X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FWinEHPrepare.cpp;h=e4e63fddebb883ae7fd4c407b156859b4e882d97;hb=042dd34f9cb1fb17873116c7560f2f011c10a9b8;hp=6f8c905201d76b6add9beb1e88a3c63db366809a;hpb=c127686d0e2afd7d345e337f71d8b5f3be6dc03b;p=oota-llvm.git diff --git a/lib/CodeGen/WinEHPrepare.cpp b/lib/CodeGen/WinEHPrepare.cpp index 6f8c905201d..e4e63fddebb 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. // //===----------------------------------------------------------------------===// @@ -18,6 +20,8 @@ #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" @@ -29,7 +33,6 @@ #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 +73,10 @@ 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; @@ -86,10 +92,20 @@ private: bool prepareExceptionHandlers(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); @@ -103,9 +119,11 @@ private: void processSEHCatchHandler(CatchHandler *Handler, BasicBlock *StartBB); + Triple TheTriple; + // All fields are reset by runOnFunction. - DominatorTree *DT; - EHPersonality Personality; + DominatorTree *DT = nullptr; + EHPersonality Personality = EHPersonality::Unknown; CatchHandlerMapTy CatchHandlerMap; CleanupHandlerMapTy CleanupHandlerMap; DenseMap LPadMaps; @@ -130,15 +148,21 @@ 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() {} + ~WinEHFrameVariableMaterializer() override {} - virtual Value *materializeValueFor(Value *V) override; + Value *materializeValueFor(Value *V) override; void escapeCatchObject(Value *V); @@ -170,12 +194,12 @@ 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, @@ -196,6 +220,9 @@ public: 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; @@ -207,15 +234,18 @@ 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, + Function *CatchFn, Value *ParentFP, Value *Selector, + FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap, DenseMap &NestedLPads) - : WinEHCloningDirectorBase(CatchFn, VarInfo, LPadMap), + : WinEHCloningDirectorBase(CatchFn, ParentFP, VarInfo, LPadMap), CurrentSelector(Selector->stripPointerCasts()), ExceptionObjectVar(nullptr), NestedLPtoOriginalLP(NestedLPads) {} @@ -231,6 +261,8 @@ public: 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; @@ -251,9 +283,10 @@ private: 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, @@ -267,6 +300,8 @@ public: 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 +341,11 @@ 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) { @@ -334,16 +368,6 @@ bool WinEHPrepare::runOnFunction(Function &Fn) { 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; - } - // If there were any landing pads, prepareExceptionHandlers will make changes. prepareExceptionHandlers(Fn, LPads); return true; @@ -355,8 +379,307 @@ void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const { 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); + } + } +} + +/// 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'); + + // 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. + SmallPtrSet NormalBlocks; + SmallPtrSet EHBlocks; + SetVector EHReturnBlocks; + SetVector Worklist; + + 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. + 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'; + }); + + 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; + } + + 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 +695,27 @@ 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()); + } + + // 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; } @@ -422,32 +752,57 @@ 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(); - // 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; + // 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())); + + // 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) { @@ -472,16 +827,29 @@ 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); - for (ActionHandler *Action : Actions) { - if (auto *CatchAction = dyn_cast(Action)) { - for (auto *Target : CatchAction->getReturnTargets()) { - Branch->addDestination(Target); + if (isAsynchronousEHPersonality(Personality)) { + // SEH can create the target list directly, since catch handlers + // are not outlined. + SetVector ReturnTargets; + for (ActionHandler *Action : Actions) { + if (auto *CatchAction = dyn_cast(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); + } else { + // C++ EH must defer populating the targets to handle the case of + // targets that are reached indirectly through nested landing pads. + IndirectBrInst *Branch = + IndirectBrInst::Create(Recover, 0, LPadBB); + + LPadImpls.push_back(std::make_pair(Recover, Branch)); } } // End for each landingpad @@ -496,6 +864,45 @@ bool WinEHPrepare::prepareExceptionHandlers( completeNestedLandingPad(&F, LPadPair.first, LPadPair.second, FrameVarInfo); NestedLPtoOriginalLP.clear(); + // Populate the indirectbr instructions' target lists if we deferred + // doing so above. + 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(); + 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. @@ -509,55 +916,26 @@ 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 @@ -571,19 +949,23 @@ 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(); @@ -597,11 +979,21 @@ bool WinEHPrepare::prepareExceptionHandlers( 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; return HandlersOutlined; } @@ -636,6 +1028,47 @@ void WinEHPrepare::promoteLandingPadValues(LandingPadInst *LPad) { PromoteMemToReg(EHAllocas, *DT); EHAllocas.clear(); } + + // After promotion, some extracts may be trivially dead. Remove them. + SmallVector Users(LPad->user_begin(), LPad->user_end()); + for (auto *U : Users) + 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, @@ -666,12 +1099,11 @@ void WinEHPrepare::completeNestedLandingPad(Function *ParentFn, IntrinsicInst *EHActions = cast(Recover->clone()); // Remap the exception variables into the outlined function. - WinEHFrameVariableMaterializer Materializer(OutlinedHandlerFn, FrameVarInfo); 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 @@ -709,7 +1141,6 @@ void WinEHPrepare::completeNestedLandingPad(Function *ParentFn, ActionTargets.push_back(NewBA); } } - DeleteContainerPointers(ActionList); ActionList.clear(); OutlinedBB->getInstList().push_back(EHActions); @@ -754,6 +1185,15 @@ static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler, return false; } +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, Value *PersonalityFn) { // FIXME: Finish this! @@ -765,6 +1205,10 @@ static BasicBlock *createStubLandingPad(Function *Handler, 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; @@ -778,6 +1222,7 @@ static BasicBlock *createStubLandingPad(Function *Handler, 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. @@ -785,18 +1230,24 @@ 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. @@ -807,35 +1258,62 @@ void WinEHPrepare::addStubInvokeToHandlerIfNeeded(Function *Handler, 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); } - + 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()); @@ -848,12 +1326,14 @@ 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, + Director.reset(new WinEHCatchDirector(Handler, ParentFP, Sel, + VarInfo, LPadMap, NestedLPtoOriginalLP)); 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))); } @@ -879,6 +1359,10 @@ 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(); @@ -886,10 +1370,19 @@ 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()); @@ -909,7 +1402,7 @@ bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn, // 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) { + 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(MapEntry.first) || MapEntry.second == nullptr) @@ -955,9 +1448,14 @@ 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); @@ -1022,6 +1520,11 @@ 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. @@ -1044,6 +1547,9 @@ CloningDirector::CloningAction WinEHCloningDirectorBase::handleInstruction( 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())) @@ -1051,6 +1557,13 @@ 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; } @@ -1164,6 +1677,30 @@ 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 @@ -1180,11 +1717,11 @@ 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; } @@ -1250,39 +1787,53 @@ 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. @@ -1344,24 +1895,61 @@ 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; @@ -1372,16 +1960,40 @@ 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; @@ -1433,6 +2045,18 @@ 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. @@ -1460,10 +2084,6 @@ 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. @@ -1526,7 +2146,7 @@ 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; @@ -1573,11 +2193,10 @@ void WinEHPrepare::findCleanupHandlers(LandingPadActions &Actions, InsertValueInst *Insert1 = nullptr; InsertValueInst *Insert2 = nullptr; Value *ResumeVal = Resume->getOperand(0); - // If there is only one landingpad, we may use the lpad directly with no - // insertions. - if (isa(ResumeVal)) - return; - if (!isa(ResumeVal)) { + // 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(ResumeVal) && !isa(ResumeVal)) { Insert2 = dyn_cast(ResumeVal); if (!Insert2) return createCleanupHandler(Actions, CleanupHandlerMap, BB); @@ -1651,14 +2270,18 @@ 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; @@ -1693,13 +2316,13 @@ void WinEHPrepare::findCleanupHandlers(LandingPadActions &Actions, return; BB = Branch->getSuccessor(0); } - return; } // 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) { for (unsigned I = 0, E = II->getNumArgOperands(); I != E;) { uint64_t ActionKind = cast(II->getArgOperand(I))->getZExtValue(); @@ -1709,16 +2332,17 @@ 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!"); }