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[WinEH] C++ EH state numbering fixes

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Differential Revision: http://reviews.llvm.org/D9787



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237854 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Kaylor
2015-05-20 23:22:24 +00:00
parent 7681f6a1b0
commit d0f4ffa472
9 changed files with 428 additions and 169 deletions
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239
lib/CodeGen/WinEHPrepare.cpp
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@ -91,6 +91,7 @@ public:
private:
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);
@ -127,6 +128,9 @@ private:
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
@ -214,6 +218,9 @@ public:
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;
@ -244,10 +251,12 @@ public:
WinEHCatchDirector(
Function *CatchFn, Value *ParentFP, Value *Selector,
FrameVarInfoMap &VarInfo, LandingPadMap &LPadMap,
DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPads)
DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPads,
DominatorTree *DT, SmallPtrSetImpl<BasicBlock *> &EHBlocks)
: WinEHCloningDirectorBase(CatchFn, ParentFP, VarInfo, LPadMap),
CurrentSelector(Selector->stripPointerCasts()),
ExceptionObjectVar(nullptr), NestedLPtoOriginalLP(NestedLPads) {}
ExceptionObjectVar(nullptr), NestedLPtoOriginalLP(NestedLPads),
DT(DT), EHBlocks(EHBlocks) {}
CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
const Instruction *Inst,
@ -257,6 +266,9 @@ public:
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,
@ -279,6 +291,8 @@ private:
// 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 {
@ -296,6 +310,9 @@ public:
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,
@ -525,13 +542,8 @@ void WinEHPrepare::findSEHEHReturnPoints(
}
}
/// 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) {
void WinEHPrepare::identifyEHBlocks(Function &F,
SmallVectorImpl<LandingPadInst *> &LPads) {
DEBUG(dbgs() << "Demoting values live across exception handlers in function "
<< F.getName() << '\n');
@ -541,10 +553,6 @@ void WinEHPrepare::demoteValuesLiveAcrossHandlers(
// - Exceptional blocks are blocks reachable from landingpads. Analysis does
// not follow llvm.eh.endcatch blocks, which mark a transition from
// exceptional to normal control.
SmallPtrSet<BasicBlock *, 4> NormalBlocks;
SmallPtrSet<BasicBlock *, 4> EHBlocks;
SetVector<BasicBlock *> EHReturnBlocks;
SetVector<BasicBlock *> Worklist;
if (Personality == EHPersonality::MSVC_CXX)
findCXXEHReturnPoints(F, EHReturnBlocks);
@ -567,6 +575,7 @@ void WinEHPrepare::demoteValuesLiveAcrossHandlers(
// 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);
@ -588,6 +597,21 @@ void WinEHPrepare::demoteValuesLiveAcrossHandlers(
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());
SetVector<Argument *> ArgsToDemote;
SetVector<Instruction *> InstrsToDemote;
for (BasicBlock &BB : F) {
@ -678,6 +702,7 @@ bool WinEHPrepare::prepareExceptionHandlers(
return false;
}
identifyEHBlocks(F, LPads);
demoteValuesLiveAcrossHandlers(F, LPads);
// These containers are used to re-map frame variables that are used in
@ -702,6 +727,16 @@ bool WinEHPrepare::prepareExceptionHandlers(
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* &L, LandingPadInst* &R) {
return DT->dominates(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
@ -829,28 +864,24 @@ bool WinEHPrepare::prepareExceptionHandlers(
CallInst *Recover =
CallInst::Create(ActionIntrin, ActionArgs, "recover", LPadBB);
if (isAsynchronousEHPersonality(Personality)) {
// SEH can create the target list directly, since catch handlers
// are not outlined.
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());
}
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);
} else {
// C++ EH must defer populating the targets to handle the case of
// targets that are reached indirectly through nested landing pads.
IndirectBrInst *Branch =
IndirectBrInst::Create(Recover, 0, LPadBB);
}
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.
@ -864,8 +895,7 @@ bool WinEHPrepare::prepareExceptionHandlers(
completeNestedLandingPad(&F, LPadPair.first, LPadPair.second, FrameVarInfo);
NestedLPtoOriginalLP.clear();
// Populate the indirectbr instructions' target lists if we deferred
// doing so above.
// Update the indirectbr instructions' target lists if necessary.
SetVector<BasicBlock*> CheckedTargets;
SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList;
for (auto &LPadImplPair : LPadImpls) {
@ -884,6 +914,12 @@ bool WinEHPrepare::prepareExceptionHandlers(
}
}
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.
@ -994,6 +1030,9 @@ bool WinEHPrepare::prepareExceptionHandlers(
HandlerToParentFP.clear();
DT = nullptr;
SEHExceptionCodeSlot = nullptr;
EHBlocks.clear();
NormalBlocks.clear();
EHReturnBlocks.clear();
return HandlersOutlined;
}
@ -1079,10 +1118,19 @@ void WinEHPrepare::completeNestedLandingPad(Function *ParentFn,
// temporarily inserted as its terminator.
LLVMContext &Context = ParentFn->getContext();
BasicBlock *OutlinedBB = OutlinedLPad->getParent();
assert(isa<UnreachableInst>(OutlinedBB->getTerminator()));
OutlinedBB->getTerminator()->eraseFromParent();
// That should leave OutlinedLPad as the last instruction in its block.
assert(&OutlinedBB->back() == OutlinedLPad);
// 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);
}
// The original landing pad will have already had its action intrinsic
// built by the outlining loop. We need to clone that into the outlined
@ -1096,9 +1144,9 @@ void WinEHPrepare::completeNestedLandingPad(Function *ParentFn,
// The instruction after the landing pad should now be a call to eh.actions.
const Instruction *Recover = II;
assert(match(Recover, m_Intrinsic<Intrinsic::eh_actions>()));
IntrinsicInst *EHActions = cast<IntrinsicInst>(Recover->clone());
const IntrinsicInst *EHActions = cast<IntrinsicInst>(Recover);
// Remap the exception variables into the outlined function.
// Remap the return target in the nested handler.
SmallVector<BlockAddress *, 4> ActionTargets;
SmallVector<std::unique_ptr<ActionHandler>, 4> ActionList;
parseEHActions(EHActions, ActionList);
@ -1125,7 +1173,7 @@ void WinEHPrepare::completeNestedLandingPad(Function *ParentFn,
// should be a block that was outlined into OutlinedHandlerFn.
assert(BA->getFunction() == ParentFn);
// Ignore targets that aren't part of OutlinedHandlerFn.
// Ignore targets that aren't part of an outlined handler function.
if (!LPadTargetBlocks.count(BA->getBasicBlock()))
continue;
@ -1142,13 +1190,25 @@ void WinEHPrepare::completeNestedLandingPad(Function *ParentFn,
}
}
ActionList.clear();
OutlinedBB->getInstList().push_back(EHActions);
// Insert an indirect branch into the outlined landing pad BB.
IndirectBrInst *IBr = IndirectBrInst::Create(EHActions, 0, OutlinedBB);
// Add the previously collected action targets.
for (auto *Target : ActionTargets)
IBr->addDestination(Target->getBasicBlock());
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());
}
}
// This function examines a block to determine whether the block ends with a
@ -1326,9 +1386,9 @@ bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn,
LPadMap.mapLandingPad(LPad);
if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
Constant *Sel = CatchAction->getSelector();
Director.reset(new WinEHCatchDirector(Handler, ParentFP, Sel,
VarInfo, LPadMap,
NestedLPtoOriginalLP));
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 {
@ -1532,15 +1592,22 @@ CloningDirector::CloningAction WinEHCloningDirectorBase::handleInstruction(
if (LPadMap.isLandingPadSpecificInst(Inst))
return CloningDirector::SkipInstruction;
// Nested landing pads will be cloned as stubs, with just the
// landingpad instruction and an unreachable instruction. When
// all landingpads have been outlined, we'll replace this with the
// llvm.eh.actions call and indirect branch created when the
// landing pad was outlined.
// 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);
@ -1570,6 +1637,20 @@ CloningDirector::CloningAction WinEHCloningDirectorBase::handleInstruction(
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());
@ -1661,6 +1742,48 @@ CloningDirector::CloningAction WinEHCatchDirector::handleTypeIdFor(
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) {
@ -1750,6 +1873,14 @@ CloningDirector::CloningAction WinEHCleanupDirector::handleTypeIdFor(
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.