//===----------------------------------------------------------------------===//
//
// 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/Triple.h"
#include "llvm/ADT/TinyPtrVector.h"
+#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/LibCallSemantics.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/CodeGen/WinEHFuncInfo.h"
+#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#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/MC/MCSymbol.h"
#include "llvm/Pass.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Utils/PromoteMemToReg.h"
+#include "llvm/Transforms/Utils/SSAUpdater.h"
#include <memory>
using namespace llvm;
#define DEBUG_TYPE "winehprepare"
-namespace {
+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));
-struct HandlerAllocas {
- TinyPtrVector<AllocaInst *> Allocas;
- int ParentFrameAllocationIndex;
-};
+static cl::opt<bool> DisableCleanups(
+ "disable-cleanups", cl::Hidden,
+ cl::desc("Do not remove implausible terminators or other similar cleanups"),
+ cl::init(false));
+
+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<AllocaInst *, HandlerAllocas> FrameVarInfoMap;
+typedef MapVector<Value *, TinyPtrVector<AllocaInst *>> FrameVarInfoMap;
-class WinEHPrepare : public FunctionPass {
- std::unique_ptr<FunctionPass> DwarfPrepare;
+// TinyPtrVector cannot hold nullptr, so we need our own sentinel that isn't
+// quite null.
+AllocaInst *getCatchObjectSentinel() {
+ return static_cast<AllocaInst *>(nullptr) + 1;
+}
+
+typedef SmallSet<BasicBlock *, 4> VisitedBlockSet;
+
+class LandingPadActions;
+class LandingPadMap;
+typedef DenseMap<const BasicBlock *, CatchHandler *> CatchHandlerMapTy;
+typedef DenseMap<const BasicBlock *, CleanupHandler *> CleanupHandlerMapTy;
+
+class WinEHPrepare : public FunctionPass {
public:
static char ID; // Pass identification, replacement for typeid.
WinEHPrepare(const TargetMachine *TM = nullptr)
- : FunctionPass(ID), DwarfPrepare(createDwarfEHPass(TM)) {}
+ : FunctionPass(ID) {
+ if (TM)
+ TheTriple = TM->getTargetTriple();
+ }
bool runOnFunction(Function &Fn) override;
}
private:
- bool prepareCPPEHHandlers(Function &F,
- SmallVectorImpl<LandingPadInst *> &LPads);
- bool outlineCatchHandler(Function *SrcFn, Constant *SelectorType,
- LandingPadInst *LPad, CallInst *&EHAlloc,
- AllocaInst *&EHObjPtr, FrameVarInfoMap &VarInfo);
+ bool prepareExceptionHandlers(Function &F,
+ SmallVectorImpl<LandingPadInst *> &LPads);
+ void identifyEHBlocks(Function &F, SmallVectorImpl<LandingPadInst *> &LPads);
+ void promoteLandingPadValues(LandingPadInst *LPad);
+ void demoteValuesLiveAcrossHandlers(Function &F,
+ SmallVectorImpl<LandingPadInst *> &LPads);
+ void findSEHEHReturnPoints(Function &F,
+ SetVector<BasicBlock *> &EHReturnBlocks);
+ void findCXXEHReturnPoints(Function &F,
+ SetVector<BasicBlock *> &EHReturnBlocks);
+ void getPossibleReturnTargets(Function *ParentF, Function *HandlerF,
+ SetVector<BasicBlock*> &Targets);
+ void completeNestedLandingPad(Function *ParentFn,
+ LandingPadInst *OutlinedLPad,
+ const LandingPadInst *OriginalLPad,
+ FrameVarInfoMap &VarInfo);
+ Function *createHandlerFunc(Function *ParentFn, Type *RetTy,
+ const Twine &Name, Module *M, Value *&ParentFP);
+ bool outlineHandler(ActionHandler *Action, Function *SrcFn,
+ LandingPadInst *LPad, BasicBlock *StartBB,
+ FrameVarInfoMap &VarInfo);
+ void addStubInvokeToHandlerIfNeeded(Function *Handler);
+
+ 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);
+
+ Triple TheTriple;
+
+ // All fields are reset by runOnFunction.
+ DominatorTree *DT = nullptr;
+ const TargetLibraryInfo *LibInfo = nullptr;
+ EHPersonality Personality = EHPersonality::Unknown;
+ CatchHandlerMapTy CatchHandlerMap;
+ CleanupHandlerMapTy CleanupHandlerMap;
+ DenseMap<const LandingPadInst *, LandingPadMap> LPadMaps;
+ SmallPtrSet<BasicBlock *, 4> NormalBlocks;
+ SmallPtrSet<BasicBlock *, 4> EHBlocks;
+ SetVector<BasicBlock *> EHReturnBlocks;
+
+ // 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;
+
+ // Map from outlined handler to call to parent local address. Only used for
+ // 32-bit EH.
+ DenseMap<Function *, Value *> HandlerToParentFP;
+
+ AllocaInst *SEHExceptionCodeSlot = nullptr;
+
+ std::map<BasicBlock *, std::set<BasicBlock *>> BlockColors;
+ std::map<BasicBlock *, std::set<BasicBlock *>> FuncletBlocks;
+ std::map<BasicBlock *, std::set<BasicBlock *>> FuncletChildren;
};
class WinEHFrameVariableMaterializer : public ValueMaterializer {
public:
- WinEHFrameVariableMaterializer(Function *OutlinedFn,
+ WinEHFrameVariableMaterializer(Function *OutlinedFn, Value *ParentFP,
FrameVarInfoMap &FrameVarInfo);
- ~WinEHFrameVariableMaterializer() {}
+ ~WinEHFrameVariableMaterializer() override {}
+
+ Value *materializeValueFor(Value *V) override;
- virtual Value *materializeValueFor(Value *V) override;
+ void escapeCatchObject(Value *V);
private:
FrameVarInfoMap &FrameVarInfo;
IRBuilder<> Builder;
};
-class WinEHCatchDirector : public CloningDirector {
+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:
- WinEHCatchDirector(LandingPadInst *LPI, Function *CatchFn, Value *Selector,
- Value *EHObj, FrameVarInfoMap &VarInfo)
- : LPI(LPI), CurrentSelector(Selector->stripPointerCasts()), EHObj(EHObj),
- Materializer(CatchFn, VarInfo),
- SelectorIDType(Type::getInt32Ty(LPI->getContext())),
- Int8PtrType(Type::getInt8PtrTy(LPI->getContext())) {}
+ WinEHCloningDirectorBase(Function *HandlerFn, Value *ParentFP,
+ FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
+ : Materializer(HandlerFn, ParentFP, VarInfo),
+ SelectorIDType(Type::getInt32Ty(HandlerFn->getContext())),
+ Int8PtrType(Type::getInt8PtrTy(HandlerFn->getContext())),
+ LPadMap(LPadMap), ParentFP(ParentFP) {}
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 handleIndirectBr(ValueToValueMapTy &VMap,
+ const IndirectBrInst *IBr,
+ BasicBlock *NewBB) = 0;
+ virtual CloningAction handleInvoke(ValueToValueMapTy &VMap,
+ const InvokeInst *Invoke,
+ BasicBlock *NewBB) = 0;
+ virtual CloningAction handleResume(ValueToValueMapTy &VMap,
+ const ResumeInst *Resume,
+ BasicBlock *NewBB) = 0;
+ virtual CloningAction handleCompare(ValueToValueMapTy &VMap,
+ const CmpInst *Compare,
+ BasicBlock *NewBB) = 0;
+ virtual CloningAction handleLandingPad(ValueToValueMapTy &VMap,
+ const LandingPadInst *LPad,
+ BasicBlock *NewBB) = 0;
+
ValueMaterializer *getValueMaterializer() override { return &Materializer; }
-private:
- LandingPadInst *LPI;
- Value *CurrentSelector;
- Value *EHObj;
+protected:
WinEHFrameVariableMaterializer Materializer;
Type *SelectorIDType;
Type *Int8PtrType;
+ LandingPadMap &LPadMap;
+
+ /// The value representing the parent frame pointer.
+ Value *ParentFP;
+};
+
+class WinEHCatchDirector : public WinEHCloningDirectorBase {
+public:
+ WinEHCatchDirector(
+ Function *CatchFn, Value *ParentFP, Value *Selector,
+ FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap,
+ DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPads,
+ DominatorTree *DT, SmallPtrSetImpl<BasicBlock *> &EHBlocks)
+ : WinEHCloningDirectorBase(CatchFn, ParentFP, VarInfo, LPadMap),
+ CurrentSelector(Selector->stripPointerCasts()),
+ ExceptionObjectVar(nullptr), NestedLPtoOriginalLP(NestedLPads),
+ DT(DT), EHBlocks(EHBlocks) {}
+
+ 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 handleIndirectBr(ValueToValueMapTy &VMap,
+ const IndirectBrInst *IBr,
+ BasicBlock *NewBB) override;
+ CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
+ BasicBlock *NewBB) override;
+ CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
+ BasicBlock *NewBB) override;
+ CloningAction handleCompare(ValueToValueMapTy &VMap, const CmpInst *Compare,
+ BasicBlock *NewBB) override;
+ CloningAction handleLandingPad(ValueToValueMapTy &VMap,
+ const LandingPadInst *LPad,
+ BasicBlock *NewBB) override;
+
+ 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;
+ DominatorTree *DT;
+ SmallPtrSetImpl<BasicBlock *> &EHBlocks;
+};
+
+class WinEHCleanupDirector : public WinEHCloningDirectorBase {
+public:
+ WinEHCleanupDirector(Function *CleanupFn, Value *ParentFP,
+ FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
+ : WinEHCloningDirectorBase(CleanupFn, ParentFP, 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 handleIndirectBr(ValueToValueMapTy &VMap,
+ const IndirectBrInst *IBr,
+ BasicBlock *NewBB) override;
+ CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
+ BasicBlock *NewBB) override;
+ CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
+ BasicBlock *NewBB) override;
+ CloningAction handleCompare(ValueToValueMapTy &VMap, const CmpInst *Compare,
+ BasicBlock *NewBB) override;
+ CloningAction handleLandingPad(ValueToValueMapTy &VMap,
+ const LandingPadInst *LPad,
+ BasicBlock *NewBB) override;
+};
+
+class LandingPadActions {
+public:
+ LandingPadActions() : HasCleanupHandlers(false) {}
+
+ void insertCatchHandler(CatchHandler *Action) { Actions.push_back(Action); }
+ void insertCleanupHandler(CleanupHandler *Action) {
+ Actions.push_back(Action);
+ HasCleanupHandlers = true;
+ }
- const Value *ExtractedEHPtr;
- const Value *ExtractedSelector;
- const Value *EHPtrStoreAddr;
- const Value *SelectorStoreAddr;
+ bool includesCleanup() const { return HasCleanupHandlers; }
+
+ SmallVectorImpl<ActionHandler *> &actions() { return Actions; }
+ SmallVectorImpl<ActionHandler *>::iterator begin() { return Actions.begin(); }
+ SmallVectorImpl<ActionHandler *>::iterator end() { return Actions.end(); }
+
+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;
};
+
} // end anonymous namespace
char WinEHPrepare::ID = 0;
return new WinEHPrepare(TM);
}
-static bool isMSVCPersonality(EHPersonality Pers) {
- return Pers == EHPersonality::MSVC_Win64SEH ||
- Pers == EHPersonality::MSVC_CXX;
-}
-
-bool WinEHPrepare::runOnFunction(Function &Fn) {
- SmallVector<LandingPadInst *, 4> LPads;
- SmallVector<ResumeInst *, 4> Resumes;
+static bool
+findExceptionalConstructs(Function &Fn,
+ SmallVectorImpl<LandingPadInst *> &LPads,
+ SmallVectorImpl<ResumeInst *> &Resumes,
+ SmallVectorImpl<BasicBlock *> &EntryBlocks) {
+ bool ForExplicitEH = false;
for (BasicBlock &BB : Fn) {
- if (auto *LP = BB.getLandingPadInst())
+ Instruction *First = BB.getFirstNonPHI();
+ if (auto *LP = dyn_cast<LandingPadInst>(First)) {
LPads.push_back(LP);
+ } else if (First->isEHPad()) {
+ if (!ForExplicitEH)
+ EntryBlocks.push_back(&Fn.getEntryBlock());
+ if (!isa<CatchEndPadInst>(First) && !isa<CleanupEndPadInst>(First))
+ EntryBlocks.push_back(&BB);
+ ForExplicitEH = true;
+ }
if (auto *Resume = dyn_cast<ResumeInst>(BB.getTerminator()))
Resumes.push_back(Resume);
}
+ return ForExplicitEH;
+}
- // No need to prepare functions that lack landing pads.
- if (LPads.empty())
+bool WinEHPrepare::runOnFunction(Function &Fn) {
+ if (!Fn.hasPersonalityFn())
+ return false;
+
+ // No need to prepare outlined handlers.
+ if (Fn.hasFnAttribute("wineh-parent"))
return false;
// Classify the personality to see what kind of preparation we need.
- EHPersonality Pers = classifyEHPersonality(LPads.back()->getPersonalityFn());
+ Personality = classifyEHPersonality(Fn.getPersonalityFn());
- // Delegate through to the DWARF pass if this is unrecognized.
- if (!isMSVCPersonality(Pers))
- return DwarfPrepare->runOnFunction(Fn);
+ // Do nothing if this is not a funclet-based personality.
+ if (!isFuncletEHPersonality(Personality))
+ return false;
- // FIXME: This only returns true if the C++ EH handlers were outlined.
- // When that code is complete, it should always return whatever
- // prepareCPPEHHandlers returns.
- if (Pers == EHPersonality::MSVC_CXX && prepareCPPEHHandlers(Fn, LPads))
- return true;
+ SmallVector<LandingPadInst *, 4> LPads;
+ SmallVector<ResumeInst *, 4> Resumes;
+ SmallVector<BasicBlock *, 4> EntryBlocks;
+ bool ForExplicitEH =
+ findExceptionalConstructs(Fn, LPads, Resumes, EntryBlocks);
- // FIXME: SEH Cleanups are unimplemented. Replace them with unreachable.
- if (Resumes.empty())
+ if (ForExplicitEH)
+ return prepareExplicitEH(Fn, EntryBlocks);
+
+ // No need to prepare functions that lack landing pads.
+ if (LPads.empty())
return false;
- for (ResumeInst *Resume : Resumes) {
- IRBuilder<>(Resume).CreateUnreachable();
- Resume->eraseFromParent();
- }
+ DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+ LibInfo = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+ // If there were any landing pads, prepareExceptionHandlers will make changes.
+ prepareExceptionHandlers(Fn, LPads);
return true;
}
-bool WinEHPrepare::doFinalization(Module &M) {
- return DwarfPrepare->doFinalization(M);
-}
+bool WinEHPrepare::doFinalization(Module &M) { return false; }
void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {
- DwarfPrepare->getAnalysisUsage(AU);
+ AU.addRequired<DominatorTreeWrapperPass>();
+ AU.addRequired<TargetLibraryInfoWrapperPass>();
+}
+
+static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler,
+ Constant *&Selector, BasicBlock *&NextBB);
+
+// Finds blocks reachable from the starting set Worklist. Does not follow unwind
+// edges or blocks listed in StopPoints.
+static void findReachableBlocks(SmallPtrSetImpl<BasicBlock *> &ReachableBBs,
+ SetVector<BasicBlock *> &Worklist,
+ const SetVector<BasicBlock *> *StopPoints) {
+ while (!Worklist.empty()) {
+ BasicBlock *BB = Worklist.pop_back_val();
+
+ // Don't cross blocks that we should stop at.
+ if (StopPoints && StopPoints->count(BB))
+ continue;
+
+ if (!ReachableBBs.insert(BB).second)
+ continue; // Already visited.
+
+ // Don't follow unwind edges of invokes.
+ if (auto *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
+ Worklist.insert(II->getNormalDest());
+ continue;
+ }
+
+ // Otherwise, follow all successors.
+ Worklist.insert(succ_begin(BB), succ_end(BB));
+ }
+}
+
+// Attempt to find an instruction where a block can be split before
+// a call to llvm.eh.begincatch and its operands. If the block
+// begins with the begincatch call or one of its adjacent operands
+// the block will not be split.
+static Instruction *findBeginCatchSplitPoint(BasicBlock *BB,
+ IntrinsicInst *II) {
+ // If the begincatch call is already the first instruction in the block,
+ // don't split.
+ Instruction *FirstNonPHI = BB->getFirstNonPHI();
+ if (II == FirstNonPHI)
+ return nullptr;
+
+ // If either operand is in the same basic block as the instruction and
+ // isn't used by another instruction before the begincatch call, include it
+ // in the split block.
+ auto *Op0 = dyn_cast<Instruction>(II->getOperand(0));
+ auto *Op1 = dyn_cast<Instruction>(II->getOperand(1));
+
+ Instruction *I = II->getPrevNode();
+ Instruction *LastI = II;
+
+ while (I == Op0 || I == Op1) {
+ // If the block begins with one of the operands and there are no other
+ // instructions between the operand and the begincatch call, don't split.
+ if (I == FirstNonPHI)
+ return nullptr;
+
+ LastI = I;
+ I = I->getPrevNode();
+ }
+
+ // If there is at least one instruction in the block before the begincatch
+ // call and its operands, split the block at either the begincatch or
+ // its operand.
+ return LastI;
+}
+
+/// Find all points where exceptional control rejoins normal control flow via
+/// llvm.eh.endcatch. Add them to the normal bb reachability worklist.
+void WinEHPrepare::findCXXEHReturnPoints(
+ Function &F, SetVector<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_begincatch>())) {
+ Instruction *SplitPt =
+ findBeginCatchSplitPoint(BB, cast<IntrinsicInst>(&I));
+ if (SplitPt) {
+ // Split the block before the llvm.eh.begincatch call to allow
+ // cleanup and catch code to be distinguished later.
+ // Do not update BBI because we still need to process the
+ // portion of the block that we are splitting off.
+ SplitBlock(BB, SplitPt, DT);
+ break;
+ }
+ }
+ if (match(&I, m_Intrinsic<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 = SplitBlock(BB, I.getNextNode(), DT);
+ }
+ // The next BB is normal control flow.
+ EHReturnBlocks.insert(BB->getTerminator()->getSuccessor(0));
+ break;
+ }
+ }
+ }
+}
+
+static bool isCatchAllLandingPad(const BasicBlock *BB) {
+ const LandingPadInst *LP = BB->getLandingPadInst();
+ if (!LP)
+ return false;
+ unsigned N = LP->getNumClauses();
+ return (N > 0 && LP->isCatch(N - 1) &&
+ isa<ConstantPointerNull>(LP->getClause(N - 1)));
+}
+
+/// Find all points where exceptions control rejoins normal control flow via
+/// selector dispatch.
+void WinEHPrepare::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;
+ }
+
+ BasicBlock *CatchHandler;
+ BasicBlock *NextBB;
+ Constant *Selector;
+ if (isSelectorDispatch(BB, CatchHandler, Selector, NextBB)) {
+ // Split the edge if there are multiple predecessors. This creates a place
+ // where we can insert EH recovery code.
+ if (!CatchHandler->getSinglePredecessor()) {
+ DEBUG(dbgs() << "splitting EH return edge from " << BB->getName()
+ << " to " << CatchHandler->getName() << '\n');
+ BBI = CatchHandler = SplitCriticalEdge(
+ BB, std::find(succ_begin(BB), succ_end(BB), CatchHandler));
+ }
+ EHReturnBlocks.insert(CatchHandler);
+ }
+ }
+}
+
+void WinEHPrepare::identifyEHBlocks(Function &F,
+ SmallVectorImpl<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.
+
+ 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.
+ SetVector<BasicBlock *> Worklist;
+ Worklist = EHReturnBlocks;
+ Worklist.insert(&F.getEntryBlock());
+ findReachableBlocks(NormalBlocks, Worklist, nullptr);
+ DEBUG({
+ dbgs() << "marked the following blocks as normal:\n";
+ for (BasicBlock *BB : NormalBlocks)
+ dbgs() << " " << BB->getName() << '\n';
+ });
+
+ // Exceptional blocks are the blocks reachable from landingpads that don't
+ // cross EH return points.
+ Worklist.clear();
+ for (auto *LPI : LPads)
+ Worklist.insert(LPI->getParent());
+ findReachableBlocks(EHBlocks, Worklist, &EHReturnBlocks);
+ DEBUG({
+ dbgs() << "marked the following blocks as exceptional:\n";
+ for (BasicBlock *BB : EHBlocks)
+ dbgs() << " " << BB->getName() << '\n';
+ });
+
+}
+
+/// Ensure that all values live into and out of exception handlers are stored
+/// in memory.
+/// FIXME: This falls down when values are defined in one handler and live into
+/// another handler. For example, a cleanup defines a value used only by a
+/// catch handler.
+void WinEHPrepare::demoteValuesLiveAcrossHandlers(
+ Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
+ DEBUG(dbgs() << "Demoting values live across exception handlers in function "
+ << F.getName() << '\n');
+
+ // identifyEHBlocks() should have been called before this function.
+ assert(!NormalBlocks.empty());
+
+ // Try to avoid demoting EH pointer and selector values. They get in the way
+ // of our pattern matching.
+ SmallPtrSet<Instruction *, 10> EHVals;
+ for (BasicBlock &BB : F) {
+ LandingPadInst *LP = BB.getLandingPadInst();
+ if (!LP)
+ continue;
+ EHVals.insert(LP);
+ for (User *U : LP->users()) {
+ auto *EI = dyn_cast<ExtractValueInst>(U);
+ if (!EI)
+ continue;
+ EHVals.insert(EI);
+ for (User *U2 : EI->users()) {
+ if (auto *PN = dyn_cast<PHINode>(U2))
+ EHVals.insert(PN);
+ }
+ }
+ }
+
+ 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;
+
+ if (auto *Arg = dyn_cast<Argument>(Op)) {
+ if (IsEHBB) {
+ DEBUG(dbgs() << "Demoting argument " << *Arg
+ << " used by EH instr: " << I << "\n");
+ ArgsToDemote.insert(Arg);
+ }
+ continue;
+ }
+
+ // Don't demote EH values.
+ auto *OpI = cast<Instruction>(Op);
+ if (EHVals.count(OpI))
+ continue;
+
+ BasicBlock *OpBB = OpI->getParent();
+ // If a value is produced and consumed in the same BB, we don't need to
+ // demote it.
+ if (OpBB == &BB)
+ continue;
+ bool IsOpNormalBB = NormalBlocks.count(OpBB);
+ bool IsOpEHBB = EHBlocks.count(OpBB);
+ if (IsNormalBB != IsOpNormalBB || IsEHBB != IsOpEHBB) {
+ DEBUG({
+ dbgs() << "Demoting instruction live in-out from EH:\n";
+ dbgs() << "Instr: " << *OpI << '\n';
+ dbgs() << "User: " << I << '\n';
+ });
+ InstrsToDemote.insert(OpI);
+ }
+ }
+ }
+ }
+
+ // Demote values live into and out of handlers.
+ // FIXME: This demotion is inefficient. We should insert spills at the point
+ // of definition, insert one reload in each handler that uses the value, and
+ // insert reloads in the BB used to rejoin normal control flow.
+ Instruction *AllocaInsertPt = F.getEntryBlock().getFirstInsertionPt();
+ for (Instruction *I : InstrsToDemote)
+ DemoteRegToStack(*I, false, AllocaInsertPt);
+
+ // Demote arguments separately, and only for uses in EH blocks.
+ for (Argument *Arg : ArgsToDemote) {
+ auto *Slot = new AllocaInst(Arg->getType(), nullptr,
+ Arg->getName() + ".reg2mem", AllocaInsertPt);
+ SmallVector<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);
+ }
+
+ // 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);
+ }
+
+ DEBUG(dbgs() << "Demoted " << InstrsToDemote.size() << " instructions and "
+ << ArgsToDemote.size() << " arguments for WinEHPrepare\n\n");
}
-bool WinEHPrepare::prepareCPPEHHandlers(
+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;
+ }
+
+ identifyEHBlocks(F, LPads);
+ demoteValuesLiveAcrossHandlers(F, LPads);
+
// These containers are used to re-map frame variables that are used in
// outlined catch and cleanup handlers. They will be populated as the
// handlers are outlined.
FrameVarInfoMap FrameVarInfo;
- SmallVector<CallInst *, 4> HandlerAllocs;
- SmallVector<AllocaInst *, 4> HandlerEHObjPtrs;
bool HandlersOutlined = false;
+ Module *M = F.getParent();
+ LLVMContext &Context = M->getContext();
+
+ // 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);
+
+ if (isAsynchronousEHPersonality(Personality)) {
+ // FIXME: Switch the ehptr type to i32 and then switch this.
+ SEHExceptionCodeSlot =
+ new AllocaInst(Int8PtrType, nullptr, "seh_exception_code",
+ F.getEntryBlock().getFirstInsertionPt());
+ }
+
+ // In order to handle the case where one outlined catch handler returns
+ // to a block within another outlined catch handler that would otherwise
+ // be unreachable, we need to outline the nested landing pad before we
+ // outline the landing pad which encloses it.
+ if (!isAsynchronousEHPersonality(Personality))
+ std::sort(LPads.begin(), LPads.end(),
+ [this](LandingPadInst *const &L, LandingPadInst *const &R) {
+ return DT->properlyDominates(R->getParent(), L->getParent());
+ });
+
+ // This container stores the llvm.eh.recover and IndirectBr instructions
+ // that make up the body of each landing pad after it has been outlined.
+ // We need to defer the population of the target list for the indirectbr
+ // until all landing pads have been outlined so that we can handle the
+ // case of blocks in the target that are reached only from nested
+ // landing pads.
+ SmallVector<std::pair<CallInst*, IndirectBrInst *>, 4> LPadImpls;
+
for (LandingPadInst *LPad : LPads) {
// Look for evidence that this landingpad has already been processed.
bool LPadHasActionList = false;
BasicBlock *LPadBB = LPad->getParent();
- for (Instruction &Inst : LPadBB->getInstList()) {
- // FIXME: Make this an intrinsic.
- if (auto *Call = dyn_cast<CallInst>(&Inst))
- if (Call->getCalledFunction()->getName() == "llvm.eh.actions") {
- LPadHasActionList = true;
- break;
- }
+ for (Instruction &Inst : *LPadBB) {
+ if (match(&Inst, m_Intrinsic<Intrinsic::eh_actions>())) {
+ LPadHasActionList = true;
+ break;
+ }
}
// If we've already outlined the handlers for this landingpad,
if (LPadHasActionList)
continue;
- for (unsigned Idx = 0, NumClauses = LPad->getNumClauses(); Idx < NumClauses;
- ++Idx) {
- if (LPad->isCatch(Idx)) {
- // Create a new instance of the handler data structure in the
- // HandlerData vector.
- CallInst *EHAlloc = nullptr;
- AllocaInst *EHObjPtr = nullptr;
- bool Outlined = outlineCatchHandler(&F, LPad->getClause(Idx), LPad,
- EHAlloc, EHObjPtr, FrameVarInfo);
- if (Outlined) {
- HandlersOutlined = true;
- // These values must be resolved after all handlers have been
- // outlined.
- if (EHAlloc)
- HandlerAllocs.push_back(EHAlloc);
- if (EHObjPtr)
- HandlerEHObjPtrs.push_back(EHObjPtr);
+ // 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);
+
+ LandingPadActions Actions;
+ mapLandingPadBlocks(LPad, Actions);
+
+ 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;
+ }
+ }
+
+ outlineHandler(Action, &F, LPad, StartBB, FrameVarInfo);
+ }
+
+ // Split the block after the landingpad instruction so that it is just a
+ // call to llvm.eh.actions followed by indirectbr.
+ assert(!isa<PHINode>(LPadBB->begin()) && "lpad phi not removed");
+ SplitBlock(LPadBB, LPad->getNextNode(), DT);
+ // Erase the branch inserted by the split so we can insert indirectbr.
+ LPadBB->getTerminator()->eraseFromParent();
+
+ // Replace all extracted values with undef and ultimately replace the
+ // landingpad with undef.
+ SmallVector<Instruction *, 4> SEHCodeUses;
+ SmallVector<Instruction *, 4> EHUndefs;
+ 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->idx_begin();
+ assert((Idx == 0 || Idx == 1) && "unexpected index");
+ if (Idx == 0 && isAsynchronousEHPersonality(Personality))
+ SEHCodeUses.push_back(E);
+ else
+ EHUndefs.push_back(E);
+ }
+ for (Instruction *E : EHUndefs) {
+ E->replaceAllUsesWith(UndefValue::get(E->getType()));
+ E->eraseFromParent();
+ }
+ LPad->replaceAllUsesWith(UndefValue::get(LPad->getType()));
+
+ // Rewrite uses of the exception pointer to loads of an alloca.
+ while (!SEHCodeUses.empty()) {
+ Instruction *E = SEHCodeUses.pop_back_val();
+ SmallVector<Use *, 4> Uses;
+ for (Use &U : E->uses())
+ Uses.push_back(&U);
+ for (Use *U : Uses) {
+ auto *I = cast<Instruction>(U->getUser());
+ if (isa<ResumeInst>(I))
+ continue;
+ if (auto *Phi = dyn_cast<PHINode>(I))
+ SEHCodeUses.push_back(Phi);
+ else
+ U->set(new LoadInst(SEHExceptionCodeSlot, "sehcode", false, I));
+ }
+ E->replaceAllUsesWith(UndefValue::get(E->getType()));
+ E->eraseFromParent();
+ }
+
+ // 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);
}
- } // End if (isCatch)
- } // End for each clause
- } // End for each landingpad
+ 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", LPadBB);
+
+ 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());
+ }
+ }
+ IndirectBrInst *Branch =
+ IndirectBrInst::Create(Recover, ReturnTargets.size(), LPadBB);
+ for (BasicBlock *Target : ReturnTargets)
+ Branch->addDestination(Target);
+
+ if (!isAsynchronousEHPersonality(Personality)) {
+ // C++ EH must repopulate the targets later to handle the case of
+ // targets that are reached indirectly through nested landing pads.
+ LPadImpls.push_back(std::make_pair(Recover, Branch));
+ }
+
+ } // End for each landingpad
// If nothing got outlined, there is no more processing to be done.
if (!HandlersOutlined)
return false;
- // FIXME: We will replace the landingpad bodies with llvm.eh.actions
- // calls and indirect branches here and then delete blocks
- // which are no longer reachable. That will get rid of the
- // handlers that we have outlined. There is code below
- // that looks for allocas with no uses in the parent function.
- // That will only happen after the pruning is implemented.
-
- // Remap the frame variables.
- SmallVector<Type *, 2> StructTys;
- StructTys.push_back(Type::getInt32Ty(F.getContext())); // EH state
- StructTys.push_back(Type::getInt8PtrTy(F.getContext())); // EH object
-
- // Start the index at two since we always have the above fields at 0 and 1.
- int Idx = 2;
-
- // FIXME: Sort the FrameVarInfo vector by the ParentAlloca size and alignment
- // and add padding as necessary to provide the proper alignment.
-
- // Map the alloca instructions to the corresponding index in the
- // frame allocation structure. If any alloca is used only in a single
- // handler and is not used in the parent frame after outlining, it will
- // be assigned an index of -1, meaning the handler can keep its
- // "temporary" alloca and the original alloca can be erased from the
- // parent function. If we later encounter this alloca in a second
- // handler, we will assign it a place in the frame allocation structure
- // at that time. Since the instruction replacement doesn't happen until
- // all the entries in the HandlerData have been processed this isn't a
- // problem.
- for (auto &VarInfoEntry : FrameVarInfo) {
- AllocaInst *ParentAlloca = VarInfoEntry.first;
- HandlerAllocas &AllocaInfo = VarInfoEntry.second;
-
- // If the instruction still has uses in the parent function or if it is
- // referenced by more than one handler, add it to the frame allocation
- // structure.
- if (ParentAlloca->getNumUses() != 0 || AllocaInfo.Allocas.size() > 1) {
- Type *VarTy = ParentAlloca->getAllocatedType();
- StructTys.push_back(VarTy);
- AllocaInfo.ParentFrameAllocationIndex = Idx++;
- } else {
- // If the variable is not used in the parent frame and it is only used
- // in one handler, the alloca can be removed from the parent frame
- // and the handler will keep its "temporary" alloca to define the value.
- // An element index of -1 is used to indicate this condition.
- AllocaInfo.ParentFrameAllocationIndex = -1;
+ // 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();
+
+ // Update the indirectbr instructions' target lists if necessary.
+ SetVector<BasicBlock*> CheckedTargets;
+ SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList;
+ for (auto &LPadImplPair : LPadImpls) {
+ IntrinsicInst *Recover = cast<IntrinsicInst>(LPadImplPair.first);
+ IndirectBrInst *Branch = LPadImplPair.second;
+
+ // Get a list of handlers called by
+ parseEHActions(Recover, ActionList);
+
+ // Add an indirect branch listing possible successors of the catch handlers.
+ SetVector<BasicBlock *> ReturnTargets;
+ for (const auto &Action : ActionList) {
+ if (auto *CA = dyn_cast<CatchHandler>(Action.get())) {
+ Function *Handler = cast<Function>(CA->getHandlerBlockOrFunc());
+ getPossibleReturnTargets(&F, Handler, ReturnTargets);
+ }
+ }
+ ActionList.clear();
+ // Clear any targets we already knew about.
+ for (unsigned int I = 0, E = Branch->getNumDestinations(); I < E; ++I) {
+ BasicBlock *KnownTarget = Branch->getDestination(I);
+ if (ReturnTargets.count(KnownTarget))
+ ReturnTargets.remove(KnownTarget);
+ }
+ for (BasicBlock *Target : ReturnTargets) {
+ Branch->addDestination(Target);
+ // The target may be a block that we excepted to get pruned.
+ // If it is, it may contain a call to llvm.eh.endcatch.
+ if (CheckedTargets.insert(Target)) {
+ // Earlier preparations guarantee that all calls to llvm.eh.endcatch
+ // will be followed by an unconditional branch.
+ auto *Br = dyn_cast<BranchInst>(Target->getTerminator());
+ if (Br && Br->isUnconditional() &&
+ Br != Target->getFirstNonPHIOrDbgOrLifetime()) {
+ Instruction *Prev = Br->getPrevNode();
+ if (match(cast<Value>(Prev), m_Intrinsic<Intrinsic::eh_endcatch>()))
+ Prev->eraseFromParent();
+ }
+ }
}
}
+ LPadImpls.clear();
- // Having filled the StructTys vector and assigned an index to each element,
- // we can now create the structure.
- StructType *EHDataStructTy = StructType::create(
- F.getContext(), StructTys, "struct." + F.getName().str() + ".ehdata");
- IRBuilder<> Builder(F.getParent()->getContext());
+ F.addFnAttr("wineh-parent", F.getName());
+
+ // Delete any blocks that were only used by handlers that were outlined above.
+ removeUnreachableBlocks(F);
- // Create a frame allocation.
- Module *M = F.getParent();
- LLVMContext &Context = M->getContext();
BasicBlock *Entry = &F.getEntryBlock();
+ IRBuilder<> Builder(F.getParent()->getContext());
Builder.SetInsertPoint(Entry->getFirstInsertionPt());
- Function *FrameAllocFn =
- Intrinsic::getDeclaration(M, Intrinsic::frameallocate);
- uint64_t EHAllocSize = M->getDataLayout()->getTypeAllocSize(EHDataStructTy);
- Value *FrameAllocArgs[] = {
- ConstantInt::get(Type::getInt32Ty(Context), EHAllocSize)};
- CallInst *FrameAlloc =
- Builder.CreateCall(FrameAllocFn, FrameAllocArgs, "frame.alloc");
-
- Value *FrameEHData = Builder.CreateBitCast(
- FrameAlloc, EHDataStructTy->getPointerTo(), "eh.data");
-
- // Now visit each handler that is using the structure and bitcast its EHAlloc
- // value to be a pointer to the frame alloc structure.
- DenseMap<Function *, Value *> EHDataMap;
- for (CallInst *EHAlloc : HandlerAllocs) {
- // The EHAlloc has no uses at this time, so we need to just insert the
- // cast before the next instruction. There is always a next instruction.
- BasicBlock::iterator II = EHAlloc;
- ++II;
- Builder.SetInsertPoint(cast<Instruction>(II));
- Value *EHData = Builder.CreateBitCast(
- EHAlloc, EHDataStructTy->getPointerTo(), "eh.data");
- EHDataMap[EHAlloc->getParent()->getParent()] = EHData;
- }
- // Next, replace the place-holder EHObjPtr allocas with GEP instructions
- // that pull the EHObjPtr from the frame alloc structure
- for (AllocaInst *EHObjPtr : HandlerEHObjPtrs) {
- Value *EHData = EHDataMap[EHObjPtr->getParent()->getParent()];
- Builder.SetInsertPoint(EHObjPtr);
- Value *ElementPtr = Builder.CreateConstInBoundsGEP2_32(EHData, 0, 1);
- EHObjPtr->replaceAllUsesWith(ElementPtr);
- EHObjPtr->removeFromParent();
- ElementPtr->takeName(EHObjPtr);
- delete EHObjPtr;
+ Function *FrameEscapeFn =
+ Intrinsic::getDeclaration(M, Intrinsic::localescape);
+ Function *RecoverFrameFn =
+ Intrinsic::getDeclaration(M, Intrinsic::localrecover);
+ SmallVector<Value *, 8> AllocasToEscape;
+
+ // Scan the entry block for an existing call to llvm.localescape. We need to
+ // keep escaping those objects.
+ for (Instruction &I : F.front()) {
+ auto *II = dyn_cast<IntrinsicInst>(&I);
+ if (II && II->getIntrinsicID() == Intrinsic::localescape) {
+ auto Args = II->arg_operands();
+ AllocasToEscape.append(Args.begin(), Args.end());
+ II->eraseFromParent();
+ break;
+ }
}
// Finally, replace all of the temporary allocas for frame variables used in
- // the outlined handlers and the original frame allocas with GEP instructions
- // that get the equivalent pointer from the frame allocation struct.
+ // the outlined handlers with calls to llvm.localrecover.
for (auto &VarInfoEntry : FrameVarInfo) {
- AllocaInst *ParentAlloca = VarInfoEntry.first;
- HandlerAllocas &AllocaInfo = VarInfoEntry.second;
- int Idx = AllocaInfo.ParentFrameAllocationIndex;
-
- // If we have an index of -1 for this instruction, it means it isn't used
- // outside of this handler. In that case, we just keep the "temporary"
- // alloca in the handler and erase the original alloca from the parent.
- if (Idx == -1) {
- ParentAlloca->eraseFromParent();
- } else {
- // Otherwise, we replace the parent alloca and all outlined allocas
- // which map to it with GEP instructions.
-
- // First replace the original alloca.
- Builder.SetInsertPoint(ParentAlloca);
- Builder.SetCurrentDebugLocation(ParentAlloca->getDebugLoc());
- Value *ElementPtr =
- Builder.CreateConstInBoundsGEP2_32(FrameEHData, 0, Idx);
- ParentAlloca->replaceAllUsesWith(ElementPtr);
- ParentAlloca->removeFromParent();
- ElementPtr->takeName(ParentAlloca);
- delete ParentAlloca;
-
- // Next replace all outlined allocas that are mapped to it.
- for (AllocaInst *TempAlloca : AllocaInfo.Allocas) {
- Value *EHData = EHDataMap[TempAlloca->getParent()->getParent()];
- // FIXME: Sink this GEP into the blocks where it is used.
- Builder.SetInsertPoint(TempAlloca);
- Builder.SetCurrentDebugLocation(TempAlloca->getDebugLoc());
- ElementPtr = Builder.CreateConstInBoundsGEP2_32(EHData, 0, Idx);
- TempAlloca->replaceAllUsesWith(ElementPtr);
- TempAlloca->removeFromParent();
- ElementPtr->takeName(TempAlloca);
- delete TempAlloca;
- }
- } // end else of if (Idx == -1)
- } // End for each FrameVarInfo entry.
+ 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();
+ llvm::Value *FP = HandlerToParentFP[HandlerFn];
+ assert(FP);
+
+ // FIXME: Sink this localrecover into the blocks where it is used.
+ Builder.SetInsertPoint(TempAlloca);
+ Builder.SetCurrentDebugLocation(TempAlloca->getDebugLoc());
+ Value *RecoverArgs[] = {
+ Builder.CreateBitCast(&F, Int8PtrType, ""), FP,
+ llvm::ConstantInt::get(Int32Type, AllocasToEscape.size() - 1)};
+ Instruction *RecoveredAlloca =
+ Builder.CreateCall(RecoverFrameFn, RecoverArgs);
+
+ // Add a pointer bitcast if the alloca wasn't an i8.
+ if (RecoveredAlloca->getType() != TempAlloca->getType()) {
+ RecoveredAlloca->setName(Twine(TempAlloca->getName()) + ".i8");
+ RecoveredAlloca = cast<Instruction>(
+ Builder.CreateBitCast(RecoveredAlloca, TempAlloca->getType()));
+ }
+ TempAlloca->replaceAllUsesWith(RecoveredAlloca);
+ TempAlloca->removeFromParent();
+ RecoveredAlloca->takeName(TempAlloca);
+ delete TempAlloca;
+ }
+ } // End for each FrameVarInfo entry.
+
+ // Insert 'call void (...)* @llvm.localescape(...)' at the end of the entry
+ // block.
+ Builder.SetInsertPoint(&F.getEntryBlock().back());
+ Builder.CreateCall(FrameEscapeFn, AllocasToEscape);
+
+ if (SEHExceptionCodeSlot) {
+ if (isAllocaPromotable(SEHExceptionCodeSlot)) {
+ SmallPtrSet<BasicBlock *, 4> UserBlocks;
+ for (User *U : SEHExceptionCodeSlot->users()) {
+ if (auto *Inst = dyn_cast<Instruction>(U))
+ UserBlocks.insert(Inst->getParent());
+ }
+ PromoteMemToReg(SEHExceptionCodeSlot, *DT);
+ // After the promotion, kill off dead instructions.
+ for (BasicBlock *BB : UserBlocks)
+ SimplifyInstructionsInBlock(BB, LibInfo);
+ }
+ }
+
+ // Clean up the handler action maps we created for this function
+ DeleteContainerSeconds(CatchHandlerMap);
+ CatchHandlerMap.clear();
+ DeleteContainerSeconds(CleanupHandlerMap);
+ CleanupHandlerMap.clear();
+ HandlerToParentFP.clear();
+ DT = nullptr;
+ LibInfo = nullptr;
+ SEHExceptionCodeSlot = nullptr;
+ EHBlocks.clear();
+ NormalBlocks.clear();
+ EHReturnBlocks.clear();
return HandlersOutlined;
}
-bool WinEHPrepare::outlineCatchHandler(Function *SrcFn, Constant *SelectorType,
- LandingPadInst *LPad, CallInst *&EHAlloc,
- AllocaInst *&EHObjPtr,
- FrameVarInfoMap &VarInfo) {
- Module *M = SrcFn->getParent();
- LLVMContext &Context = M->getContext();
-
- // Create a new function to receive the handler contents.
- Type *Int8PtrType = Type::getInt8PtrTy(Context);
- std::vector<Type *> ArgTys;
- ArgTys.push_back(Int8PtrType);
- ArgTys.push_back(Int8PtrType);
- FunctionType *FnType = FunctionType::get(Int8PtrType, ArgTys, false);
- Function *CatchHandler = Function::Create(
- FnType, GlobalVariable::ExternalLinkage, SrcFn->getName() + ".catch", M);
-
- // Generate a standard prolog to setup the frame recovery structure.
- IRBuilder<> Builder(Context);
- BasicBlock *Entry = BasicBlock::Create(Context, "catch.entry");
- CatchHandler->getBasicBlockList().push_front(Entry);
- Builder.SetInsertPoint(Entry);
- Builder.SetCurrentDebugLocation(LPad->getDebugLoc());
+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;
- // The outlined handler will be called with the parent's frame pointer as
- // its second argument. To enable the handler to access variables from
- // the parent frame, we use that pointer to get locate a special block
- // of memory that was allocated using llvm.eh.allocateframe for this
- // purpose. During the outlining process we will determine which frame
- // variables are used in handlers and create a structure that maps these
- // variables into the frame allocation block.
- //
- // The frame allocation block also contains an exception state variable
- // used by the runtime and a pointer to the exception object pointer
- // which will be filled in by the runtime for use in the handler.
- Function *RecoverFrameFn =
- Intrinsic::getDeclaration(M, Intrinsic::framerecover);
- Value *RecoverArgs[] = {Builder.CreateBitCast(SrcFn, Int8PtrType, ""),
- &(CatchHandler->getArgumentList().back())};
- EHAlloc = Builder.CreateCall(RecoverFrameFn, RecoverArgs, "eh.alloc");
-
- // This alloca is only temporary. We'll be replacing it once we know all the
- // frame variables that need to go in the frame allocation structure.
- EHObjPtr = Builder.CreateAlloca(Int8PtrType, 0, "eh.obj.ptr");
-
- // This will give us a raw pointer to the exception object, which
- // corresponds to the formal parameter of the catch statement. If the
- // handler uses this object, we will generate code during the outlining
- // process to cast the pointer to the appropriate type and deference it
- // as necessary. The un-outlined landing pad code represents the
- // exception object as the result of the llvm.eh.begincatch call.
- Value *EHObj = Builder.CreateLoad(EHObjPtr, false, "eh.obj");
+ for (auto *EU : Extract->users()) {
+ if (auto *Store = dyn_cast<StoreInst>(EU)) {
+ auto *AV = cast<AllocaInst>(Store->getPointerOperand());
+ EHAllocas.push_back(AV);
+ }
+ }
+ }
- ValueToValueMapTy VMap;
+ // We can't do this without a dominator tree.
+ assert(DT);
- // FIXME: Map other values referenced in the filter handler.
+ if (!EHAllocas.empty()) {
+ PromoteMemToReg(EHAllocas, *DT);
+ EHAllocas.clear();
+ }
- WinEHCatchDirector Director(LPad, CatchHandler, SelectorType, EHObj, VarInfo);
+ // 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);
+}
- SmallVector<ReturnInst *, 8> Returns;
- ClonedCodeInfo InlinedFunctionInfo;
+void WinEHPrepare::getPossibleReturnTargets(Function *ParentF,
+ Function *HandlerF,
+ SetVector<BasicBlock*> &Targets) {
+ for (BasicBlock &BB : *HandlerF) {
+ // If the handler contains landing pads, check for any
+ // handlers that may return directly to a block in the
+ // parent function.
+ if (auto *LPI = BB.getLandingPadInst()) {
+ IntrinsicInst *Recover = cast<IntrinsicInst>(LPI->getNextNode());
+ SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList;
+ parseEHActions(Recover, ActionList);
+ for (const auto &Action : ActionList) {
+ if (auto *CH = dyn_cast<CatchHandler>(Action.get())) {
+ Function *NestedF = cast<Function>(CH->getHandlerBlockOrFunc());
+ getPossibleReturnTargets(ParentF, NestedF, Targets);
+ }
+ }
+ }
- BasicBlock::iterator II = LPad;
+ auto *Ret = dyn_cast<ReturnInst>(BB.getTerminator());
+ if (!Ret)
+ continue;
- CloneAndPruneIntoFromInst(CatchHandler, SrcFn, ++II, VMap,
- /*ModuleLevelChanges=*/false, Returns, "",
- &InlinedFunctionInfo,
- SrcFn->getParent()->getDataLayout(), &Director);
+ // Handler functions must always return a block address.
+ BlockAddress *BA = cast<BlockAddress>(Ret->getReturnValue());
- // 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();
+ // If this is the handler for a nested landing pad, the
+ // return address may have been remapped to a block in the
+ // parent handler. We're not interested in those.
+ if (BA->getFunction() != ParentF)
+ continue;
- return true;
+ Targets.insert(BA->getBasicBlock());
+ }
}
-CloningDirector::CloningAction WinEHCatchDirector::handleInstruction(
- ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
- // Intercept instructions which extract values from the landing pad aggregate.
- if (auto *Extract = dyn_cast<ExtractValueInst>(Inst)) {
- if (Extract->getAggregateOperand() == LPI) {
- assert(Extract->getNumIndices() == 1 &&
- "Unexpected operation: extracting both landing pad values");
- assert((*(Extract->idx_begin()) == 0 || *(Extract->idx_begin()) == 1) &&
- "Unexpected operation: extracting an unknown landing pad element");
-
- if (*(Extract->idx_begin()) == 0) {
- // Element 0 doesn't directly corresponds to anything in the WinEH
- // scheme.
- // It will be stored to a memory location, then later loaded and finally
- // the loaded value will be used as the argument to an
- // llvm.eh.begincatch
- // call. We're tracking it here so that we can skip the store and load.
- ExtractedEHPtr = Inst;
- } else {
- // Element 1 corresponds to the filter selector. We'll map it to 1 for
- // matching purposes, but it will also probably be stored to memory and
- // reloaded, so we need to track the instuction so that we can map the
- // loaded value too.
- VMap[Inst] = ConstantInt::get(SelectorIDType, 1);
- ExtractedSelector = Inst;
- }
-
- // Tell the caller not to clone this instruction.
- return CloningDirector::SkipInstruction;
- }
- // Other extract value instructions just get cloned.
- return CloningDirector::CloneInstruction;
+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();
+ // If the nested landing pad was outlined before the landing pad that enclosed
+ // it, it will already be in outlined form. In that case, we just need to see
+ // if the returns and the enclosing branch instruction need to be updated.
+ IndirectBrInst *Branch =
+ dyn_cast<IndirectBrInst>(OutlinedBB->getTerminator());
+ if (!Branch) {
+ // If the landing pad wasn't in outlined form, it should be a stub with
+ // an unreachable terminator.
+ assert(isa<UnreachableInst>(OutlinedBB->getTerminator()));
+ OutlinedBB->getTerminator()->eraseFromParent();
+ // That should leave OutlinedLPad as the last instruction in its block.
+ assert(&OutlinedBB->back() == OutlinedLPad);
}
- if (auto *Store = dyn_cast<StoreInst>(Inst)) {
- // Look for and suppress stores of the extracted landingpad values.
- const Value *StoredValue = Store->getValueOperand();
- if (StoredValue == ExtractedEHPtr) {
- EHPtrStoreAddr = Store->getPointerOperand();
- return CloningDirector::SkipInstruction;
- }
- if (StoredValue == ExtractedSelector) {
- SelectorStoreAddr = Store->getPointerOperand();
- return CloningDirector::SkipInstruction;
+ // 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;
+ const IntrinsicInst *EHActions = cast<IntrinsicInst>(Recover);
+
+ // Remap the return target in the nested handler.
+ SmallVector<BlockAddress *, 4> ActionTargets;
+ SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList;
+ parseEHActions(EHActions, ActionList);
+ for (const auto &Action : ActionList) {
+ auto *Catch = dyn_cast<CatchHandler>(Action.get());
+ 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)
+ 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 an outlined handler function.
+ if (!LPadTargetBlocks.count(BA->getBasicBlock()))
+ 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);
}
-
- // Any other store just gets cloned.
- return CloningDirector::CloneInstruction;
}
+ ActionList.clear();
+
+ if (Branch) {
+ // If the landing pad was already in outlined form, just update its targets.
+ for (unsigned int I = Branch->getNumDestinations(); I > 0; --I)
+ Branch->removeDestination(I);
+ // Add the previously collected action targets.
+ for (auto *Target : ActionTargets)
+ Branch->addDestination(Target->getBasicBlock());
+ } else {
+ // If the landing pad was previously stubbed out, fill in its outlined form.
+ IntrinsicInst *NewEHActions = cast<IntrinsicInst>(EHActions->clone());
+ OutlinedBB->getInstList().push_back(NewEHActions);
+
+ // Insert an indirect branch into the outlined landing pad BB.
+ IndirectBrInst *IBr = IndirectBrInst::Create(NewEHActions, 0, OutlinedBB);
+ // Add the previously collected action targets.
+ for (auto *Target : ActionTargets)
+ IBr->addDestination(Target->getBasicBlock());
+ }
+}
- if (auto *Load = dyn_cast<LoadInst>(Inst)) {
- // Look for loads of (previously suppressed) landingpad values.
- // The EHPtr load can be ignored (it should only be used as
- // an argument to llvm.eh.begincatch), but the selector value
- // needs to be mapped to a constant value of 1 to be used to
- // simplify the branching to always flow to the current handler.
- const Value *LoadAddr = Load->getPointerOperand();
- if (LoadAddr == EHPtrStoreAddr) {
- VMap[Inst] = UndefValue::get(Int8PtrType);
- return CloningDirector::SkipInstruction;
- }
- if (LoadAddr == SelectorStoreAddr) {
- VMap[Inst] = ConstantInt::get(SelectorIDType, 1);
- return CloningDirector::SkipInstruction;
- }
+// 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;
- // Any other loads just get cloned.
- return CloningDirector::CloneInstruction;
+ 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;
+
+ if (Pred == CmpInst::ICMP_EQ) {
+ CatchHandler = TBB;
+ NextBB = FBB;
+ return true;
}
- if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>())) {
- // The argument to the call is some form of the first element of the
- // landingpad aggregate value, but that doesn't matter. It isn't used
- // here.
- // The return value of this instruction, however, is used to access the
- // EH object pointer. We have generated an instruction to get that value
- // from the EH alloc block, so we can just map to that here.
- VMap[Inst] = EHObj;
- return CloningDirector::SkipInstruction;
+ if (Pred == CmpInst::ICMP_NE) {
+ CatchHandler = FBB;
+ NextBB = TBB;
+ return true;
}
- if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>())) {
- auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst);
- // It might be interesting to track whether or not we are inside a catch
- // function, but that might make the algorithm more brittle than it needs
- // to be.
-
- // The end catch call can occur in one of two places: either in a
- // landingpad
- // block that is part of the catch handlers exception mechanism, or at the
- // end of the catch block. If it occurs in a landing pad, we must skip it
- // and continue so that the landing pad gets cloned.
- // FIXME: This case isn't fully supported yet and shouldn't turn up in any
- // of the test cases until it is.
- if (IntrinCall->getParent()->isLandingPad())
- return CloningDirector::SkipInstruction;
-
- // If an end catch occurs anywhere else the next instruction should be an
- // unconditional branch instruction that we want to replace with a return
- // to the the address of the branch target.
- const BasicBlock *EndCatchBB = IntrinCall->getParent();
- const TerminatorInst *Terminator = EndCatchBB->getTerminator();
- const BranchInst *Branch = dyn_cast<BranchInst>(Terminator);
- assert(Branch && Branch->isUnconditional());
- assert(std::next(BasicBlock::const_iterator(IntrinCall)) ==
- BasicBlock::const_iterator(Branch));
- ReturnInst::Create(NewBB->getContext(),
- BlockAddress::get(Branch->getSuccessor(0)), NewBB);
+ return false;
+}
- // We just added a terminator to the cloned block.
- // Tell the caller to stop processing the current basic block so that
- // the branch instruction will be skipped.
- return CloningDirector::StopCloningBB;
- }
- if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>())) {
- auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst);
- Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts();
- // This causes a replacement that will collapse the landing pad CFG based
- // on the filter function we intend to match.
- if (Selector == CurrentSelector)
- VMap[Inst] = ConstantInt::get(SelectorIDType, 1);
- else
- VMap[Inst] = ConstantInt::get(SelectorIDType, 0);
- // Tell the caller not to clone this instruction.
- return CloningDirector::SkipInstruction;
+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;
}
-
- // Continue with the default cloning behavior.
- return CloningDirector::CloneInstruction;
+ return false;
}
-WinEHFrameVariableMaterializer::WinEHFrameVariableMaterializer(
- Function *OutlinedFn, FrameVarInfoMap &FrameVarInfo)
- : FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) {
- Builder.SetInsertPoint(&OutlinedFn->getEntryBlock());
- // FIXME: Do something with the FrameVarMapped so that it is shared across the
- // function.
+static BasicBlock *createStubLandingPad(Function *Handler) {
+ // 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),
+ 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;
}
-Value *WinEHFrameVariableMaterializer::materializeValueFor(Value *V) {
- // If we're asked to materialize an alloca variable, we temporarily
- // create a matching alloca in the outlined function. When all the
- // outlining is complete, we'll collect these into a structure and
- // replace these temporary allocas with GEPs referencing the frame
- // allocation block.
- if (auto *AV = dyn_cast<AllocaInst>(V)) {
- AllocaInst *NewAlloca = Builder.CreateAlloca(
- AV->getAllocatedType(), AV->getArraySize(), AV->getName());
- FrameVarInfo[AV].Allocas.push_back(NewAlloca);
- return NewAlloca;
+// 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) {
+ 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);
}
-// FIXME: Do PHI nodes need special handling?
-
-// FIXME: Are there other cases we can handle better? GEP, ExtractValue, etc.
+ // 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, DT);
+ // SplitBlock adds an unconditional branch instruction at the end of the
+ // parent block. We want to replace that with an invoke call, so we can
+ // erase it now.
+ OldRetBB->getTerminator()->eraseFromParent();
+ BasicBlock *StubLandingPad = createStubLandingPad(Handler);
+ Function *F =
+ Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::donothing);
+ InvokeInst::Create(F, NewRetBB, StubLandingPad, None, "", OldRetBB);
+}
-// FIXME: This doesn't work during cloning because it finds an instruction
-// in the use list that isn't yet part of a basic block.
-#if 0
- // If we're asked to remap some other instruction, we'll need to
- // spill it to an alloca variable in the parent function and add a
- // temporary alloca in the outlined function to be processed as
- // described above.
- Instruction *Inst = dyn_cast<Instruction>(V);
- if (Inst) {
- AllocaInst *Spill = DemoteRegToStack(*Inst, true);
- AllocaInst *NewAlloca = Builder.CreateAlloca(Spill->getAllocatedType(),
- Spill->getArraySize());
- FrameVarMap[AV] = NewAlloca;
- return NewAlloca;
+// FIXME: Consider sinking this into lib/Target/X86 somehow. TargetLowering
+// usually doesn't build LLVM IR, so that's probably the wrong place.
+Function *WinEHPrepare::createHandlerFunc(Function *ParentFn, Type *RetTy,
+ const Twine &Name, Module *M,
+ Value *&ParentFP) {
+ // x64 uses a two-argument prototype where the parent FP is the second
+ // argument. x86 uses no arguments, just the incoming EBP value.
+ LLVMContext &Context = M->getContext();
+ Type *Int8PtrType = Type::getInt8PtrTy(Context);
+ FunctionType *FnType;
+ if (TheTriple.getArch() == Triple::x86_64) {
+ Type *ArgTys[2] = {Int8PtrType, Int8PtrType};
+ FnType = FunctionType::get(RetTy, ArgTys, false);
+ } else {
+ FnType = FunctionType::get(RetTy, None, false);
}
-#endif
+ Function *Handler =
+ Function::Create(FnType, GlobalVariable::InternalLinkage, Name, M);
+ BasicBlock *Entry = BasicBlock::Create(Context, "entry");
+ Handler->getBasicBlockList().push_front(Entry);
+ if (TheTriple.getArch() == Triple::x86_64) {
+ ParentFP = &(Handler->getArgumentList().back());
+ } else {
+ assert(M);
+ Function *FrameAddressFn =
+ Intrinsic::getDeclaration(M, Intrinsic::frameaddress);
+ Function *RecoverFPFn =
+ Intrinsic::getDeclaration(M, Intrinsic::x86_seh_recoverfp);
+ IRBuilder<> Builder(&Handler->getEntryBlock());
+ Value *EBP =
+ Builder.CreateCall(FrameAddressFn, {Builder.getInt32(1)}, "ebp");
+ Value *ParentI8Fn = Builder.CreateBitCast(ParentFn, Int8PtrType);
+ ParentFP = Builder.CreateCall(RecoverFPFn, {ParentI8Fn, EBP});
+ }
+ return Handler;
+}
+
+bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn,
+ LandingPadInst *LPad, BasicBlock *StartBB,
+ FrameVarInfoMap &VarInfo) {
+ Module *M = SrcFn->getParent();
+ LLVMContext &Context = M->getContext();
+ Type *Int8PtrType = Type::getInt8PtrTy(Context);
+
+ // Create a new function to receive the handler contents.
+ Value *ParentFP;
+ Function *Handler;
+ if (Action->getType() == Catch) {
+ Handler = createHandlerFunc(SrcFn, Int8PtrType, SrcFn->getName() + ".catch", M,
+ ParentFP);
+ } else {
+ Handler = createHandlerFunc(SrcFn, Type::getVoidTy(Context),
+ SrcFn->getName() + ".cleanup", M, ParentFP);
+ }
+ Handler->setPersonalityFn(SrcFn->getPersonalityFn());
+ HandlerToParentFP[Handler] = ParentFP;
+ Handler->addFnAttr("wineh-parent", SrcFn->getName());
+ BasicBlock *Entry = &Handler->getEntryBlock();
+
+ // Generate a standard prolog to setup the frame recovery structure.
+ IRBuilder<> Builder(Context);
+ Builder.SetInsertPoint(Entry);
+ Builder.SetCurrentDebugLocation(LPad->getDebugLoc());
+
+ std::unique_ptr<WinEHCloningDirectorBase> Director;
+
+ ValueToValueMapTy VMap;
+
+ 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, ParentFP, Sel, VarInfo,
+ LPadMap, NestedLPtoOriginalLP, DT,
+ EHBlocks));
+ LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
+ ConstantInt::get(Type::getInt32Ty(Context), 1));
+ } else {
+ Director.reset(
+ new WinEHCleanupDirector(Handler, ParentFP, VarInfo, LPadMap));
+ LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
+ UndefValue::get(Type::getInt32Ty(Context)));
+ }
+
+ 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());
+ }
+ ++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 cloned "entry" block into our entry block.
+ // Depending on how the parent function was laid out, the block that will
+ // correspond to the outlined entry block may not be the first block in the
+ // list. We can recognize it, however, as the cloned block which has no
+ // predecessors. Any other block wouldn't have been cloned if it didn't
+ // have a predecessor which was also cloned.
+ Function::iterator ClonedIt = std::next(Function::iterator(Entry));
+ while (!pred_empty(ClonedIt))
+ ++ClonedIt;
+ BasicBlock *ClonedEntryBB = ClonedIt;
+ assert(ClonedEntryBB);
+ Entry->getInstList().splice(Entry->end(), ClonedEntryBB->getInstList());
+ ClonedEntryBB->eraseFromParent();
+
+ // Make sure we can identify the handler's personality later.
+ addStubInvokeToHandlerIfNeeded(Handler);
+
+ 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);
+ }
+ }
+ }
+ } // End if (CatchAction)
+
+ Action->setHandlerBlockOrFunc(Handler);
+
+ return true;
+}
+
+/// 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 = SplitBlock(StartBB, StartBB->getFirstInsertionPt(), DT);
+ }
+ IRBuilder<> Builder(HandlerBB->getFirstInsertionPt());
+ Function *EHCodeFn = Intrinsic::getDeclaration(
+ StartBB->getParent()->getParent(), Intrinsic::eh_exceptioncode_old);
+ Value *Code = Builder.CreateCall(EHCodeFn, {}, "sehcode");
+ Code = Builder.CreateIntToPtr(Code, SEHExceptionCodeSlot->getAllocatedType());
+ Builder.CreateStore(Code, SEHExceptionCodeSlot);
+ 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);
+
+ // If the landing pad has already been mapped, there's nothing more to do.
+ if (OriginLPad == LPad)
+ return;
+
+ OriginLPad = LPad;
+
+ // 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);
+ }
+ }
+}
+
+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 isLocalAddressCall(const Value *V) {
+ return match(const_cast<Value *>(V), m_Intrinsic<Intrinsic::localaddress>());
+}
+
+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 that have not already been outlined will be cloned as
+ // stubs, with just the landingpad instruction and an unreachable instruction.
+ // When all landingpads have been outlined, we'll replace this with the
+ // llvm.eh.actions call and indirect branch created when the landing pad was
+ // outlined.
+ if (auto *LPad = dyn_cast<LandingPadInst>(Inst)) {
+ return handleLandingPad(VMap, LPad, NewBB);
+ }
+
+ // Nested landing pads that have already been outlined will be cloned in their
+ // outlined form, but we need to intercept the ibr instruction to filter out
+ // targets that do not return to the handler we are outlining.
+ if (auto *IBr = dyn_cast<IndirectBrInst>(Inst)) {
+ return handleIndirectBr(VMap, IBr, 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);
+
+ // When outlining llvm.localaddress(), remap that to the second argument,
+ // which is the FP of the parent.
+ if (isLocalAddressCall(Inst)) {
+ VMap[Inst] = ParentFP;
+ return CloningDirector::SkipInstruction;
+ }
+
+ // Continue with the default cloning behavior.
+ return CloningDirector::CloneInstruction;
+}
+
+CloningDirector::CloningAction WinEHCatchDirector::handleLandingPad(
+ ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
+ // If the instruction after the landing pad is a call to llvm.eh.actions
+ // the landing pad has already been outlined. In this case, we should
+ // clone it because it may return to a block in the handler we are
+ // outlining now that would otherwise be unreachable. The landing pads
+ // are sorted before outlining begins to enable this case to work
+ // properly.
+ const Instruction *NextI = LPad->getNextNode();
+ if (match(NextI, m_Intrinsic<Intrinsic::eh_actions>()))
+ return CloningDirector::CloneInstruction;
+
+ // If the landing pad hasn't been outlined yet, the landing pad we are
+ // outlining now does not dominate it and so it cannot return to a block
+ // in this handler. In that case, we can just insert a stub landing
+ // pad now and patch it up later.
+ Instruction *NewInst = LPad->clone();
+ if (LPad->hasName())
+ NewInst->setName(LPad->getName());
+ // 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);
+ }
+
+ 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::handleIndirectBr(
+ ValueToValueMapTy &VMap,
+ const IndirectBrInst *IBr,
+ BasicBlock *NewBB) {
+ // If this indirect branch is not part of a landing pad block, just clone it.
+ const BasicBlock *ParentBB = IBr->getParent();
+ if (!ParentBB->isLandingPad())
+ return CloningDirector::CloneInstruction;
+
+ // If it is part of a landing pad, we want to filter out target blocks
+ // that are not part of the handler we are outlining.
+ const LandingPadInst *LPad = ParentBB->getLandingPadInst();
+
+ // Save this correlation for later processing.
+ NestedLPtoOriginalLP[cast<LandingPadInst>(VMap[LPad])] = LPad;
+
+ // We should only get here for landing pads that have already been outlined.
+ assert(match(LPad->getNextNode(), m_Intrinsic<Intrinsic::eh_actions>()));
+
+ // Copy the indirectbr, but only include targets that were previously
+ // identified as EH blocks and are dominated by the nested landing pad.
+ SetVector<const BasicBlock *> ReturnTargets;
+ for (int I = 0, E = IBr->getNumDestinations(); I < E; ++I) {
+ auto *TargetBB = IBr->getDestination(I);
+ if (EHBlocks.count(const_cast<BasicBlock*>(TargetBB)) &&
+ DT->dominates(ParentBB, TargetBB)) {
+ DEBUG(dbgs() << " Adding destination " << TargetBB->getName() << "\n");
+ ReturnTargets.insert(TargetBB);
+ }
+ }
+ IndirectBrInst *NewBranch =
+ IndirectBrInst::Create(const_cast<Value *>(IBr->getAddress()),
+ ReturnTargets.size(), NewBB);
+ for (auto *Target : ReturnTargets)
+ NewBranch->addDestination(const_cast<BasicBlock*>(Target));
+
+ // The operands and targets of the branch instruction are remapped later
+ // because it is a terminator. Tell the cloning code to clone the
+ // blocks we just added to the target list.
+ return CloningDirector::CloneSuccessors;
+}
+
+CloningDirector::CloningAction
+WinEHCatchDirector::handleInvoke(ValueToValueMapTy &VMap,
+ const InvokeInst *Invoke, BasicBlock *NewBB) {
+ 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;
+}
+
+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);
+ }
+ 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;
+}
+
+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;
+}
+
+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;
+}
+
+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;
+}
+
+CloningDirector::CloningAction WinEHCleanupDirector::handleIndirectBr(
+ ValueToValueMapTy &VMap,
+ const IndirectBrInst *IBr,
+ BasicBlock *NewBB) {
+ // No special handling is required for cleanup cloning.
+ return CloningDirector::CloneInstruction;
+}
+
+CloningDirector::CloningAction WinEHCleanupDirector::handleInvoke(
+ ValueToValueMapTy &VMap, const InvokeInst *Invoke, BasicBlock *NewBB) {
+ // All invokes in cleanup handlers can be replaced with calls.
+ 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;
+ }
+ return CloningDirector::CloneInstruction;
+}
+
+WinEHFrameVariableMaterializer::WinEHFrameVariableMaterializer(
+ Function *OutlinedFn, Value *ParentFP, FrameVarInfoMap &FrameVarInfo)
+ : FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) {
+ BasicBlock *EntryBB = &OutlinedFn->getEntryBlock();
+
+ // New allocas should be inserted in the entry block, but after the parent FP
+ // is established if it is an instruction.
+ Instruction *InsertPoint = EntryBB->getFirstInsertionPt();
+ if (auto *FPInst = dyn_cast<Instruction>(ParentFP))
+ InsertPoint = FPInst->getNextNode();
+ Builder.SetInsertPoint(EntryBB, InsertPoint);
+}
+
+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.localrecover.
+ 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;
+ }
+
+ if (isa<Instruction>(V) || isa<Argument>(V)) {
+ Function *Parent = isa<Instruction>(V)
+ ? cast<Instruction>(V)->getParent()->getParent()
+ : cast<Argument>(V)->getParent();
+ errs()
+ << "Failed to demote instruction used in exception handler of function "
+ << GlobalValue::getRealLinkageName(Parent->getName()) << ":\n";
+ errs() << " " << *V << '\n';
+ report_fatal_error("WinEHPrepare failed to demote instruction");
+ }
+
+ // Don't materialize other values.
return nullptr;
}
+
+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.localescape.
+ FrameVarInfo[V].push_back(getCatchObjectSentinel());
+}
+
+// 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;
+ }
+
+ VisitedBlockSet VisitedBlocks;
+
+ while (HandlersFound != NumClauses) {
+ BasicBlock *NextBB = nullptr;
+
+ // Skip over filter clauses.
+ if (LPad->isFilter(HandlersFound)) {
+ ++HandlersFound;
+ continue;
+ }
+
+ // See if the clause we're looking for is a catch-all.
+ // If so, the catch begins immediately.
+ 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;
+ }
+
+ // 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 {
+ // We don't expect a selector dispatch, but there may be a call to
+ // llvm.eh.begincatch, which separates catch handling code from
+ // cleanup code in the same control flow. This call looks for the
+ // begincatch intrinsic.
+ Action = findCatchHandler(BB, NextBB, VisitedBlocks);
+ if (Action) {
+ // For C++ EH, check if there is any interesting cleanup code before
+ // we begin the catch. This is important because cleanups cannot
+ // rethrow exceptions but code called from catches can. For SEH, it
+ // isn't important if some finally code before a catch-all is executed
+ // out of line or after recovering from the exception.
+ if (Personality == EHPersonality::MSVC_CXX)
+ findCleanupHandlers(Actions, BB, BB);
+ } else {
+ // If an action was not found, it means that the control flows
+ // directly into the catch-all handler and there is no cleanup code.
+ // That's an expected situation and we must create a catch action.
+ // Since this is a catch-all handler, the selector won't actually
+ // appear in the code anywhere. ExpectedSelector here is the constant
+ // null ptr that we got from the landing pad instruction.
+ Action = new CatchHandler(BB, ExpectedSelector, nullptr);
+ CatchHandlerMap[BB] = Action;
+ }
+ }
+ Actions.insertCatchHandler(Action);
+ DEBUG(dbgs() << " Catch all handler at block " << BB->getName() << "\n");
+ ++HandlersFound;
+
+ // Once we reach a catch-all, don't expect to hit a resume instruction.
+ BB = nullptr;
+ break;
+ }
+
+ CatchHandler *CatchAction = findCatchHandler(BB, NextBB, VisitedBlocks);
+ assert(CatchAction);
+
+ // See if there is any interesting code executed before the dispatch.
+ findCleanupHandlers(Actions, BB, CatchAction->getStartBlock());
+
+ // When the source program contains multiple nested try blocks the catch
+ // handlers can get strung together in such a way that we can encounter
+ // a dispatch for a selector that we've already had a handler for.
+ if (CatchAction->getSelector()->stripPointerCasts() == ExpectedSelector) {
+ ++HandlersFound;
+
+ // Add the catch handler to the action list.
+ DEBUG(dbgs() << " Found catch dispatch in block "
+ << CatchAction->getStartBlock()->getName() << "\n");
+ Actions.insertCatchHandler(CatchAction);
+ } else {
+ // Under some circumstances optimized IR will flow unconditionally into a
+ // handler block without checking the selector. This can only happen if
+ // the landing pad has a catch-all handler and the handler for the
+ // preceding 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;
+ }
+
+ 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;
+ }
+
+ // 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;
+ }
+ }
+
+ // 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;
+}
+
+// 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");
+}
+
+static CallSite matchOutlinedFinallyCall(BasicBlock *BB,
+ Instruction *MaybeCall) {
+ // Look for finally blocks that Clang has already outlined for us.
+ // %fp = call i8* @llvm.localaddress()
+ // call void @"fin$parent"(iN 1, i8* %fp)
+ if (isLocalAddressCall(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 (!isLocalAddressCall(FinallyCall.getArgument(1)))
+ return CallSite();
+ return FinallyCall;
+}
+
+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;
+ }
+ 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 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 on x64, since those happen to match the
+ // prototype provided by the runtime.
+ if (TheTriple.getArch() == Triple::x86_64) {
+ 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 =
+ SplitBlock(BB, FinallyCall.getInstruction()->getNextNode(), DT);
+ } 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;
+ }
+ }
+ }
+
+ // 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);
+ }
+
+ // Only unconditional branches in empty blocks should get this far.
+ assert(Branch && Branch->isUnconditional());
+ if (BB == EndBB)
+ return;
+ BB = Branch->getSuccessor(0);
+ }
+}
+
+// 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<std::unique_ptr<ActionHandler>> &Actions) {
+ assert(II->getIntrinsicID() == Intrinsic::eh_actions &&
+ "attempted to parse non eh.actions intrinsic");
+ for (unsigned I = 0, E = II->getNumArgOperands(); I != E;) {
+ uint64_t ActionKind =
+ cast<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 = make_unique<CatchHandler>(/*BB=*/nullptr, Selector,
+ /*NextBB=*/nullptr);
+ CH->setHandlerBlockOrFunc(Handler);
+ CH->setExceptionVarIndex(EHObjIndexVal);
+ Actions.push_back(std::move(CH));
+ } else if (ActionKind == 0) {
+ Constant *Handler = cast<Constant>(II->getArgOperand(I + 1));
+ I += 2;
+ auto CH = make_unique<CleanupHandler>(/*BB=*/nullptr);
+ CH->setHandlerBlockOrFunc(Handler);
+ Actions.push_back(std::move(CH));
+ } else {
+ llvm_unreachable("Expected either a catch or cleanup handler!");
+ }
+ }
+ std::reverse(Actions.begin(), Actions.end());
+}
+
+static int addUnwindMapEntry(WinEHFuncInfo &FuncInfo, int ToState,
+ const Value *V) {
+ WinEHUnwindMapEntry UME;
+ UME.ToState = ToState;
+ UME.Cleanup = V;
+ FuncInfo.UnwindMap.push_back(UME);
+ return FuncInfo.getLastStateNumber();
+}
+
+static void addTryBlockMapEntry(WinEHFuncInfo &FuncInfo, int TryLow,
+ int TryHigh, int CatchHigh,
+ ArrayRef<const CatchPadInst *> Handlers) {
+ WinEHTryBlockMapEntry TBME;
+ TBME.TryLow = TryLow;
+ TBME.TryHigh = TryHigh;
+ TBME.CatchHigh = CatchHigh;
+ assert(TBME.TryLow <= TBME.TryHigh);
+ for (const CatchPadInst *CPI : Handlers) {
+ WinEHHandlerType HT;
+ Constant *TypeInfo = cast<Constant>(CPI->getArgOperand(0));
+ if (TypeInfo->isNullValue())
+ HT.TypeDescriptor = nullptr;
+ else
+ HT.TypeDescriptor = cast<GlobalVariable>(TypeInfo->stripPointerCasts());
+ HT.Adjectives = cast<ConstantInt>(CPI->getArgOperand(1))->getZExtValue();
+ HT.Handler = CPI->getParent();
+ HT.CatchObjRecoverIdx = -2;
+ 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);
+}
+
+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;
+}
+
+/// 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());
+}
+
+// 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();
+}
+
+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;
+
+ 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)) {
+ 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 (isa<TerminatePadInst>(FirstNonPHI)) {
+ report_fatal_error("Not yet implemented!");
+ } else {
+ llvm_unreachable("unexpected EH Pad!");
+ }
+}
+
+static int addSEHExcept(WinEHFuncInfo &FuncInfo, int ParentState,
+ const Function *Filter, const BasicBlock *Handler) {
+ SEHUnwindMapEntry Entry;
+ Entry.ToState = ParentState;
+ Entry.IsFinally = false;
+ Entry.Filter = Filter;
+ Entry.Handler = Handler;
+ FuncInfo.SEHUnwindMap.push_back(Entry);
+ return FuncInfo.SEHUnwindMap.size() - 1;
+}
+
+static int addSEHFinally(WinEHFuncInfo &FuncInfo, int ParentState,
+ const BasicBlock *Handler) {
+ SEHUnwindMapEntry Entry;
+ Entry.ToState = ParentState;
+ Entry.IsFinally = true;
+ Entry.Filter = nullptr;
+ Entry.Handler = Handler;
+ FuncInfo.SEHUnwindMap.push_back(Entry);
+ return FuncInfo.SEHUnwindMap.size() - 1;
+}
+
+static void 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;
+
+ 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)) {
+ 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 (isa<CleanupEndPadInst>(FirstNonPHI)) {
+ // 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!");
+ }
+}
+
+/// 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();
+
+ // This cleanup does not return or unwind, so we say it unwinds to caller.
+ if (CPI->use_empty())
+ return true;
+
+ const Instruction *User = CPI->user_back();
+ if (auto *CRI = dyn_cast<CleanupReturnInst>(User))
+ return CRI->unwindsToCaller();
+ return cast<CleanupEndPadInst>(User)->unwindsToCaller();
+}
+
+void llvm::calculateSEHStateNumbers(const Function *Fn,
+ WinEHFuncInfo &FuncInfo) {
+ // Don't compute state numbers twice.
+ if (!FuncInfo.SEHUnwindMap.empty())
+ return;
+
+ for (const BasicBlock &BB : *Fn) {
+ if (!BB.isEHPad() || !doesEHPadUnwindToCaller(BB.getFirstNonPHI()))
+ continue;
+ calculateExplicitSEHStateNumbers(FuncInfo, BB, -1);
+ }
+}
+
+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();
+ // Skip cleanupendpads; they are exits, not entries.
+ if (isa<CleanupEndPadInst>(FirstNonPHI))
+ continue;
+ if (!doesEHPadUnwindToCaller(FirstNonPHI))
+ continue;
+ calculateExplicitCXXStateNumbers(FuncInfo, BB, -1);
+ }
+}
+
+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;
+}
+
+void llvm::calculateClrEHStateNumbers(const Function *Fn,
+ WinEHFuncInfo &FuncInfo) {
+ // Return if it's already been done.
+ if (!FuncInfo.EHPadStateMap.empty())
+ return;
+
+ SmallVector<std::pair<const Instruction *, int>, 8> Worklist;
+
+ // 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);
+ }
+
+ 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 *Handler = Catch->getNormalDest();
+ uint32_t TypeToken = static_cast<uint32_t>(
+ cast<ConstantInt>(Catch->getArgOperand(0))->getZExtValue());
+ int NewState = addClrEHHandler(FuncInfo, ParentState,
+ ClrHandlerType::Catch, TypeToken, Handler);
+ FuncInfo.EHPadStateMap[Catch] = NewState;
+ // Preds of the catch get its state
+ PredState = NewState;
+ } else {
+ llvm_unreachable("Unexpected EH pad");
+ }
+
+ // Queue all predecessors with the given state
+ for (const BasicBlock *Pred : predecessors(Pad->getParent())) {
+ if ((Pred = getEHPadFromPredecessor(Pred)))
+ Worklist.emplace_back(Pred->getFirstNonPHI(), PredState);
+ }
+ }
+}
+
+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 (TPI->getNumArgOperands() != 1)
+ report_fatal_error(
+ "Expected a unary terminatepad for MSVC C++ personalities!");
+
+ auto *TerminateFn = dyn_cast<Function>(TPI->getArgOperand(0));
+ if (!TerminateFn)
+ report_fatal_error("Function operand expected in terminatepad for MSVC "
+ "C++ personalities!");
+
+ // Insert the cleanuppad instruction.
+ auto *CPI = CleanupPadInst::Create(
+ BB.getContext(), {}, Twine("terminatepad.for.", BB.getName()), &BB);
+
+ // Insert the call to the terminate instruction.
+ auto *CallTerminate = CallInst::Create(TerminateFn, {}, &BB);
+ CallTerminate->setDoesNotThrow();
+ CallTerminate->setDoesNotReturn();
+ CallTerminate->setCallingConv(TerminateFn->getCallingConv());
+
+ // Insert a new terminator for the cleanuppad using the same successor as
+ // the terminatepad.
+ CleanupReturnInst::Create(CPI, TPI->getUnwindDest(), &BB);
+
+ // Let's remove the terminatepad now that we've inserted the new
+ // instructions.
+ TPI->eraseFromParent();
+ }
+}
+
+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 with the parent color.
+ for (User *U : VisitingHead->users()) {
+ if (auto *Exit = dyn_cast<TerminatorInst>(U)) {
+ for (BasicBlock *Succ : successors(Exit->getParent()))
+ if (BlockColors[Succ].insert(Color).second)
+ Worklist.push_back({Succ, Color});
+ }
+ }
+ // 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);
+ }
+
+ 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;
+ }
+ 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;
+ }
+ if (BlockColors[Succ].insert(Color).second) {
+ Worklist.push_back({Succ, Color});
+ }
+ }
+ }
+
+ // 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);
+ }
+}
+
+void WinEHPrepare::colorFunclets(Function &F,
+ SmallVectorImpl<BasicBlock *> &EntryBlocks) {
+ ::colorFunclets(F, EntryBlocks, BlockColors, FuncletBlocks, FuncletChildren);
+}
+
+void llvm::calculateCatchReturnSuccessorColors(const Function *Fn,
+ WinEHFuncInfo &FuncInfo) {
+ SmallVector<LandingPadInst *, 4> LPads;
+ SmallVector<ResumeInst *, 4> Resumes;
+ SmallVector<BasicBlock *, 4> EntryBlocks;
+ // colorFunclets needs the set of EntryBlocks, get them using
+ // findExceptionalConstructs.
+ bool ForExplicitEH = findExceptionalConstructs(const_cast<Function &>(*Fn),
+ LPads, Resumes, EntryBlocks);
+ if (!ForExplicitEH)
+ return;
+
+ 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;
+
+ // The users of a catchpad are always catchrets.
+ for (User *Exit : CatchPad->users()) {
+ auto *CatchReturn = dyn_cast<CatchReturnInst>(Exit);
+ if (!CatchReturn)
+ continue;
+ BasicBlock *CatchRetSuccessor = CatchReturn->getSuccessor();
+ std::set<BasicBlock *> &SuccessorColors = BlockColors[CatchRetSuccessor];
+ assert(SuccessorColors.size() == 1 && "Expected BB to be monochrome!");
+ BasicBlock *Color = *SuccessorColors.begin();
+ if (auto *CPI = dyn_cast<CatchPadInst>(Color->getFirstNonPHI()))
+ Color = CPI->getNormalDest();
+ // Record the catchret successor's funclet membership.
+ FuncInfo.CatchRetSuccessorColorMap[CatchReturn] = Color;
+ }
+ }
+}
+
+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;
+
+ AllocaInst *SpillSlot = insertPHILoads(PN, F);
+ if (SpillSlot)
+ insertPHIStores(PN, SpillSlot);
+
+ PHINodes.push_back(PN);
+ }
+ }
+
+ for (auto *PN : PHINodes) {
+ // There may be lingering uses on other EH PHIs being removed
+ PN->replaceAllUsesWith(UndefValue::get(PN->getType()));
+ PN->eraseFromParent();
+ }
+}
+
+void WinEHPrepare::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);
+ }
+ }
+}
+
+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);
+}
+
+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;
+
+ // Create a new basic block and copy instructions into it!
+ BasicBlock *CBB =
+ CloneBasicBlock(BB, VMap, Twine(".for.", FuncletPadBB->getName()));
+ // Insert the clone immediately after the original to ensure determinism
+ // and to keep the same relative ordering of any funclet's blocks.
+ CBB->insertInto(&F, BB->getNextNode());
+
+ // Add basic block mapping.
+ VMap[BB] = CBB;
+
+ // Record delta operations that we need to perform to our color mappings.
+ Orig2Clone[BB] = CBB;
+ }
+
+ // Update our color mappings to reflect that one block has lost a color and
+ // another has gained a color.
+ for (auto &BBMapping : Orig2Clone) {
+ BasicBlock *OldBlock = BBMapping.first;
+ BasicBlock *NewBlock = BBMapping.second;
+
+ BlocksInFunclet.insert(NewBlock);
+ BlockColors[NewBlock].insert(FuncletPadBB);
+
+ BlocksInFunclet.erase(OldBlock);
+ BlockColors[OldBlock].erase(FuncletPadBB);
+ }
+
+ // Loop over all of the instructions in the function, 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);
+
+ // 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);
+ }
+ }
+ }
+
+ for (ValueToValueMapTy::value_type VT : VMap) {
+ // If there were values defined in BB that are used outside the funclet,
+ // then we now have to update all uses of the value to use either the
+ // original value, the cloned value, or some PHI derived value. This can
+ // require arbitrary PHI insertion, of which we are prepared to do, clean
+ // these up now.
+ SmallVector<Use *, 16> UsesToRename;
+
+ auto *OldI = dyn_cast<Instruction>(const_cast<Value *>(VT.first));
+ if (!OldI)
+ continue;
+ auto *NewI = cast<Instruction>(VT.second);
+ // Scan all uses of this instruction to see if it is used outside of its
+ // funclet, and if so, record them in UsesToRename.
+ for (Use &U : OldI->uses()) {
+ Instruction *UserI = cast<Instruction>(U.getUser());
+ BasicBlock *UserBB = UserI->getParent();
+ std::set<BasicBlock *> &ColorsForUserBB = BlockColors[UserBB];
+ assert(!ColorsForUserBB.empty());
+ if (ColorsForUserBB.size() > 1 ||
+ *ColorsForUserBB.begin() != FuncletPadBB)
+ UsesToRename.push_back(&U);
+ }
+
+ // If there are no uses outside the block, we're done with this
+ // instruction.
+ if (UsesToRename.empty())
+ continue;
+
+ // We found a use of OldI outside of the funclet. Rename all uses of OldI
+ // that are outside its funclet to be uses of the appropriate PHI node
+ // etc.
+ SSAUpdater SSAUpdate;
+ SSAUpdate.Initialize(OldI->getType(), OldI->getName());
+ SSAUpdate.AddAvailableValue(OldI->getParent(), OldI);
+ SSAUpdate.AddAvailableValue(NewI->getParent(), NewI);
+
+ while (!UsesToRename.empty())
+ SSAUpdate.RewriteUseAfterInsertions(*UsesToRename.pop_back_val());
+ }
+ }
+}
+
+void WinEHPrepare::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);
+ }
+ }
+
+ 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).
+ }
+ }
+}
+
+void WinEHPrepare::cleanupPreparedFunclets(Function &F) {
+ // Clean-up some of the mess we made by removing useles PHI nodes, trivial
+ // branches, etc.
+ for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE;) {
+ BasicBlock *BB = FI++;
+ SimplifyInstructionsInBlock(BB);
+ ConstantFoldTerminator(BB, /*DeleteDeadConditions=*/true);
+ MergeBlockIntoPredecessor(BB);
+ }
+
+ // We might have some unreachable blocks after cleaning up some impossible
+ // control flow.
+ removeUnreachableBlocks(F);
+}
+
+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!");
+ }
+ }
+}
+
+bool WinEHPrepare::prepareExplicitEH(
+ Function &F, SmallVectorImpl<BasicBlock *> &EntryBlocks) {
+ // Remove unreachable blocks. It is not valuable to assign them a color and
+ // their existence can trick us into thinking values are alive when they are
+ // not.
+ removeUnreachableBlocks(F);
+
+ replaceTerminatePadWithCleanup(F);
+
+ // Determine which blocks are reachable from which funclet entries.
+ colorFunclets(F, EntryBlocks);
+
+ if (!DisableDemotion) {
+ demotePHIsOnFunclets(F);
+
+ demoteUsesBetweenFunclets(F);
+
+ demoteArgumentUses(F);
+ }
+
+ cloneCommonBlocks(F, EntryBlocks);
+
+ if (!DisableCleanups) {
+ removeImplausibleTerminators(F);
+
+ cleanupPreparedFunclets(F);
+ }
+
+ verifyPreparedFunclets(F);
+
+ BlockColors.clear();
+ FuncletBlocks.clear();
+ FuncletChildren.clear();
+
+ return true;
+}
+
+// TODO: Share loads when one use dominates another, or when a catchpad exit
+// dominates uses (needs dominators).
+AllocaInst *WinEHPrepare::insertPHILoads(PHINode *PN, Function &F) {
+ BasicBlock *PHIBlock = PN->getParent();
+ AllocaInst *SpillSlot = nullptr;
+
+ 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().begin());
+ Value *V = new LoadInst(SpillSlot, Twine(PN->getName(), ".wineh.reload"),
+ PHIBlock->getFirstInsertionPt());
+ PN->replaceAllUsesWith(V);
+ return SpillSlot;
+ }
+
+ 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;
+}
+
+// TODO: improve store placement. Inserting at def is probably good, but need
+// to be careful not to introduce interfering stores (needs liveness analysis).
+// TODO: identify related phi nodes that can share spill slots, and share them
+// (also needs liveness).
+void WinEHPrepare::insertPHIStores(PHINode *OriginalPHI,
+ AllocaInst *SpillSlot) {
+ // Use a worklist of (Block, Value) pairs -- the given Value needs to be
+ // stored to the spill slot by the end of the given Block.
+ SmallVector<std::pair<BasicBlock *, Value *>, 4> Worklist;
+
+ Worklist.push_back({OriginalPHI->getParent(), OriginalPHI});
+
+ while (!Worklist.empty()) {
+ BasicBlock *EHBlock;
+ Value *InVal;
+ std::tie(EHBlock, InVal) = Worklist.pop_back_val();
+
+ PHINode *PN = dyn_cast<PHINode>(InVal);
+ if (PN && PN->getParent() == EHBlock) {
+ // The value is defined by another PHI we need to remove, with no room to
+ // insert a store after the PHI, so each predecessor needs to store its
+ // incoming value.
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i < e; ++i) {
+ Value *PredVal = PN->getIncomingValue(i);
+
+ // Undef can safely be skipped.
+ if (isa<UndefValue>(PredVal))
+ continue;
+
+ insertPHIStore(PN->getIncomingBlock(i), PredVal, SpillSlot, Worklist);
+ }
+ } else {
+ // We need to store InVal, which dominates EHBlock, but can't put a store
+ // in EHBlock, so need to put stores in each predecessor.
+ for (BasicBlock *PredBlock : predecessors(EHBlock)) {
+ insertPHIStore(PredBlock, InVal, SpillSlot, Worklist);
+ }
+ }
+ }
+}
+
+void WinEHPrepare::insertPHIStore(
+ BasicBlock *PredBlock, Value *PredVal, AllocaInst *SpillSlot,
+ SmallVectorImpl<std::pair<BasicBlock *, Value *>> &Worklist) {
+
+ if (PredBlock->isEHPad() &&
+ !isa<CleanupPadInst>(PredBlock->getFirstNonPHI())) {
+ // Pred is unsplittable, so we need to queue it on the worklist.
+ Worklist.push_back({PredBlock, PredVal});
+ return;
+ }
+
+ // Otherwise, insert the store at the end of the basic block.
+ new StoreInst(PredVal, SpillSlot, PredBlock->getTerminator());
+}
+
+// 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;
+
+ 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;
+
+ replaceUseWithLoad(V, U, SpillSlot, Loads, F);
+ }
+ 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();
+ } 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);
+ ++InsertPt;
+ // Don't insert before PHI nodes or EH pad instrs.
+ for (; isa<PHINode>(InsertPt) || InsertPt->isEHPad(); ++InsertPt)
+ ;
+ }
+ new StoreInst(V, SpillSlot, InsertPt);
+ }
+}
+
+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().begin());
+
+ 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());
+
+ 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);
+ }
+}
+
+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