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Diffstat (limited to 'llvm/lib/CodeGen/WinEHPrepare.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/WinEHPrepare.cpp | 1247 |
1 files changed, 1247 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/WinEHPrepare.cpp b/llvm/lib/CodeGen/WinEHPrepare.cpp new file mode 100644 index 000000000000..cdf79374e974 --- /dev/null +++ b/llvm/lib/CodeGen/WinEHPrepare.cpp @@ -0,0 +1,1247 @@ +//===-- WinEHPrepare - Prepare exception handling for code generation ---===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This pass lowers LLVM IR exception handling into something closer to what the +// backend wants for functions using a personality function from a runtime +// provided by MSVC. Functions with other personality functions are left alone +// and may be prepared by other passes. In particular, all supported MSVC +// personality functions require cleanup code to be outlined, and the C++ +// personality requires catch handler code to be outlined. +// +//===----------------------------------------------------------------------===// + +#include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/MapVector.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/Analysis/CFG.h" +#include "llvm/Analysis/EHPersonalities.h" +#include "llvm/Transforms/Utils/Local.h" +#include "llvm/CodeGen/MachineBasicBlock.h" +#include "llvm/CodeGen/Passes.h" +#include "llvm/CodeGen/WinEHFuncInfo.h" +#include "llvm/IR/Verifier.h" +#include "llvm/MC/MCSymbol.h" +#include "llvm/Pass.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Transforms/Utils/BasicBlockUtils.h" +#include "llvm/Transforms/Utils/Cloning.h" +#include "llvm/Transforms/Utils/SSAUpdater.h" + +using namespace llvm; + +#define DEBUG_TYPE "winehprepare" + +static cl::opt<bool> DisableDemotion( + "disable-demotion", cl::Hidden, + cl::desc( + "Clone multicolor basic blocks but do not demote cross scopes"), + cl::init(false)); + +static cl::opt<bool> DisableCleanups( + "disable-cleanups", cl::Hidden, + cl::desc("Do not remove implausible terminators or other similar cleanups"), + cl::init(false)); + +static cl::opt<bool> DemoteCatchSwitchPHIOnlyOpt( + "demote-catchswitch-only", cl::Hidden, + cl::desc("Demote catchswitch BBs only (for wasm EH)"), cl::init(false)); + +namespace { + +class WinEHPrepare : public FunctionPass { +public: + static char ID; // Pass identification, replacement for typeid. + WinEHPrepare(bool DemoteCatchSwitchPHIOnly = false) + : FunctionPass(ID), DemoteCatchSwitchPHIOnly(DemoteCatchSwitchPHIOnly) {} + + bool runOnFunction(Function &Fn) override; + + bool doFinalization(Module &M) override; + + void getAnalysisUsage(AnalysisUsage &AU) const override; + + StringRef getPassName() const override { + return "Windows exception handling preparation"; + } + +private: + void insertPHIStores(PHINode *OriginalPHI, AllocaInst *SpillSlot); + void + insertPHIStore(BasicBlock *PredBlock, Value *PredVal, AllocaInst *SpillSlot, + SmallVectorImpl<std::pair<BasicBlock *, Value *>> &Worklist); + AllocaInst *insertPHILoads(PHINode *PN, Function &F); + void replaceUseWithLoad(Value *V, Use &U, AllocaInst *&SpillSlot, + DenseMap<BasicBlock *, Value *> &Loads, Function &F); + bool prepareExplicitEH(Function &F); + void colorFunclets(Function &F); + + void demotePHIsOnFunclets(Function &F, bool DemoteCatchSwitchPHIOnly); + void cloneCommonBlocks(Function &F); + void removeImplausibleInstructions(Function &F); + void cleanupPreparedFunclets(Function &F); + void verifyPreparedFunclets(Function &F); + + bool DemoteCatchSwitchPHIOnly; + + // All fields are reset by runOnFunction. + EHPersonality Personality = EHPersonality::Unknown; + + const DataLayout *DL = nullptr; + DenseMap<BasicBlock *, ColorVector> BlockColors; + MapVector<BasicBlock *, std::vector<BasicBlock *>> FuncletBlocks; +}; + +} // end anonymous namespace + +char WinEHPrepare::ID = 0; +INITIALIZE_PASS(WinEHPrepare, DEBUG_TYPE, "Prepare Windows exceptions", + false, false) + +FunctionPass *llvm::createWinEHPass(bool DemoteCatchSwitchPHIOnly) { + return new WinEHPrepare(DemoteCatchSwitchPHIOnly); +} + +bool WinEHPrepare::runOnFunction(Function &Fn) { + if (!Fn.hasPersonalityFn()) + return false; + + // Classify the personality to see what kind of preparation we need. + Personality = classifyEHPersonality(Fn.getPersonalityFn()); + + // Do nothing if this is not a scope-based personality. + if (!isScopedEHPersonality(Personality)) + return false; + + DL = &Fn.getParent()->getDataLayout(); + return prepareExplicitEH(Fn); +} + +bool WinEHPrepare::doFinalization(Module &M) { return false; } + +void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {} + +static int addUnwindMapEntry(WinEHFuncInfo &FuncInfo, int ToState, + const BasicBlock *BB) { + CxxUnwindMapEntry UME; + UME.ToState = ToState; + UME.Cleanup = BB; + FuncInfo.CxxUnwindMap.push_back(UME); + return FuncInfo.getLastStateNumber(); +} + +static void addTryBlockMapEntry(WinEHFuncInfo &FuncInfo, int TryLow, + int TryHigh, int CatchHigh, + ArrayRef<const CatchPadInst *> Handlers) { + WinEHTryBlockMapEntry TBME; + TBME.TryLow = TryLow; + TBME.TryHigh = TryHigh; + TBME.CatchHigh = CatchHigh; + assert(TBME.TryLow <= TBME.TryHigh); + for (const CatchPadInst *CPI : Handlers) { + WinEHHandlerType HT; + Constant *TypeInfo = cast<Constant>(CPI->getArgOperand(0)); + if (TypeInfo->isNullValue()) + HT.TypeDescriptor = nullptr; + else + HT.TypeDescriptor = cast<GlobalVariable>(TypeInfo->stripPointerCasts()); + HT.Adjectives = cast<ConstantInt>(CPI->getArgOperand(1))->getZExtValue(); + HT.Handler = CPI->getParent(); + if (auto *AI = + dyn_cast<AllocaInst>(CPI->getArgOperand(2)->stripPointerCasts())) + HT.CatchObj.Alloca = AI; + else + HT.CatchObj.Alloca = nullptr; + TBME.HandlerArray.push_back(HT); + } + FuncInfo.TryBlockMap.push_back(TBME); +} + +static BasicBlock *getCleanupRetUnwindDest(const CleanupPadInst *CleanupPad) { + for (const User *U : CleanupPad->users()) + if (const auto *CRI = dyn_cast<CleanupReturnInst>(U)) + return CRI->getUnwindDest(); + return nullptr; +} + +static void calculateStateNumbersForInvokes(const Function *Fn, + WinEHFuncInfo &FuncInfo) { + auto *F = const_cast<Function *>(Fn); + DenseMap<BasicBlock *, ColorVector> BlockColors = colorEHFunclets(*F); + for (BasicBlock &BB : *F) { + auto *II = dyn_cast<InvokeInst>(BB.getTerminator()); + if (!II) + continue; + + auto &BBColors = BlockColors[&BB]; + assert(BBColors.size() == 1 && "multi-color BB not removed by preparation"); + BasicBlock *FuncletEntryBB = BBColors.front(); + + BasicBlock *FuncletUnwindDest; + auto *FuncletPad = + dyn_cast<FuncletPadInst>(FuncletEntryBB->getFirstNonPHI()); + assert(FuncletPad || FuncletEntryBB == &Fn->getEntryBlock()); + if (!FuncletPad) + FuncletUnwindDest = nullptr; + else if (auto *CatchPad = dyn_cast<CatchPadInst>(FuncletPad)) + FuncletUnwindDest = CatchPad->getCatchSwitch()->getUnwindDest(); + else if (auto *CleanupPad = dyn_cast<CleanupPadInst>(FuncletPad)) + FuncletUnwindDest = getCleanupRetUnwindDest(CleanupPad); + else + llvm_unreachable("unexpected funclet pad!"); + + BasicBlock *InvokeUnwindDest = II->getUnwindDest(); + int BaseState = -1; + if (FuncletUnwindDest == InvokeUnwindDest) { + auto BaseStateI = FuncInfo.FuncletBaseStateMap.find(FuncletPad); + if (BaseStateI != FuncInfo.FuncletBaseStateMap.end()) + BaseState = BaseStateI->second; + } + + if (BaseState != -1) { + FuncInfo.InvokeStateMap[II] = BaseState; + } else { + Instruction *PadInst = InvokeUnwindDest->getFirstNonPHI(); + assert(FuncInfo.EHPadStateMap.count(PadInst) && "EH Pad has no state!"); + FuncInfo.InvokeStateMap[II] = FuncInfo.EHPadStateMap[PadInst]; + } + } +} + +// Given BB which ends in an unwind edge, return the EHPad that this BB belongs +// to. If the unwind edge came from an invoke, return null. +static const BasicBlock *getEHPadFromPredecessor(const BasicBlock *BB, + Value *ParentPad) { + const Instruction *TI = BB->getTerminator(); + if (isa<InvokeInst>(TI)) + return nullptr; + if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(TI)) { + if (CatchSwitch->getParentPad() != ParentPad) + return nullptr; + return BB; + } + assert(!TI->isEHPad() && "unexpected EHPad!"); + auto *CleanupPad = cast<CleanupReturnInst>(TI)->getCleanupPad(); + if (CleanupPad->getParentPad() != ParentPad) + return nullptr; + return CleanupPad->getParent(); +} + +static void calculateCXXStateNumbers(WinEHFuncInfo &FuncInfo, + const Instruction *FirstNonPHI, + int ParentState) { + const BasicBlock *BB = FirstNonPHI->getParent(); + assert(BB->isEHPad() && "not a funclet!"); + + if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(FirstNonPHI)) { + assert(FuncInfo.EHPadStateMap.count(CatchSwitch) == 0 && + "shouldn't revist catch funclets!"); + + SmallVector<const CatchPadInst *, 2> Handlers; + for (const BasicBlock *CatchPadBB : CatchSwitch->handlers()) { + auto *CatchPad = cast<CatchPadInst>(CatchPadBB->getFirstNonPHI()); + Handlers.push_back(CatchPad); + } + int TryLow = addUnwindMapEntry(FuncInfo, ParentState, nullptr); + FuncInfo.EHPadStateMap[CatchSwitch] = TryLow; + for (const BasicBlock *PredBlock : predecessors(BB)) + if ((PredBlock = getEHPadFromPredecessor(PredBlock, + CatchSwitch->getParentPad()))) + calculateCXXStateNumbers(FuncInfo, PredBlock->getFirstNonPHI(), + TryLow); + int CatchLow = addUnwindMapEntry(FuncInfo, ParentState, nullptr); + + // catchpads are separate funclets in C++ EH due to the way rethrow works. + int TryHigh = CatchLow - 1; + for (const auto *CatchPad : Handlers) { + FuncInfo.FuncletBaseStateMap[CatchPad] = CatchLow; + for (const User *U : CatchPad->users()) { + const auto *UserI = cast<Instruction>(U); + if (auto *InnerCatchSwitch = dyn_cast<CatchSwitchInst>(UserI)) { + BasicBlock *UnwindDest = InnerCatchSwitch->getUnwindDest(); + if (!UnwindDest || UnwindDest == CatchSwitch->getUnwindDest()) + calculateCXXStateNumbers(FuncInfo, UserI, CatchLow); + } + if (auto *InnerCleanupPad = dyn_cast<CleanupPadInst>(UserI)) { + BasicBlock *UnwindDest = getCleanupRetUnwindDest(InnerCleanupPad); + // If a nested cleanup pad reports a null unwind destination and the + // enclosing catch pad doesn't it must be post-dominated by an + // unreachable instruction. + if (!UnwindDest || UnwindDest == CatchSwitch->getUnwindDest()) + calculateCXXStateNumbers(FuncInfo, UserI, CatchLow); + } + } + } + int CatchHigh = FuncInfo.getLastStateNumber(); + addTryBlockMapEntry(FuncInfo, TryLow, TryHigh, CatchHigh, Handlers); + LLVM_DEBUG(dbgs() << "TryLow[" << BB->getName() << "]: " << TryLow << '\n'); + LLVM_DEBUG(dbgs() << "TryHigh[" << BB->getName() << "]: " << TryHigh + << '\n'); + LLVM_DEBUG(dbgs() << "CatchHigh[" << BB->getName() << "]: " << CatchHigh + << '\n'); + } else { + auto *CleanupPad = cast<CleanupPadInst>(FirstNonPHI); + + // It's possible for a cleanup to be visited twice: it might have multiple + // cleanupret instructions. + if (FuncInfo.EHPadStateMap.count(CleanupPad)) + return; + + int CleanupState = addUnwindMapEntry(FuncInfo, ParentState, BB); + FuncInfo.EHPadStateMap[CleanupPad] = CleanupState; + LLVM_DEBUG(dbgs() << "Assigning state #" << CleanupState << " to BB " + << BB->getName() << '\n'); + for (const BasicBlock *PredBlock : predecessors(BB)) { + if ((PredBlock = getEHPadFromPredecessor(PredBlock, + CleanupPad->getParentPad()))) { + calculateCXXStateNumbers(FuncInfo, PredBlock->getFirstNonPHI(), + CleanupState); + } + } + for (const User *U : CleanupPad->users()) { + const auto *UserI = cast<Instruction>(U); + if (UserI->isEHPad()) + report_fatal_error("Cleanup funclets for the MSVC++ personality cannot " + "contain exceptional actions"); + } + } +} + +static int addSEHExcept(WinEHFuncInfo &FuncInfo, int ParentState, + const Function *Filter, const BasicBlock *Handler) { + SEHUnwindMapEntry Entry; + Entry.ToState = ParentState; + Entry.IsFinally = false; + Entry.Filter = Filter; + Entry.Handler = Handler; + FuncInfo.SEHUnwindMap.push_back(Entry); + return FuncInfo.SEHUnwindMap.size() - 1; +} + +static int addSEHFinally(WinEHFuncInfo &FuncInfo, int ParentState, + const BasicBlock *Handler) { + SEHUnwindMapEntry Entry; + Entry.ToState = ParentState; + Entry.IsFinally = true; + Entry.Filter = nullptr; + Entry.Handler = Handler; + FuncInfo.SEHUnwindMap.push_back(Entry); + return FuncInfo.SEHUnwindMap.size() - 1; +} + +static void calculateSEHStateNumbers(WinEHFuncInfo &FuncInfo, + const Instruction *FirstNonPHI, + int ParentState) { + const BasicBlock *BB = FirstNonPHI->getParent(); + assert(BB->isEHPad() && "no a funclet!"); + + if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(FirstNonPHI)) { + assert(FuncInfo.EHPadStateMap.count(CatchSwitch) == 0 && + "shouldn't revist catch funclets!"); + + // Extract the filter function and the __except basic block and create a + // state for them. + assert(CatchSwitch->getNumHandlers() == 1 && + "SEH doesn't have multiple handlers per __try"); + const auto *CatchPad = + cast<CatchPadInst>((*CatchSwitch->handler_begin())->getFirstNonPHI()); + const BasicBlock *CatchPadBB = CatchPad->getParent(); + const Constant *FilterOrNull = + cast<Constant>(CatchPad->getArgOperand(0)->stripPointerCasts()); + const Function *Filter = dyn_cast<Function>(FilterOrNull); + assert((Filter || FilterOrNull->isNullValue()) && + "unexpected filter value"); + int TryState = addSEHExcept(FuncInfo, ParentState, Filter, CatchPadBB); + + // Everything in the __try block uses TryState as its parent state. + FuncInfo.EHPadStateMap[CatchSwitch] = TryState; + LLVM_DEBUG(dbgs() << "Assigning state #" << TryState << " to BB " + << CatchPadBB->getName() << '\n'); + for (const BasicBlock *PredBlock : predecessors(BB)) + if ((PredBlock = getEHPadFromPredecessor(PredBlock, + CatchSwitch->getParentPad()))) + calculateSEHStateNumbers(FuncInfo, PredBlock->getFirstNonPHI(), + TryState); + + // Everything in the __except block unwinds to ParentState, just like code + // outside the __try. + for (const User *U : CatchPad->users()) { + const auto *UserI = cast<Instruction>(U); + if (auto *InnerCatchSwitch = dyn_cast<CatchSwitchInst>(UserI)) { + BasicBlock *UnwindDest = InnerCatchSwitch->getUnwindDest(); + if (!UnwindDest || UnwindDest == CatchSwitch->getUnwindDest()) + calculateSEHStateNumbers(FuncInfo, UserI, ParentState); + } + if (auto *InnerCleanupPad = dyn_cast<CleanupPadInst>(UserI)) { + BasicBlock *UnwindDest = getCleanupRetUnwindDest(InnerCleanupPad); + // If a nested cleanup pad reports a null unwind destination and the + // enclosing catch pad doesn't it must be post-dominated by an + // unreachable instruction. + if (!UnwindDest || UnwindDest == CatchSwitch->getUnwindDest()) + calculateSEHStateNumbers(FuncInfo, UserI, ParentState); + } + } + } else { + auto *CleanupPad = cast<CleanupPadInst>(FirstNonPHI); + + // It's possible for a cleanup to be visited twice: it might have multiple + // cleanupret instructions. + if (FuncInfo.EHPadStateMap.count(CleanupPad)) + return; + + int CleanupState = addSEHFinally(FuncInfo, ParentState, BB); + FuncInfo.EHPadStateMap[CleanupPad] = CleanupState; + LLVM_DEBUG(dbgs() << "Assigning state #" << CleanupState << " to BB " + << BB->getName() << '\n'); + for (const BasicBlock *PredBlock : predecessors(BB)) + if ((PredBlock = + getEHPadFromPredecessor(PredBlock, CleanupPad->getParentPad()))) + calculateSEHStateNumbers(FuncInfo, PredBlock->getFirstNonPHI(), + CleanupState); + for (const User *U : CleanupPad->users()) { + const auto *UserI = cast<Instruction>(U); + if (UserI->isEHPad()) + report_fatal_error("Cleanup funclets for the SEH personality cannot " + "contain exceptional actions"); + } + } +} + +static bool isTopLevelPadForMSVC(const Instruction *EHPad) { + if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(EHPad)) + return isa<ConstantTokenNone>(CatchSwitch->getParentPad()) && + CatchSwitch->unwindsToCaller(); + if (auto *CleanupPad = dyn_cast<CleanupPadInst>(EHPad)) + return isa<ConstantTokenNone>(CleanupPad->getParentPad()) && + getCleanupRetUnwindDest(CleanupPad) == nullptr; + if (isa<CatchPadInst>(EHPad)) + return false; + llvm_unreachable("unexpected EHPad!"); +} + +void llvm::calculateSEHStateNumbers(const Function *Fn, + WinEHFuncInfo &FuncInfo) { + // Don't compute state numbers twice. + if (!FuncInfo.SEHUnwindMap.empty()) + return; + + for (const BasicBlock &BB : *Fn) { + if (!BB.isEHPad()) + continue; + const Instruction *FirstNonPHI = BB.getFirstNonPHI(); + if (!isTopLevelPadForMSVC(FirstNonPHI)) + continue; + ::calculateSEHStateNumbers(FuncInfo, FirstNonPHI, -1); + } + + calculateStateNumbersForInvokes(Fn, FuncInfo); +} + +void llvm::calculateWinCXXEHStateNumbers(const Function *Fn, + WinEHFuncInfo &FuncInfo) { + // Return if it's already been done. + if (!FuncInfo.EHPadStateMap.empty()) + return; + + for (const BasicBlock &BB : *Fn) { + if (!BB.isEHPad()) + continue; + const Instruction *FirstNonPHI = BB.getFirstNonPHI(); + if (!isTopLevelPadForMSVC(FirstNonPHI)) + continue; + calculateCXXStateNumbers(FuncInfo, FirstNonPHI, -1); + } + + calculateStateNumbersForInvokes(Fn, FuncInfo); +} + +static int addClrEHHandler(WinEHFuncInfo &FuncInfo, int HandlerParentState, + int TryParentState, ClrHandlerType HandlerType, + uint32_t TypeToken, const BasicBlock *Handler) { + ClrEHUnwindMapEntry Entry; + Entry.HandlerParentState = HandlerParentState; + Entry.TryParentState = TryParentState; + Entry.Handler = Handler; + Entry.HandlerType = HandlerType; + Entry.TypeToken = TypeToken; + FuncInfo.ClrEHUnwindMap.push_back(Entry); + return FuncInfo.ClrEHUnwindMap.size() - 1; +} + +void llvm::calculateClrEHStateNumbers(const Function *Fn, + WinEHFuncInfo &FuncInfo) { + // Return if it's already been done. + if (!FuncInfo.EHPadStateMap.empty()) + return; + + // This numbering assigns one state number to each catchpad and cleanuppad. + // It also computes two tree-like relations over states: + // 1) Each state has a "HandlerParentState", which is the state of the next + // outer handler enclosing this state's handler (same as nearest ancestor + // per the ParentPad linkage on EH pads, but skipping over catchswitches). + // 2) Each state has a "TryParentState", which: + // a) for a catchpad that's not the last handler on its catchswitch, is + // the state of the next catchpad on that catchswitch + // b) for all other pads, is the state of the pad whose try region is the + // next outer try region enclosing this state's try region. The "try + // regions are not present as such in the IR, but will be inferred + // based on the placement of invokes and pads which reach each other + // by exceptional exits + // Catchswitches do not get their own states, but each gets mapped to the + // state of its first catchpad. + + // Step one: walk down from outermost to innermost funclets, assigning each + // catchpad and cleanuppad a state number. Add an entry to the + // ClrEHUnwindMap for each state, recording its HandlerParentState and + // handler attributes. Record the TryParentState as well for each catchpad + // that's not the last on its catchswitch, but initialize all other entries' + // TryParentStates to a sentinel -1 value that the next pass will update. + + // Seed a worklist with pads that have no parent. + SmallVector<std::pair<const Instruction *, int>, 8> Worklist; + for (const BasicBlock &BB : *Fn) { + const Instruction *FirstNonPHI = BB.getFirstNonPHI(); + const Value *ParentPad; + if (const auto *CPI = dyn_cast<CleanupPadInst>(FirstNonPHI)) + ParentPad = CPI->getParentPad(); + else if (const auto *CSI = dyn_cast<CatchSwitchInst>(FirstNonPHI)) + ParentPad = CSI->getParentPad(); + else + continue; + if (isa<ConstantTokenNone>(ParentPad)) + Worklist.emplace_back(FirstNonPHI, -1); + } + + // Use the worklist to visit all pads, from outer to inner. Record + // HandlerParentState for all pads. Record TryParentState only for catchpads + // that aren't the last on their catchswitch (setting all other entries' + // TryParentStates to an initial value of -1). This loop is also responsible + // for setting the EHPadStateMap entry for all catchpads, cleanuppads, and + // catchswitches. + while (!Worklist.empty()) { + const Instruction *Pad; + int HandlerParentState; + std::tie(Pad, HandlerParentState) = Worklist.pop_back_val(); + + if (const auto *Cleanup = dyn_cast<CleanupPadInst>(Pad)) { + // Create the entry for this cleanup with the appropriate handler + // properties. Finally and fault handlers are distinguished by arity. + ClrHandlerType HandlerType = + (Cleanup->getNumArgOperands() ? ClrHandlerType::Fault + : ClrHandlerType::Finally); + int CleanupState = addClrEHHandler(FuncInfo, HandlerParentState, -1, + HandlerType, 0, Pad->getParent()); + // Queue any child EH pads on the worklist. + for (const User *U : Cleanup->users()) + if (const auto *I = dyn_cast<Instruction>(U)) + if (I->isEHPad()) + Worklist.emplace_back(I, CleanupState); + // Remember this pad's state. + FuncInfo.EHPadStateMap[Cleanup] = CleanupState; + } else { + // Walk the handlers of this catchswitch in reverse order since all but + // the last need to set the following one as its TryParentState. + const auto *CatchSwitch = cast<CatchSwitchInst>(Pad); + int CatchState = -1, FollowerState = -1; + SmallVector<const BasicBlock *, 4> CatchBlocks(CatchSwitch->handlers()); + for (auto CBI = CatchBlocks.rbegin(), CBE = CatchBlocks.rend(); + CBI != CBE; ++CBI, FollowerState = CatchState) { + const BasicBlock *CatchBlock = *CBI; + // Create the entry for this catch with the appropriate handler + // properties. + const auto *Catch = cast<CatchPadInst>(CatchBlock->getFirstNonPHI()); + uint32_t TypeToken = static_cast<uint32_t>( + cast<ConstantInt>(Catch->getArgOperand(0))->getZExtValue()); + CatchState = + addClrEHHandler(FuncInfo, HandlerParentState, FollowerState, + ClrHandlerType::Catch, TypeToken, CatchBlock); + // Queue any child EH pads on the worklist. + for (const User *U : Catch->users()) + if (const auto *I = dyn_cast<Instruction>(U)) + if (I->isEHPad()) + Worklist.emplace_back(I, CatchState); + // Remember this catch's state. + FuncInfo.EHPadStateMap[Catch] = CatchState; + } + // Associate the catchswitch with the state of its first catch. + assert(CatchSwitch->getNumHandlers()); + FuncInfo.EHPadStateMap[CatchSwitch] = CatchState; + } + } + + // Step two: record the TryParentState of each state. For cleanuppads that + // don't have cleanuprets, we may need to infer this from their child pads, + // so visit pads in descendant-most to ancestor-most order. + for (auto Entry = FuncInfo.ClrEHUnwindMap.rbegin(), + End = FuncInfo.ClrEHUnwindMap.rend(); + Entry != End; ++Entry) { + const Instruction *Pad = + Entry->Handler.get<const BasicBlock *>()->getFirstNonPHI(); + // For most pads, the TryParentState is the state associated with the + // unwind dest of exceptional exits from it. + const BasicBlock *UnwindDest; + if (const auto *Catch = dyn_cast<CatchPadInst>(Pad)) { + // If a catch is not the last in its catchswitch, its TryParentState is + // the state associated with the next catch in the switch, even though + // that's not the unwind dest of exceptions escaping the catch. Those + // cases were already assigned a TryParentState in the first pass, so + // skip them. + if (Entry->TryParentState != -1) + continue; + // Otherwise, get the unwind dest from the catchswitch. + UnwindDest = Catch->getCatchSwitch()->getUnwindDest(); + } else { + const auto *Cleanup = cast<CleanupPadInst>(Pad); + UnwindDest = nullptr; + for (const User *U : Cleanup->users()) { + if (auto *CleanupRet = dyn_cast<CleanupReturnInst>(U)) { + // Common and unambiguous case -- cleanupret indicates cleanup's + // unwind dest. + UnwindDest = CleanupRet->getUnwindDest(); + break; + } + + // Get an unwind dest for the user + const BasicBlock *UserUnwindDest = nullptr; + if (auto *Invoke = dyn_cast<InvokeInst>(U)) { + UserUnwindDest = Invoke->getUnwindDest(); + } else if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(U)) { + UserUnwindDest = CatchSwitch->getUnwindDest(); + } else if (auto *ChildCleanup = dyn_cast<CleanupPadInst>(U)) { + int UserState = FuncInfo.EHPadStateMap[ChildCleanup]; + int UserUnwindState = + FuncInfo.ClrEHUnwindMap[UserState].TryParentState; + if (UserUnwindState != -1) + UserUnwindDest = FuncInfo.ClrEHUnwindMap[UserUnwindState] + .Handler.get<const BasicBlock *>(); + } + + // Not having an unwind dest for this user might indicate that it + // doesn't unwind, so can't be taken as proof that the cleanup itself + // may unwind to caller (see e.g. SimplifyUnreachable and + // RemoveUnwindEdge). + if (!UserUnwindDest) + continue; + + // Now we have an unwind dest for the user, but we need to see if it + // unwinds all the way out of the cleanup or if it stays within it. + const Instruction *UserUnwindPad = UserUnwindDest->getFirstNonPHI(); + const Value *UserUnwindParent; + if (auto *CSI = dyn_cast<CatchSwitchInst>(UserUnwindPad)) + UserUnwindParent = CSI->getParentPad(); + else + UserUnwindParent = + cast<CleanupPadInst>(UserUnwindPad)->getParentPad(); + + // The unwind stays within the cleanup iff it targets a child of the + // cleanup. + if (UserUnwindParent == Cleanup) + continue; + + // This unwind exits the cleanup, so its dest is the cleanup's dest. + UnwindDest = UserUnwindDest; + break; + } + } + + // Record the state of the unwind dest as the TryParentState. + int UnwindDestState; + + // If UnwindDest is null at this point, either the pad in question can + // be exited by unwind to caller, or it cannot be exited by unwind. In + // either case, reporting such cases as unwinding to caller is correct. + // This can lead to EH tables that "look strange" -- if this pad's is in + // a parent funclet which has other children that do unwind to an enclosing + // pad, the try region for this pad will be missing the "duplicate" EH + // clause entries that you'd expect to see covering the whole parent. That + // should be benign, since the unwind never actually happens. If it were + // an issue, we could add a subsequent pass that pushes unwind dests down + // from parents that have them to children that appear to unwind to caller. + if (!UnwindDest) { + UnwindDestState = -1; + } else { + UnwindDestState = FuncInfo.EHPadStateMap[UnwindDest->getFirstNonPHI()]; + } + + Entry->TryParentState = UnwindDestState; + } + + // Step three: transfer information from pads to invokes. + calculateStateNumbersForInvokes(Fn, FuncInfo); +} + +void WinEHPrepare::colorFunclets(Function &F) { + BlockColors = colorEHFunclets(F); + + // Invert the map from BB to colors to color to BBs. + for (BasicBlock &BB : F) { + ColorVector &Colors = BlockColors[&BB]; + for (BasicBlock *Color : Colors) + FuncletBlocks[Color].push_back(&BB); + } +} + +void WinEHPrepare::demotePHIsOnFunclets(Function &F, + bool DemoteCatchSwitchPHIOnly) { + // Strip PHI nodes off of EH pads. + SmallVector<PHINode *, 16> PHINodes; + for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) { + BasicBlock *BB = &*FI++; + if (!BB->isEHPad()) + continue; + if (DemoteCatchSwitchPHIOnly && !isa<CatchSwitchInst>(BB->getFirstNonPHI())) + continue; + + for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) { + Instruction *I = &*BI++; + auto *PN = dyn_cast<PHINode>(I); + // Stop at the first non-PHI. + if (!PN) + break; + + AllocaInst *SpillSlot = insertPHILoads(PN, F); + if (SpillSlot) + insertPHIStores(PN, SpillSlot); + + PHINodes.push_back(PN); + } + } + + for (auto *PN : PHINodes) { + // There may be lingering uses on other EH PHIs being removed + PN->replaceAllUsesWith(UndefValue::get(PN->getType())); + PN->eraseFromParent(); + } +} + +void WinEHPrepare::cloneCommonBlocks(Function &F) { + // We need to clone all blocks which belong to multiple funclets. Values are + // remapped throughout the funclet to propagate both the new instructions + // *and* the new basic blocks themselves. + for (auto &Funclets : FuncletBlocks) { + BasicBlock *FuncletPadBB = Funclets.first; + std::vector<BasicBlock *> &BlocksInFunclet = Funclets.second; + Value *FuncletToken; + if (FuncletPadBB == &F.getEntryBlock()) + FuncletToken = ConstantTokenNone::get(F.getContext()); + else + FuncletToken = FuncletPadBB->getFirstNonPHI(); + + std::vector<std::pair<BasicBlock *, BasicBlock *>> Orig2Clone; + ValueToValueMapTy VMap; + for (BasicBlock *BB : BlocksInFunclet) { + ColorVector &ColorsForBB = BlockColors[BB]; + // We don't need to do anything if the block is monochromatic. + size_t NumColorsForBB = ColorsForBB.size(); + if (NumColorsForBB == 1) + continue; + + DEBUG_WITH_TYPE("winehprepare-coloring", + dbgs() << " Cloning block \'" << BB->getName() + << "\' for funclet \'" << FuncletPadBB->getName() + << "\'.\n"); + + // Create a new basic block and copy instructions into it! + BasicBlock *CBB = + CloneBasicBlock(BB, VMap, Twine(".for.", FuncletPadBB->getName())); + // Insert the clone immediately after the original to ensure determinism + // and to keep the same relative ordering of any funclet's blocks. + CBB->insertInto(&F, BB->getNextNode()); + + // Add basic block mapping. + VMap[BB] = CBB; + + // Record delta operations that we need to perform to our color mappings. + Orig2Clone.emplace_back(BB, CBB); + } + + // If nothing was cloned, we're done cloning in this funclet. + if (Orig2Clone.empty()) + continue; + + // Update our color mappings to reflect that one block has lost a color and + // another has gained a color. + for (auto &BBMapping : Orig2Clone) { + BasicBlock *OldBlock = BBMapping.first; + BasicBlock *NewBlock = BBMapping.second; + + BlocksInFunclet.push_back(NewBlock); + ColorVector &NewColors = BlockColors[NewBlock]; + assert(NewColors.empty() && "A new block should only have one color!"); + NewColors.push_back(FuncletPadBB); + + DEBUG_WITH_TYPE("winehprepare-coloring", + dbgs() << " Assigned color \'" << FuncletPadBB->getName() + << "\' to block \'" << NewBlock->getName() + << "\'.\n"); + + BlocksInFunclet.erase( + std::remove(BlocksInFunclet.begin(), BlocksInFunclet.end(), OldBlock), + BlocksInFunclet.end()); + ColorVector &OldColors = BlockColors[OldBlock]; + OldColors.erase( + std::remove(OldColors.begin(), OldColors.end(), FuncletPadBB), + OldColors.end()); + + DEBUG_WITH_TYPE("winehprepare-coloring", + dbgs() << " Removed color \'" << FuncletPadBB->getName() + << "\' from block \'" << OldBlock->getName() + << "\'.\n"); + } + + // Loop over all of the instructions in this funclet, fixing up operand + // references as we go. This uses VMap to do all the hard work. + for (BasicBlock *BB : BlocksInFunclet) + // Loop over all instructions, fixing each one as we find it... + for (Instruction &I : *BB) + RemapInstruction(&I, VMap, + RF_IgnoreMissingLocals | RF_NoModuleLevelChanges); + + // Catchrets targeting cloned blocks need to be updated separately from + // the loop above because they are not in the current funclet. + SmallVector<CatchReturnInst *, 2> FixupCatchrets; + for (auto &BBMapping : Orig2Clone) { + BasicBlock *OldBlock = BBMapping.first; + BasicBlock *NewBlock = BBMapping.second; + + FixupCatchrets.clear(); + for (BasicBlock *Pred : predecessors(OldBlock)) + if (auto *CatchRet = dyn_cast<CatchReturnInst>(Pred->getTerminator())) + if (CatchRet->getCatchSwitchParentPad() == FuncletToken) + FixupCatchrets.push_back(CatchRet); + + for (CatchReturnInst *CatchRet : FixupCatchrets) + CatchRet->setSuccessor(NewBlock); + } + + auto UpdatePHIOnClonedBlock = [&](PHINode *PN, bool IsForOldBlock) { + unsigned NumPreds = PN->getNumIncomingValues(); + for (unsigned PredIdx = 0, PredEnd = NumPreds; PredIdx != PredEnd; + ++PredIdx) { + BasicBlock *IncomingBlock = PN->getIncomingBlock(PredIdx); + bool EdgeTargetsFunclet; + if (auto *CRI = + dyn_cast<CatchReturnInst>(IncomingBlock->getTerminator())) { + EdgeTargetsFunclet = (CRI->getCatchSwitchParentPad() == FuncletToken); + } else { + ColorVector &IncomingColors = BlockColors[IncomingBlock]; + assert(!IncomingColors.empty() && "Block not colored!"); + assert((IncomingColors.size() == 1 || + llvm::all_of(IncomingColors, + [&](BasicBlock *Color) { + return Color != FuncletPadBB; + })) && + "Cloning should leave this funclet's blocks monochromatic"); + EdgeTargetsFunclet = (IncomingColors.front() == FuncletPadBB); + } + if (IsForOldBlock != EdgeTargetsFunclet) + continue; + PN->removeIncomingValue(IncomingBlock, /*DeletePHIIfEmpty=*/false); + // Revisit the next entry. + --PredIdx; + --PredEnd; + } + }; + + for (auto &BBMapping : Orig2Clone) { + BasicBlock *OldBlock = BBMapping.first; + BasicBlock *NewBlock = BBMapping.second; + for (PHINode &OldPN : OldBlock->phis()) { + UpdatePHIOnClonedBlock(&OldPN, /*IsForOldBlock=*/true); + } + for (PHINode &NewPN : NewBlock->phis()) { + UpdatePHIOnClonedBlock(&NewPN, /*IsForOldBlock=*/false); + } + } + + // Check to see if SuccBB has PHI nodes. If so, we need to add entries to + // the PHI nodes for NewBB now. + for (auto &BBMapping : Orig2Clone) { + BasicBlock *OldBlock = BBMapping.first; + BasicBlock *NewBlock = BBMapping.second; + for (BasicBlock *SuccBB : successors(NewBlock)) { + for (PHINode &SuccPN : SuccBB->phis()) { + // Ok, we have a PHI node. Figure out what the incoming value was for + // the OldBlock. + int OldBlockIdx = SuccPN.getBasicBlockIndex(OldBlock); + if (OldBlockIdx == -1) + break; + Value *IV = SuccPN.getIncomingValue(OldBlockIdx); + + // Remap the value if necessary. + if (auto *Inst = dyn_cast<Instruction>(IV)) { + ValueToValueMapTy::iterator I = VMap.find(Inst); + if (I != VMap.end()) + IV = I->second; + } + + SuccPN.addIncoming(IV, NewBlock); + } + } + } + + for (ValueToValueMapTy::value_type VT : VMap) { + // If there were values defined in BB that are used outside the funclet, + // then we now have to update all uses of the value to use either the + // original value, the cloned value, or some PHI derived value. This can + // require arbitrary PHI insertion, of which we are prepared to do, clean + // these up now. + SmallVector<Use *, 16> UsesToRename; + + auto *OldI = dyn_cast<Instruction>(const_cast<Value *>(VT.first)); + if (!OldI) + continue; + auto *NewI = cast<Instruction>(VT.second); + // Scan all uses of this instruction to see if it is used outside of its + // funclet, and if so, record them in UsesToRename. + for (Use &U : OldI->uses()) { + Instruction *UserI = cast<Instruction>(U.getUser()); + BasicBlock *UserBB = UserI->getParent(); + ColorVector &ColorsForUserBB = BlockColors[UserBB]; + assert(!ColorsForUserBB.empty()); + if (ColorsForUserBB.size() > 1 || + *ColorsForUserBB.begin() != FuncletPadBB) + UsesToRename.push_back(&U); + } + + // If there are no uses outside the block, we're done with this + // instruction. + if (UsesToRename.empty()) + continue; + + // We found a use of OldI outside of the funclet. Rename all uses of OldI + // that are outside its funclet to be uses of the appropriate PHI node + // etc. + SSAUpdater SSAUpdate; + SSAUpdate.Initialize(OldI->getType(), OldI->getName()); + SSAUpdate.AddAvailableValue(OldI->getParent(), OldI); + SSAUpdate.AddAvailableValue(NewI->getParent(), NewI); + + while (!UsesToRename.empty()) + SSAUpdate.RewriteUseAfterInsertions(*UsesToRename.pop_back_val()); + } + } +} + +void WinEHPrepare::removeImplausibleInstructions(Function &F) { + // Remove implausible terminators and replace them with UnreachableInst. + for (auto &Funclet : FuncletBlocks) { + BasicBlock *FuncletPadBB = Funclet.first; + std::vector<BasicBlock *> &BlocksInFunclet = Funclet.second; + Instruction *FirstNonPHI = FuncletPadBB->getFirstNonPHI(); + auto *FuncletPad = dyn_cast<FuncletPadInst>(FirstNonPHI); + auto *CatchPad = dyn_cast_or_null<CatchPadInst>(FuncletPad); + auto *CleanupPad = dyn_cast_or_null<CleanupPadInst>(FuncletPad); + + for (BasicBlock *BB : BlocksInFunclet) { + for (Instruction &I : *BB) { + CallSite CS(&I); + if (!CS) + continue; + + Value *FuncletBundleOperand = nullptr; + if (auto BU = CS.getOperandBundle(LLVMContext::OB_funclet)) + FuncletBundleOperand = BU->Inputs.front(); + + if (FuncletBundleOperand == FuncletPad) + continue; + + // Skip call sites which are nounwind intrinsics or inline asm. + auto *CalledFn = + dyn_cast<Function>(CS.getCalledValue()->stripPointerCasts()); + if (CalledFn && ((CalledFn->isIntrinsic() && CS.doesNotThrow()) || + CS.isInlineAsm())) + continue; + + // This call site was not part of this funclet, remove it. + if (CS.isInvoke()) { + // Remove the unwind edge if it was an invoke. + removeUnwindEdge(BB); + // Get a pointer to the new call. + BasicBlock::iterator CallI = + std::prev(BB->getTerminator()->getIterator()); + auto *CI = cast<CallInst>(&*CallI); + changeToUnreachable(CI, /*UseLLVMTrap=*/false); + } else { + changeToUnreachable(&I, /*UseLLVMTrap=*/false); + } + + // There are no more instructions in the block (except for unreachable), + // we are done. + break; + } + + Instruction *TI = BB->getTerminator(); + // CatchPadInst and CleanupPadInst can't transfer control to a ReturnInst. + bool IsUnreachableRet = isa<ReturnInst>(TI) && FuncletPad; + // The token consumed by a CatchReturnInst must match the funclet token. + bool IsUnreachableCatchret = false; + if (auto *CRI = dyn_cast<CatchReturnInst>(TI)) + IsUnreachableCatchret = CRI->getCatchPad() != CatchPad; + // The token consumed by a CleanupReturnInst must match the funclet token. + bool IsUnreachableCleanupret = false; + if (auto *CRI = dyn_cast<CleanupReturnInst>(TI)) + IsUnreachableCleanupret = CRI->getCleanupPad() != CleanupPad; + if (IsUnreachableRet || IsUnreachableCatchret || + IsUnreachableCleanupret) { + changeToUnreachable(TI, /*UseLLVMTrap=*/false); + } else if (isa<InvokeInst>(TI)) { + if (Personality == EHPersonality::MSVC_CXX && CleanupPad) { + // Invokes within a cleanuppad for the MSVC++ personality never + // transfer control to their unwind edge: the personality will + // terminate the program. + removeUnwindEdge(BB); + } + } + } + } +} + +void WinEHPrepare::cleanupPreparedFunclets(Function &F) { + // Clean-up some of the mess we made by removing useles PHI nodes, trivial + // branches, etc. + for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) { + BasicBlock *BB = &*FI++; + SimplifyInstructionsInBlock(BB); + ConstantFoldTerminator(BB, /*DeleteDeadConditions=*/true); + MergeBlockIntoPredecessor(BB); + } + + // We might have some unreachable blocks after cleaning up some impossible + // control flow. + removeUnreachableBlocks(F); +} + +#ifndef NDEBUG +void WinEHPrepare::verifyPreparedFunclets(Function &F) { + for (BasicBlock &BB : F) { + size_t NumColors = BlockColors[&BB].size(); + assert(NumColors == 1 && "Expected monochromatic BB!"); + if (NumColors == 0) + report_fatal_error("Uncolored BB!"); + if (NumColors > 1) + report_fatal_error("Multicolor BB!"); + assert((DisableDemotion || !(BB.isEHPad() && isa<PHINode>(BB.begin()))) && + "EH Pad still has a PHI!"); + } +} +#endif + +bool WinEHPrepare::prepareExplicitEH(Function &F) { + // Remove unreachable blocks. It is not valuable to assign them a color and + // their existence can trick us into thinking values are alive when they are + // not. + removeUnreachableBlocks(F); + + // Determine which blocks are reachable from which funclet entries. + colorFunclets(F); + + cloneCommonBlocks(F); + + if (!DisableDemotion) + demotePHIsOnFunclets(F, DemoteCatchSwitchPHIOnly || + DemoteCatchSwitchPHIOnlyOpt); + + if (!DisableCleanups) { + LLVM_DEBUG(verifyFunction(F)); + removeImplausibleInstructions(F); + + LLVM_DEBUG(verifyFunction(F)); + cleanupPreparedFunclets(F); + } + + LLVM_DEBUG(verifyPreparedFunclets(F)); + // Recolor the CFG to verify that all is well. + LLVM_DEBUG(colorFunclets(F)); + LLVM_DEBUG(verifyPreparedFunclets(F)); + + BlockColors.clear(); + FuncletBlocks.clear(); + + return true; +} + +// TODO: Share loads when one use dominates another, or when a catchpad exit +// dominates uses (needs dominators). +AllocaInst *WinEHPrepare::insertPHILoads(PHINode *PN, Function &F) { + BasicBlock *PHIBlock = PN->getParent(); + AllocaInst *SpillSlot = nullptr; + Instruction *EHPad = PHIBlock->getFirstNonPHI(); + + if (!EHPad->isTerminator()) { + // If the EHPad isn't a terminator, then we can insert a load in this block + // that will dominate all uses. + SpillSlot = new AllocaInst(PN->getType(), DL->getAllocaAddrSpace(), nullptr, + Twine(PN->getName(), ".wineh.spillslot"), + &F.getEntryBlock().front()); + Value *V = new LoadInst(PN->getType(), SpillSlot, + Twine(PN->getName(), ".wineh.reload"), + &*PHIBlock->getFirstInsertionPt()); + PN->replaceAllUsesWith(V); + return SpillSlot; + } + + // Otherwise, we have a PHI on a terminator EHPad, and we give up and insert + // loads of the slot before every use. + DenseMap<BasicBlock *, Value *> Loads; + for (Value::use_iterator UI = PN->use_begin(), UE = PN->use_end(); + UI != UE;) { + Use &U = *UI++; + auto *UsingInst = cast<Instruction>(U.getUser()); + if (isa<PHINode>(UsingInst) && UsingInst->getParent()->isEHPad()) { + // Use is on an EH pad phi. Leave it alone; we'll insert loads and + // stores for it separately. + continue; + } + replaceUseWithLoad(PN, U, SpillSlot, Loads, F); + } + return SpillSlot; +} + +// TODO: improve store placement. Inserting at def is probably good, but need +// to be careful not to introduce interfering stores (needs liveness analysis). +// TODO: identify related phi nodes that can share spill slots, and share them +// (also needs liveness). +void WinEHPrepare::insertPHIStores(PHINode *OriginalPHI, + AllocaInst *SpillSlot) { + // Use a worklist of (Block, Value) pairs -- the given Value needs to be + // stored to the spill slot by the end of the given Block. + SmallVector<std::pair<BasicBlock *, Value *>, 4> Worklist; + + Worklist.push_back({OriginalPHI->getParent(), OriginalPHI}); + + while (!Worklist.empty()) { + BasicBlock *EHBlock; + Value *InVal; + std::tie(EHBlock, InVal) = Worklist.pop_back_val(); + + PHINode *PN = dyn_cast<PHINode>(InVal); + if (PN && PN->getParent() == EHBlock) { + // The value is defined by another PHI we need to remove, with no room to + // insert a store after the PHI, so each predecessor needs to store its + // incoming value. + for (unsigned i = 0, e = PN->getNumIncomingValues(); i < e; ++i) { + Value *PredVal = PN->getIncomingValue(i); + + // Undef can safely be skipped. + if (isa<UndefValue>(PredVal)) + continue; + + insertPHIStore(PN->getIncomingBlock(i), PredVal, SpillSlot, Worklist); + } + } else { + // We need to store InVal, which dominates EHBlock, but can't put a store + // in EHBlock, so need to put stores in each predecessor. + for (BasicBlock *PredBlock : predecessors(EHBlock)) { + insertPHIStore(PredBlock, InVal, SpillSlot, Worklist); + } + } + } +} + +void WinEHPrepare::insertPHIStore( + BasicBlock *PredBlock, Value *PredVal, AllocaInst *SpillSlot, + SmallVectorImpl<std::pair<BasicBlock *, Value *>> &Worklist) { + + if (PredBlock->isEHPad() && PredBlock->getFirstNonPHI()->isTerminator()) { + // Pred is unsplittable, so we need to queue it on the worklist. + Worklist.push_back({PredBlock, PredVal}); + return; + } + + // Otherwise, insert the store at the end of the basic block. + new StoreInst(PredVal, SpillSlot, PredBlock->getTerminator()); +} + +void WinEHPrepare::replaceUseWithLoad(Value *V, Use &U, AllocaInst *&SpillSlot, + DenseMap<BasicBlock *, Value *> &Loads, + Function &F) { + // Lazilly create the spill slot. + if (!SpillSlot) + SpillSlot = new AllocaInst(V->getType(), DL->getAllocaAddrSpace(), nullptr, + Twine(V->getName(), ".wineh.spillslot"), + &F.getEntryBlock().front()); + + auto *UsingInst = cast<Instruction>(U.getUser()); + if (auto *UsingPHI = dyn_cast<PHINode>(UsingInst)) { + // If this is a PHI node, we can't insert a load of the value before + // the use. Instead insert the load in the predecessor block + // corresponding to the incoming value. + // + // Note that if there are multiple edges from a basic block to this + // PHI node that we cannot have multiple loads. The problem is that + // the resulting PHI node will have multiple values (from each load) + // coming in from the same block, which is illegal SSA form. + // For this reason, we keep track of and reuse loads we insert. + BasicBlock *IncomingBlock = UsingPHI->getIncomingBlock(U); + if (auto *CatchRet = + dyn_cast<CatchReturnInst>(IncomingBlock->getTerminator())) { + // Putting a load above a catchret and use on the phi would still leave + // a cross-funclet def/use. We need to split the edge, change the + // catchret to target the new block, and put the load there. + BasicBlock *PHIBlock = UsingInst->getParent(); + BasicBlock *NewBlock = SplitEdge(IncomingBlock, PHIBlock); + // SplitEdge gives us: + // IncomingBlock: + // ... + // br label %NewBlock + // NewBlock: + // catchret label %PHIBlock + // But we need: + // IncomingBlock: + // ... + // catchret label %NewBlock + // NewBlock: + // br label %PHIBlock + // So move the terminators to each others' blocks and swap their + // successors. + BranchInst *Goto = cast<BranchInst>(IncomingBlock->getTerminator()); + Goto->removeFromParent(); + CatchRet->removeFromParent(); + IncomingBlock->getInstList().push_back(CatchRet); + NewBlock->getInstList().push_back(Goto); + Goto->setSuccessor(0, PHIBlock); + CatchRet->setSuccessor(NewBlock); + // Update the color mapping for the newly split edge. + // Grab a reference to the ColorVector to be inserted before getting the + // reference to the vector we are copying because inserting the new + // element in BlockColors might cause the map to be reallocated. + ColorVector &ColorsForNewBlock = BlockColors[NewBlock]; + ColorVector &ColorsForPHIBlock = BlockColors[PHIBlock]; + ColorsForNewBlock = ColorsForPHIBlock; + for (BasicBlock *FuncletPad : ColorsForPHIBlock) + FuncletBlocks[FuncletPad].push_back(NewBlock); + // Treat the new block as incoming for load insertion. + IncomingBlock = NewBlock; + } + Value *&Load = Loads[IncomingBlock]; + // Insert the load into the predecessor block + if (!Load) + Load = new LoadInst(V->getType(), SpillSlot, + Twine(V->getName(), ".wineh.reload"), + /*isVolatile=*/false, IncomingBlock->getTerminator()); + + U.set(Load); + } else { + // Reload right before the old use. + auto *Load = new LoadInst(V->getType(), SpillSlot, + Twine(V->getName(), ".wineh.reload"), + /*isVolatile=*/false, UsingInst); + U.set(Load); + } +} + +void WinEHFuncInfo::addIPToStateRange(const InvokeInst *II, + MCSymbol *InvokeBegin, + MCSymbol *InvokeEnd) { + assert(InvokeStateMap.count(II) && + "should get invoke with precomputed state"); + LabelToStateMap[InvokeBegin] = std::make_pair(InvokeStateMap[II], InvokeEnd); +} + +WinEHFuncInfo::WinEHFuncInfo() {} |