @@ CloningDirector::CloningAction WinEHCloningDirectorBase::handleInstruction( if (LPadMap.isLandingPadSpecificInst(Inst)) return CloningDirector::SkipInstruction; - // Nested landing pads will be cloned as stubs, with just the - // landingpad instruction and an unreachable instruction. When - // all landingpads have been outlined, we'll replace this with the - // llvm.eh.actions call and indirect branch created when the - // landing pad was outlined. + // 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(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(Inst)) { + return handleIndirectBr(VMap, IBr, NewBB); + } + if (auto *Invoke = dyn_cast(Inst)) return handleInvoke(VMap, Invoke, NewBB); if (auto *Resume = dyn_cast(Inst)) return handleResume(VMap, Resume, NewBB); + if (auto *Cmp = dyn_cast(Inst)) + return handleCompare(VMap, Cmp, NewBB); + if (match(Inst, m_Intrinsic())) return handleBeginCatch(VMap, Inst, NewBB); if (match(Inst, m_Intrinsic())) @@ -1060,12 +1634,33 @@ CloningDirector::CloningAction WinEHCloningDirectorBase::handleInstruction( if (match(Inst, m_Intrinsic())) 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())) + 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()); @@ -1157,6 +1752,48 @@ CloningDirector::CloningAction WinEHCatchDirector::handleTypeIdFor( 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(VMap[LPad])] = LPad; + + // We should only get here for landing pads that have already been outlined. + assert(match(LPad->getNextNode(), m_Intrinsic())); + + // Copy the indirectbr, but only include targets that were previously + // identified as EH blocks and are dominated by the nested landing pad. + SetVector ReturnTargets; + for (int I = 0, E = IBr->getNumDestinations(); I < E; ++I) { + auto *TargetBB = IBr->getDestination(I); + if (EHBlocks.count(const_cast(TargetBB)) && + DT->dominates(ParentBB, TargetBB)) { + DEBUG(dbgs() << " Adding destination " << TargetBB->getName() << "\n"); + ReturnTargets.insert(TargetBB); + } + } + IndirectBrInst *NewBranch = + IndirectBrInst::Create(const_cast(IBr->getAddress()), + ReturnTargets.size(), NewBB); + for (auto *Target : ReturnTargets) + NewBranch->addDestination(const_cast(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) { @@ -1173,6 +1810,30 @@ WinEHCatchDirector::handleResume(ValueToValueMapTy &VMap, 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())) { + IntrinCall = dyn_cast(Compare->getOperand(0)); + } else if (match(Compare->getOperand(1), + m_Intrinsic())) { + IntrinCall = dyn_cast(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 @@ -1189,11 +1850,11 @@ CloningDirector::CloningAction WinEHCleanupDirector::handleLandingPad( CloningDirector::CloningAction WinEHCleanupDirector::handleBeginCatch( ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) { - // Catch blocks within cleanup handlers will always be unreachable. - // We'll insert an unreachable instruction now, but it will be pruned - // before the cloning process is complete. - BasicBlock::InstListType &InstList = NewBB->getInstList(); - InstList.push_back(new UnreachableInst(NewBB->getContext())); + // 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; } @@ -1222,6 +1883,14 @@ CloningDirector::CloningAction WinEHCleanupDirector::handleTypeIdFor( 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. @@ -1259,39 +1928,53 @@ CloningDirector::CloningAction WinEHCleanupDirector::handleResume( return CloningDirector::StopCloningBB; } +CloningDirector::CloningAction +WinEHCleanupDirector::handleCompare(ValueToValueMapTy &VMap, + const CmpInst *Compare, BasicBlock *NewBB) { + if (match(Compare->getOperand(0), m_Intrinsic()) || + match(Compare->getOperand(1), m_Intrinsic())) { + VMap[Compare] = ConstantInt::get(SelectorIDType, 1); + return CloningDirector::SkipInstruction; + } + return CloningDirector::CloneInstruction; +} + WinEHFrameVariableMaterializer::WinEHFrameVariableMaterializer( - Function *OutlinedFn, FrameVarInfoMap &FrameVarInfo) + Function *OutlinedFn, Value *ParentFP, FrameVarInfoMap &FrameVarInfo) : FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) { BasicBlock *EntryBB = &OutlinedFn->getEntryBlock(); - Builder.SetInsertPoint(EntryBB, EntryBB->getFirstInsertionPt()); + + // 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(ParentFP)) + InsertPoint = FPInst->getNextNode(); + Builder.SetInsertPoint(EntryBB, InsertPoint); } Value *WinEHFrameVariableMaterializer::materializeValueFor(Value *V) { - // If we're asked to materialize a value that is an instruction, we - // temporarily create an alloca in the outlined function and add this - // to the FrameVarInfo map. When all the outlining is complete, we'll - // collect these into a structure, spilling non-alloca values in the - // parent frame as necessary, and replace these temporary allocas with - // GEPs referencing the frame allocation block. - - // If the value is an alloca, the mapping is direct. + // If 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(V)) { + assert(AV->isStaticAlloca() && + "cannot materialize un-demoted dynamic alloca"); AllocaInst *NewAlloca = dyn_cast(AV->clone()); Builder.Insert(NewAlloca, AV->getName()); FrameVarInfo[AV].push_back(NewAlloca); return NewAlloca; } - // For other types of instructions or arguments, we need an alloca based on - // the value's type and a load of the alloca. The alloca will be replaced - // by a GEP, but the load will stay. In the parent function, the value will - // be spilled to a location in the frame allocation block. if (isa(V) || isa(V)) { - AllocaInst *NewAlloca = - Builder.CreateAlloca(V->getType(), nullptr, "eh.temp.alloca"); - FrameVarInfo[V].push_back(NewAlloca); - LoadInst *NewLoad = Builder.CreateLoad(NewAlloca, V->getName() + ".reload"); - return NewLoad; + Function *Parent = isa(V) + ? cast(V)->getParent()->getParent() + : cast(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. @@ -1353,24 +2036,61 @@ void WinEHPrepare::mapLandingPadBlocks(LandingPadInst *LPad, 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. - if (isa(LPad->getClause(HandlersFound))) { + Constant *ExpectedSelector = + LPad->getClause(HandlersFound)->stripPointerCasts(); + if (isa(ExpectedSelector)) { // The catch all must occur last. assert(HandlersFound == NumClauses - 1); - // For C++ EH, check if there is any interesting cleanup code before we - // begin the catch. This is important because cleanups cannot rethrow - // exceptions but code called from catches can. For SEH, it isn't - // important if some finally code before a catch-all is executed out of - // line or after recovering from the exception. - if (Personality == EHPersonality::MSVC_CXX) - findCleanupHandlers(Actions, BB, BB); + // 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 = - new CatchHandler(BB, LPad->getClause(HandlersFound), nullptr); - CatchHandlerMap[BB] = Action; + 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; @@ -1381,16 +2101,40 @@ void WinEHPrepare::mapLandingPadBlocks(LandingPadInst *LPad, } CatchHandler *CatchAction = findCatchHandler(BB, NextBB, VisitedBlocks); + assert(CatchAction); + // See if there is any interesting code executed before the dispatch. findCleanupHandlers(Actions, BB, CatchAction->getStartBlock()); - assert(CatchAction); - ++HandlersFound; + // 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. - Actions.insertCatchHandler(CatchAction); - DEBUG(dbgs() << " Found catch dispatch in block " - << CatchAction->getStartBlock()->getName() << "\n"); + // 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( + 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; @@ -1442,6 +2186,18 @@ CatchHandler *WinEHPrepare::findCatchHandler(BasicBlock *BB, 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. @@ -1469,10 +2225,6 @@ static void createCleanupHandler(LandingPadActions &Actions, << Action->getStartBlock()->getName() << "\n"); } -static bool isFrameAddressCall(Value *V) { - return match(V, m_Intrinsic(m_SpecificInt(0))); -} - static CallSite matchOutlinedFinallyCall(BasicBlock *BB, Instruction *MaybeCall) { // Look for finally blocks that Clang has already outlined for us. @@ -1535,7 +2287,7 @@ void WinEHPrepare::findCleanupHandlers(LandingPadActions &Actions, if (auto *Action = CleanupHandlerMap[BB]) { Actions.insertCleanupHandler(Action); DEBUG(dbgs() << " Found cleanup code in block " - << Action->getStartBlock()->getName() << "\n"); + << Action->getStartBlock()->getName() << "\n"); // FIXME: This cleanup might chain into another, and we need to discover // that. return; @@ -1544,7 +2296,7 @@ void WinEHPrepare::findCleanupHandlers(LandingPadActions &Actions, // 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 + // know the block must end in either an unconditional branch, a // resume or a conditional branch that is predicated on a comparison // with a selector. Either the resume or the selector dispatch // would terminate the search for cleanup code, so the unconditional @@ -1659,14 +2411,18 @@ void WinEHPrepare::findCleanupHandlers(LandingPadActions &Actions, // for finally calls in the normal successor block. BasicBlock *SuccBB = BB; if (FinallyCall.getInstruction() != BB->getTerminator() && - FinallyCall.getInstruction()->getNextNode() != BB->getTerminator()) { - SuccBB = BB->splitBasicBlock(FinallyCall.getInstruction()->getNextNode()); + FinallyCall.getInstruction()->getNextNode() != + BB->getTerminator()) { + SuccBB = + SplitBlock(BB, FinallyCall.getInstruction()->getNextNode(), DT); } else { if (FinallyCall.isInvoke()) { - SuccBB = cast(FinallyCall.getInstruction())->getNormalDest(); + SuccBB = + cast(FinallyCall.getInstruction())->getNormalDest(); } else { SuccBB = BB->getUniqueSuccessor(); - assert(SuccBB && "splitOutlinedFinallyCalls didn't insert a branch"); + assert(SuccBB && + "splitOutlinedFinallyCalls didn't insert a branch"); } } BB = SuccBB; @@ -1705,8 +2461,11 @@ void WinEHPrepare::findCleanupHandlers(LandingPadActions &Actions, // 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 &Actions) { +void llvm::parseEHActions( + const IntrinsicInst *II, + SmallVectorImpl> &Actions) { + assert(II->getIntrinsicID() == Intrinsic::eh_actions && + "attempted to parse non eh.actions intrinsic"); for (unsigned I = 0, E = II->getNumArgOperands(); I != E;) { uint64_t ActionKind = cast(II->getArgOperand(I))->getZExtValue(); @@ -1716,19 +2475,393 @@ void llvm::parseEHActions(const IntrinsicInst *II, int64_t EHObjIndexVal = EHObjIndex->getSExtValue(); Constant *Handler = cast(II->getArgOperand(I + 3)); I += 4; - auto *CH = new CatchHandler(/*BB=*/nullptr, Selector, /*NextBB=*/nullptr); + auto CH = make_unique(/*BB=*/nullptr, Selector, + /*NextBB=*/nullptr); CH->setHandlerBlockOrFunc(Handler); CH->setExceptionVarIndex(EHObjIndexVal); - Actions.push_back(CH); + Actions.push_back(std::move(CH)); } else if (ActionKind == 0) { Constant *Handler = cast(II->getArgOperand(I + 1)); I += 2; - auto *CH = new CleanupHandler(/*BB=*/nullptr); + auto CH = make_unique(/*BB=*/nullptr); CH->setHandlerBlockOrFunc(Handler); - Actions.push_back(CH); + 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, 4> HandlerStack; + SmallPtrSet VisitedHandlers; + + int currentEHNumber() const { + return HandlerStack.empty() ? CurrentBaseState : HandlerStack.back()->getEHState(); + } + + void createUnwindMapEntry(int ToState, ActionHandler *AH); + void createTryBlockMapEntry(int TryLow, int TryHigh, + ArrayRef Handlers); + void processCallSite(MutableArrayRef> 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(AH)) + UME.Cleanup = cast(CH->getHandlerBlockOrFunc()); + else + UME.Cleanup = nullptr; + FuncInfo.UnwindMap.push_back(UME); +} + +void WinEHNumbering::createTryBlockMapEntry(int TryLow, int TryHigh, + ArrayRef 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(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(GV->getInitializer()); + HT.Adjectives = + cast(CS->getAggregateElement(0U))->getZExtValue(); + HT.TypeDescriptor = + cast(CS->getAggregateElement(1)->stripPointerCasts()); + } + HT.Handler = cast(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(V)) + DEBUG(dbgs() << F->getName()); + else + DEBUG(V->dump()); +#endif +} + +void WinEHNumbering::processCallSite( + MutableArrayRef> 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(Actions[I].get()); + auto *Handler = cast(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(HandlerStack[I]->getHandlerBlockOrFunc()); + if (FuncInfo.LastInvoke[Handler] != cast(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 PoppedCatches; + for (int I = HandlerStack.size() - 1; I >= FirstMismatch; --I) { + std::unique_ptr Handler = HandlerStack.pop_back_val(); + if (isa(Handler.get())) + PoppedCatches.push_back(cast(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(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, 4> ActionList; + for (const BasicBlock &BB : F) { + for (const Instruction &I : BB) { + const auto *CI = dyn_cast(&I); + if (!CI || CI->doesNotThrow()) + continue; + processCallSite(None, CI); + } + const auto *II = dyn_cast(BB.getTerminator()); + if (!II) + continue; + const LandingPadInst *LPI = II->getLandingPadInst(); + auto *ActionsCall = dyn_cast(LPI->getNextNode()); + if (!ActionsCall) + continue; + parseEHActions(ActionsCall, ActionList); + if (ActionList.empty()) + continue; + processCallSite(ActionList, II); + ActionList.clear(); + FuncInfo.LandingPadStateMap[LPI] = currentEHNumber(); + DEBUG(dbgs() << "Assigning state " << currentEHNumber() + << " to landing pad at " << LPI->getParent()->getName() + << '\n'); + } + + // Pop any actions that were pushed on the stack for this function. + popUnmatchedActions(SavedHandlerStackSize); + + DEBUG(dbgs() << "Assigning max state " << NextState - 1 + << " to " << F.getName() << '\n'); + FuncInfo.CatchHandlerMaxState[&F] = NextState - 1; + + CurrentBaseState = OldBaseState; +} + +// This function follows the same basic traversal as calculateStateNumbers +// but it is necessary to identify the root landing pad associated +// with each action before we start assigning state numbers. +void WinEHNumbering::findActionRootLPads(const Function &F) { + auto I = VisitedHandlers.insert(&F); + if (!I.second) + return; // We've already visited this handler, don't revisit it. + + SmallVector, 4> ActionList; + for (const BasicBlock &BB : F) { + const auto *II = dyn_cast(BB.getTerminator()); + if (!II) + continue; + const LandingPadInst *LPI = II->getLandingPadInst(); + auto *ActionsCall = dyn_cast(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(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(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()); +}