#include "llvm/CodeGen/Passes.h"
#include "llvm/ADT/MapVector.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/TinyPtrVector.h"
#include "llvm/Analysis/LibCallSemantics.h"
+#include "llvm/CodeGen/WinEHFuncInfo.h"
+#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Pass.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Utils/PromoteMemToReg.h"
#include <memory>
using namespace llvm;
// frame allocation structure.
typedef MapVector<Value *, TinyPtrVector<AllocaInst *>> FrameVarInfoMap;
-class WinEHPrepare : public FunctionPass {
- std::unique_ptr<FunctionPass> DwarfPrepare;
+typedef SmallSet<BasicBlock *, 4> VisitedBlockSet;
+
+class LandingPadActions;
+class LandingPadMap;
- enum HandlerType { Catch, Cleanup };
+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), DT(nullptr) {}
bool runOnFunction(Function &Fn) override;
}
private:
- bool prepareCPPEHHandlers(Function &F,
- SmallVectorImpl<LandingPadInst *> &LPads);
- bool outlineHandler(HandlerType CatchOrCleanup, Function *SrcFn,
- Constant *SelectorType, LandingPadInst *LPad,
+ bool prepareExceptionHandlers(Function &F,
+ SmallVectorImpl<LandingPadInst *> &LPads);
+ void promoteLandingPadValues(LandingPadInst *LPad);
+ bool outlineHandler(ActionHandler *Action, Function *SrcFn,
+ LandingPadInst *LPad, BasicBlock *StartBB,
FrameVarInfoMap &VarInfo);
+
+ void mapLandingPadBlocks(LandingPadInst *LPad, LandingPadActions &Actions);
+ CatchHandler *findCatchHandler(BasicBlock *BB, BasicBlock *&NextBB,
+ VisitedBlockSet &VisitedBlocks);
+ CleanupHandler *findCleanupHandler(BasicBlock *StartBB, BasicBlock *EndBB);
+
+ void processSEHCatchHandler(CatchHandler *Handler, BasicBlock *StartBB);
+
+ // All fields are reset by runOnFunction.
+ DominatorTree *DT;
+ EHPersonality Personality;
+ CatchHandlerMapTy CatchHandlerMap;
+ CleanupHandlerMapTy CleanupHandlerMap;
+ DenseMap<const LandingPadInst *, LandingPadMap> LPadMaps;
};
class WinEHFrameVariableMaterializer : public ValueMaterializer {
IRBuilder<> Builder;
};
+class LandingPadMap {
+public:
+ LandingPadMap() : OriginLPad(nullptr) {}
+ void mapLandingPad(const LandingPadInst *LPad);
+
+ bool isInitialized() { return OriginLPad != nullptr; }
+
+ bool isOriginLandingPadBlock(const BasicBlock *BB) const;
+ bool isLandingPadSpecificInst(const Instruction *Inst) const;
+
+ void remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
+ Value *SelectorValue) const;
+
+private:
+ const LandingPadInst *OriginLPad;
+ // We will normally only see one of each of these instructions, but
+ // if more than one occurs for some reason we can handle that.
+ TinyPtrVector<const ExtractValueInst *> ExtractedEHPtrs;
+ TinyPtrVector<const ExtractValueInst *> ExtractedSelectors;
+};
+
class WinEHCloningDirectorBase : public CloningDirector {
public:
- WinEHCloningDirectorBase(LandingPadInst *LPI, Function *HandlerFn,
- FrameVarInfoMap &VarInfo)
- : LPI(LPI), Materializer(HandlerFn, VarInfo),
- SelectorIDType(Type::getInt32Ty(LPI->getContext())),
- Int8PtrType(Type::getInt8PtrTy(LPI->getContext())),
- ExtractedEHPtr(nullptr), ExtractedSelector(nullptr),
- EHPtrStoreAddr(nullptr), SelectorStoreAddr(nullptr) {}
+ WinEHCloningDirectorBase(Function *HandlerFn,
+ FrameVarInfoMap &VarInfo,
+ LandingPadMap &LPadMap)
+ : Materializer(HandlerFn, VarInfo),
+ SelectorIDType(Type::getInt32Ty(HandlerFn->getContext())),
+ Int8PtrType(Type::getInt8PtrTy(HandlerFn->getContext())),
+ LPadMap(LPadMap) {}
CloningAction handleInstruction(ValueToValueMapTy &VMap,
const Instruction *Inst,
virtual CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
const Instruction *Inst,
BasicBlock *NewBB) = 0;
+ virtual CloningAction handleInvoke(ValueToValueMapTy &VMap,
+ const InvokeInst *Invoke,
+ BasicBlock *NewBB) = 0;
virtual CloningAction handleResume(ValueToValueMapTy &VMap,
const ResumeInst *Resume,
BasicBlock *NewBB) = 0;
ValueMaterializer *getValueMaterializer() override { return &Materializer; }
protected:
- LandingPadInst *LPI;
WinEHFrameVariableMaterializer Materializer;
Type *SelectorIDType;
Type *Int8PtrType;
-
- const Value *ExtractedEHPtr;
- const Value *ExtractedSelector;
- const Value *EHPtrStoreAddr;
- const Value *SelectorStoreAddr;
+ LandingPadMap &LPadMap;
};
class WinEHCatchDirector : public WinEHCloningDirectorBase {
public:
- WinEHCatchDirector(LandingPadInst *LPI, Function *CatchFn, Value *Selector,
- FrameVarInfoMap &VarInfo)
- : WinEHCloningDirectorBase(LPI, CatchFn, VarInfo),
- CurrentSelector(Selector->stripPointerCasts()) {}
+ WinEHCatchDirector(Function *CatchFn, Value *Selector,
+ FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
+ : WinEHCloningDirectorBase(CatchFn, VarInfo, LPadMap),
+ CurrentSelector(Selector->stripPointerCasts()),
+ ExceptionObjectVar(nullptr) {}
CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
const Instruction *Inst,
CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
const Instruction *Inst,
BasicBlock *NewBB) override;
+ CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
+ BasicBlock *NewBB) override;
CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
BasicBlock *NewBB) override;
+ const Value *getExceptionVar() { return ExceptionObjectVar; }
+ TinyPtrVector<BasicBlock *> &getReturnTargets() { return ReturnTargets; }
+
private:
Value *CurrentSelector;
+
+ const Value *ExceptionObjectVar;
+ TinyPtrVector<BasicBlock *> ReturnTargets;
};
class WinEHCleanupDirector : public WinEHCloningDirectorBase {
public:
- WinEHCleanupDirector(LandingPadInst *LPI, Function *CleanupFn,
- FrameVarInfoMap &VarInfo)
- : WinEHCloningDirectorBase(LPI, CleanupFn, VarInfo) {}
+ WinEHCleanupDirector(Function *CleanupFn,
+ FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap)
+ : WinEHCloningDirectorBase(CleanupFn, VarInfo, LPadMap) {}
CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
const Instruction *Inst,
CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
const Instruction *Inst,
BasicBlock *NewBB) override;
+ CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
+ BasicBlock *NewBB) override;
CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
BasicBlock *NewBB) override;
};
+class LandingPadActions {
+public:
+ LandingPadActions() : HasCleanupHandlers(false) {}
+
+ void insertCatchHandler(CatchHandler *Action) { Actions.push_back(Action); }
+ void insertCleanupHandler(CleanupHandler *Action) {
+ Actions.push_back(Action);
+ HasCleanupHandlers = true;
+ }
+
+ bool includesCleanup() const { return HasCleanupHandlers; }
+
+ SmallVectorImpl<ActionHandler *> &actions() { return Actions; }
+ SmallVectorImpl<ActionHandler *>::iterator begin() { return Actions.begin(); }
+ SmallVectorImpl<ActionHandler *>::iterator end() { return Actions.end(); }
+
+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;
-}
+// FIXME: Remove this once the backend can handle the prepared IR.
+static cl::opt<bool>
+SEHPrepare("sehprepare", cl::Hidden,
+ cl::desc("Prepare functions with SEH personalities"));
bool WinEHPrepare::runOnFunction(Function &Fn) {
SmallVector<LandingPadInst *, 4> LPads;
return false;
// Classify the personality to see what kind of preparation we need.
- EHPersonality Pers = classifyEHPersonality(LPads.back()->getPersonalityFn());
-
- // Delegate through to the DWARF pass if this is unrecognized.
- if (!isMSVCPersonality(Pers))
- return DwarfPrepare->runOnFunction(Fn);
+ Personality = classifyEHPersonality(LPads.back()->getPersonalityFn());
- // FIXME: This only returns true if the C++ EH handlers were outlined.
- // When that code is complete, it should always return whatever
- // prepareCPPEHHandlers returns.
- if (Pers == EHPersonality::MSVC_CXX && prepareCPPEHHandlers(Fn, LPads))
- return true;
-
- // FIXME: SEH Cleanups are unimplemented. Replace them with unreachable.
- if (Resumes.empty())
+ // Do nothing if this is not an MSVC personality.
+ if (!isMSVCEHPersonality(Personality))
return false;
- for (ResumeInst *Resume : Resumes) {
- IRBuilder<>(Resume).CreateUnreachable();
- Resume->eraseFromParent();
+ DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+
+ if (isAsynchronousEHPersonality(Personality) && !SEHPrepare) {
+ // Replace all resume instructions with unreachable.
+ // FIXME: Remove this once the backend can handle the prepared IR.
+ for (ResumeInst *Resume : Resumes) {
+ IRBuilder<>(Resume).CreateUnreachable();
+ Resume->eraseFromParent();
+ }
+ return true;
}
+ // If there were any landing pads, prepareExceptionHandlers will make changes.
+ prepareExceptionHandlers(Fn, LPads);
return true;
}
bool WinEHPrepare::doFinalization(Module &M) {
- return DwarfPrepare->doFinalization(M);
+ return false;
}
void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {
- DwarfPrepare->getAnalysisUsage(AU);
+ AU.addRequired<DominatorTreeWrapperPass>();
}
-bool WinEHPrepare::prepareCPPEHHandlers(
+bool WinEHPrepare::prepareExceptionHandlers(
Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
// These containers are used to re-map frame variables that are used in
// outlined catch and cleanup handlers. They will be populated as the
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);
+
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") {
+ for (Instruction &Inst : *LPadBB) {
+ if (auto *IntrinCall = dyn_cast<IntrinsicInst>(&Inst)) {
+ if (IntrinCall->getIntrinsicID() == Intrinsic::eh_actions) {
LPadHasActionList = true;
break;
}
+ }
+ // FIXME: This is here to help with the development of nested landing pad
+ // outlining. It should be removed when that is finished.
+ if (isa<UnreachableInst>(Inst)) {
+ 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.
- bool Outlined = outlineHandler(Catch, &F, LPad->getClause(Idx), LPad,
- FrameVarInfo);
- if (Outlined) {
+ // 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);
+
+ 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);
HandlersOutlined = true;
+ continue;
}
- } // End if (isCatch)
- } // End for each clause
-
- // FIXME: This only handles the simple case where there is a 1:1
- // correspondence between landing pad and cleanup blocks.
- // It does not handle cases where there are catch blocks between
- // cleanup blocks or the case where a cleanup block is shared by
- // multiple landing pads. Those cases will be supported later
- // when landing pad block analysis is added.
- if (LPad->isCleanup()) {
- bool Outlined =
- outlineHandler(Cleanup, &F, nullptr, LPad, FrameVarInfo);
- if (Outlined) {
+ }
+
+ if (outlineHandler(Action, &F, LPad, StartBB, FrameVarInfo)) {
HandlersOutlined = true;
}
+ } // End for each Action
+
+ // FIXME: We need a guard against partially outlined functions.
+ if (!HandlersOutlined)
+ continue;
+
+ // Replace the landing pad with a new llvm.eh.action based landing pad.
+ BasicBlock *NewLPadBB = BasicBlock::Create(Context, "lpad", &F, LPadBB);
+ assert(!isa<PHINode>(LPadBB->begin()));
+ auto *NewLPad = cast<LandingPadInst>(LPad->clone());
+ NewLPadBB->getInstList().push_back(NewLPad);
+ while (!pred_empty(LPadBB)) {
+ auto *pred = *pred_begin(LPadBB);
+ InvokeInst *Invoke = cast<InvokeInst>(pred->getTerminator());
+ Invoke->setUnwindDest(NewLPadBB);
+ }
+
+ // Replace uses of the old lpad in phis with this block and delete the old
+ // block.
+ LPadBB->replaceSuccessorsPhiUsesWith(NewLPadBB);
+ LPadBB->getTerminator()->eraseFromParent();
+ new UnreachableInst(LPadBB->getContext(), LPadBB);
+
+ // Add a call to describe the actions for this landing pad.
+ std::vector<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());
+ Value *EHObj = const_cast<Value *>(CatchAction->getExceptionVar());
+ if (EHObj)
+ ActionArgs.push_back(EHObj);
+ else
+ ActionArgs.push_back(ConstantPointerNull::get(Int8PtrType));
+ } else {
+ ActionArgs.push_back(ConstantInt::get(Int32Type, 0));
+ }
+ ActionArgs.push_back(Action->getHandlerBlockOrFunc());
+ }
+ CallInst *Recover =
+ CallInst::Create(ActionIntrin, ActionArgs, "recover", NewLPadBB);
+
+ // Add an indirect branch listing possible successors of the catch handlers.
+ IndirectBrInst *Branch = IndirectBrInst::Create(Recover, 0, NewLPadBB);
+ for (ActionHandler *Action : Actions) {
+ if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
+ for (auto *Target : CatchAction->getReturnTargets()) {
+ Branch->addDestination(Target);
+ }
+ }
}
} // End for each landingpad
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.
+ F.addFnAttr("wineh-parent", F.getName());
+
+ // Delete any blocks that were only used by handlers that were outlined above.
+ removeUnreachableBlocks(F);
- Module *M = F.getParent();
- LLVMContext &Context = M->getContext();
BasicBlock *Entry = &F.getEntryBlock();
IRBuilder<> Builder(F.getParent()->getContext());
Builder.SetInsertPoint(Entry->getFirstInsertionPt());
Intrinsic::getDeclaration(M, Intrinsic::frameescape);
Function *RecoverFrameFn =
Intrinsic::getDeclaration(M, Intrinsic::framerecover);
- Type *Int8PtrType = Type::getInt8PtrTy(Context);
- Type *Int32Type = Type::getInt32Ty(Context);
// Finally, replace all of the temporary allocas for frame variables used in
// the outlined handlers with calls to llvm.framerecover.
ParentAlloca = DemotePHIToStack(PN, AllocaInsertPt);
} else {
Instruction *ParentInst = cast<Instruction>(ParentVal);
- ParentAlloca = DemoteRegToStack(*ParentInst, true, ParentInst);
+ // FIXME: This is a work-around to temporarily handle the case where an
+ // instruction that is only used in handlers is not sunk.
+ // Without uses, DemoteRegToStack would just eliminate the value.
+ // This will fail if ParentInst is an invoke.
+ if (ParentInst->getNumUses() == 0) {
+ BasicBlock::iterator InsertPt = ParentInst;
+ ++InsertPt;
+ ParentAlloca =
+ new AllocaInst(ParentInst->getType(), nullptr,
+ ParentInst->getName() + ".reg2mem", InsertPt);
+ new StoreInst(ParentInst, ParentAlloca, InsertPt);
+ } else {
+ ParentAlloca = DemoteRegToStack(*ParentInst, true, ParentInst);
+ }
}
}
Builder.CreateBitCast(&F, Int8PtrType, ""),
&(HandlerFn->getArgumentList().back()),
llvm::ConstantInt::get(Int32Type, AllocasToEscape.size() - 1)};
- Value *RecoveredAlloca =
- Builder.CreateCall(RecoverFrameFn, RecoverArgs);
+ Value *RecoveredAlloca = Builder.CreateCall(RecoverFrameFn, RecoverArgs);
// Add a pointer bitcast if the alloca wasn't an i8.
if (RecoveredAlloca->getType() != TempAlloca->getType()) {
RecoveredAlloca->setName(Twine(TempAlloca->getName()) + ".i8");
RecoveredAlloca->takeName(TempAlloca);
delete TempAlloca;
}
- } // End for each FrameVarInfo entry.
+ } // End for each FrameVarInfo entry.
// Insert 'call void (...)* @llvm.frameescape(...)' at the end of the entry
// block.
Builder.SetInsertPoint(&F.getEntryBlock().back());
Builder.CreateCall(FrameEscapeFn, AllocasToEscape);
+ // Insert an alloca for the EH state in the entry block. On x86, we will also
+ // insert stores to update the EH state, but on other ISAs, the runtime does
+ // it for us.
+ // FIXME: This record is different on x86.
+ Type *UnwindHelpTy = Type::getInt64Ty(Context);
+ AllocaInst *UnwindHelp =
+ new AllocaInst(UnwindHelpTy, "unwindhelp", &F.getEntryBlock().front());
+ Builder.CreateStore(llvm::ConstantInt::get(UnwindHelpTy, -2), UnwindHelp,
+ /*isVolatile=*/true);
+ Function *UnwindHelpFn =
+ Intrinsic::getDeclaration(M, Intrinsic::eh_unwindhelp);
+ Builder.CreateCall(UnwindHelpFn,
+ Builder.CreateBitCast(UnwindHelp, Int8PtrType));
+
+ // Clean up the handler action maps we created for this function
+ DeleteContainerSeconds(CatchHandlerMap);
+ CatchHandlerMap.clear();
+ DeleteContainerSeconds(CleanupHandlerMap);
+ CleanupHandlerMap.clear();
+
return HandlersOutlined;
}
-bool WinEHPrepare::outlineHandler(HandlerType CatchOrCleanup, Function *SrcFn,
- Constant *SelectorType, LandingPadInst *LPad,
+void WinEHPrepare::promoteLandingPadValues(LandingPadInst *LPad) {
+ // If the return values of the landing pad instruction are extracted and
+ // stored to memory, we want to promote the store locations to reg values.
+ SmallVector<AllocaInst *, 2> EHAllocas;
+
+ // The landingpad instruction returns an aggregate value. Typically, its
+ // value will be passed to a pair of extract value instructions and the
+ // results of those extracts are often passed to store instructions.
+ // In unoptimized code the stored value will often be loaded and then stored
+ // again.
+ for (auto *U : LPad->users()) {
+ ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
+ if (!Extract)
+ continue;
+
+ for (auto *EU : Extract->users()) {
+ if (auto *Store = dyn_cast<StoreInst>(EU)) {
+ auto *AV = cast<AllocaInst>(Store->getPointerOperand());
+ EHAllocas.push_back(AV);
+ }
+ }
+ }
+
+ // We can't do this without a dominator tree.
+ assert(DT);
+
+ if (!EHAllocas.empty()) {
+ PromoteMemToReg(EHAllocas, *DT);
+ EHAllocas.clear();
+ }
+}
+
+// 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;
+
+ 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 (Pred == CmpInst::ICMP_NE) {
+ CatchHandler = FBB;
+ NextBB = TBB;
+ return true;
+ }
+
+ return false;
+}
+
+bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn,
+ LandingPadInst *LPad, BasicBlock *StartBB,
FrameVarInfoMap &VarInfo) {
Module *M = SrcFn->getParent();
LLVMContext &Context = M->getContext();
ArgTys.push_back(Int8PtrType);
ArgTys.push_back(Int8PtrType);
Function *Handler;
- if (CatchOrCleanup == Catch) {
+ if (Action->getType() == Catch) {
FunctionType *FnType = FunctionType::get(Int8PtrType, ArgTys, false);
Handler = Function::Create(FnType, GlobalVariable::InternalLinkage,
SrcFn->getName() + ".catch", M);
SrcFn->getName() + ".cleanup", M);
}
+ Handler->addFnAttr("wineh-parent", SrcFn->getName());
+
// Generate a standard prolog to setup the frame recovery structure.
IRBuilder<> Builder(Context);
BasicBlock *Entry = BasicBlock::Create(Context, "entry");
std::unique_ptr<WinEHCloningDirectorBase> Director;
- if (CatchOrCleanup == Catch) {
- Director.reset(
- new WinEHCatchDirector(LPad, Handler, SelectorType, VarInfo));
- } else {
- Director.reset(new WinEHCleanupDirector(LPad, Handler, VarInfo));
- }
-
ValueToValueMapTy VMap;
- // FIXME: Map other values referenced in the filter handler.
+ LandingPadMap &LPadMap = LPadMaps[LPad];
+ if (!LPadMap.isInitialized())
+ LPadMap.mapLandingPad(LPad);
+ if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
+ Constant *Sel = CatchAction->getSelector();
+ Director.reset(new WinEHCatchDirector(Handler, Sel, VarInfo, LPadMap));
+ LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
+ ConstantInt::get(Type::getInt32Ty(Context), 1));
+ } else {
+ Director.reset(new WinEHCleanupDirector(Handler, VarInfo, LPadMap));
+ LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
+ UndefValue::get(Type::getInt32Ty(Context)));
+ }
SmallVector<ReturnInst *, 8> Returns;
- ClonedCodeInfo InlinedFunctionInfo;
+ 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;
+ }
- BasicBlock::iterator II = LPad;
+ // Skip over PHIs and, if applicable, landingpad instructions.
+ II = StartBB->getFirstInsertionPt();
- CloneAndPruneIntoFromInst(
- Handler, SrcFn, ++II, VMap,
- /*ModuleLevelChanges=*/false, Returns, "", &InlinedFunctionInfo,
- &SrcFn->getParent()->getDataLayout(), Director.get());
+ CloneAndPruneIntoFromInst(Handler, SrcFn, II, VMap,
+ /*ModuleLevelChanges=*/false, Returns, "",
+ &OutlinedFunctionInfo, Director.get());
// Move all the instructions in the first cloned block into our entry block.
BasicBlock *FirstClonedBB = std::next(Function::iterator(Entry));
Entry->getInstList().splice(Entry->end(), FirstClonedBB->getInstList());
FirstClonedBB->eraseFromParent();
+ if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
+ WinEHCatchDirector *CatchDirector =
+ reinterpret_cast<WinEHCatchDirector *>(Director.get());
+ CatchAction->setExceptionVar(CatchDirector->getExceptionVar());
+ CatchAction->setReturnTargets(CatchDirector->getReturnTargets());
+ }
+
+ Action->setHandlerBlockOrFunc(Handler);
+
return true;
}
-CloningDirector::CloningAction WinEHCloningDirectorBase::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;
- }
+/// This BB must end in a selector dispatch. All we need to do is pass the
+/// handler block to llvm.eh.actions and list it as a possible indirectbr
+/// target.
+void WinEHPrepare::processSEHCatchHandler(CatchHandler *CatchAction,
+ BasicBlock *StartBB) {
+ BasicBlock *HandlerBB;
+ BasicBlock *NextBB;
+ Constant *Selector;
+ bool Res = isSelectorDispatch(StartBB, HandlerBB, Selector, NextBB);
+ if (Res) {
+ // If this was EH dispatch, this must be a conditional branch to the handler
+ // block.
+ // FIXME: Handle instructions in the dispatch block. Currently we drop them,
+ // leading to crashes if some optimization hoists stuff here.
+ assert(CatchAction->getSelector() && HandlerBB &&
+ "expected catch EH dispatch");
+ } else {
+ // This must be a catch-all. Split the block after the landingpad.
+ assert(CatchAction->getSelector()->isNullValue() && "expected catch-all");
+ HandlerBB =
+ StartBB->splitBasicBlock(StartBB->getFirstInsertionPt(), "catch.all");
+ }
+ CatchAction->setHandlerBlockOrFunc(BlockAddress::get(HandlerBB));
+ TinyPtrVector<BasicBlock *> Targets(HandlerBB);
+ CatchAction->setReturnTargets(Targets);
+}
+
+void LandingPadMap::mapLandingPad(const LandingPadInst *LPad) {
+ // Each instance of this class should only ever be used to map a single
+ // landing pad.
+ assert(OriginLPad == nullptr || OriginLPad == LPad);
- // Tell the caller not to clone this instruction.
- return CloningDirector::SkipInstruction;
+ // 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);
}
- // Other extract value instructions just get cloned.
- return CloningDirector::CloneInstruction;
}
+}
- if (auto *Store = dyn_cast<StoreInst>(Inst)) {
- // Look for and suppress stores of the extracted landingpad values.
- const Value *StoredValue = Store->getValueOperand();
- if (StoredValue == ExtractedEHPtr) {
- EHPtrStoreAddr = Store->getPointerOperand();
- return CloningDirector::SkipInstruction;
- }
- if (StoredValue == ExtractedSelector) {
- SelectorStoreAddr = Store->getPointerOperand();
- return CloningDirector::SkipInstruction;
- }
+bool LandingPadMap::isOriginLandingPadBlock(const BasicBlock *BB) const {
+ return BB->getLandingPadInst() == OriginLPad;
+}
- // Any other store just gets cloned.
- return CloningDirector::CloneInstruction;
+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;
+}
- 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;
- }
+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;
+}
+
+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;
- // Any other loads just get cloned.
- return CloningDirector::CloneInstruction;
+ // Nested landing pads will be cloned as stubs, with just the
+ // landingpad instruction and an unreachable instruction. When
+ // all landingpads have been outlined, we'll replace this with the
+ // llvm.eh.actions call and indirect branch created when the
+ // landing pad was outlined.
+ if (auto *NestedLPad = dyn_cast<LandingPadInst>(Inst)) {
+ Instruction *NewInst = NestedLPad->clone();
+ if (NestedLPad->hasName())
+ NewInst->setName(NestedLPad->getName());
+ // FIXME: Store this mapping somewhere else also.
+ VMap[NestedLPad] = NewInst;
+ BasicBlock::InstListType &InstList = NewBB->getInstList();
+ InstList.push_back(NewInst);
+ InstList.push_back(new UnreachableInst(NewBB->getContext()));
+ return CloningDirector::StopCloningBB;
}
+ if (auto *Invoke = dyn_cast<InvokeInst>(Inst))
+ return handleInvoke(VMap, Invoke, NewBB);
+
if (auto *Resume = dyn_cast<ResumeInst>(Inst))
return handleResume(VMap, Resume, NewBB);
// 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();
return CloningDirector::SkipInstruction;
}
// 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())
+ // 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 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));
+ // 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(Branch->getSuccessor(0)), NewBB);
+ 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
return CloningDirector::SkipInstruction;
}
+CloningDirector::CloningAction
+WinEHCatchDirector::handleInvoke(ValueToValueMapTy &VMap,
+ const InvokeInst *Invoke, BasicBlock *NewBB) {
+ return CloningDirector::CloneInstruction;
+}
+
CloningDirector::CloningAction
WinEHCatchDirector::handleResume(ValueToValueMapTy &VMap,
const ResumeInst *Resume, BasicBlock *NewBB) {
CloningDirector::CloningAction WinEHCleanupDirector::handleTypeIdFor(
ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
- // This causes a replacement that will collapse the landing pad CFG
- // to just the cleanup code.
+ // 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);
- // Tell the caller not to clone this instruction.
return CloningDirector::SkipInstruction;
}
+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;
+
+ // 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::StopCloningBB;
+}
+
CloningDirector::CloningAction WinEHCleanupDirector::handleResume(
ValueToValueMapTy &VMap, const ResumeInst *Resume, BasicBlock *NewBB) {
ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
Function *OutlinedFn, FrameVarInfoMap &FrameVarInfo)
: FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) {
Builder.SetInsertPoint(&OutlinedFn->getEntryBlock());
- // FIXME: Do something with the FrameVarMapped so that it is shared across the
- // function.
}
Value *WinEHFrameVariableMaterializer::materializeValueFor(Value *V) {
// Don't materialize other values.
return nullptr;
}
+
+// 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) {
+ // This landing pad contains only cleanup code.
+ CleanupHandler *Action = new CleanupHandler(BB);
+ CleanupHandlerMap[BB] = Action;
+ Actions.insertCleanupHandler(Action);
+ DEBUG(dbgs() << " Assuming cleanup code in block " << BB->getName()
+ << "\n");
+ assert(LPad->isCleanup());
+ return;
+ }
+
+ VisitedBlockSet VisitedBlocks;
+
+ while (HandlersFound != NumClauses) {
+ BasicBlock *NextBB = nullptr;
+
+ // See if the clause we're looking for is a catch-all.
+ // If so, the catch begins immediately.
+ if (isa<ConstantPointerNull>(LPad->getClause(HandlersFound))) {
+ // The catch all must occur last.
+ assert(HandlersFound == NumClauses - 1);
+
+ // For C++ EH, check if there is any interesting cleanup code before we
+ // begin the catch. This is important because cleanups cannot rethrow
+ // exceptions but code called from catches can. For SEH, it isn't
+ // important if some finally code before a catch-all is executed out of
+ // line or after recovering from the exception.
+ if (Personality == EHPersonality::MSVC_CXX) {
+ if (auto *CleanupAction = findCleanupHandler(BB, BB)) {
+ // Add a cleanup entry to the list
+ Actions.insertCleanupHandler(CleanupAction);
+ DEBUG(dbgs() << " Found cleanup code in block "
+ << CleanupAction->getStartBlock()->getName() << "\n");
+ }
+ }
+
+ // Add the catch handler to the action list.
+ CatchHandler *Action =
+ new CatchHandler(BB, LPad->getClause(HandlersFound), 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);
+ // See if there is any interesting code executed before the dispatch.
+ if (auto *CleanupAction =
+ findCleanupHandler(BB, CatchAction->getStartBlock())) {
+ // Add a cleanup entry to the list
+ Actions.insertCleanupHandler(CleanupAction);
+ DEBUG(dbgs() << " Found cleanup code in block "
+ << CleanupAction->getStartBlock()->getName() << "\n");
+ }
+
+ assert(CatchAction);
+ ++HandlersFound;
+
+ // Add the catch handler to the action list.
+ Actions.insertCatchHandler(CatchAction);
+ DEBUG(dbgs() << " Found 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.
+ if (auto *CleanupAction = findCleanupHandler(BB, BB)) {
+ // Add a cleanup entry to the list
+ Actions.insertCleanupHandler(CleanupAction);
+ DEBUG(dbgs() << " Found cleanup code in block "
+ << CleanupAction->getStartBlock()->getName() << "\n");
+ }
+
+ // 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;
+ }
+ }
+
+ // 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 findCleanupHandler.
+static CleanupHandler *createCleanupHandler(CleanupHandlerMapTy &CleanupHandlerMap,
+ BasicBlock *BB) {
+ CleanupHandler *Action = new CleanupHandler(BB);
+ CleanupHandlerMap[BB] = Action;
+ return Action;
+}
+
+// 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.
+//
+CleanupHandler *WinEHPrepare::findCleanupHandler(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) {
+ // 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]) {
+ return cast<CleanupHandler>(Action);
+ } else {
+ // Here we handle the case where the cleanup handler map contains a
+ // value for this block but the value is a nullptr. This means that
+ // we have previously analyzed the block and determined that it did
+ // not contain any cleanup code. Based on the earlier analysis, we
+ // know the the block must end in either an unconditional branch, a
+ // resume or a conditional branch that is predicated on a comparison
+ // with a selector. Either the resume or the selector dispatch
+ // would terminate the search for cleanup code, so the unconditional
+ // branch is the only case for which we might need to continue
+ // searching.
+ if (BB == EndBB)
+ return nullptr;
+ BasicBlock *SuccBB;
+ if (!match(BB->getTerminator(), m_UnconditionalBr(SuccBB)))
+ return nullptr;
+ 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 there is only one landingpad, we may use the lpad directly with no
+ // insertions.
+ if (isa<LandingPadInst>(ResumeVal))
+ return nullptr;
+ if (!isa<PHINode>(ResumeVal)) {
+ Insert2 = dyn_cast<InsertValueInst>(ResumeVal);
+ if (!Insert2)
+ return createCleanupHandler(CleanupHandlerMap, BB);
+ Insert1 = dyn_cast<InsertValueInst>(Insert2->getAggregateOperand());
+ if (!Insert1)
+ return createCleanupHandler(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(CleanupHandlerMap, BB);
+ }
+ }
+ return nullptr;
+ }
+
+ 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(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(CleanupHandlerMap, BB);
+ }
+ // The selector dispatch block should always terminate our search.
+ assert(BB == EndBB);
+ return nullptr;
+ }
+
+ // 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 nullptr;
+ // Anything else makes this interesting cleanup code.
+ return createCleanupHandler(CleanupHandlerMap, BB);
+ }
+
+ // Only unconditional branches in empty blocks should get this far.
+ assert(Branch && Branch->isUnconditional());
+ if (BB == EndBB)
+ return nullptr;
+ BB = Branch->getSuccessor(0);
+ }
+ return nullptr;
+}
projects / oota-llvm.git / blobdiff