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Diffstat (limited to 'lib/CodeGen/WinEHPrepare.cpp')
| -rw-r--r-- | lib/CodeGen/WinEHPrepare.cpp | 626 |
1 files changed, 626 insertions, 0 deletions
diff --git a/lib/CodeGen/WinEHPrepare.cpp b/lib/CodeGen/WinEHPrepare.cpp new file mode 100644 index 0000000..6f712a9 --- /dev/null +++ b/lib/CodeGen/WinEHPrepare.cpp @@ -0,0 +1,626 @@ +//===-- WinEHPrepare - Prepare exception handling for code generation ---===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This pass lowers LLVM IR exception handling into something closer to what the +// backend wants. 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. +// +//===----------------------------------------------------------------------===// + +#include "llvm/CodeGen/Passes.h" +#include "llvm/ADT/MapVector.h" +#include "llvm/ADT/TinyPtrVector.h" +#include "llvm/Analysis/LibCallSemantics.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/IRBuilder.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/Module.h" +#include "llvm/IR/PatternMatch.h" +#include "llvm/Pass.h" +#include "llvm/Transforms/Utils/Cloning.h" +#include "llvm/Transforms/Utils/Local.h" +#include <memory> + +using namespace llvm; +using namespace llvm::PatternMatch; + +#define DEBUG_TYPE "winehprepare" + +namespace { + +struct HandlerAllocas { + TinyPtrVector<AllocaInst *> Allocas; + int ParentFrameAllocationIndex; +}; + +// This map is used to model frame variable usage during outlining, to +// construct a structure type to hold the frame variables in a frame +// allocation block, and to remap the frame variable allocas (including +// spill locations as needed) to GEPs that get the variable from the +// frame allocation structure. +typedef MapVector<AllocaInst *, HandlerAllocas> FrameVarInfoMap; + +class WinEHPrepare : public FunctionPass { + std::unique_ptr<FunctionPass> DwarfPrepare; + +public: + static char ID; // Pass identification, replacement for typeid. + WinEHPrepare(const TargetMachine *TM = nullptr) + : FunctionPass(ID), DwarfPrepare(createDwarfEHPass(TM)) {} + + bool runOnFunction(Function &Fn) override; + + bool doFinalization(Module &M) override; + + void getAnalysisUsage(AnalysisUsage &AU) const override; + + const char *getPassName() const override { + return "Windows exception handling preparation"; + } + +private: + bool prepareCPPEHHandlers(Function &F, + SmallVectorImpl<LandingPadInst *> &LPads); + bool outlineCatchHandler(Function *SrcFn, Constant *SelectorType, + LandingPadInst *LPad, CallInst *&EHAlloc, + AllocaInst *&EHObjPtr, FrameVarInfoMap &VarInfo); +}; + +class WinEHFrameVariableMaterializer : public ValueMaterializer { +public: + WinEHFrameVariableMaterializer(Function *OutlinedFn, + FrameVarInfoMap &FrameVarInfo); + ~WinEHFrameVariableMaterializer() {} + + virtual Value *materializeValueFor(Value *V) override; + +private: + FrameVarInfoMap &FrameVarInfo; + IRBuilder<> Builder; +}; + +class WinEHCatchDirector : public CloningDirector { +public: + WinEHCatchDirector(LandingPadInst *LPI, Function *CatchFn, Value *Selector, + Value *EHObj, FrameVarInfoMap &VarInfo) + : LPI(LPI), CurrentSelector(Selector->stripPointerCasts()), EHObj(EHObj), + Materializer(CatchFn, VarInfo), + SelectorIDType(Type::getInt32Ty(LPI->getContext())), + Int8PtrType(Type::getInt8PtrTy(LPI->getContext())) {} + + CloningAction handleInstruction(ValueToValueMapTy &VMap, + const Instruction *Inst, + BasicBlock *NewBB) override; + + ValueMaterializer *getValueMaterializer() override { return &Materializer; } + +private: + LandingPadInst *LPI; + Value *CurrentSelector; + Value *EHObj; + WinEHFrameVariableMaterializer Materializer; + Type *SelectorIDType; + Type *Int8PtrType; + + const Value *ExtractedEHPtr; + const Value *ExtractedSelector; + const Value *EHPtrStoreAddr; + const Value *SelectorStoreAddr; +}; +} // end anonymous namespace + +char WinEHPrepare::ID = 0; +INITIALIZE_TM_PASS(WinEHPrepare, "winehprepare", "Prepare Windows exceptions", + false, false) + +FunctionPass *llvm::createWinEHPass(const TargetMachine *TM) { + return new WinEHPrepare(TM); +} + +static bool isMSVCPersonality(EHPersonality Pers) { + return Pers == EHPersonality::MSVC_Win64SEH || + Pers == EHPersonality::MSVC_CXX; +} + +bool WinEHPrepare::runOnFunction(Function &Fn) { + SmallVector<LandingPadInst *, 4> LPads; + SmallVector<ResumeInst *, 4> Resumes; + for (BasicBlock &BB : Fn) { + if (auto *LP = BB.getLandingPadInst()) + LPads.push_back(LP); + if (auto *Resume = dyn_cast<ResumeInst>(BB.getTerminator())) + Resumes.push_back(Resume); + } + + // No need to prepare functions that lack landing pads. + if (LPads.empty()) + return false; + + // Classify the personality to see what kind of preparation we need. + EHPersonality Pers = classifyEHPersonality(LPads.back()->getPersonalityFn()); + + // Delegate through to the DWARF pass if this is unrecognized. + if (!isMSVCPersonality(Pers)) + return DwarfPrepare->runOnFunction(Fn); + + // FIXME: This only returns true if the C++ EH handlers were outlined. + // When that code is complete, it should always return whatever + // prepareCPPEHHandlers returns. + if (Pers == EHPersonality::MSVC_CXX && prepareCPPEHHandlers(Fn, LPads)) + return true; + + // FIXME: SEH Cleanups are unimplemented. Replace them with unreachable. + if (Resumes.empty()) + return false; + + for (ResumeInst *Resume : Resumes) { + IRBuilder<>(Resume).CreateUnreachable(); + Resume->eraseFromParent(); + } + + return true; +} + +bool WinEHPrepare::doFinalization(Module &M) { + return DwarfPrepare->doFinalization(M); +} + +void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const { + DwarfPrepare->getAnalysisUsage(AU); +} + +bool WinEHPrepare::prepareCPPEHHandlers( + Function &F, SmallVectorImpl<LandingPadInst *> &LPads) { + // These containers are used to re-map frame variables that are used in + // outlined catch and cleanup handlers. They will be populated as the + // handlers are outlined. + FrameVarInfoMap FrameVarInfo; + SmallVector<CallInst *, 4> HandlerAllocs; + SmallVector<AllocaInst *, 4> HandlerEHObjPtrs; + + bool HandlersOutlined = false; + + 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->getInstList()) { + // FIXME: Make this an intrinsic. + if (auto *Call = dyn_cast<CallInst>(&Inst)) + if (Call->getCalledFunction()->getName() == "llvm.eh.actions") { + LPadHasActionList = true; + break; + } + } + + // If we've already outlined the handlers for this landingpad, + // there's nothing more to do here. + if (LPadHasActionList) + continue; + + for (unsigned Idx = 0, NumClauses = LPad->getNumClauses(); Idx < NumClauses; + ++Idx) { + if (LPad->isCatch(Idx)) { + // Create a new instance of the handler data structure in the + // HandlerData vector. + CallInst *EHAlloc = nullptr; + AllocaInst *EHObjPtr = nullptr; + bool Outlined = outlineCatchHandler(&F, LPad->getClause(Idx), LPad, + EHAlloc, EHObjPtr, FrameVarInfo); + if (Outlined) { + HandlersOutlined = true; + // These values must be resolved after all handlers have been + // outlined. + if (EHAlloc) + HandlerAllocs.push_back(EHAlloc); + if (EHObjPtr) + HandlerEHObjPtrs.push_back(EHObjPtr); + } + } // End if (isCatch) + } // End for each clause + } // End for each landingpad + + // If nothing got outlined, there is no more processing to be done. + if (!HandlersOutlined) + return false; + + // FIXME: We will replace the landingpad bodies with llvm.eh.actions + // calls and indirect branches here and then delete blocks + // which are no longer reachable. That will get rid of the + // handlers that we have outlined. There is code below + // that looks for allocas with no uses in the parent function. + // That will only happen after the pruning is implemented. + + // Remap the frame variables. + SmallVector<Type *, 2> StructTys; + StructTys.push_back(Type::getInt32Ty(F.getContext())); // EH state + StructTys.push_back(Type::getInt8PtrTy(F.getContext())); // EH object + + // Start the index at two since we always have the above fields at 0 and 1. + int Idx = 2; + + // FIXME: Sort the FrameVarInfo vector by the ParentAlloca size and alignment + // and add padding as necessary to provide the proper alignment. + + // Map the alloca instructions to the corresponding index in the + // frame allocation structure. If any alloca is used only in a single + // handler and is not used in the parent frame after outlining, it will + // be assigned an index of -1, meaning the handler can keep its + // "temporary" alloca and the original alloca can be erased from the + // parent function. If we later encounter this alloca in a second + // handler, we will assign it a place in the frame allocation structure + // at that time. Since the instruction replacement doesn't happen until + // all the entries in the HandlerData have been processed this isn't a + // problem. + for (auto &VarInfoEntry : FrameVarInfo) { + AllocaInst *ParentAlloca = VarInfoEntry.first; + HandlerAllocas &AllocaInfo = VarInfoEntry.second; + + // If the instruction still has uses in the parent function or if it is + // referenced by more than one handler, add it to the frame allocation + // structure. + if (ParentAlloca->getNumUses() != 0 || AllocaInfo.Allocas.size() > 1) { + Type *VarTy = ParentAlloca->getAllocatedType(); + StructTys.push_back(VarTy); + AllocaInfo.ParentFrameAllocationIndex = Idx++; + } else { + // If the variable is not used in the parent frame and it is only used + // in one handler, the alloca can be removed from the parent frame + // and the handler will keep its "temporary" alloca to define the value. + // An element index of -1 is used to indicate this condition. + AllocaInfo.ParentFrameAllocationIndex = -1; + } + } + + // Having filled the StructTys vector and assigned an index to each element, + // we can now create the structure. + StructType *EHDataStructTy = StructType::create( + F.getContext(), StructTys, "struct." + F.getName().str() + ".ehdata"); + IRBuilder<> Builder(F.getParent()->getContext()); + + // Create a frame allocation. + Module *M = F.getParent(); + LLVMContext &Context = M->getContext(); + BasicBlock *Entry = &F.getEntryBlock(); + Builder.SetInsertPoint(Entry->getFirstInsertionPt()); + Function *FrameAllocFn = + Intrinsic::getDeclaration(M, Intrinsic::frameallocate); + uint64_t EHAllocSize = M->getDataLayout()->getTypeAllocSize(EHDataStructTy); + Value *FrameAllocArgs[] = { + ConstantInt::get(Type::getInt32Ty(Context), EHAllocSize)}; + CallInst *FrameAlloc = + Builder.CreateCall(FrameAllocFn, FrameAllocArgs, "frame.alloc"); + + Value *FrameEHData = Builder.CreateBitCast( + FrameAlloc, EHDataStructTy->getPointerTo(), "eh.data"); + + // Now visit each handler that is using the structure and bitcast its EHAlloc + // value to be a pointer to the frame alloc structure. + DenseMap<Function *, Value *> EHDataMap; + for (CallInst *EHAlloc : HandlerAllocs) { + // The EHAlloc has no uses at this time, so we need to just insert the + // cast before the next instruction. There is always a next instruction. + BasicBlock::iterator II = EHAlloc; + ++II; + Builder.SetInsertPoint(cast<Instruction>(II)); + Value *EHData = Builder.CreateBitCast( + EHAlloc, EHDataStructTy->getPointerTo(), "eh.data"); + EHDataMap[EHAlloc->getParent()->getParent()] = EHData; + } + + // Next, replace the place-holder EHObjPtr allocas with GEP instructions + // that pull the EHObjPtr from the frame alloc structure + for (AllocaInst *EHObjPtr : HandlerEHObjPtrs) { + Value *EHData = EHDataMap[EHObjPtr->getParent()->getParent()]; + Builder.SetInsertPoint(EHObjPtr); + Value *ElementPtr = Builder.CreateConstInBoundsGEP2_32(EHData, 0, 1); + EHObjPtr->replaceAllUsesWith(ElementPtr); + EHObjPtr->removeFromParent(); + ElementPtr->takeName(EHObjPtr); + delete EHObjPtr; + } + + // Finally, replace all of the temporary allocas for frame variables used in + // the outlined handlers and the original frame allocas with GEP instructions + // that get the equivalent pointer from the frame allocation struct. + for (auto &VarInfoEntry : FrameVarInfo) { + AllocaInst *ParentAlloca = VarInfoEntry.first; + HandlerAllocas &AllocaInfo = VarInfoEntry.second; + int Idx = AllocaInfo.ParentFrameAllocationIndex; + + // If we have an index of -1 for this instruction, it means it isn't used + // outside of this handler. In that case, we just keep the "temporary" + // alloca in the handler and erase the original alloca from the parent. + if (Idx == -1) { + ParentAlloca->eraseFromParent(); + } else { + // Otherwise, we replace the parent alloca and all outlined allocas + // which map to it with GEP instructions. + + // First replace the original alloca. + Builder.SetInsertPoint(ParentAlloca); + Builder.SetCurrentDebugLocation(ParentAlloca->getDebugLoc()); + Value *ElementPtr = + Builder.CreateConstInBoundsGEP2_32(FrameEHData, 0, Idx); + ParentAlloca->replaceAllUsesWith(ElementPtr); + ParentAlloca->removeFromParent(); + ElementPtr->takeName(ParentAlloca); + delete ParentAlloca; + + // Next replace all outlined allocas that are mapped to it. + for (AllocaInst *TempAlloca : AllocaInfo.Allocas) { + Value *EHData = EHDataMap[TempAlloca->getParent()->getParent()]; + // FIXME: Sink this GEP into the blocks where it is used. + Builder.SetInsertPoint(TempAlloca); + Builder.SetCurrentDebugLocation(TempAlloca->getDebugLoc()); + ElementPtr = Builder.CreateConstInBoundsGEP2_32(EHData, 0, Idx); + TempAlloca->replaceAllUsesWith(ElementPtr); + TempAlloca->removeFromParent(); + ElementPtr->takeName(TempAlloca); + delete TempAlloca; + } + } // end else of if (Idx == -1) + } // End for each FrameVarInfo entry. + + return HandlersOutlined; +} + +bool WinEHPrepare::outlineCatchHandler(Function *SrcFn, Constant *SelectorType, + LandingPadInst *LPad, CallInst *&EHAlloc, + AllocaInst *&EHObjPtr, + FrameVarInfoMap &VarInfo) { + Module *M = SrcFn->getParent(); + LLVMContext &Context = M->getContext(); + + // Create a new function to receive the handler contents. + Type *Int8PtrType = Type::getInt8PtrTy(Context); + std::vector<Type *> ArgTys; + ArgTys.push_back(Int8PtrType); + ArgTys.push_back(Int8PtrType); + FunctionType *FnType = FunctionType::get(Int8PtrType, ArgTys, false); + Function *CatchHandler = Function::Create( + FnType, GlobalVariable::ExternalLinkage, SrcFn->getName() + ".catch", M); + + // Generate a standard prolog to setup the frame recovery structure. + IRBuilder<> Builder(Context); + BasicBlock *Entry = BasicBlock::Create(Context, "catch.entry"); + CatchHandler->getBasicBlockList().push_front(Entry); + Builder.SetInsertPoint(Entry); + Builder.SetCurrentDebugLocation(LPad->getDebugLoc()); + + // The outlined handler will be called with the parent's frame pointer as + // its second argument. To enable the handler to access variables from + // the parent frame, we use that pointer to get locate a special block + // of memory that was allocated using llvm.eh.allocateframe for this + // purpose. During the outlining process we will determine which frame + // variables are used in handlers and create a structure that maps these + // variables into the frame allocation block. + // + // The frame allocation block also contains an exception state variable + // used by the runtime and a pointer to the exception object pointer + // which will be filled in by the runtime for use in the handler. + Function *RecoverFrameFn = + Intrinsic::getDeclaration(M, Intrinsic::framerecover); + Value *RecoverArgs[] = {Builder.CreateBitCast(SrcFn, Int8PtrType, ""), + &(CatchHandler->getArgumentList().back())}; + EHAlloc = Builder.CreateCall(RecoverFrameFn, RecoverArgs, "eh.alloc"); + + // This alloca is only temporary. We'll be replacing it once we know all the + // frame variables that need to go in the frame allocation structure. + EHObjPtr = Builder.CreateAlloca(Int8PtrType, 0, "eh.obj.ptr"); + + // This will give us a raw pointer to the exception object, which + // corresponds to the formal parameter of the catch statement. If the + // handler uses this object, we will generate code during the outlining + // process to cast the pointer to the appropriate type and deference it + // as necessary. The un-outlined landing pad code represents the + // exception object as the result of the llvm.eh.begincatch call. + Value *EHObj = Builder.CreateLoad(EHObjPtr, false, "eh.obj"); + + ValueToValueMapTy VMap; + + // FIXME: Map other values referenced in the filter handler. + + WinEHCatchDirector Director(LPad, CatchHandler, SelectorType, EHObj, VarInfo); + + SmallVector<ReturnInst *, 8> Returns; + ClonedCodeInfo InlinedFunctionInfo; + + BasicBlock::iterator II = LPad; + + CloneAndPruneIntoFromInst(CatchHandler, SrcFn, ++II, VMap, + /*ModuleLevelChanges=*/false, Returns, "", + &InlinedFunctionInfo, + SrcFn->getParent()->getDataLayout(), &Director); + + // 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(); + + return true; +} + +CloningDirector::CloningAction WinEHCatchDirector::handleInstruction( + ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) { + // Intercept instructions which extract values from the landing pad aggregate. + if (auto *Extract = dyn_cast<ExtractValueInst>(Inst)) { + if (Extract->getAggregateOperand() == LPI) { + assert(Extract->getNumIndices() == 1 && + "Unexpected operation: extracting both landing pad values"); + assert((*(Extract->idx_begin()) == 0 || *(Extract->idx_begin()) == 1) && + "Unexpected operation: extracting an unknown landing pad element"); + + if (*(Extract->idx_begin()) == 0) { + // Element 0 doesn't directly corresponds to anything in the WinEH + // scheme. + // It will be stored to a memory location, then later loaded and finally + // the loaded value will be used as the argument to an + // llvm.eh.begincatch + // call. We're tracking it here so that we can skip the store and load. + ExtractedEHPtr = Inst; + } else { + // Element 1 corresponds to the filter selector. We'll map it to 1 for + // matching purposes, but it will also probably be stored to memory and + // reloaded, so we need to track the instuction so that we can map the + // loaded value too. + VMap[Inst] = ConstantInt::get(SelectorIDType, 1); + ExtractedSelector = Inst; + } + + // Tell the caller not to clone this instruction. + return CloningDirector::SkipInstruction; + } + // Other extract value instructions just get cloned. + return CloningDirector::CloneInstruction; + } + + if (auto *Store = dyn_cast<StoreInst>(Inst)) { + // Look for and suppress stores of the extracted landingpad values. + const Value *StoredValue = Store->getValueOperand(); + if (StoredValue == ExtractedEHPtr) { + EHPtrStoreAddr = Store->getPointerOperand(); + return CloningDirector::SkipInstruction; + } + if (StoredValue == ExtractedSelector) { + SelectorStoreAddr = Store->getPointerOperand(); + return CloningDirector::SkipInstruction; + } + + // Any other store just gets cloned. + return CloningDirector::CloneInstruction; + } + + if (auto *Load = dyn_cast<LoadInst>(Inst)) { + // Look for loads of (previously suppressed) landingpad values. + // The EHPtr load can be ignored (it should only be used as + // an argument to llvm.eh.begincatch), but the selector value + // needs to be mapped to a constant value of 1 to be used to + // simplify the branching to always flow to the current handler. + const Value *LoadAddr = Load->getPointerOperand(); + if (LoadAddr == EHPtrStoreAddr) { + VMap[Inst] = UndefValue::get(Int8PtrType); + return CloningDirector::SkipInstruction; + } + if (LoadAddr == SelectorStoreAddr) { + VMap[Inst] = ConstantInt::get(SelectorIDType, 1); + return CloningDirector::SkipInstruction; + } + + // Any other loads just get cloned. + return CloningDirector::CloneInstruction; + } + + if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>())) { + // The argument to the call is some form of the first element of the + // landingpad aggregate value, but that doesn't matter. It isn't used + // here. + // The return value of this instruction, however, is used to access the + // EH object pointer. We have generated an instruction to get that value + // from the EH alloc block, so we can just map to that here. + VMap[Inst] = EHObj; + return CloningDirector::SkipInstruction; + } + if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>())) { + auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst); + // It might be interesting to track whether or not we are inside a catch + // function, but that might make the algorithm more brittle than it needs + // to be. + + // The end catch call can occur in one of two places: either in a + // landingpad + // block that is part of the catch handlers exception mechanism, or at the + // end of the catch block. If it occurs in a landing pad, we must skip it + // and continue so that the landing pad gets cloned. + // FIXME: This case isn't fully supported yet and shouldn't turn up in any + // of the test cases until it is. + if (IntrinCall->getParent()->isLandingPad()) + return CloningDirector::SkipInstruction; + + // If an end catch occurs anywhere else the next instruction should be an + // unconditional branch instruction that we want to replace with a return + // to the the address of the branch target. + const BasicBlock *EndCatchBB = IntrinCall->getParent(); + const TerminatorInst *Terminator = EndCatchBB->getTerminator(); + const BranchInst *Branch = dyn_cast<BranchInst>(Terminator); + assert(Branch && Branch->isUnconditional()); + assert(std::next(BasicBlock::const_iterator(IntrinCall)) == + BasicBlock::const_iterator(Branch)); + + ReturnInst::Create(NewBB->getContext(), + BlockAddress::get(Branch->getSuccessor(0)), NewBB); + + // We just added a terminator to the cloned block. + // Tell the caller to stop processing the current basic block so that + // the branch instruction will be skipped. + return CloningDirector::StopCloningBB; + } + if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>())) { + auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst); + Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts(); + // This causes a replacement that will collapse the landing pad CFG based + // on the filter function we intend to match. + if (Selector == CurrentSelector) + VMap[Inst] = ConstantInt::get(SelectorIDType, 1); + else + VMap[Inst] = ConstantInt::get(SelectorIDType, 0); + // Tell the caller not to clone this instruction. + return CloningDirector::SkipInstruction; + } + + // Continue with the default cloning behavior. + return CloningDirector::CloneInstruction; +} + +WinEHFrameVariableMaterializer::WinEHFrameVariableMaterializer( + Function *OutlinedFn, FrameVarInfoMap &FrameVarInfo) + : FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) { + Builder.SetInsertPoint(&OutlinedFn->getEntryBlock()); + // FIXME: Do something with the FrameVarMapped so that it is shared across the + // function. +} + +Value *WinEHFrameVariableMaterializer::materializeValueFor(Value *V) { + // If we're asked to materialize an alloca variable, we temporarily + // create a matching alloca in the outlined function. When all the + // outlining is complete, we'll collect these into a structure and + // replace these temporary allocas with GEPs referencing the frame + // allocation block. + if (auto *AV = dyn_cast<AllocaInst>(V)) { + AllocaInst *NewAlloca = Builder.CreateAlloca( + AV->getAllocatedType(), AV->getArraySize(), AV->getName()); + FrameVarInfo[AV].Allocas.push_back(NewAlloca); + return NewAlloca; + } + +// FIXME: Do PHI nodes need special handling? + +// FIXME: Are there other cases we can handle better? GEP, ExtractValue, etc. + +// FIXME: This doesn't work during cloning because it finds an instruction +// in the use list that isn't yet part of a basic block. +#if 0 + // If we're asked to remap some other instruction, we'll need to + // spill it to an alloca variable in the parent function and add a + // temporary alloca in the outlined function to be processed as + // described above. + Instruction *Inst = dyn_cast<Instruction>(V); + if (Inst) { + AllocaInst *Spill = DemoteRegToStack(*Inst, true); + AllocaInst *NewAlloca = Builder.CreateAlloca(Spill->getAllocatedType(), + Spill->getArraySize()); + FrameVarMap[AV] = NewAlloca; + return NewAlloca; + } +#endif + + return nullptr; +} |