//===----------------------------------------------------------------------===//
//
// 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.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/Passes.h"
-#include "llvm/ADT/MapVector.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/SmallSet.h"
-#include "llvm/ADT/SetVector.h"
-#include "llvm/ADT/TinyPtrVector.h"
+#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/LibCallSemantics.h"
#include "llvm/CodeGen/WinEHFuncInfo.h"
-#include "llvm/IR/Dominators.h"
-#include "llvm/IR/Function.h"
-#include "llvm/IR/IRBuilder.h"
-#include "llvm/IR/Instructions.h"
-#include "llvm/IR/IntrinsicInst.h"
-#include "llvm/IR/Module.h"
-#include "llvm/IR/PatternMatch.h"
#include "llvm/Pass.h"
-#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Transforms/Utils/PromoteMemToReg.h"
-#include <memory>
+#include "llvm/Transforms/Utils/SSAUpdater.h"
using namespace llvm;
-using namespace llvm::PatternMatch;
#define DEBUG_TYPE "winehprepare"
-namespace {
-
-// This map is used to model frame variable usage during outlining, to
-// construct a structure type to hold the frame variables in a frame
-// allocation block, and to remap the frame variable allocas (including
-// spill locations as needed) to GEPs that get the variable from the
-// frame allocation structure.
-typedef MapVector<Value *, TinyPtrVector<AllocaInst *>> FrameVarInfoMap;
-
-// TinyPtrVector cannot hold nullptr, so we need our own sentinel that isn't
-// quite null.
-AllocaInst *getCatchObjectSentinel() {
- return static_cast<AllocaInst *>(nullptr) + 1;
-}
+static cl::opt<bool> DisableDemotion(
+ "disable-demotion", cl::Hidden,
+ cl::desc(
+ "Clone multicolor basic blocks but do not demote cross funclet values"),
+ cl::init(false));
-typedef SmallSet<BasicBlock *, 4> VisitedBlockSet;
+static cl::opt<bool> DisableCleanups(
+ "disable-cleanups", cl::Hidden,
+ cl::desc("Do not remove implausible terminators or other similar cleanups"),
+ cl::init(false));
-class LandingPadActions;
-class LandingPadMap;
-
-typedef DenseMap<const BasicBlock *, CatchHandler *> CatchHandlerMapTy;
-typedef DenseMap<const BasicBlock *, CleanupHandler *> CleanupHandlerMapTy;
+namespace {
class WinEHPrepare : public FunctionPass {
public:
static char ID; // Pass identification, replacement for typeid.
- WinEHPrepare(const TargetMachine *TM = nullptr)
- : FunctionPass(ID), DT(nullptr) {}
+ WinEHPrepare(const TargetMachine *TM = nullptr) : FunctionPass(ID) {}
bool runOnFunction(Function &Fn) override;
}
private:
- bool prepareExceptionHandlers(Function &F,
- SmallVectorImpl<LandingPadInst *> &LPads);
- void promoteLandingPadValues(LandingPadInst *LPad);
- void demoteValuesLiveAcrossHandlers(Function &F,
- SmallVectorImpl<LandingPadInst *> &LPads);
- void completeNestedLandingPad(Function *ParentFn,
- LandingPadInst *OutlinedLPad,
- const LandingPadInst *OriginalLPad,
- FrameVarInfoMap &VarInfo);
- bool outlineHandler(ActionHandler *Action, Function *SrcFn,
- LandingPadInst *LPad, BasicBlock *StartBB,
- FrameVarInfoMap &VarInfo);
- void addStubInvokeToHandlerIfNeeded(Function *Handler, Value *PersonalityFn);
-
- void mapLandingPadBlocks(LandingPadInst *LPad, LandingPadActions &Actions);
- CatchHandler *findCatchHandler(BasicBlock *BB, BasicBlock *&NextBB,
- VisitedBlockSet &VisitedBlocks);
- void findCleanupHandlers(LandingPadActions &Actions, BasicBlock *StartBB,
- BasicBlock *EndBB);
-
- void processSEHCatchHandler(CatchHandler *Handler, BasicBlock *StartBB);
+ 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);
+ void demoteNonlocalUses(Value *V, std::set<BasicBlock *> &ColorsForBB,
+ Function &F);
+ bool prepareExplicitEH(Function &F,
+ SmallVectorImpl<BasicBlock *> &EntryBlocks);
+ void replaceTerminatePadWithCleanup(Function &F);
+ void colorFunclets(Function &F, SmallVectorImpl<BasicBlock *> &EntryBlocks);
+ void demotePHIsOnFunclets(Function &F);
+ void demoteUsesBetweenFunclets(Function &F);
+ void demoteArgumentUses(Function &F);
+ void cloneCommonBlocks(Function &F,
+ SmallVectorImpl<BasicBlock *> &EntryBlocks);
+ void removeImplausibleTerminators(Function &F);
+ void cleanupPreparedFunclets(Function &F);
+ void verifyPreparedFunclets(Function &F);
// All fields are reset by runOnFunction.
- DominatorTree *DT;
- EHPersonality Personality;
- CatchHandlerMapTy CatchHandlerMap;
- CleanupHandlerMapTy CleanupHandlerMap;
- DenseMap<const LandingPadInst *, LandingPadMap> LPadMaps;
-
- // This maps landing pad instructions found in outlined handlers to
- // the landing pad instruction in the parent function from which they
- // were cloned. The cloned/nested landing pad is used as the key
- // because the landing pad may be cloned into multiple handlers.
- // This map will be used to add the llvm.eh.actions call to the nested
- // landing pads after all handlers have been outlined.
- DenseMap<LandingPadInst *, const LandingPadInst *> NestedLPtoOriginalLP;
-
- // This maps blocks in the parent function which are destinations of
- // catch handlers to cloned blocks in (other) outlined handlers. This
- // handles the case where a nested landing pads has a catch handler that
- // returns to a handler function rather than the parent function.
- // The original block is used as the key here because there should only
- // ever be one handler function from which the cloned block is not pruned.
- // The original block will be pruned from the parent function after all
- // handlers have been outlined. This map will be used to adjust the
- // return instructions of handlers which return to the block that was
- // outlined into a handler. This is done after all handlers have been
- // outlined but before the outlined code is pruned from the parent function.
- DenseMap<const BasicBlock *, BasicBlock *> LPadTargetBlocks;
-};
-
-class WinEHFrameVariableMaterializer : public ValueMaterializer {
-public:
- WinEHFrameVariableMaterializer(Function *OutlinedFn,
- FrameVarInfoMap &FrameVarInfo);
- ~WinEHFrameVariableMaterializer() override {}
-
- Value *materializeValueFor(Value *V) override;
-
- void escapeCatchObject(Value *V);
-
-private:
- FrameVarInfoMap &FrameVarInfo;
- IRBuilder<> Builder;
-};
-
-class LandingPadMap {
-public:
- LandingPadMap() : OriginLPad(nullptr) {}
- void mapLandingPad(const LandingPadInst *LPad);
-
- bool isInitialized() { return OriginLPad != nullptr; }
-
- bool isOriginLandingPadBlock(const BasicBlock *BB) const;
- bool isLandingPadSpecificInst(const Instruction *Inst) const;
-
- void remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
- Value *SelectorValue) const;
-
-private:
- const LandingPadInst *OriginLPad;
- // We will normally only see one of each of these instructions, but
- // if more than one occurs for some reason we can handle that.
- TinyPtrVector<const ExtractValueInst *> ExtractedEHPtrs;
- TinyPtrVector<const ExtractValueInst *> ExtractedSelectors;
-};
-
-class WinEHCloningDirectorBase : public CloningDirector {
-public:
- WinEHCloningDirectorBase(Function *HandlerFn, FrameVarInfoMap &VarInfo,
- LandingPadMap &LPadMap)
- : Materializer(HandlerFn, VarInfo),
- SelectorIDType(Type::getInt32Ty(HandlerFn->getContext())),
- Int8PtrType(Type::getInt8PtrTy(HandlerFn->getContext())),
- LPadMap(LPadMap) {
- auto AI = HandlerFn->getArgumentList().begin();
- ++AI;
- EstablisherFrame = AI;
- }
-
- CloningAction handleInstruction(ValueToValueMapTy &VMap,
- const Instruction *Inst,
- BasicBlock *NewBB) override;
-
- virtual CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
- const Instruction *Inst,
- BasicBlock *NewBB) = 0;
- virtual CloningAction handleEndCatch(ValueToValueMapTy &VMap,
- const Instruction *Inst,
- BasicBlock *NewBB) = 0;
- virtual CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
- const Instruction *Inst,
- BasicBlock *NewBB) = 0;
- virtual CloningAction handleInvoke(ValueToValueMapTy &VMap,
- const InvokeInst *Invoke,
- BasicBlock *NewBB) = 0;
- virtual CloningAction handleResume(ValueToValueMapTy &VMap,
- const ResumeInst *Resume,
- BasicBlock *NewBB) = 0;
- virtual CloningAction handleCompare(ValueToValueMapTy &VMap,
- const CmpInst *Compare,
- BasicBlock *NewBB) = 0;
- virtual CloningAction handleLandingPad(ValueToValueMapTy &VMap,
- const LandingPadInst *LPad,
- BasicBlock *NewBB) = 0;
-
- ValueMaterializer *getValueMaterializer() override { return &Materializer; }
-
-protected:
- WinEHFrameVariableMaterializer Materializer;
- Type *SelectorIDType;
- Type *Int8PtrType;
- LandingPadMap &LPadMap;
-
- /// The value representing the parent frame pointer.
- Value *EstablisherFrame;
-};
-
-class WinEHCatchDirector : public WinEHCloningDirectorBase {
-public:
- WinEHCatchDirector(
- Function *CatchFn, Value *Selector, FrameVarInfoMap &VarInfo,
- LandingPadMap &LPadMap,
- DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPads)
- : WinEHCloningDirectorBase(CatchFn, VarInfo, LPadMap),
- CurrentSelector(Selector->stripPointerCasts()),
- ExceptionObjectVar(nullptr), NestedLPtoOriginalLP(NestedLPads) {}
-
- CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
- const Instruction *Inst,
- BasicBlock *NewBB) override;
- CloningAction handleEndCatch(ValueToValueMapTy &VMap, const Instruction *Inst,
- BasicBlock *NewBB) override;
- CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
- const Instruction *Inst,
- BasicBlock *NewBB) override;
- CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
- BasicBlock *NewBB) override;
- CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
- BasicBlock *NewBB) override;
- CloningAction handleCompare(ValueToValueMapTy &VMap,
- const CmpInst *Compare, BasicBlock *NewBB) override;
- CloningAction handleLandingPad(ValueToValueMapTy &VMap,
- const LandingPadInst *LPad,
- BasicBlock *NewBB) override;
-
- Value *getExceptionVar() { return ExceptionObjectVar; }
- TinyPtrVector<BasicBlock *> &getReturnTargets() { return ReturnTargets; }
-
-private:
- Value *CurrentSelector;
-
- Value *ExceptionObjectVar;
- TinyPtrVector<BasicBlock *> ReturnTargets;
-
- // This will be a reference to the field of the same name in the WinEHPrepare
- // object which instantiates this WinEHCatchDirector object.
- DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPtoOriginalLP;
-};
-
-class WinEHCleanupDirector : public WinEHCloningDirectorBase {
-public:
- WinEHCleanupDirector(Function *CleanupFn, FrameVarInfoMap &VarInfo,
- LandingPadMap &LPadMap)
- : WinEHCloningDirectorBase(CleanupFn, VarInfo, LPadMap) {}
-
- CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
- const Instruction *Inst,
- BasicBlock *NewBB) override;
- CloningAction handleEndCatch(ValueToValueMapTy &VMap, const Instruction *Inst,
- BasicBlock *NewBB) override;
- CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
- const Instruction *Inst,
- BasicBlock *NewBB) override;
- CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
- BasicBlock *NewBB) override;
- CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
- BasicBlock *NewBB) override;
- CloningAction handleCompare(ValueToValueMapTy &VMap,
- const CmpInst *Compare, BasicBlock *NewBB) override;
- CloningAction handleLandingPad(ValueToValueMapTy &VMap,
- const LandingPadInst *LPad,
- BasicBlock *NewBB) override;
-};
-
-class LandingPadActions {
-public:
- LandingPadActions() : HasCleanupHandlers(false) {}
-
- void insertCatchHandler(CatchHandler *Action) { Actions.push_back(Action); }
- void insertCleanupHandler(CleanupHandler *Action) {
- Actions.push_back(Action);
- HasCleanupHandlers = true;
- }
-
- bool includesCleanup() const { return HasCleanupHandlers; }
-
- SmallVectorImpl<ActionHandler *> &actions() { return Actions; }
- SmallVectorImpl<ActionHandler *>::iterator begin() { return Actions.begin(); }
- SmallVectorImpl<ActionHandler *>::iterator end() { return Actions.end(); }
+ EHPersonality Personality = EHPersonality::Unknown;
-private:
- // Note that this class does not own the ActionHandler objects in this vector.
- // The ActionHandlers are owned by the CatchHandlerMap and CleanupHandlerMap
- // in the WinEHPrepare class.
- SmallVector<ActionHandler *, 4> Actions;
- bool HasCleanupHandlers;
+ std::map<BasicBlock *, std::set<BasicBlock *>> BlockColors;
+ std::map<BasicBlock *, std::set<BasicBlock *>> FuncletBlocks;
+ std::map<BasicBlock *, std::set<BasicBlock *>> FuncletChildren;
};
} // end anonymous namespace
return new WinEHPrepare(TM);
}
-// FIXME: Remove this once the backend can handle the prepared IR.
-static cl::opt<bool>
- 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<LandingPadInst *, 4> LPads;
- SmallVector<ResumeInst *, 4> Resumes;
+static void findFuncletEntryPoints(Function &Fn,
+ SmallVectorImpl<BasicBlock *> &EntryBlocks) {
+ EntryBlocks.push_back(&Fn.getEntryBlock());
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);
+ Instruction *First = BB.getFirstNonPHI();
+ if (!First->isEHPad())
+ continue;
+ assert(!isa<LandingPadInst>(First) &&
+ "landingpad cannot be used with funclet EH personality");
+ // Find EH pad blocks that represent funclet start points.
+ if (!isa<CatchEndPadInst>(First) && !isa<CleanupEndPadInst>(First))
+ EntryBlocks.push_back(&BB);
}
+}
- // No need to prepare functions that lack landing pads.
- if (LPads.empty())
+bool WinEHPrepare::runOnFunction(Function &Fn) {
+ if (!Fn.hasPersonalityFn())
return false;
// Classify the personality to see what kind of preparation we need.
- Personality = classifyEHPersonality(LPads.back()->getPersonalityFn());
+ Personality = classifyEHPersonality(Fn.getPersonalityFn());
- // Do nothing if this is not an MSVC personality.
- if (!isMSVCEHPersonality(Personality))
+ // Do nothing if this is not a funclet-based personality.
+ if (!isFuncletEHPersonality(Personality))
return false;
- DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+ // 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(Fn);
- 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;
+ SmallVector<BasicBlock *, 4> EntryBlocks;
+ findFuncletEntryPoints(Fn, EntryBlocks);
+ return prepareExplicitEH(Fn, EntryBlocks);
}
bool WinEHPrepare::doFinalization(Module &M) { return false; }
-void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired<DominatorTreeWrapperPass>();
+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 bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler,
- Constant *&Selector, BasicBlock *&NextBB);
+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 (isa<ConstantPointerNull>(CPI->getArgOperand(2)))
+ HT.CatchObj.Alloca = nullptr;
+ else
+ HT.CatchObj.Alloca = cast<AllocaInst>(CPI->getArgOperand(2));
+ TBME.HandlerArray.push_back(HT);
+ }
+ FuncInfo.TryBlockMap.push_back(TBME);
+}
-// Finds blocks reachable from the starting set Worklist. Does not follow unwind
-// edges or blocks listed in StopPoints.
-static void findReachableBlocks(SmallPtrSetImpl<BasicBlock *> &ReachableBBs,
- SetVector<BasicBlock *> &Worklist,
- const SetVector<BasicBlock *> *StopPoints) {
- while (!Worklist.empty()) {
- BasicBlock *BB = Worklist.pop_back_val();
+static const CatchPadInst *getSingleCatchPadPredecessor(const BasicBlock *BB) {
+ for (const BasicBlock *PredBlock : predecessors(BB))
+ if (auto *CPI = dyn_cast<CatchPadInst>(PredBlock->getFirstNonPHI()))
+ return CPI;
+ return nullptr;
+}
- // Don't cross blocks that we should stop at.
- if (StopPoints && StopPoints->count(BB))
- continue;
+/// Find all the catchpads that feed directly into the catchendpad. Frontends
+/// using this personality should ensure that each catchendpad and catchpad has
+/// one or zero catchpad predecessors.
+///
+/// The following C++ generates the IR after it:
+/// try {
+/// } catch (A) {
+/// } catch (B) {
+/// }
+///
+/// IR:
+/// %catchpad.A
+/// catchpad [i8* A typeinfo]
+/// to label %catch.A unwind label %catchpad.B
+/// %catchpad.B
+/// catchpad [i8* B typeinfo]
+/// to label %catch.B unwind label %endcatches
+/// %endcatches
+/// catchendblock unwind to caller
+static void
+findCatchPadsForCatchEndPad(const BasicBlock *CatchEndBB,
+ SmallVectorImpl<const CatchPadInst *> &Handlers) {
+ const CatchPadInst *CPI = getSingleCatchPadPredecessor(CatchEndBB);
+ while (CPI) {
+ Handlers.push_back(CPI);
+ CPI = getSingleCatchPadPredecessor(CPI->getParent());
+ }
+ // We've pushed these back into reverse source order. Reverse them to get
+ // the list back into source order.
+ std::reverse(Handlers.begin(), Handlers.end());
+}
- if (!ReachableBBs.insert(BB).second)
- continue; // Already visited.
+// 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) {
+ const TerminatorInst *TI = BB->getTerminator();
+ if (isa<InvokeInst>(TI))
+ return nullptr;
+ if (TI->isEHPad())
+ return BB;
+ return cast<CleanupReturnInst>(TI)->getCleanupPad()->getParent();
+}
- // Don't follow unwind edges of invokes.
- if (auto *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
- Worklist.insert(II->getNormalDest());
- continue;
- }
+static void calculateExplicitCXXStateNumbers(WinEHFuncInfo &FuncInfo,
+ const BasicBlock &BB,
+ int ParentState) {
+ assert(BB.isEHPad());
+ const Instruction *FirstNonPHI = BB.getFirstNonPHI();
+ // All catchpad instructions will be handled when we process their
+ // respective catchendpad instruction.
+ if (isa<CatchPadInst>(FirstNonPHI))
+ return;
- // Otherwise, follow all successors.
- Worklist.insert(succ_begin(BB), succ_end(BB));
+ if (isa<CatchEndPadInst>(FirstNonPHI)) {
+ SmallVector<const CatchPadInst *, 2> Handlers;
+ findCatchPadsForCatchEndPad(&BB, Handlers);
+ const BasicBlock *FirstTryPad = Handlers.front()->getParent();
+ int TryLow = addUnwindMapEntry(FuncInfo, ParentState, nullptr);
+ FuncInfo.EHPadStateMap[Handlers.front()] = TryLow;
+ for (const BasicBlock *PredBlock : predecessors(FirstTryPad))
+ if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
+ calculateExplicitCXXStateNumbers(FuncInfo, *PredBlock, TryLow);
+ int CatchLow = addUnwindMapEntry(FuncInfo, ParentState, nullptr);
+
+ // catchpads are separate funclets in C++ EH due to the way rethrow works.
+ // In SEH, they aren't, so no invokes will unwind to the catchendpad.
+ FuncInfo.EHPadStateMap[FirstNonPHI] = CatchLow;
+ int TryHigh = CatchLow - 1;
+ for (const BasicBlock *PredBlock : predecessors(&BB))
+ if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
+ calculateExplicitCXXStateNumbers(FuncInfo, *PredBlock, CatchLow);
+ int CatchHigh = FuncInfo.getLastStateNumber();
+ addTryBlockMapEntry(FuncInfo, TryLow, TryHigh, CatchHigh, Handlers);
+ DEBUG(dbgs() << "TryLow[" << FirstTryPad->getName() << "]: " << TryLow
+ << '\n');
+ DEBUG(dbgs() << "TryHigh[" << FirstTryPad->getName() << "]: " << TryHigh
+ << '\n');
+ DEBUG(dbgs() << "CatchHigh[" << FirstTryPad->getName() << "]: " << CatchHigh
+ << '\n');
+ } else if (isa<CleanupPadInst>(FirstNonPHI)) {
+ // A cleanup can have multiple exits; don't re-process after the first.
+ if (FuncInfo.EHPadStateMap.count(FirstNonPHI))
+ return;
+ int CleanupState = addUnwindMapEntry(FuncInfo, ParentState, &BB);
+ FuncInfo.EHPadStateMap[FirstNonPHI] = CleanupState;
+ DEBUG(dbgs() << "Assigning state #" << CleanupState << " to BB "
+ << BB.getName() << '\n');
+ for (const BasicBlock *PredBlock : predecessors(&BB))
+ if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
+ calculateExplicitCXXStateNumbers(FuncInfo, *PredBlock, CleanupState);
+ } else if (auto *CEPI = dyn_cast<CleanupEndPadInst>(FirstNonPHI)) {
+ // Propagate ParentState to the cleanuppad in case it doesn't have
+ // any cleanuprets.
+ BasicBlock *CleanupBlock = CEPI->getCleanupPad()->getParent();
+ calculateExplicitCXXStateNumbers(FuncInfo, *CleanupBlock, ParentState);
+ // Anything unwinding through CleanupEndPadInst is in ParentState.
+ FuncInfo.EHPadStateMap[FirstNonPHI] = ParentState;
+ for (const BasicBlock *PredBlock : predecessors(&BB))
+ if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
+ calculateExplicitCXXStateNumbers(FuncInfo, *PredBlock, ParentState);
+ } else if (isa<TerminatePadInst>(FirstNonPHI)) {
+ report_fatal_error("Not yet implemented!");
+ } else {
+ llvm_unreachable("unexpected EH Pad!");
}
}
-/// Find all points where exceptional control rejoins normal control flow via
-/// llvm.eh.endcatch. Add them to the normal bb reachability worklist.
-static void findCXXEHReturnPoints(Function &F,
- SetVector<BasicBlock *> &EHReturnBlocks) {
- for (auto BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) {
- BasicBlock *BB = BBI;
- for (Instruction &I : *BB) {
- if (match(&I, m_Intrinsic<Intrinsic::eh_endcatch>())) {
- // Split the block after the call to llvm.eh.endcatch if there is
- // anything other than an unconditional branch, or if the successor
- // starts with a phi.
- auto *Br = dyn_cast<BranchInst>(I.getNextNode());
- if (!Br || !Br->isUnconditional() ||
- isa<PHINode>(Br->getSuccessor(0)->begin())) {
- DEBUG(dbgs() << "splitting block " << BB->getName()
- << " with llvm.eh.endcatch\n");
- BBI = BB->splitBasicBlock(I.getNextNode(), "ehreturn");
- }
- // The next BB is normal control flow.
- EHReturnBlocks.insert(BB->getTerminator()->getSuccessor(0));
- break;
- }
- }
- }
+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 bool isCatchAllLandingPad(const BasicBlock *BB) {
- const LandingPadInst *LP = BB->getLandingPadInst();
- if (!LP)
- return false;
- unsigned N = LP->getNumClauses();
- return (N > 0 && LP->isCatch(N - 1) &&
- isa<ConstantPointerNull>(LP->getClause(N - 1)));
+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;
}
-/// Find all points where exceptions control rejoins normal control flow via
-/// selector dispatch.
-static void findSEHEHReturnPoints(Function &F,
- SetVector<BasicBlock *> &EHReturnBlocks) {
- for (auto BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) {
- BasicBlock *BB = BBI;
- // If the landingpad is a catch-all, treat the whole lpad as if it is
- // reachable from normal control flow.
- // FIXME: This is imprecise. We need a better way of identifying where a
- // catch-all starts and cleanups stop. As far as LLVM is concerned, there
- // is no difference.
- if (isCatchAllLandingPad(BB)) {
- EHReturnBlocks.insert(BB);
- continue;
- }
+static void calculateExplicitSEHStateNumbers(WinEHFuncInfo &FuncInfo,
+ const BasicBlock &BB,
+ int ParentState) {
+ assert(BB.isEHPad());
+ const Instruction *FirstNonPHI = BB.getFirstNonPHI();
+ // All catchpad instructions will be handled when we process their
+ // respective catchendpad instruction.
+ if (isa<CatchPadInst>(FirstNonPHI))
+ return;
- BasicBlock *CatchHandler;
- BasicBlock *NextBB;
- Constant *Selector;
- if (isSelectorDispatch(BB, CatchHandler, Selector, NextBB)) {
- // Split the edge if there is a phi node. Returning from EH to a phi node
- // is just as impossible as having a phi after an indirectbr.
- if (isa<PHINode>(CatchHandler->begin())) {
- DEBUG(dbgs() << "splitting EH return edge from " << BB->getName()
- << " to " << CatchHandler->getName() << '\n');
- BBI = CatchHandler = SplitCriticalEdge(
- BB, std::find(succ_begin(BB), succ_end(BB), CatchHandler));
- }
- EHReturnBlocks.insert(CatchHandler);
- }
+ if (isa<CatchEndPadInst>(FirstNonPHI)) {
+ // Extract the filter function and the __except basic block and create a
+ // state for them.
+ SmallVector<const CatchPadInst *, 1> Handlers;
+ findCatchPadsForCatchEndPad(&BB, Handlers);
+ assert(Handlers.size() == 1 &&
+ "SEH doesn't have multiple handlers per __try");
+ const CatchPadInst *CPI = Handlers.front();
+ const BasicBlock *CatchPadBB = CPI->getParent();
+ const Constant *FilterOrNull =
+ cast<Constant>(CPI->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[CPI] = TryState;
+ DEBUG(dbgs() << "Assigning state #" << TryState << " to BB "
+ << CatchPadBB->getName() << '\n');
+ for (const BasicBlock *PredBlock : predecessors(CatchPadBB))
+ if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
+ calculateExplicitSEHStateNumbers(FuncInfo, *PredBlock, TryState);
+
+ // Everything in the __except block unwinds to ParentState, just like code
+ // outside the __try.
+ FuncInfo.EHPadStateMap[FirstNonPHI] = ParentState;
+ DEBUG(dbgs() << "Assigning state #" << ParentState << " to BB "
+ << BB.getName() << '\n');
+ for (const BasicBlock *PredBlock : predecessors(&BB))
+ if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
+ calculateExplicitSEHStateNumbers(FuncInfo, *PredBlock, ParentState);
+ } else if (isa<CleanupPadInst>(FirstNonPHI)) {
+ // A cleanup can have multiple exits; don't re-process after the first.
+ if (FuncInfo.EHPadStateMap.count(FirstNonPHI))
+ return;
+ int CleanupState = addSEHFinally(FuncInfo, ParentState, &BB);
+ FuncInfo.EHPadStateMap[FirstNonPHI] = CleanupState;
+ DEBUG(dbgs() << "Assigning state #" << CleanupState << " to BB "
+ << BB.getName() << '\n');
+ for (const BasicBlock *PredBlock : predecessors(&BB))
+ if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
+ calculateExplicitSEHStateNumbers(FuncInfo, *PredBlock, CleanupState);
+ } else if (auto *CEPI = dyn_cast<CleanupEndPadInst>(FirstNonPHI)) {
+ // Propagate ParentState to the cleanuppad in case it doesn't have
+ // any cleanuprets.
+ BasicBlock *CleanupBlock = CEPI->getCleanupPad()->getParent();
+ calculateExplicitSEHStateNumbers(FuncInfo, *CleanupBlock, ParentState);
+ // Anything unwinding through CleanupEndPadInst is in ParentState.
+ FuncInfo.EHPadStateMap[FirstNonPHI] = ParentState;
+ DEBUG(dbgs() << "Assigning state #" << ParentState << " to BB "
+ << BB.getName() << '\n');
+ for (const BasicBlock *PredBlock : predecessors(&BB))
+ if ((PredBlock = getEHPadFromPredecessor(PredBlock)))
+ calculateExplicitSEHStateNumbers(FuncInfo, *PredBlock, ParentState);
+ } else if (isa<TerminatePadInst>(FirstNonPHI)) {
+ report_fatal_error("Not yet implemented!");
+ } else {
+ llvm_unreachable("unexpected EH Pad!");
}
}
-/// Ensure that all values live into and out of exception handlers are stored
-/// in memory.
-/// FIXME: This falls down when values are defined in one handler and live into
-/// another handler. For example, a cleanup defines a value used only by a
-/// catch handler.
-void WinEHPrepare::demoteValuesLiveAcrossHandlers(
- Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
- DEBUG(dbgs() << "Demoting values live across exception handlers in function "
- << F.getName() << '\n');
-
- // 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<BasicBlock *, 4> NormalBlocks;
- SmallPtrSet<BasicBlock *, 4> EHBlocks;
- SetVector<BasicBlock *> EHReturnBlocks;
- SetVector<BasicBlock *> 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<PHINode>(BB->begin())) &&
- "non-lpad EH return block has phi");
-#endif
-
- // Normal blocks are the blocks reachable from the entry block and all EH
- // return points.
- 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<Argument *> ArgsToDemote;
- SetVector<Instruction *> InstrsToDemote;
- for (BasicBlock &BB : F) {
- bool IsNormalBB = NormalBlocks.count(&BB);
- bool IsEHBB = EHBlocks.count(&BB);
- if (!IsNormalBB && !IsEHBB)
- continue; // Blocks that are neither normal nor EH are unreachable.
- for (Instruction &I : BB) {
- for (Value *Op : I.operands()) {
- // Don't demote static allocas, constants, and labels.
- if (isa<Constant>(Op) || isa<BasicBlock>(Op) || isa<InlineAsm>(Op))
- continue;
- auto *AI = dyn_cast<AllocaInst>(Op);
- if (AI && AI->isStaticAlloca())
- continue;
+/// Check if the EH Pad unwinds to caller. Cleanups are a little bit of a
+/// special case because we have to look at the cleanupret instruction that uses
+/// the cleanuppad.
+static bool doesEHPadUnwindToCaller(const Instruction *EHPad) {
+ auto *CPI = dyn_cast<CleanupPadInst>(EHPad);
+ if (!CPI)
+ return EHPad->mayThrow();
- if (auto *Arg = dyn_cast<Argument>(Op)) {
- if (IsEHBB) {
- DEBUG(dbgs() << "Demoting argument " << *Arg
- << " used by EH instr: " << I << "\n");
- ArgsToDemote.insert(Arg);
- }
- continue;
- }
+ // This cleanup does not return or unwind, so we say it unwinds to caller.
+ if (CPI->use_empty())
+ return true;
- auto *OpI = cast<Instruction>(Op);
- BasicBlock *OpBB = OpI->getParent();
- // If a value is produced and consumed in the same BB, we don't need to
- // demote it.
- if (OpBB == &BB)
- continue;
- bool IsOpNormalBB = NormalBlocks.count(OpBB);
- bool IsOpEHBB = EHBlocks.count(OpBB);
- if (IsNormalBB != IsOpNormalBB || IsEHBB != IsOpEHBB) {
- DEBUG({
- dbgs() << "Demoting instruction live in-out from EH:\n";
- dbgs() << "Instr: " << *OpI << '\n';
- dbgs() << "User: " << I << '\n';
- });
- InstrsToDemote.insert(OpI);
- }
- }
- }
- }
+ const Instruction *User = CPI->user_back();
+ if (auto *CRI = dyn_cast<CleanupReturnInst>(User))
+ return CRI->unwindsToCaller();
+ return cast<CleanupEndPadInst>(User)->unwindsToCaller();
+}
- // Demote values live into and out of handlers.
- // FIXME: This demotion is inefficient. We should insert spills at the point
- // of definition, insert one reload in each handler that uses the value, and
- // insert reloads in the BB used to rejoin normal control flow.
- Instruction *AllocaInsertPt = F.getEntryBlock().getFirstInsertionPt();
- for (Instruction *I : InstrsToDemote)
- DemoteRegToStack(*I, false, AllocaInsertPt);
-
- // Demote arguments separately, and only for uses in EH blocks.
- for (Argument *Arg : ArgsToDemote) {
- auto *Slot = new AllocaInst(Arg->getType(), nullptr,
- Arg->getName() + ".reg2mem", AllocaInsertPt);
- SmallVector<User *, 4> Users(Arg->user_begin(), Arg->user_end());
- for (User *U : Users) {
- auto *I = dyn_cast<Instruction>(U);
- if (I && EHBlocks.count(I->getParent())) {
- auto *Reload = new LoadInst(Slot, Arg->getName() + ".reload", false, I);
- U->replaceUsesOfWith(Arg, Reload);
- }
- }
- new StoreInst(Arg, Slot, AllocaInsertPt);
- }
+void llvm::calculateSEHStateNumbers(const Function *Fn,
+ WinEHFuncInfo &FuncInfo) {
+ // Don't compute state numbers twice.
+ if (!FuncInfo.SEHUnwindMap.empty())
+ return;
- // Demote landingpad phis, as the landingpad will be removed from the machine
- // CFG.
- for (LandingPadInst *LPI : LPads) {
- BasicBlock *BB = LPI->getParent();
- while (auto *Phi = dyn_cast<PHINode>(BB->begin()))
- DemotePHIToStack(Phi, AllocaInsertPt);
+ for (const BasicBlock &BB : *Fn) {
+ if (!BB.isEHPad() || !doesEHPadUnwindToCaller(BB.getFirstNonPHI()))
+ continue;
+ calculateExplicitSEHStateNumbers(FuncInfo, BB, -1);
}
-
- DEBUG(dbgs() << "Demoted " << InstrsToDemote.size() << " instructions and "
- << ArgsToDemote.size() << " arguments for WinEHPrepare\n\n");
}
-bool WinEHPrepare::prepareExceptionHandlers(
- Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
- // Don't run on functions that are already prepared.
- for (LandingPadInst *LPad : LPads) {
- BasicBlock *LPadBB = LPad->getParent();
- for (Instruction &Inst : *LPadBB)
- if (match(&Inst, m_Intrinsic<Intrinsic::eh_actions>()))
- return false;
+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;
+ if (BB.isLandingPad())
+ report_fatal_error("MSVC C++ EH cannot use landingpads");
+ const Instruction *FirstNonPHI = BB.getFirstNonPHI();
+ if (!doesEHPadUnwindToCaller(FirstNonPHI))
+ continue;
+ calculateExplicitCXXStateNumbers(FuncInfo, BB, -1);
}
+}
- demoteValuesLiveAcrossHandlers(F, LPads);
+static int addClrEHHandler(WinEHFuncInfo &FuncInfo, int ParentState,
+ ClrHandlerType HandlerType, uint32_t TypeToken,
+ const BasicBlock *Handler) {
+ ClrEHUnwindMapEntry Entry;
+ Entry.Parent = ParentState;
+ Entry.Handler = Handler;
+ Entry.HandlerType = HandlerType;
+ Entry.TypeToken = TypeToken;
+ FuncInfo.ClrEHUnwindMap.push_back(Entry);
+ return FuncInfo.ClrEHUnwindMap.size() - 1;
+}
- // 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;
+void llvm::calculateClrEHStateNumbers(const Function *Fn,
+ WinEHFuncInfo &FuncInfo) {
+ // Return if it's already been done.
+ if (!FuncInfo.EHPadStateMap.empty())
+ return;
- bool HandlersOutlined = false;
+ SmallVector<std::pair<const Instruction *, int>, 8> Worklist;
- Module *M = F.getParent();
- LLVMContext &Context = M->getContext();
+ // Each pad needs to be able to refer to its parent, so scan the function
+ // looking for top-level handlers and seed the worklist with them.
+ for (const BasicBlock &BB : *Fn) {
+ if (!BB.isEHPad())
+ continue;
+ if (BB.isLandingPad())
+ report_fatal_error("CoreCLR EH cannot use landingpads");
+ const Instruction *FirstNonPHI = BB.getFirstNonPHI();
+ if (!doesEHPadUnwindToCaller(FirstNonPHI))
+ continue;
+ // queue this with sentinel parent state -1 to mean unwind to caller.
+ Worklist.emplace_back(FirstNonPHI, -1);
+ }
- // Create a new function to receive the handler contents.
- PointerType *Int8PtrType = Type::getInt8PtrTy(Context);
- Type *Int32Type = Type::getInt32Ty(Context);
- Function *ActionIntrin = Intrinsic::getDeclaration(M, Intrinsic::eh_actions);
+ while (!Worklist.empty()) {
+ const Instruction *Pad;
+ int ParentState;
+ std::tie(Pad, ParentState) = Worklist.pop_back_val();
+
+ int PredState;
+ if (const CleanupEndPadInst *EndPad = dyn_cast<CleanupEndPadInst>(Pad)) {
+ FuncInfo.EHPadStateMap[EndPad] = ParentState;
+ // Queue the cleanuppad, in case it doesn't have a cleanupret.
+ Worklist.emplace_back(EndPad->getCleanupPad(), ParentState);
+ // Preds of the endpad should get the parent state.
+ PredState = ParentState;
+ } else if (const CleanupPadInst *Cleanup = dyn_cast<CleanupPadInst>(Pad)) {
+ // A cleanup can have multiple exits; don't re-process after the first.
+ if (FuncInfo.EHPadStateMap.count(Pad))
+ continue;
+ // CoreCLR personality uses arity to distinguish faults from finallies.
+ const BasicBlock *PadBlock = Cleanup->getParent();
+ ClrHandlerType HandlerType =
+ (Cleanup->getNumOperands() ? ClrHandlerType::Fault
+ : ClrHandlerType::Finally);
+ int NewState =
+ addClrEHHandler(FuncInfo, ParentState, HandlerType, 0, PadBlock);
+ FuncInfo.EHPadStateMap[Cleanup] = NewState;
+ // Propagate the new state to all preds of the cleanup
+ PredState = NewState;
+ } else if (const CatchEndPadInst *EndPad = dyn_cast<CatchEndPadInst>(Pad)) {
+ FuncInfo.EHPadStateMap[EndPad] = ParentState;
+ // Preds of the endpad should get the parent state.
+ PredState = ParentState;
+ } else if (const CatchPadInst *Catch = dyn_cast<CatchPadInst>(Pad)) {
+ const BasicBlock *PadBlock = Catch->getParent();
+ uint32_t TypeToken = static_cast<uint32_t>(
+ cast<ConstantInt>(Catch->getArgOperand(0))->getZExtValue());
+ int NewState = addClrEHHandler(FuncInfo, ParentState,
+ ClrHandlerType::Catch, TypeToken, PadBlock);
+ FuncInfo.EHPadStateMap[Catch] = NewState;
+ // Preds of the catch get its state
+ PredState = NewState;
+ } else {
+ llvm_unreachable("Unexpected EH pad");
+ }
- for (LandingPadInst *LPad : LPads) {
- // Look for evidence that this landingpad has already been processed.
- bool LPadHasActionList = false;
- BasicBlock *LPadBB = LPad->getParent();
- for (Instruction &Inst : *LPadBB) {
- if (match(&Inst, m_Intrinsic<Intrinsic::eh_actions>())) {
- LPadHasActionList = true;
- break;
- }
+ // Queue all predecessors with the given state
+ for (const BasicBlock *Pred : predecessors(Pad->getParent())) {
+ if ((Pred = getEHPadFromPredecessor(Pred)))
+ Worklist.emplace_back(Pred->getFirstNonPHI(), PredState);
}
+ }
+}
- // If we've already outlined the handlers for this landingpad,
- // there's nothing more to do here.
- if (LPadHasActionList)
+void WinEHPrepare::replaceTerminatePadWithCleanup(Function &F) {
+ if (Personality != EHPersonality::MSVC_CXX)
+ return;
+ for (BasicBlock &BB : F) {
+ Instruction *First = BB.getFirstNonPHI();
+ auto *TPI = dyn_cast<TerminatePadInst>(First);
+ if (!TPI)
continue;
- // If either of the values in the aggregate returned by the landing pad is
- // extracted and stored to memory, promote the stored value to a register.
- promoteLandingPadValues(LPad);
+ if (TPI->getNumArgOperands() != 1)
+ report_fatal_error(
+ "Expected a unary terminatepad for MSVC C++ personalities!");
- LandingPadActions Actions;
- mapLandingPadBlocks(LPad, Actions);
+ auto *TerminateFn = dyn_cast<Function>(TPI->getArgOperand(0));
+ if (!TerminateFn)
+ report_fatal_error("Function operand expected in terminatepad for MSVC "
+ "C++ personalities!");
- HandlersOutlined |= !Actions.actions().empty();
- for (ActionHandler *Action : Actions) {
- if (Action->hasBeenProcessed())
- continue;
- BasicBlock *StartBB = Action->getStartBlock();
-
- // SEH doesn't do any outlining for catches. Instead, pass the handler
- // basic block addr to llvm.eh.actions and list the block as a return
- // target.
- if (isAsynchronousEHPersonality(Personality)) {
- if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
- processSEHCatchHandler(CatchAction, StartBB);
- continue;
- }
- }
+ // Insert the cleanuppad instruction.
+ auto *CPI = CleanupPadInst::Create(
+ BB.getContext(), {}, Twine("terminatepad.for.", BB.getName()), &BB);
- outlineHandler(Action, &F, LPad, StartBB, FrameVarInfo);
- }
+ // Insert the call to the terminate instruction.
+ auto *CallTerminate = CallInst::Create(TerminateFn, {}, &BB);
+ CallTerminate->setDoesNotThrow();
+ CallTerminate->setDoesNotReturn();
+ CallTerminate->setCallingConv(TerminateFn->getCallingConv());
- // Replace the landing pad with a new llvm.eh.action based landing pad.
- BasicBlock *NewLPadBB = BasicBlock::Create(Context, "lpad", &F, LPadBB);
- assert(!isa<PHINode>(LPadBB->begin()));
- auto *NewLPad = cast<LandingPadInst>(LPad->clone());
- NewLPadBB->getInstList().push_back(NewLPad);
- while (!pred_empty(LPadBB)) {
- auto *pred = *pred_begin(LPadBB);
- InvokeInst *Invoke = cast<InvokeInst>(pred->getTerminator());
- Invoke->setUnwindDest(NewLPadBB);
- }
+ // Insert a new terminator for the cleanuppad using the same successor as
+ // the terminatepad.
+ CleanupReturnInst::Create(CPI, TPI->getUnwindDest(), &BB);
- // 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;
- }
- }
+ // Let's remove the terminatepad now that we've inserted the new
+ // instructions.
+ TPI->eraseFromParent();
+ }
+}
- // Replace all extracted values with undef and ultimately replace the
- // landingpad with undef.
- // FIXME: This doesn't handle SEH GetExceptionCode(). For now, we just give
- // out undef until we figure out the codegen support.
- SmallVector<Instruction *, 4> Extracts;
- for (User *U : LPad->users()) {
- auto *E = dyn_cast<ExtractValueInst>(U);
- if (!E)
- continue;
- assert(E->getNumIndices() == 1 &&
- "Unexpected operation: extracting both landing pad values");
- unsigned Idx = E->getIndices()[0];
- assert(Idx == 0 || Idx == 1);
- Extracts.push_back(E);
- }
- for (Instruction *E : Extracts) {
- E->replaceAllUsesWith(UndefValue::get(E->getType()));
- E->eraseFromParent();
- }
- LPad->replaceAllUsesWith(UndefValue::get(LPad->getType()));
-
- // Add a call to describe the actions for this landing pad.
- std::vector<Value *> ActionArgs;
- for (ActionHandler *Action : Actions) {
- // Action codes from docs are: 0 cleanup, 1 catch.
- if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
- ActionArgs.push_back(ConstantInt::get(Int32Type, 1));
- ActionArgs.push_back(CatchAction->getSelector());
- // Find the frame escape index of the exception object alloca in the
- // parent.
- int FrameEscapeIdx = -1;
- Value *EHObj = const_cast<Value *>(CatchAction->getExceptionVar());
- if (EHObj && !isa<ConstantPointerNull>(EHObj)) {
- auto I = FrameVarInfo.find(EHObj);
- assert(I != FrameVarInfo.end() &&
- "failed to map llvm.eh.begincatch var");
- FrameEscapeIdx = std::distance(FrameVarInfo.begin(), I);
+static void
+colorFunclets(Function &F, SmallVectorImpl<BasicBlock *> &EntryBlocks,
+ std::map<BasicBlock *, std::set<BasicBlock *>> &BlockColors,
+ std::map<BasicBlock *, std::set<BasicBlock *>> &FuncletBlocks,
+ std::map<BasicBlock *, std::set<BasicBlock *>> &FuncletChildren) {
+ SmallVector<std::pair<BasicBlock *, BasicBlock *>, 16> Worklist;
+ BasicBlock *EntryBlock = &F.getEntryBlock();
+
+ // Build up the color map, which maps each block to its set of 'colors'.
+ // For any block B, the "colors" of B are the set of funclets F (possibly
+ // including a root "funclet" representing the main function), such that
+ // F will need to directly contain B or a copy of B (where the term "directly
+ // contain" is used to distinguish from being "transitively contained" in
+ // a nested funclet).
+ // Use a CFG walk driven by a worklist of (block, color) pairs. The "color"
+ // sets attached during this processing to a block which is the entry of some
+ // funclet F is actually the set of F's parents -- i.e. the union of colors
+ // of all predecessors of F's entry. For all other blocks, the color sets
+ // are as defined above. A post-pass fixes up the block color map to reflect
+ // the same sense of "color" for funclet entries as for other blocks.
+
+ Worklist.push_back({EntryBlock, EntryBlock});
+
+ while (!Worklist.empty()) {
+ BasicBlock *Visiting;
+ BasicBlock *Color;
+ std::tie(Visiting, Color) = Worklist.pop_back_val();
+ Instruction *VisitingHead = Visiting->getFirstNonPHI();
+ if (VisitingHead->isEHPad() && !isa<CatchEndPadInst>(VisitingHead) &&
+ !isa<CleanupEndPadInst>(VisitingHead)) {
+ // Mark this as a funclet head as a member of itself.
+ FuncletBlocks[Visiting].insert(Visiting);
+ // Queue exits (i.e. successors of rets/endpads) with the parent color.
+ // Skip any exits that are catchendpads, since the parent color must then
+ // represent one of the catches chained to that catchendpad, but the
+ // catchendpad should get the color of the common parent of all its
+ // chained catches (i.e. the grandparent color of the current pad).
+ // We don't need to worry abou catchendpads going unvisited, since the
+ // catches chained to them must have unwind edges to them by which we will
+ // visit them.
+ for (User *U : VisitingHead->users()) {
+ if (auto *Exit = dyn_cast<TerminatorInst>(U)) {
+ for (BasicBlock *Succ : successors(Exit->getParent()))
+ if (!isa<CatchEndPadInst>(*Succ->getFirstNonPHI()))
+ if (BlockColors[Succ].insert(Color).second)
+ Worklist.push_back({Succ, Color});
}
- ActionArgs.push_back(ConstantInt::get(Int32Type, FrameEscapeIdx));
- } else {
- ActionArgs.push_back(ConstantInt::get(Int32Type, 0));
}
- ActionArgs.push_back(Action->getHandlerBlockOrFunc());
- }
- CallInst *Recover =
- CallInst::Create(ActionIntrin, ActionArgs, "recover", NewLPadBB);
-
- // Add an indirect branch listing possible successors of the catch handlers.
- SetVector<BasicBlock *> ReturnTargets;
- for (ActionHandler *Action : Actions) {
- if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
- const auto &CatchTargets = CatchAction->getReturnTargets();
- ReturnTargets.insert(CatchTargets.begin(), CatchTargets.end());
+ // Handle CatchPad specially since its successors need different colors.
+ if (CatchPadInst *CatchPad = dyn_cast<CatchPadInst>(VisitingHead)) {
+ // Visit the normal successor with the color of the new EH pad, and
+ // visit the unwind successor with the color of the parent.
+ BasicBlock *NormalSucc = CatchPad->getNormalDest();
+ if (BlockColors[NormalSucc].insert(Visiting).second) {
+ Worklist.push_back({NormalSucc, Visiting});
+ }
+ BasicBlock *UnwindSucc = CatchPad->getUnwindDest();
+ if (BlockColors[UnwindSucc].insert(Color).second) {
+ Worklist.push_back({UnwindSucc, Color});
+ }
+ continue;
}
+ // Switch color to the current node, except for terminate pads which
+ // have no bodies and only unwind successors and so need their successors
+ // visited with the color of the parent.
+ if (!isa<TerminatePadInst>(VisitingHead))
+ Color = Visiting;
+ } else {
+ // Note that this is a member of the given color.
+ FuncletBlocks[Color].insert(Visiting);
}
- IndirectBrInst *Branch =
- IndirectBrInst::Create(Recover, ReturnTargets.size(), NewLPadBB);
- for (BasicBlock *Target : ReturnTargets)
- Branch->addDestination(Target);
- } // End for each landingpad
-
- // If nothing got outlined, there is no more processing to be done.
- if (!HandlersOutlined)
- return false;
-
- // Replace any nested landing pad stubs with the correct action handler.
- // This must be done before we remove unreachable blocks because it
- // cleans up references to outlined blocks that will be deleted.
- for (auto &LPadPair : NestedLPtoOriginalLP)
- completeNestedLandingPad(&F, LPadPair.first, LPadPair.second, FrameVarInfo);
- NestedLPtoOriginalLP.clear();
-
- F.addFnAttr("wineh-parent", F.getName());
- // Delete any blocks that were only used by handlers that were outlined above.
- removeUnreachableBlocks(F);
-
- BasicBlock *Entry = &F.getEntryBlock();
- IRBuilder<> Builder(F.getParent()->getContext());
- Builder.SetInsertPoint(Entry->getFirstInsertionPt());
-
- Function *FrameEscapeFn =
- Intrinsic::getDeclaration(M, Intrinsic::frameescape);
- Function *RecoverFrameFn =
- Intrinsic::getDeclaration(M, Intrinsic::framerecover);
- SmallVector<Value *, 8> AllocasToEscape;
-
- // Scan the entry block for an existing call to llvm.frameescape. We need to
- // keep escaping those objects.
- for (Instruction &I : F.front()) {
- auto *II = dyn_cast<IntrinsicInst>(&I);
- if (II && II->getIntrinsicID() == Intrinsic::frameescape) {
- auto Args = II->arg_operands();
- AllocasToEscape.append(Args.begin(), Args.end());
- II->eraseFromParent();
- break;
+ TerminatorInst *Terminator = Visiting->getTerminator();
+ if (isa<CleanupReturnInst>(Terminator) ||
+ isa<CatchReturnInst>(Terminator) ||
+ isa<CleanupEndPadInst>(Terminator)) {
+ // These blocks' successors have already been queued with the parent
+ // color.
+ continue;
}
- }
-
- // Finally, replace all of the temporary allocas for frame variables used in
- // the outlined handlers with calls to llvm.framerecover.
- for (auto &VarInfoEntry : FrameVarInfo) {
- Value *ParentVal = VarInfoEntry.first;
- TinyPtrVector<AllocaInst *> &Allocas = VarInfoEntry.second;
- AllocaInst *ParentAlloca = cast<AllocaInst>(ParentVal);
-
- // FIXME: We should try to sink unescaped allocas from the parent frame into
- // the child frame. If the alloca is escaped, we have to use the lifetime
- // markers to ensure that the alloca is only live within the child frame.
-
- // Add this alloca to the list of things to escape.
- AllocasToEscape.push_back(ParentAlloca);
-
- // Next replace all outlined allocas that are mapped to it.
- for (AllocaInst *TempAlloca : Allocas) {
- if (TempAlloca == getCatchObjectSentinel())
- continue; // Skip catch parameter sentinels.
- Function *HandlerFn = TempAlloca->getParent()->getParent();
- // FIXME: Sink this GEP into the blocks where it is used.
- Builder.SetInsertPoint(TempAlloca);
- Builder.SetCurrentDebugLocation(TempAlloca->getDebugLoc());
- Value *RecoverArgs[] = {
- Builder.CreateBitCast(&F, Int8PtrType, ""),
- &(HandlerFn->getArgumentList().back()),
- llvm::ConstantInt::get(Int32Type, AllocasToEscape.size() - 1)};
- Value *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());
+ for (BasicBlock *Succ : successors(Visiting)) {
+ if (isa<CatchEndPadInst>(Succ->getFirstNonPHI())) {
+ // The catchendpad needs to be visited with the parent's color, not
+ // the current color. This will happen in the code above that visits
+ // any catchpad unwind successor with the parent color, so we can
+ // safely skip this successor here.
+ continue;
}
- TempAlloca->replaceAllUsesWith(RecoveredAlloca);
- TempAlloca->removeFromParent();
- RecoveredAlloca->takeName(TempAlloca);
- delete TempAlloca;
- }
- } // End for each FrameVarInfo entry.
-
- // Insert 'call void (...)* @llvm.frameescape(...)' at the end of the entry
- // block.
- Builder.SetInsertPoint(&F.getEntryBlock().back());
- Builder.CreateCall(FrameEscapeFn, AllocasToEscape);
-
- // Clean up the handler action maps we created for this function
- DeleteContainerSeconds(CatchHandlerMap);
- CatchHandlerMap.clear();
- DeleteContainerSeconds(CleanupHandlerMap);
- CleanupHandlerMap.clear();
-
- return HandlersOutlined;
-}
-
-void WinEHPrepare::promoteLandingPadValues(LandingPadInst *LPad) {
- // If the return values of the landing pad instruction are extracted and
- // stored to memory, we want to promote the store locations to reg values.
- SmallVector<AllocaInst *, 2> EHAllocas;
-
- // The landingpad instruction returns an aggregate value. Typically, its
- // value will be passed to a pair of extract value instructions and the
- // results of those extracts are often passed to store instructions.
- // In unoptimized code the stored value will often be loaded and then stored
- // again.
- for (auto *U : LPad->users()) {
- ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
- if (!Extract)
- continue;
-
- for (auto *EU : Extract->users()) {
- if (auto *Store = dyn_cast<StoreInst>(EU)) {
- auto *AV = cast<AllocaInst>(Store->getPointerOperand());
- EHAllocas.push_back(AV);
+ if (BlockColors[Succ].insert(Color).second) {
+ Worklist.push_back({Succ, Color});
}
}
}
- // We can't do this without a dominator tree.
- assert(DT);
-
- if (!EHAllocas.empty()) {
- PromoteMemToReg(EHAllocas, *DT);
- EHAllocas.clear();
+ // The processing above actually accumulated the parent set for this
+ // funclet into the color set for its entry; use the parent set to
+ // populate the children map, and reset the color set to include just
+ // the funclet itself (no instruction can target a funclet entry except on
+ // that transitions to the child funclet).
+ for (BasicBlock *FuncletEntry : EntryBlocks) {
+ std::set<BasicBlock *> &ColorMapItem = BlockColors[FuncletEntry];
+ for (BasicBlock *Parent : ColorMapItem)
+ FuncletChildren[Parent].insert(FuncletEntry);
+ ColorMapItem.clear();
+ ColorMapItem.insert(FuncletEntry);
}
+}
- // After promotion, some extracts may be trivially dead. Remove them.
- SmallVector<Value *, 4> Users(LPad->user_begin(), LPad->user_end());
- for (auto *U : Users)
- RecursivelyDeleteTriviallyDeadInstructions(U);
+void WinEHPrepare::colorFunclets(Function &F,
+ SmallVectorImpl<BasicBlock *> &EntryBlocks) {
+ ::colorFunclets(F, EntryBlocks, BlockColors, FuncletBlocks, FuncletChildren);
}
-void WinEHPrepare::completeNestedLandingPad(Function *ParentFn,
- LandingPadInst *OutlinedLPad,
- const LandingPadInst *OriginalLPad,
- FrameVarInfoMap &FrameVarInfo) {
- // Get the nested block and erase the unreachable instruction that was
- // temporarily inserted as its terminator.
- LLVMContext &Context = ParentFn->getContext();
- BasicBlock *OutlinedBB = OutlinedLPad->getParent();
- assert(isa<UnreachableInst>(OutlinedBB->getTerminator()));
- OutlinedBB->getTerminator()->eraseFromParent();
- // That should leave OutlinedLPad as the last instruction in its block.
- assert(&OutlinedBB->back() == OutlinedLPad);
-
- // The original landing pad will have already had its action intrinsic
- // built by the outlining loop. We need to clone that into the outlined
- // location. It may also be necessary to add references to the exception
- // variables to the outlined handler in which this landing pad is nested
- // and remap return instructions in the nested handlers that should return
- // to an address in the outlined handler.
- Function *OutlinedHandlerFn = OutlinedBB->getParent();
- BasicBlock::const_iterator II = OriginalLPad;
- ++II;
- // The instruction after the landing pad should now be a call to eh.actions.
- const Instruction *Recover = II;
- assert(match(Recover, m_Intrinsic<Intrinsic::eh_actions>()));
- IntrinsicInst *EHActions = cast<IntrinsicInst>(Recover->clone());
-
- // Remap the exception variables into the outlined function.
- WinEHFrameVariableMaterializer Materializer(OutlinedHandlerFn, FrameVarInfo);
- SmallVector<BlockAddress *, 4> ActionTargets;
- SmallVector<ActionHandler *, 4> ActionList;
- parseEHActions(EHActions, ActionList);
- for (auto *Action : ActionList) {
- auto *Catch = dyn_cast<CatchHandler>(Action);
- if (!Catch)
- continue;
- // The dyn_cast to function here selects C++ catch handlers and skips
- // SEH catch handlers.
- auto *Handler = dyn_cast<Function>(Catch->getHandlerBlockOrFunc());
- if (!Handler)
+void llvm::calculateCatchReturnSuccessorColors(const Function *Fn,
+ WinEHFuncInfo &FuncInfo) {
+ SmallVector<BasicBlock *, 4> EntryBlocks;
+ // colorFunclets needs the set of EntryBlocks, get them using
+ // findFuncletEntryPoints.
+ findFuncletEntryPoints(const_cast<Function &>(*Fn), EntryBlocks);
+
+ std::map<BasicBlock *, std::set<BasicBlock *>> BlockColors;
+ std::map<BasicBlock *, std::set<BasicBlock *>> FuncletBlocks;
+ std::map<BasicBlock *, std::set<BasicBlock *>> FuncletChildren;
+ // Figure out which basic blocks belong to which funclets.
+ colorFunclets(const_cast<Function &>(*Fn), EntryBlocks, BlockColors,
+ FuncletBlocks, FuncletChildren);
+
+ // We need to find the catchret successors. To do this, we must first find
+ // all the catchpad funclets.
+ for (auto &Funclet : FuncletBlocks) {
+ // Figure out what kind of funclet we are looking at; We only care about
+ // catchpads.
+ BasicBlock *FuncletPadBB = Funclet.first;
+ Instruction *FirstNonPHI = FuncletPadBB->getFirstNonPHI();
+ auto *CatchPad = dyn_cast<CatchPadInst>(FirstNonPHI);
+ if (!CatchPad)
continue;
- // Visit all the return instructions, looking for places that return
- // to a location within OutlinedHandlerFn.
- for (BasicBlock &NestedHandlerBB : *Handler) {
- auto *Ret = dyn_cast<ReturnInst>(NestedHandlerBB.getTerminator());
- if (!Ret)
- continue;
- // Handler functions must always return a block address.
- BlockAddress *BA = cast<BlockAddress>(Ret->getReturnValue());
- // The original target will have been in the main parent function,
- // but if it is the address of a block that has been outlined, it
- // should be a block that was outlined into OutlinedHandlerFn.
- assert(BA->getFunction() == ParentFn);
-
- // Ignore targets that aren't part of OutlinedHandlerFn.
- if (!LPadTargetBlocks.count(BA->getBasicBlock()))
+ // The users of a catchpad are always catchrets.
+ for (User *Exit : CatchPad->users()) {
+ auto *CatchReturn = dyn_cast<CatchReturnInst>(Exit);
+ if (!CatchReturn)
continue;
-
- // If the return value is the address ofF a block that we
- // previously outlined into the parent handler function, replace
- // the return instruction and add the mapped target to the list
- // of possible return addresses.
- BasicBlock *MappedBB = LPadTargetBlocks[BA->getBasicBlock()];
- assert(MappedBB->getParent() == OutlinedHandlerFn);
- BlockAddress *NewBA = BlockAddress::get(OutlinedHandlerFn, MappedBB);
- Ret->eraseFromParent();
- ReturnInst::Create(Context, NewBA, &NestedHandlerBB);
- ActionTargets.push_back(NewBA);
+ BasicBlock *CatchRetSuccessor = CatchReturn->getSuccessor();
+ std::set<BasicBlock *> &SuccessorColors = BlockColors[CatchRetSuccessor];
+ assert(SuccessorColors.size() == 1 && "Expected BB to be monochrome!");
+ BasicBlock *Color = *SuccessorColors.begin();
+ // Record the catchret successor's funclet membership.
+ FuncInfo.CatchRetSuccessorColorMap[CatchReturn] = Color;
}
}
- DeleteContainerPointers(ActionList);
- ActionList.clear();
- OutlinedBB->getInstList().push_back(EHActions);
-
- // Insert an indirect branch into the outlined landing pad BB.
- IndirectBrInst *IBr = IndirectBrInst::Create(EHActions, 0, OutlinedBB);
- // Add the previously collected action targets.
- for (auto *Target : ActionTargets)
- IBr->addDestination(Target->getBasicBlock());
}
-// This function examines a block to determine whether the block ends with a
-// conditional branch to a catch handler based on a selector comparison.
-// This function is used both by the WinEHPrepare::findSelectorComparison() and
-// WinEHCleanupDirector::handleTypeIdFor().
-static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler,
- Constant *&Selector, BasicBlock *&NextBB) {
- ICmpInst::Predicate Pred;
- BasicBlock *TBB, *FBB;
- Value *LHS, *RHS;
-
- if (!match(BB->getTerminator(),
- m_Br(m_ICmp(Pred, m_Value(LHS), m_Value(RHS)), TBB, FBB)))
- return false;
+void WinEHPrepare::demotePHIsOnFunclets(Function &F) {
+ // 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;
+ 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;
- if (!match(LHS,
- m_Intrinsic<Intrinsic::eh_typeid_for>(m_Constant(Selector))) &&
- !match(RHS, m_Intrinsic<Intrinsic::eh_typeid_for>(m_Constant(Selector))))
- return false;
+ AllocaInst *SpillSlot = insertPHILoads(PN, F);
+ if (SpillSlot)
+ insertPHIStores(PN, SpillSlot);
- if (Pred == CmpInst::ICMP_EQ) {
- CatchHandler = TBB;
- NextBB = FBB;
- return true;
+ PHINodes.push_back(PN);
+ }
}
- if (Pred == CmpInst::ICMP_NE) {
- CatchHandler = FBB;
- NextBB = TBB;
- return true;
+ for (auto *PN : PHINodes) {
+ // There may be lingering uses on other EH PHIs being removed
+ PN->replaceAllUsesWith(UndefValue::get(PN->getType()));
+ PN->eraseFromParent();
}
-
- return false;
}
-static bool isCatchBlock(BasicBlock *BB) {
- for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
- II != IE; ++II) {
- if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_begincatch>()))
- return true;
+void WinEHPrepare::demoteUsesBetweenFunclets(Function &F) {
+ // Turn all inter-funclet uses of a Value into loads and stores.
+ for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) {
+ BasicBlock *BB = &*FI++;
+ std::set<BasicBlock *> &ColorsForBB = BlockColors[BB];
+ for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); BI != BE;) {
+ Instruction *I = &*BI++;
+ // Funclets are permitted to use static allocas.
+ if (auto *AI = dyn_cast<AllocaInst>(I))
+ if (AI->isStaticAlloca())
+ continue;
+
+ demoteNonlocalUses(I, ColorsForBB, F);
+ }
}
- return false;
}
-static BasicBlock *createStubLandingPad(Function *Handler,
- Value *PersonalityFn) {
- // FIXME: Finish this!
- LLVMContext &Context = Handler->getContext();
- BasicBlock *StubBB = BasicBlock::Create(Context, "stub");
- Handler->getBasicBlockList().push_back(StubBB);
- IRBuilder<> Builder(StubBB);
- LandingPadInst *LPad = Builder.CreateLandingPad(
- llvm::StructType::get(Type::getInt8PtrTy(Context),
- Type::getInt32Ty(Context), nullptr),
- PersonalityFn, 0);
- // Insert a call to llvm.eh.actions so that we don't try to outline this lpad.
- Function *ActionIntrin = Intrinsic::getDeclaration(Handler->getParent(),
- Intrinsic::eh_actions);
- Builder.CreateCall(ActionIntrin, "recover");
- LPad->setCleanup(true);
- Builder.CreateUnreachable();
- return StubBB;
+void WinEHPrepare::demoteArgumentUses(Function &F) {
+ // Also demote function parameters used in funclets.
+ std::set<BasicBlock *> &ColorsForEntry = BlockColors[&F.getEntryBlock()];
+ for (Argument &Arg : F.args())
+ demoteNonlocalUses(&Arg, ColorsForEntry, F);
}
-// Cycles through the blocks in an outlined handler function looking for an
-// invoke instruction and inserts an invoke of llvm.donothing with an empty
-// landing pad if none is found. The code that generates the .xdata tables for
-// the handler needs at least one landing pad to identify the parent function's
-// personality.
-void WinEHPrepare::addStubInvokeToHandlerIfNeeded(Function *Handler,
- Value *PersonalityFn) {
- ReturnInst *Ret = nullptr;
- UnreachableInst *Unreached = nullptr;
- for (BasicBlock &BB : *Handler) {
- TerminatorInst *Terminator = BB.getTerminator();
- // If we find an invoke, there is nothing to be done.
- auto *II = dyn_cast<InvokeInst>(Terminator);
- if (II)
- return;
- // If we've already recorded a return instruction, keep looking for invokes.
- if (!Ret)
- Ret = dyn_cast<ReturnInst>(Terminator);
- // If we haven't recorded an unreachable instruction, try this terminator.
- if (!Unreached)
- Unreached = dyn_cast<UnreachableInst>(Terminator);
- }
-
- // If we got this far, the handler contains no invokes. We should have seen
- // at least one return or unreachable instruction. We'll insert an invoke of
- // llvm.donothing ahead of that instruction.
- assert(Ret || Unreached);
- TerminatorInst *Term;
- if (Ret)
- Term = Ret;
- else
- Term = Unreached;
- BasicBlock *OldRetBB = Term->getParent();
- BasicBlock *NewRetBB = SplitBlock(OldRetBB, Term);
- // SplitBlock adds an unconditional branch instruction at the end of the
- // parent block. We want to replace that with an invoke call, so we can
- // erase it now.
- OldRetBB->getTerminator()->eraseFromParent();
- BasicBlock *StubLandingPad = createStubLandingPad(Handler, PersonalityFn);
- Function *F =
- Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::donothing);
- InvokeInst::Create(F, NewRetBB, StubLandingPad, None, "", OldRetBB);
-}
+void WinEHPrepare::cloneCommonBlocks(
+ Function &F, SmallVectorImpl<BasicBlock *> &EntryBlocks) {
+ // We need to clone all blocks which belong to multiple funclets. Values are
+ // remapped throughout the funclet to propogate both the new instructions
+ // *and* the new basic blocks themselves.
+ for (BasicBlock *FuncletPadBB : EntryBlocks) {
+ std::set<BasicBlock *> &BlocksInFunclet = FuncletBlocks[FuncletPadBB];
+
+ std::map<BasicBlock *, BasicBlock *> Orig2Clone;
+ ValueToValueMapTy VMap;
+ for (BasicBlock *BB : BlocksInFunclet) {
+ std::set<BasicBlock *> &ColorsForBB = BlockColors[BB];
+ // We don't need to do anything if the block is monochromatic.
+ size_t NumColorsForBB = ColorsForBB.size();
+ if (NumColorsForBB == 1)
+ continue;
-bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn,
- LandingPadInst *LPad, BasicBlock *StartBB,
- 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);
- Function *Handler;
- if (Action->getType() == Catch) {
- FunctionType *FnType = FunctionType::get(Int8PtrType, ArgTys, false);
- Handler = Function::Create(FnType, GlobalVariable::InternalLinkage,
- SrcFn->getName() + ".catch", M);
- } else {
- FunctionType *FnType =
- FunctionType::get(Type::getVoidTy(Context), ArgTys, false);
- Handler = Function::Create(FnType, GlobalVariable::InternalLinkage,
- SrcFn->getName() + ".cleanup", M);
- }
+ // 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());
- Handler->addFnAttr("wineh-parent", SrcFn->getName());
+ // Add basic block mapping.
+ VMap[BB] = CBB;
- // 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());
+ // Record delta operations that we need to perform to our color mappings.
+ Orig2Clone[BB] = CBB;
+ }
- std::unique_ptr<WinEHCloningDirectorBase> Director;
+ // If nothing was cloned, we're done cloning in this funclet.
+ if (Orig2Clone.empty())
+ continue;
- ValueToValueMapTy VMap;
+ // 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;
- LandingPadMap &LPadMap = LPadMaps[LPad];
- if (!LPadMap.isInitialized())
- LPadMap.mapLandingPad(LPad);
- if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
- Constant *Sel = CatchAction->getSelector();
- Director.reset(new WinEHCatchDirector(Handler, Sel, VarInfo, LPadMap,
- NestedLPtoOriginalLP));
- LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
- ConstantInt::get(Type::getInt32Ty(Context), 1));
- } else {
- Director.reset(new WinEHCleanupDirector(Handler, VarInfo, LPadMap));
- LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
- UndefValue::get(Type::getInt32Ty(Context)));
- }
+ BlocksInFunclet.insert(NewBlock);
+ BlockColors[NewBlock].insert(FuncletPadBB);
- SmallVector<ReturnInst *, 8> Returns;
- ClonedCodeInfo OutlinedFunctionInfo;
-
- // If the start block contains PHI nodes, we need to map them.
- BasicBlock::iterator II = StartBB->begin();
- while (auto *PN = dyn_cast<PHINode>(II)) {
- bool Mapped = false;
- // Look for PHI values that we have already mapped (such as the selector).
- for (Value *Val : PN->incoming_values()) {
- if (VMap.count(Val)) {
- VMap[PN] = VMap[Val];
- Mapped = true;
- }
- }
- // If we didn't find a match for this value, map it as an undef.
- if (!Mapped) {
- VMap[PN] = UndefValue::get(PN->getType());
+ BlocksInFunclet.erase(OldBlock);
+ BlockColors[OldBlock].erase(FuncletPadBB);
}
- ++II;
- }
- // The landing pad value may be used by PHI nodes. It will ultimately be
- // eliminated, but we need it in the map for intermediate handling.
- VMap[LPad] = UndefValue::get(LPad->getType());
-
- // Skip over PHIs and, if applicable, landingpad instructions.
- II = StartBB->getFirstInsertionPt();
-
- CloneAndPruneIntoFromInst(Handler, SrcFn, II, VMap,
- /*ModuleLevelChanges=*/false, Returns, "",
- &OutlinedFunctionInfo, Director.get());
-
- // Move all the instructions in the first cloned block into our entry block.
- BasicBlock *FirstClonedBB = std::next(Function::iterator(Entry));
- Entry->getInstList().splice(Entry->end(), FirstClonedBB->getInstList());
- FirstClonedBB->eraseFromParent();
-
- // Make sure we can identify the handler's personality later.
- addStubInvokeToHandlerIfNeeded(Handler, LPad->getPersonalityFn());
-
- if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
- WinEHCatchDirector *CatchDirector =
- reinterpret_cast<WinEHCatchDirector *>(Director.get());
- CatchAction->setExceptionVar(CatchDirector->getExceptionVar());
- CatchAction->setReturnTargets(CatchDirector->getReturnTargets());
-
- // Look for blocks that are not part of the landing pad that we just
- // outlined but terminate with a call to llvm.eh.endcatch and a
- // branch to a block that is in the handler we just outlined.
- // These blocks will be part of a nested landing pad that intends to
- // return to an address in this handler. This case is best handled
- // after both landing pads have been outlined, so for now we'll just
- // save the association of the blocks in LPadTargetBlocks. The
- // return instructions which are created from these branches will be
- // replaced after all landing pads have been outlined.
- for (const auto MapEntry : VMap) {
- // VMap maps all values and blocks that were just cloned, but dead
- // blocks which were pruned will map to nullptr.
- if (!isa<BasicBlock>(MapEntry.first) || MapEntry.second == nullptr)
- continue;
- const BasicBlock *MappedBB = cast<BasicBlock>(MapEntry.first);
- for (auto *Pred : predecessors(const_cast<BasicBlock *>(MappedBB))) {
- auto *Branch = dyn_cast<BranchInst>(Pred->getTerminator());
- if (!Branch || !Branch->isUnconditional() || Pred->size() <= 1)
- continue;
- BasicBlock::iterator II = const_cast<BranchInst *>(Branch);
- --II;
- if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_endcatch>())) {
- // This would indicate that a nested landing pad wants to return
- // to a block that is outlined into two different handlers.
- assert(!LPadTargetBlocks.count(MappedBB));
- LPadTargetBlocks[MappedBB] = cast<BasicBlock>(MapEntry.second);
+ // 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_IgnoreMissingEntries | RF_NoModuleLevelChanges);
+
+ // 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 (Instruction &SuccI : *SuccBB) {
+ auto *SuccPN = dyn_cast<PHINode>(&SuccI);
+ if (!SuccPN)
+ break;
+
+ // 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);
}
}
}
- } // End if (CatchAction)
-
- Action->setHandlerBlockOrFunc(Handler);
- return true;
-}
+ 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;
-/// This BB must end in a selector dispatch. All we need to do is pass the
-/// handler block to llvm.eh.actions and list it as a possible indirectbr
-/// target.
-void WinEHPrepare::processSEHCatchHandler(CatchHandler *CatchAction,
- BasicBlock *StartBB) {
- BasicBlock *HandlerBB;
- BasicBlock *NextBB;
- Constant *Selector;
- bool Res = isSelectorDispatch(StartBB, HandlerBB, Selector, NextBB);
- if (Res) {
- // If this was EH dispatch, this must be a conditional branch to the handler
- // block.
- // FIXME: Handle instructions in the dispatch block. Currently we drop them,
- // leading to crashes if some optimization hoists stuff here.
- assert(CatchAction->getSelector() && HandlerBB &&
- "expected catch EH dispatch");
- } else {
- // This must be a catch-all. Split the block after the landingpad.
- assert(CatchAction->getSelector()->isNullValue() && "expected catch-all");
- HandlerBB =
- StartBB->splitBasicBlock(StartBB->getFirstInsertionPt(), "catch.all");
- }
- CatchAction->setHandlerBlockOrFunc(BlockAddress::get(HandlerBB));
- TinyPtrVector<BasicBlock *> Targets(HandlerBB);
- CatchAction->setReturnTargets(Targets);
-}
-
-void LandingPadMap::mapLandingPad(const LandingPadInst *LPad) {
- // Each instance of this class should only ever be used to map a single
- // landing pad.
- assert(OriginLPad == nullptr || OriginLPad == LPad);
+ 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();
+ std::set<BasicBlock *> &ColorsForUserBB = BlockColors[UserBB];
+ assert(!ColorsForUserBB.empty());
+ if (ColorsForUserBB.size() > 1 ||
+ *ColorsForUserBB.begin() != FuncletPadBB)
+ UsesToRename.push_back(&U);
+ }
- // If the landing pad has already been mapped, there's nothing more to do.
- if (OriginLPad == LPad)
- return;
+ // If there are no uses outside the block, we're done with this
+ // instruction.
+ if (UsesToRename.empty())
+ continue;
- OriginLPad = LPad;
+ // 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);
- // The landingpad instruction returns an aggregate value. Typically, its
- // value will be passed to a pair of extract value instructions and the
- // results of those extracts will have been promoted to reg values before
- // this routine is called.
- for (auto *U : LPad->users()) {
- const ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
- if (!Extract)
- continue;
- assert(Extract->getNumIndices() == 1 &&
- "Unexpected operation: extracting both landing pad values");
- unsigned int Idx = *(Extract->idx_begin());
- assert((Idx == 0 || Idx == 1) &&
- "Unexpected operation: extracting an unknown landing pad element");
- if (Idx == 0) {
- ExtractedEHPtrs.push_back(Extract);
- } else if (Idx == 1) {
- ExtractedSelectors.push_back(Extract);
+ while (!UsesToRename.empty())
+ SSAUpdate.RewriteUseAfterInsertions(*UsesToRename.pop_back_val());
}
}
}
-bool LandingPadMap::isOriginLandingPadBlock(const BasicBlock *BB) const {
- return BB->getLandingPadInst() == OriginLPad;
-}
-
-bool LandingPadMap::isLandingPadSpecificInst(const Instruction *Inst) const {
- if (Inst == OriginLPad)
- return true;
- for (auto *Extract : ExtractedEHPtrs) {
- if (Inst == Extract)
- return true;
- }
- for (auto *Extract : ExtractedSelectors) {
- if (Inst == Extract)
- return true;
- }
- return false;
-}
-
-void LandingPadMap::remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
- Value *SelectorValue) const {
- // Remap all landing pad extract instructions to the specified values.
- for (auto *Extract : ExtractedEHPtrs)
- VMap[Extract] = EHPtrValue;
- for (auto *Extract : ExtractedSelectors)
- VMap[Extract] = SelectorValue;
-}
-
-static bool isFrameAddressCall(const Value *V) {
- return match(const_cast<Value *>(V),
- m_Intrinsic<Intrinsic::frameaddress>(m_SpecificInt(0)));
-}
-
-CloningDirector::CloningAction WinEHCloningDirectorBase::handleInstruction(
- ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
- // If this is one of the boilerplate landing pad instructions, skip it.
- // The instruction will have already been remapped in VMap.
- if (LPadMap.isLandingPadSpecificInst(Inst))
- return CloningDirector::SkipInstruction;
-
- // Nested landing pads will be cloned as stubs, with just the
- // landingpad instruction and an unreachable instruction. When
- // all landingpads have been outlined, we'll replace this with the
- // llvm.eh.actions call and indirect branch created when the
- // landing pad was outlined.
- if (auto *LPad = dyn_cast<LandingPadInst>(Inst)) {
- return handleLandingPad(VMap, LPad, NewBB);
- }
-
- if (auto *Invoke = dyn_cast<InvokeInst>(Inst))
- return handleInvoke(VMap, Invoke, NewBB);
-
- if (auto *Resume = dyn_cast<ResumeInst>(Inst))
- return handleResume(VMap, Resume, NewBB);
-
- if (auto *Cmp = dyn_cast<CmpInst>(Inst))
- return handleCompare(VMap, Cmp, NewBB);
-
- if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>()))
- return handleBeginCatch(VMap, Inst, NewBB);
- if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
- return handleEndCatch(VMap, Inst, NewBB);
- if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
- return handleTypeIdFor(VMap, Inst, NewBB);
+void WinEHPrepare::removeImplausibleTerminators(Function &F) {
+ // Remove implausible terminators and replace them with UnreachableInst.
+ for (auto &Funclet : FuncletBlocks) {
+ BasicBlock *FuncletPadBB = Funclet.first;
+ std::set<BasicBlock *> &BlocksInFunclet = Funclet.second;
+ Instruction *FirstNonPHI = FuncletPadBB->getFirstNonPHI();
+ auto *CatchPad = dyn_cast<CatchPadInst>(FirstNonPHI);
+ auto *CleanupPad = dyn_cast<CleanupPadInst>(FirstNonPHI);
+
+ for (BasicBlock *BB : BlocksInFunclet) {
+ TerminatorInst *TI = BB->getTerminator();
+ // CatchPadInst and CleanupPadInst can't transfer control to a ReturnInst.
+ bool IsUnreachableRet = isa<ReturnInst>(TI) && (CatchPad || CleanupPad);
+ // 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;
+ // The token consumed by a CleanupEndPadInst must match the funclet token.
+ bool IsUnreachableCleanupendpad = false;
+ if (auto *CEPI = dyn_cast<CleanupEndPadInst>(TI))
+ IsUnreachableCleanupendpad = CEPI->getCleanupPad() != CleanupPad;
+ if (IsUnreachableRet || IsUnreachableCatchret ||
+ IsUnreachableCleanupret || IsUnreachableCleanupendpad) {
+ // Loop through all of our successors and make sure they know that one
+ // of their predecessors is going away.
+ for (BasicBlock *SuccBB : TI->successors())
+ SuccBB->removePredecessor(BB);
+
+ if (IsUnreachableCleanupendpad) {
+ // We can't simply replace a cleanupendpad with unreachable, because
+ // its predecessor edges are EH edges and unreachable is not an EH
+ // pad. Change all predecessors to the "unwind to caller" form.
+ for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
+ PI != PE;) {
+ BasicBlock *Pred = *PI++;
+ removeUnwindEdge(Pred);
+ }
+ }
- // When outlining llvm.frameaddress(i32 0), remap that to the second argument,
- // which is the FP of the parent.
- if (isFrameAddressCall(Inst)) {
- VMap[Inst] = EstablisherFrame;
- return CloningDirector::SkipInstruction;
+ new UnreachableInst(BB->getContext(), TI);
+ TI->eraseFromParent();
+ }
+ // FIXME: Check for invokes/cleanuprets/cleanupendpads which unwind to
+ // implausible catchendpads (i.e. catchendpad not in immediate parent
+ // funclet).
+ }
}
-
- // Continue with the default cloning behavior.
- return CloningDirector::CloneInstruction;
-}
-
-CloningDirector::CloningAction WinEHCatchDirector::handleLandingPad(
- ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
- Instruction *NewInst = LPad->clone();
- if (LPad->hasName())
- NewInst->setName(LPad->getName());
- // Save this correlation for later processing.
- NestedLPtoOriginalLP[cast<LandingPadInst>(NewInst)] = LPad;
- VMap[LPad] = NewInst;
- BasicBlock::InstListType &InstList = NewBB->getInstList();
- InstList.push_back(NewInst);
- InstList.push_back(new UnreachableInst(NewBB->getContext()));
- return CloningDirector::StopCloningBB;
-}
-
-CloningDirector::CloningAction WinEHCatchDirector::handleBeginCatch(
- ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
- // The argument to the call is some form of the first element of the
- // landingpad aggregate value, but that doesn't matter. It isn't used
- // here.
- // The second argument is an outparameter where the exception object will be
- // stored. Typically the exception object is a scalar, but it can be an
- // aggregate when catching by value.
- // FIXME: Leave something behind to indicate where the exception object lives
- // for this handler. Should it be part of llvm.eh.actions?
- assert(ExceptionObjectVar == nullptr && "Multiple calls to "
- "llvm.eh.begincatch found while "
- "outlining catch handler.");
- ExceptionObjectVar = Inst->getOperand(1)->stripPointerCasts();
- if (isa<ConstantPointerNull>(ExceptionObjectVar))
- return CloningDirector::SkipInstruction;
- assert(cast<AllocaInst>(ExceptionObjectVar)->isStaticAlloca() &&
- "catch parameter is not static alloca");
- Materializer.escapeCatchObject(ExceptionObjectVar);
- return CloningDirector::SkipInstruction;
}
-CloningDirector::CloningAction
-WinEHCatchDirector::handleEndCatch(ValueToValueMapTy &VMap,
- const Instruction *Inst, BasicBlock *NewBB) {
- auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst);
- // It might be interesting to track whether or not we are inside a catch
- // function, but that might make the algorithm more brittle than it needs
- // to be.
-
- // The end catch call can occur in one of two places: either in a
- // landingpad block that is part of the catch handlers exception mechanism,
- // or at the end of the catch block. However, a catch-all handler may call
- // end catch from the original landing pad. If the call occurs in a nested
- // landing pad block, we must skip it and continue so that the landing pad
- // gets cloned.
- auto *ParentBB = IntrinCall->getParent();
- if (ParentBB->isLandingPad() && !LPadMap.isOriginLandingPadBlock(ParentBB))
- return CloningDirector::SkipInstruction;
-
- // If an end catch occurs anywhere else we want to terminate the handler
- // with a return to the code that follows the endcatch call. If the
- // next instruction is not an unconditional branch, we need to split the
- // block to provide a clear target for the return instruction.
- BasicBlock *ContinueBB;
- auto Next = std::next(BasicBlock::const_iterator(IntrinCall));
- const BranchInst *Branch = dyn_cast<BranchInst>(Next);
- if (!Branch || !Branch->isUnconditional()) {
- // We're interrupting the cloning process at this location, so the
- // const_cast we're doing here will not cause a problem.
- ContinueBB = SplitBlock(const_cast<BasicBlock *>(ParentBB),
- const_cast<Instruction *>(cast<Instruction>(Next)));
- } else {
- ContinueBB = Branch->getSuccessor(0);
+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);
}
- ReturnInst::Create(NewBB->getContext(), BlockAddress::get(ContinueBB), NewBB);
- ReturnTargets.push_back(ContinueBB);
-
- // We just added a terminator to the cloned block.
- // Tell the caller to stop processing the current basic block so that
- // the branch instruction will be skipped.
- return CloningDirector::StopCloningBB;
-}
-
-CloningDirector::CloningAction WinEHCatchDirector::handleTypeIdFor(
- ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
- auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst);
- Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts();
- // This causes a replacement that will collapse the landing pad CFG based
- // on the filter function we intend to match.
- if (Selector == CurrentSelector)
- VMap[Inst] = ConstantInt::get(SelectorIDType, 1);
- else
- VMap[Inst] = ConstantInt::get(SelectorIDType, 0);
- // Tell the caller not to clone this instruction.
- return CloningDirector::SkipInstruction;
-}
-
-CloningDirector::CloningAction
-WinEHCatchDirector::handleInvoke(ValueToValueMapTy &VMap,
- const InvokeInst *Invoke, BasicBlock *NewBB) {
- return CloningDirector::CloneInstruction;
-}
-
-CloningDirector::CloningAction
-WinEHCatchDirector::handleResume(ValueToValueMapTy &VMap,
- const ResumeInst *Resume, BasicBlock *NewBB) {
- // Resume instructions shouldn't be reachable from catch handlers.
- // We still need to handle it, but it will be pruned.
- BasicBlock::InstListType &InstList = NewBB->getInstList();
- InstList.push_back(new UnreachableInst(NewBB->getContext()));
- return CloningDirector::StopCloningBB;
+ // We might have some unreachable blocks after cleaning up some impossible
+ // control flow.
+ removeUnreachableBlocks(F);
}
-CloningDirector::CloningAction
-WinEHCatchDirector::handleCompare(ValueToValueMapTy &VMap,
- const CmpInst *Compare, BasicBlock *NewBB) {
- const IntrinsicInst *IntrinCall = nullptr;
- if (match(Compare->getOperand(0), m_Intrinsic<Intrinsic::eh_typeid_for>())) {
- IntrinCall = dyn_cast<IntrinsicInst>(Compare->getOperand(0));
- } else if (match(Compare->getOperand(1), m_Intrinsic<Intrinsic::eh_typeid_for>())) {
- IntrinCall = dyn_cast<IntrinsicInst>(Compare->getOperand(1));
- }
- if (IntrinCall) {
- Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts();
- // This causes a replacement that will collapse the landing pad CFG based
- // on the filter function we intend to match.
- if (Selector == CurrentSelector->stripPointerCasts()) {
- VMap[Compare] = ConstantInt::get(SelectorIDType, 1);
- }
- else {
- VMap[Compare] = ConstantInt::get(SelectorIDType, 0);
+void WinEHPrepare::verifyPreparedFunclets(Function &F) {
+ // Recolor the CFG to verify that all is well.
+ 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!");
+ if (!DisableDemotion) {
+ bool EHPadHasPHI = BB.isEHPad() && isa<PHINode>(BB.begin());
+ assert(!EHPadHasPHI && "EH Pad still has a PHI!");
+ if (EHPadHasPHI)
+ report_fatal_error("EH Pad still has a PHI!");
}
- return CloningDirector::SkipInstruction;
}
- return CloningDirector::CloneInstruction;
}
-CloningDirector::CloningAction WinEHCleanupDirector::handleLandingPad(
- ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
- // The MS runtime will terminate the process if an exception occurs in a
- // cleanup handler, so we shouldn't encounter landing pads in the actual
- // cleanup code, but they may appear in catch blocks. Depending on where
- // we started cloning we may see one, but it will get dropped during dead
- // block pruning.
- Instruction *NewInst = new UnreachableInst(NewBB->getContext());
- VMap[LPad] = NewInst;
- BasicBlock::InstListType &InstList = NewBB->getInstList();
- InstList.push_back(NewInst);
- return CloningDirector::StopCloningBB;
-}
+bool WinEHPrepare::prepareExplicitEH(
+ Function &F, SmallVectorImpl<BasicBlock *> &EntryBlocks) {
+ replaceTerminatePadWithCleanup(F);
-CloningDirector::CloningAction WinEHCleanupDirector::handleBeginCatch(
- ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
- // Cleanup code may flow into catch blocks or the catch block may be part
- // of a branch that will be optimized away. We'll insert a return
- // instruction now, but it may be pruned before the cloning process is
- // complete.
- ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
- return CloningDirector::StopCloningBB;
-}
+ // Determine which blocks are reachable from which funclet entries.
+ colorFunclets(F, EntryBlocks);
-CloningDirector::CloningAction WinEHCleanupDirector::handleEndCatch(
- ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
- // Cleanup handlers nested within catch handlers may begin with a call to
- // eh.endcatch. We can just ignore that instruction.
- return CloningDirector::SkipInstruction;
-}
+ if (!DisableDemotion) {
+ demotePHIsOnFunclets(F);
-CloningDirector::CloningAction WinEHCleanupDirector::handleTypeIdFor(
- ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
- // If we encounter a selector comparison while cloning a cleanup handler,
- // we want to stop cloning immediately. Anything after the dispatch
- // will be outlined into a different handler.
- BasicBlock *CatchHandler;
- Constant *Selector;
- BasicBlock *NextBB;
- if (isSelectorDispatch(const_cast<BasicBlock *>(Inst->getParent()),
- CatchHandler, Selector, NextBB)) {
- ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
- return CloningDirector::StopCloningBB;
- }
- // If eg.typeid.for is called for any other reason, it can be ignored.
- VMap[Inst] = ConstantInt::get(SelectorIDType, 0);
- return CloningDirector::SkipInstruction;
-}
+ demoteUsesBetweenFunclets(F);
-CloningDirector::CloningAction WinEHCleanupDirector::handleInvoke(
- ValueToValueMapTy &VMap, const InvokeInst *Invoke, BasicBlock *NewBB) {
- // All invokes in cleanup handlers can be replaced with calls.
- SmallVector<Value *, 16> CallArgs(Invoke->op_begin(), Invoke->op_end() - 3);
- // Insert a normal call instruction...
- CallInst *NewCall =
- CallInst::Create(const_cast<Value *>(Invoke->getCalledValue()), CallArgs,
- Invoke->getName(), NewBB);
- NewCall->setCallingConv(Invoke->getCallingConv());
- NewCall->setAttributes(Invoke->getAttributes());
- NewCall->setDebugLoc(Invoke->getDebugLoc());
- VMap[Invoke] = NewCall;
-
- // Remap the operands.
- llvm::RemapInstruction(NewCall, VMap, RF_None, nullptr, &Materializer);
-
- // Insert an unconditional branch to the normal destination.
- BranchInst::Create(Invoke->getNormalDest(), NewBB);
-
- // The unwind destination won't be cloned into the new function, so
- // we don't need to clean up its phi nodes.
-
- // We just added a terminator to the cloned block.
- // Tell the caller to stop processing the current basic block.
- return CloningDirector::CloneSuccessors;
-}
-
-CloningDirector::CloningAction WinEHCleanupDirector::handleResume(
- ValueToValueMapTy &VMap, const ResumeInst *Resume, BasicBlock *NewBB) {
- ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
-
- // We just added a terminator to the cloned block.
- // Tell the caller to stop processing the current basic block so that
- // the branch instruction will be skipped.
- return CloningDirector::StopCloningBB;
-}
-
-CloningDirector::CloningAction
-WinEHCleanupDirector::handleCompare(ValueToValueMapTy &VMap,
- const CmpInst *Compare, BasicBlock *NewBB) {
- if (match(Compare->getOperand(0), m_Intrinsic<Intrinsic::eh_typeid_for>()) ||
- match(Compare->getOperand(1), m_Intrinsic<Intrinsic::eh_typeid_for>())) {
- VMap[Compare] = ConstantInt::get(SelectorIDType, 1);
- return CloningDirector::SkipInstruction;
+ demoteArgumentUses(F);
}
- return CloningDirector::CloneInstruction;
-}
+ cloneCommonBlocks(F, EntryBlocks);
-WinEHFrameVariableMaterializer::WinEHFrameVariableMaterializer(
- Function *OutlinedFn, FrameVarInfoMap &FrameVarInfo)
- : FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) {
- BasicBlock *EntryBB = &OutlinedFn->getEntryBlock();
- Builder.SetInsertPoint(EntryBB, EntryBB->getFirstInsertionPt());
-}
+ if (!DisableCleanups) {
+ removeImplausibleTerminators(F);
-Value *WinEHFrameVariableMaterializer::materializeValueFor(Value *V) {
- // If we're asked to materialize a static alloca, we temporarily create an
- // alloca in the outlined function and add this to the FrameVarInfo map. When
- // all the outlining is complete, we'll replace these temporary allocas with
- // calls to llvm.framerecover.
- if (auto *AV = dyn_cast<AllocaInst>(V)) {
- assert(AV->isStaticAlloca() &&
- "cannot materialize un-demoted dynamic alloca");
- AllocaInst *NewAlloca = dyn_cast<AllocaInst>(AV->clone());
- Builder.Insert(NewAlloca, AV->getName());
- FrameVarInfo[AV].push_back(NewAlloca);
- return NewAlloca;
+ cleanupPreparedFunclets(F);
}
- if (isa<Instruction>(V) || isa<Argument>(V)) {
- errs() << "Failed to demote instruction used in exception handler:\n";
- errs() << " " << *V << '\n';
- report_fatal_error("WinEHPrepare failed to demote instruction");
- }
+ verifyPreparedFunclets(F);
- // Don't materialize other values.
- return nullptr;
-}
+ BlockColors.clear();
+ FuncletBlocks.clear();
+ FuncletChildren.clear();
-void WinEHFrameVariableMaterializer::escapeCatchObject(Value *V) {
- // Catch parameter objects have to live in the parent frame. When we see a use
- // of a catch parameter, add a sentinel to the multimap to indicate that it's
- // used from another handler. This will prevent us from trying to sink the
- // alloca into the handler and ensure that the catch parameter is present in
- // the call to llvm.frameescape.
- FrameVarInfo[V].push_back(getCatchObjectSentinel());
+ return true;
}
-// This function maps the catch and cleanup handlers that are reachable from the
-// specified landing pad. The landing pad sequence will have this basic shape:
-//
-// <cleanup handler>
-// <selector comparison>
-// <catch handler>
-// <cleanup handler>
-// <selector comparison>
-// <catch handler>
-// <cleanup handler>
-// ...
-//
-// Any of the cleanup slots may be absent. The cleanup slots may be occupied by
-// any arbitrary control flow, but all paths through the cleanup code must
-// eventually reach the next selector comparison and no path can skip to a
-// different selector comparisons, though some paths may terminate abnormally.
-// Therefore, we will use a depth first search from the start of any given
-// cleanup block and stop searching when we find the next selector comparison.
-//
-// If the landingpad instruction does not have a catch clause, we will assume
-// that any instructions other than selector comparisons and catch handlers can
-// be ignored. In practice, these will only be the boilerplate instructions.
-//
-// The catch handlers may also have any control structure, but we are only
-// interested in the start of the catch handlers, so we don't need to actually
-// follow the flow of the catch handlers. The start of the catch handlers can
-// be located from the compare instructions, but they can be skipped in the
-// flow by following the contrary branch.
-void WinEHPrepare::mapLandingPadBlocks(LandingPadInst *LPad,
- LandingPadActions &Actions) {
- unsigned int NumClauses = LPad->getNumClauses();
- unsigned int HandlersFound = 0;
- BasicBlock *BB = LPad->getParent();
-
- DEBUG(dbgs() << "Mapping landing pad: " << BB->getName() << "\n");
-
- if (NumClauses == 0) {
- findCleanupHandlers(Actions, BB, nullptr);
- return;
+// 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;
+
+ if (isa<CleanupPadInst>(PHIBlock->getFirstNonPHI())) {
+ // Insert a load in place of the PHI and replace all uses.
+ SpillSlot = new AllocaInst(PN->getType(), nullptr,
+ Twine(PN->getName(), ".wineh.spillslot"),
+ &F.getEntryBlock().front());
+ Value *V = new LoadInst(SpillSlot, Twine(PN->getName(), ".wineh.reload"),
+ &*PHIBlock->getFirstInsertionPt());
+ PN->replaceAllUsesWith(V);
+ return SpillSlot;
}
- VisitedBlockSet VisitedBlocks;
-
- while (HandlersFound != NumClauses) {
- BasicBlock *NextBB = nullptr;
-
- // See if the clause we're looking for is a catch-all.
- // If so, the catch begins immediately.
- Constant *ExpectedSelector = LPad->getClause(HandlersFound)->stripPointerCasts();
- if (isa<ConstantPointerNull>(ExpectedSelector)) {
- // The catch all must occur last.
- assert(HandlersFound == NumClauses - 1);
-
- // There can be additional selector dispatches in the call chain that we
- // need to ignore.
- BasicBlock *CatchBlock = nullptr;
- Constant *Selector;
- while (BB && isSelectorDispatch(BB, CatchBlock, Selector, NextBB)) {
- DEBUG(dbgs() << " Found extra catch dispatch in block "
- << CatchBlock->getName() << "\n");
- BB = NextBB;
- }
-
- // 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);
-
- // Add the catch handler to the action list.
- CatchHandler *Action = nullptr;
- if (CatchHandlerMap.count(BB) && CatchHandlerMap[BB] != nullptr) {
- // If the CatchHandlerMap already has an entry for this BB, re-use it.
- Action = CatchHandlerMap[BB];
- assert(Action->getSelector() == ExpectedSelector);
- } else {
- // Since this is a catch-all handler, the selector won't actually appear
- // in the code anywhere. ExpectedSelector here is the constant null ptr
- // that we got from the landing pad instruction.
- Action = new CatchHandler(BB, ExpectedSelector, nullptr);
- CatchHandlerMap[BB] = Action;
- }
- Actions.insertCatchHandler(Action);
- DEBUG(dbgs() << " Catch all handler at block " << BB->getName() << "\n");
- ++HandlersFound;
-
- // Once we reach a catch-all, don't expect to hit a resume instruction.
- BB = nullptr;
- break;
+ 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());
+ BasicBlock *UsingBB = UsingInst->getParent();
+ if (UsingBB->isEHPad()) {
+ // Use is on an EH pad phi. Leave it alone; we'll insert loads and
+ // stores for it separately.
+ assert(isa<PHINode>(UsingInst));
+ continue;
}
+ replaceUseWithLoad(PN, U, SpillSlot, Loads, F);
+ }
+ return SpillSlot;
+}
- CatchHandler *CatchAction = findCatchHandler(BB, NextBB, VisitedBlocks);
- assert(CatchAction);
+// 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;
- // See if there is any interesting code executed before the dispatch.
- findCleanupHandlers(Actions, BB, CatchAction->getStartBlock());
+ Worklist.push_back({OriginalPHI->getParent(), OriginalPHI});
- // 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;
+ 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;
- // Add the catch handler to the action list.
- DEBUG(dbgs() << " Found catch dispatch in block "
- << CatchAction->getStartBlock()->getName() << "\n");
- Actions.insertCatchHandler(CatchAction);
+ insertPHIStore(PN->getIncomingBlock(i), PredVal, SpillSlot, Worklist);
+ }
} else {
- // Under some circumstances optimized IR will flow unconditionally into a
- // handler block without checking the selector. This can only happen if
- // the landing pad has a catch-all handler and the handler for the
- // preceeding catch clause is identical to the catch-call handler
- // (typically an empty catch). In this case, the handler must be shared
- // by all remaining clauses.
- if (isa<ConstantPointerNull>(
- CatchAction->getSelector()->stripPointerCasts())) {
- DEBUG(dbgs() << " Applying early catch-all handler in block "
- << CatchAction->getStartBlock()->getName()
- << " to all remaining clauses.\n");
- Actions.insertCatchHandler(CatchAction);
- return;
+ // 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);
}
-
- DEBUG(dbgs() << " Found extra catch dispatch in block "
- << CatchAction->getStartBlock()->getName() << "\n");
}
-
- // Move on to the block after the catch handler.
- BB = NextBB;
}
-
- // If we didn't wind up in a catch-all, see if there is any interesting code
- // executed before the resume.
- findCleanupHandlers(Actions, BB, BB);
-
- // It's possible that some optimization moved code into a landingpad that
- // wasn't
- // previously being used for cleanup. If that happens, we need to execute
- // that
- // extra code from a cleanup handler.
- if (Actions.includesCleanup() && !LPad->isCleanup())
- LPad->setCleanup(true);
}
-// This function searches starting with the input block for the next
-// block that terminates with a branch whose condition is based on a selector
-// comparison. This may be the input block. See the mapLandingPadBlocks
-// comments for a discussion of control flow assumptions.
-//
-CatchHandler *WinEHPrepare::findCatchHandler(BasicBlock *BB,
- BasicBlock *&NextBB,
- VisitedBlockSet &VisitedBlocks) {
- // See if we've already found a catch handler use it.
- // Call count() first to avoid creating a null entry for blocks
- // we haven't seen before.
- if (CatchHandlerMap.count(BB) && CatchHandlerMap[BB] != nullptr) {
- CatchHandler *Action = cast<CatchHandler>(CatchHandlerMap[BB]);
- NextBB = Action->getNextBB();
- return Action;
- }
+void WinEHPrepare::insertPHIStore(
+ BasicBlock *PredBlock, Value *PredVal, AllocaInst *SpillSlot,
+ SmallVectorImpl<std::pair<BasicBlock *, Value *>> &Worklist) {
- // VisitedBlocks applies only to the current search. We still
- // need to consider blocks that we've visited while mapping other
- // landing pads.
- VisitedBlocks.insert(BB);
-
- BasicBlock *CatchBlock = nullptr;
- Constant *Selector = nullptr;
-
- // If this is the first time we've visited this block from any landing pad
- // look to see if it is a selector dispatch block.
- if (!CatchHandlerMap.count(BB)) {
- if (isSelectorDispatch(BB, CatchBlock, Selector, NextBB)) {
- CatchHandler *Action = new CatchHandler(BB, Selector, NextBB);
- CatchHandlerMap[BB] = Action;
- return Action;
- }
- // If we encounter a block containing an llvm.eh.begincatch before we
- // find a selector dispatch block, the handler is assumed to be
- // reached unconditionally. This happens for catch-all blocks, but
- // it can also happen for other catch handlers that have been combined
- // with the catch-all handler during optimization.
- if (isCatchBlock(BB)) {
- PointerType *Int8PtrTy = Type::getInt8PtrTy(BB->getContext());
- Constant *NullSelector = ConstantPointerNull::get(Int8PtrTy);
- CatchHandler *Action = new CatchHandler(BB, NullSelector, nullptr);
- CatchHandlerMap[BB] = Action;
- return Action;
- }
+ if (PredBlock->isEHPad() &&
+ !isa<CleanupPadInst>(PredBlock->getFirstNonPHI())) {
+ // Pred is unsplittable, so we need to queue it on the worklist.
+ Worklist.push_back({PredBlock, PredVal});
+ return;
}
- // Visit each successor, looking for the dispatch.
- // FIXME: We expect to find the dispatch quickly, so this will probably
- // work better as a breadth first search.
- for (BasicBlock *Succ : successors(BB)) {
- if (VisitedBlocks.count(Succ))
- continue;
-
- CatchHandler *Action = findCatchHandler(Succ, NextBB, VisitedBlocks);
- if (Action)
- return Action;
- }
- return nullptr;
+ // Otherwise, insert the store at the end of the basic block.
+ new StoreInst(PredVal, SpillSlot, PredBlock->getTerminator());
}
-// These are helper functions to combine repeated code from findCleanupHandlers.
-static void createCleanupHandler(LandingPadActions &Actions,
- CleanupHandlerMapTy &CleanupHandlerMap,
- BasicBlock *BB) {
- CleanupHandler *Action = new CleanupHandler(BB);
- CleanupHandlerMap[BB] = Action;
- Actions.insertCleanupHandler(Action);
- DEBUG(dbgs() << " Found cleanup code in block "
- << Action->getStartBlock()->getName() << "\n");
-}
+// TODO: Share loads for same-funclet uses (requires dominators if funclets
+// aren't properly nested).
+void WinEHPrepare::demoteNonlocalUses(Value *V,
+ std::set<BasicBlock *> &ColorsForBB,
+ Function &F) {
+ // Tokens can only be used non-locally due to control flow involving
+ // unreachable edges. Don't try to demote the token usage, we'll simply
+ // delete the cloned user later.
+ if (isa<CatchPadInst>(V) || isa<CleanupPadInst>(V))
+ return;
-static CallSite matchOutlinedFinallyCall(BasicBlock *BB,
- Instruction *MaybeCall) {
- // Look for finally blocks that Clang has already outlined for us.
- // %fp = call i8* @llvm.frameaddress(i32 0)
- // call void @"fin$parent"(iN 1, i8* %fp)
- if (isFrameAddressCall(MaybeCall) && MaybeCall != BB->getTerminator())
- MaybeCall = MaybeCall->getNextNode();
- CallSite FinallyCall(MaybeCall);
- if (!FinallyCall || FinallyCall.arg_size() != 2)
- return CallSite();
- if (!match(FinallyCall.getArgument(0), m_SpecificInt(1)))
- return CallSite();
- if (!isFrameAddressCall(FinallyCall.getArgument(1)))
- return CallSite();
- return FinallyCall;
-}
+ DenseMap<BasicBlock *, Value *> Loads;
+ AllocaInst *SpillSlot = nullptr;
+ for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE;) {
+ Use &U = *UI++;
+ auto *UsingInst = cast<Instruction>(U.getUser());
+ BasicBlock *UsingBB = UsingInst->getParent();
+
+ // Is the Use inside a block which is colored the same as the Def?
+ // If so, we don't need to escape the Def because we will clone
+ // ourselves our own private copy.
+ std::set<BasicBlock *> &ColorsForUsingBB = BlockColors[UsingBB];
+ if (ColorsForUsingBB == ColorsForBB)
+ continue;
-static BasicBlock *followSingleUnconditionalBranches(BasicBlock *BB) {
- // Skip single ubr blocks.
- while (BB->getFirstNonPHIOrDbg() == BB->getTerminator()) {
- auto *Br = dyn_cast<BranchInst>(BB->getTerminator());
- if (Br && Br->isUnconditional())
- BB = Br->getSuccessor(0);
- else
- return BB;
+ replaceUseWithLoad(V, U, SpillSlot, Loads, F);
}
- return BB;
-}
-
-// This function searches starting with the input block for the next block that
-// contains code that is not part of a catch handler and would not be eliminated
-// during handler outlining.
-//
-void WinEHPrepare::findCleanupHandlers(LandingPadActions &Actions,
- BasicBlock *StartBB, BasicBlock *EndBB) {
- // Here we will skip over the following:
- //
- // landing pad prolog:
- //
- // Unconditional branches
- //
- // Selector dispatch
- //
- // Resume pattern
- //
- // Anything else marks the start of an interesting block
-
- BasicBlock *BB = StartBB;
- // Anything other than an unconditional branch will kick us out of this loop
- // one way or another.
- while (BB) {
- BB = followSingleUnconditionalBranches(BB);
- // If we've already scanned this block, don't scan it again. If it is
- // a cleanup block, there will be an action in the CleanupHandlerMap.
- // If we've scanned it and it is not a cleanup block, there will be a
- // nullptr in the CleanupHandlerMap. If we have not scanned it, there will
- // be no entry in the CleanupHandlerMap. We must call count() first to
- // avoid creating a null entry for blocks we haven't scanned.
- if (CleanupHandlerMap.count(BB)) {
- if (auto *Action = CleanupHandlerMap[BB]) {
- Actions.insertCleanupHandler(Action);
- DEBUG(dbgs() << " Found cleanup code in block "
- << Action->getStartBlock()->getName() << "\n");
- // FIXME: This cleanup might chain into another, and we need to discover
- // that.
- return;
- } else {
- // Here we handle the case where the cleanup handler map contains a
- // value for this block but the value is a nullptr. This means that
- // we have previously analyzed the block and determined that it did
- // not contain any cleanup code. Based on the earlier analysis, we
- // know the the block must end in either an unconditional branch, a
- // resume or a conditional branch that is predicated on a comparison
- // with a selector. Either the resume or the selector dispatch
- // would terminate the search for cleanup code, so the unconditional
- // branch is the only case for which we might need to continue
- // searching.
- BasicBlock *SuccBB = followSingleUnconditionalBranches(BB);
- if (SuccBB == BB || SuccBB == EndBB)
- return;
- BB = SuccBB;
- continue;
- }
- }
-
- // Create an entry in the cleanup handler map for this block. Initially
- // we create an entry that says this isn't a cleanup block. If we find
- // cleanup code, the caller will replace this entry.
- CleanupHandlerMap[BB] = nullptr;
-
- TerminatorInst *Terminator = BB->getTerminator();
-
- // Landing pad blocks have extra instructions we need to accept.
- LandingPadMap *LPadMap = nullptr;
- if (BB->isLandingPad()) {
- LandingPadInst *LPad = BB->getLandingPadInst();
- LPadMap = &LPadMaps[LPad];
- if (!LPadMap->isInitialized())
- LPadMap->mapLandingPad(LPad);
- }
-
- // Look for the bare resume pattern:
- // %lpad.val1 = insertvalue { i8*, i32 } undef, i8* %exn, 0
- // %lpad.val2 = insertvalue { i8*, i32 } %lpad.val1, i32 %sel, 1
- // resume { i8*, i32 } %lpad.val2
- if (auto *Resume = dyn_cast<ResumeInst>(Terminator)) {
- InsertValueInst *Insert1 = nullptr;
- InsertValueInst *Insert2 = nullptr;
- Value *ResumeVal = Resume->getOperand(0);
- // If the resume value isn't a phi or landingpad value, it should be a
- // series of insertions. Identify them so we can avoid them when scanning
- // for cleanups.
- if (!isa<PHINode>(ResumeVal) && !isa<LandingPadInst>(ResumeVal)) {
- Insert2 = dyn_cast<InsertValueInst>(ResumeVal);
- if (!Insert2)
- return createCleanupHandler(Actions, CleanupHandlerMap, BB);
- Insert1 = dyn_cast<InsertValueInst>(Insert2->getAggregateOperand());
- if (!Insert1)
- return createCleanupHandler(Actions, CleanupHandlerMap, BB);
- }
- for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
- II != IE; ++II) {
- Instruction *Inst = II;
- if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
- continue;
- if (Inst == Insert1 || Inst == Insert2 || Inst == Resume)
- continue;
- if (!Inst->hasOneUse() ||
- (Inst->user_back() != Insert1 && Inst->user_back() != Insert2)) {
- return createCleanupHandler(Actions, CleanupHandlerMap, BB);
- }
- }
- return;
- }
-
- BranchInst *Branch = dyn_cast<BranchInst>(Terminator);
- if (Branch && Branch->isConditional()) {
- // Look for the selector dispatch.
- // %2 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIf to i8*))
- // %matches = icmp eq i32 %sel, %2
- // br i1 %matches, label %catch14, label %eh.resume
- CmpInst *Compare = dyn_cast<CmpInst>(Branch->getCondition());
- if (!Compare || !Compare->isEquality())
- return createCleanupHandler(Actions, CleanupHandlerMap, BB);
- for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
- II != IE; ++II) {
- Instruction *Inst = II;
- if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
- continue;
- if (Inst == Compare || Inst == Branch)
- continue;
- if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
- continue;
- return createCleanupHandler(Actions, CleanupHandlerMap, BB);
- }
- // The selector dispatch block should always terminate our search.
- assert(BB == EndBB);
- return;
- }
-
- if (isAsynchronousEHPersonality(Personality)) {
- // If this is a landingpad block, split the block at the first non-landing
- // pad instruction.
- Instruction *MaybeCall = BB->getFirstNonPHIOrDbg();
- if (LPadMap) {
- while (MaybeCall != BB->getTerminator() &&
- LPadMap->isLandingPadSpecificInst(MaybeCall))
- MaybeCall = MaybeCall->getNextNode();
- }
-
- // Look for outlined finally calls.
- if (CallSite FinallyCall = matchOutlinedFinallyCall(BB, MaybeCall)) {
- Function *Fin = FinallyCall.getCalledFunction();
- assert(Fin && "outlined finally call should be direct");
- auto *Action = new CleanupHandler(BB);
- Action->setHandlerBlockOrFunc(Fin);
- Actions.insertCleanupHandler(Action);
- CleanupHandlerMap[BB] = Action;
- DEBUG(dbgs() << " Found frontend-outlined finally call to "
- << Fin->getName() << " in block "
- << Action->getStartBlock()->getName() << "\n");
-
- // Split the block if there were more interesting instructions and look
- // for finally calls in the normal successor block.
- BasicBlock *SuccBB = BB;
- if (FinallyCall.getInstruction() != BB->getTerminator() &&
- FinallyCall.getInstruction()->getNextNode() != BB->getTerminator()) {
- SuccBB = BB->splitBasicBlock(FinallyCall.getInstruction()->getNextNode());
- } else {
- if (FinallyCall.isInvoke()) {
- SuccBB = cast<InvokeInst>(FinallyCall.getInstruction())->getNormalDest();
- } else {
- SuccBB = BB->getUniqueSuccessor();
- assert(SuccBB && "splitOutlinedFinallyCalls didn't insert a branch");
- }
- }
- BB = SuccBB;
- if (BB == EndBB)
- return;
- continue;
+ if (SpillSlot) {
+ // Insert stores of the computed value into the stack slot.
+ // We have to be careful if I is an invoke instruction,
+ // because we can't insert the store AFTER the terminator instruction.
+ BasicBlock::iterator InsertPt;
+ if (isa<Argument>(V)) {
+ InsertPt = F.getEntryBlock().getTerminator()->getIterator();
+ } else if (isa<TerminatorInst>(V)) {
+ auto *II = cast<InvokeInst>(V);
+ // We cannot demote invoke instructions to the stack if their normal
+ // edge is critical. Therefore, split the critical edge and create a
+ // basic block into which the store can be inserted.
+ if (!II->getNormalDest()->getSinglePredecessor()) {
+ unsigned SuccNum =
+ GetSuccessorNumber(II->getParent(), II->getNormalDest());
+ assert(isCriticalEdge(II, SuccNum) && "Expected a critical edge!");
+ BasicBlock *NewBlock = SplitCriticalEdge(II, SuccNum);
+ assert(NewBlock && "Unable to split critical edge.");
+ // Update the color mapping for the newly split edge.
+ std::set<BasicBlock *> &ColorsForUsingBB = BlockColors[II->getParent()];
+ BlockColors[NewBlock] = ColorsForUsingBB;
+ for (BasicBlock *FuncletPad : ColorsForUsingBB)
+ FuncletBlocks[FuncletPad].insert(NewBlock);
}
+ InsertPt = II->getNormalDest()->getFirstInsertionPt();
+ } else {
+ InsertPt = cast<Instruction>(V)->getIterator();
+ ++InsertPt;
+ // Don't insert before PHI nodes or EH pad instrs.
+ for (; isa<PHINode>(InsertPt) || InsertPt->isEHPad(); ++InsertPt)
+ ;
}
+ new StoreInst(V, SpillSlot, &*InsertPt);
+ }
+}
- // Anything else is either a catch block or interesting cleanup code.
- for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
- II != IE; ++II) {
- Instruction *Inst = II;
- if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
- continue;
- // Unconditional branches fall through to this loop.
- if (Inst == Branch)
- continue;
- // If this is a catch block, there is no cleanup code to be found.
- if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>()))
- return;
- // If this a nested landing pad, it may contain an endcatch call.
- if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
- return;
- // Anything else makes this interesting cleanup code.
- return createCleanupHandler(Actions, CleanupHandlerMap, BB);
+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(), 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.
+ std::set<BasicBlock *> &ColorsForPHIBlock = BlockColors[PHIBlock];
+ BlockColors[NewBlock] = ColorsForPHIBlock;
+ for (BasicBlock *FuncletPad : ColorsForPHIBlock)
+ FuncletBlocks[FuncletPad].insert(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(SpillSlot, Twine(V->getName(), ".wineh.reload"),
+ /*Volatile=*/false, IncomingBlock->getTerminator());
- // Only unconditional branches in empty blocks should get this far.
- assert(Branch && Branch->isUnconditional());
- if (BB == EndBB)
- return;
- BB = Branch->getSuccessor(0);
+ U.set(Load);
+ } else {
+ // Reload right before the old use.
+ auto *Load = new LoadInst(SpillSlot, Twine(V->getName(), ".wineh.reload"),
+ /*Volatile=*/false, UsingInst);
+ U.set(Load);
}
}
-// 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<ActionHandler *> &Actions) {
- for (unsigned I = 0, E = II->getNumArgOperands(); I != E;) {
- uint64_t ActionKind =
- cast<ConstantInt>(II->getArgOperand(I))->getZExtValue();
- if (ActionKind == /*catch=*/1) {
- auto *Selector = cast<Constant>(II->getArgOperand(I + 1));
- ConstantInt *EHObjIndex = cast<ConstantInt>(II->getArgOperand(I + 2));
- int64_t EHObjIndexVal = EHObjIndex->getSExtValue();
- Constant *Handler = cast<Constant>(II->getArgOperand(I + 3));
- I += 4;
- auto *CH = new CatchHandler(/*BB=*/nullptr, Selector, /*NextBB=*/nullptr);
- CH->setHandlerBlockOrFunc(Handler);
- CH->setExceptionVarIndex(EHObjIndexVal);
- Actions.push_back(CH);
- } else if (ActionKind == 0) {
- Constant *Handler = cast<Constant>(II->getArgOperand(I + 1));
- I += 2;
- auto *CH = new CleanupHandler(/*BB=*/nullptr);
- CH->setHandlerBlockOrFunc(Handler);
- Actions.push_back(CH);
- } else {
- llvm_unreachable("Expected either a catch or cleanup handler!");
- }
- }
- std::reverse(Actions.begin(), Actions.end());
+void WinEHFuncInfo::addIPToStateRange(const BasicBlock *PadBB,
+ MCSymbol *InvokeBegin,
+ MCSymbol *InvokeEnd) {
+ assert(PadBB->isEHPad() && EHPadStateMap.count(PadBB->getFirstNonPHI()) &&
+ "should get EH pad BB with precomputed state");
+ InvokeToStateMap[InvokeBegin] =
+ std::make_pair(EHPadStateMap[PadBB->getFirstNonPHI()], InvokeEnd);
}
projects / oota-llvm.git / blobdiff