[llvm] r234360 - [WinEH] Add invoke of llvm.donothing to outlined catch and cleanup handlers to identify their personality.
Andrew Kaylor
andrew.kaylor at intel.com
Tue Apr 7 14:30:23 PDT 2015
Author: akaylor
Date: Tue Apr 7 16:30:23 2015
New Revision: 234360
URL: http://llvm.org/viewvc/llvm-project?rev=234360&view=rev
Log:
[WinEH] Add invoke of llvm.donothing to outlined catch and cleanup handlers to identify their personality.
Differential Review: http://reviews.llvm.org/D8835
Modified:
llvm/trunk/lib/CodeGen/WinEHPrepare.cpp
Modified: llvm/trunk/lib/CodeGen/WinEHPrepare.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/WinEHPrepare.cpp?rev=234360&r1=234359&r2=234360&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/WinEHPrepare.cpp (original)
+++ llvm/trunk/lib/CodeGen/WinEHPrepare.cpp Tue Apr 7 16:30:23 2015
@@ -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(BasicBloc
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(Action
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 WinEHClea
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::findCleanu
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::findCleanu
}
// 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 Intrinsi
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 Intrinsi
}
std::reverse(Actions.begin(), Actions.end());
}
-
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