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[WinEH] Add invoke of llvm.donothing to outlined catch and cleanup handlers to identify their personality. 

Differential Review: http://reviews.llvm.org/D8835

llvm-svn: 234360
This commit is contained in:
Andrew Kaylor 2015-04-07 21:30:23 +00:00
parent f3fc3019d3
commit bb11132e65
1 changed files with 65 additions and 14 deletions
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79
llvm/lib/CodeGen/WinEHPrepare.cpp
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@ -93,6 +93,7 @@ private:
bool outlineHandler(ActionHandler *Action, Function *SrcFn,
LandingPadInst *LPad, BasicBlock *StartBB,
FrameVarInfoMap &VarInfo);
void addStubInvokeToHandlerIfNeeded(Function *Handler, Value *PersonalityFn);
void mapLandingPadBlocks(LandingPadInst *LPad, LandingPadActions &Actions);
CatchHandler *findCatchHandler(BasicBlock *BB, BasicBlock *&NextBB,
@ -756,6 +757,59 @@ static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler,
return false;
}
static BasicBlock *createStubLandingPad(Function *Handler,
Value *PersonalityFn) {
// FIXME: Finish this!
LLVMContext &Context = Handler->getContext();
BasicBlock *StubBB = BasicBlock::Create(Context, "stub");
Handler->getBasicBlockList().push_back(StubBB);
IRBuilder<> Builder(StubBB);
LandingPadInst *LPad = Builder.CreateLandingPad(
llvm::StructType::get(Type::getInt8PtrTy(Context),
Type::getInt32Ty(Context), nullptr),
PersonalityFn, 0);
LPad->setCleanup(true);
Builder.CreateUnreachable();
return StubBB;
}
// Cycles through the blocks in an outlined handler function looking for an
// invoke instruction and inserts an invoke of llvm.donothing with an empty
// landing pad if none is found. The code that generates the .xdata tables for
// the handler needs at least one landing pad to identify the parent function's
// personality.
void WinEHPrepare::addStubInvokeToHandlerIfNeeded(Function *Handler,
Value *PersonalityFn) {
ReturnInst *Ret = nullptr;
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)
continue;
// If we haven't recorded a return instruction yet, try this terminator.
Ret = dyn_cast<ReturnInst>(Terminator);
}
// If we got this far, the handler contains no invokes. We should have seen
// at least one return. We'll insert an invoke of llvm.donothing ahead of
// that return.
assert(Ret);
BasicBlock *OldRetBB = Ret->getParent();
BasicBlock *NewRetBB = SplitBlock(OldRetBB, Ret);
// SplitBlock adds an unconditional branch instruction at the end of the
// parent block. We want to replace that with an invoke call, so we can
// erase it now.
OldRetBB->getTerminator()->eraseFromParent();
BasicBlock *StubLandingPad = createStubLandingPad(Handler, PersonalityFn);
Function *F =
Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::donothing);
InvokeInst::Create(F, NewRetBB, StubLandingPad, None, "", OldRetBB);
}
bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn,
LandingPadInst *LPad, BasicBlock *StartBB,
FrameVarInfoMap &VarInfo) {
@ -840,6 +894,9 @@ bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn,
Entry->getInstList().splice(Entry->end(), FirstClonedBB->getInstList());
FirstClonedBB->eraseFromParent();
// Make sure we can identify the handler's personality later.
addStubInvokeToHandlerIfNeeded(Handler, LPad->getPersonalityFn());
if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
WinEHCatchDirector *CatchDirector =
reinterpret_cast<WinEHCatchDirector *>(Director.get());
@ -1136,12 +1193,9 @@ CloningDirector::CloningAction WinEHCleanupDirector::handleBeginCatch(
CloningDirector::CloningAction WinEHCleanupDirector::handleEndCatch(
ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
// Catch blocks within cleanup handlers will always be unreachable.
// We'll insert an unreachable instruction now, but it will be pruned
// before the cloning process is complete.
BasicBlock::InstListType &InstList = NewBB->getInstList();
InstList.push_back(new UnreachableInst(NewBB->getContext()));
return CloningDirector::StopCloningBB;
// 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(
@ -1538,9 +1592,8 @@ CleanupHandler *WinEHPrepare::findCleanupHandler(BasicBlock *StartBB,
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) {
for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
II != IE; ++II) {
Instruction *Inst = II;
if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
continue;
@ -1556,9 +1609,8 @@ CleanupHandler *WinEHPrepare::findCleanupHandler(BasicBlock *StartBB,
}
// Anything else is either a catch block or interesting cleanup code.
for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(),
IE = BB->end();
II != IE; ++II) {
for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
II != IE; ++II) {
Instruction *Inst = II;
if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
continue;
@ -1590,7 +1642,7 @@ void llvm::parseEHActions(const IntrinsicInst *II,
SmallVectorImpl<ActionHandler *> &Actions) {
for (unsigned I = 0, E = II->getNumArgOperands(); I != E;) {
uint64_t ActionKind =
cast<ConstantInt>(II->getArgOperand(I))->getZExtValue();
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));
@ -1613,4 +1665,3 @@ void llvm::parseEHActions(const IntrinsicInst *II,
}
std::reverse(Actions.begin(), Actions.end());
}