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-rw-r--r--llvm/lib/Transforms/Utils/InlineFunction.cpp331
1 files changed, 314 insertions, 17 deletions
diff --git a/llvm/lib/Transforms/Utils/InlineFunction.cpp b/llvm/lib/Transforms/Utils/InlineFunction.cpp
index 185bc6da31e..db98de89183 100644
--- a/llvm/lib/Transforms/Utils/InlineFunction.cpp
+++ b/llvm/lib/Transforms/Utils/InlineFunction.cpp
@@ -179,13 +179,244 @@ void LandingPadInliningInfo::forwardResume(
RI->eraseFromParent();
}
+/// Helper for getUnwindDestToken/getUnwindDestTokenHelper.
+static Value *getParentPad(Value *EHPad) {
+ if (auto *FPI = dyn_cast<FuncletPadInst>(EHPad))
+ return FPI->getParentPad();
+ return cast<CatchSwitchInst>(EHPad)->getParentPad();
+}
+
+typedef DenseMap<Instruction *, Value *> UnwindDestMemoTy;
+
+/// Helper for getUnwindDestToken that does the descendant-ward part of
+/// the search.
+static Value *getUnwindDestTokenHelper(Instruction *EHPad,
+ UnwindDestMemoTy &MemoMap) {
+ SmallVector<Instruction *, 8> Worklist(1, EHPad);
+
+ while (!Worklist.empty()) {
+ Instruction *CurrentPad = Worklist.pop_back_val();
+ // We only put pads on the worklist that aren't in the MemoMap. When
+ // we find an unwind dest for a pad we may update its ancestors, but
+ // the queue only ever contains uncles/great-uncles/etc. of CurrentPad,
+ // so they should never get updated while queued on the worklist.
+ assert(!MemoMap.count(CurrentPad));
+ Value *UnwindDestToken = nullptr;
+ if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(CurrentPad)) {
+ if (CatchSwitch->hasUnwindDest()) {
+ UnwindDestToken = CatchSwitch->getUnwindDest()->getFirstNonPHI();
+ } else {
+ // Catchswitch doesn't have a 'nounwind' variant, and one might be
+ // annotated as "unwinds to caller" when really it's nounwind (see
+ // e.g. SimplifyCFGOpt::SimplifyUnreachable), so we can't infer the
+ // parent's unwind dest from this. We can check its catchpads'
+ // descendants, since they might include a cleanuppad with an
+ // "unwinds to caller" cleanupret, which can be trusted.
+ for (auto HI = CatchSwitch->handler_begin(),
+ HE = CatchSwitch->handler_end();
+ HI != HE && !UnwindDestToken; ++HI) {
+ BasicBlock *HandlerBlock = *HI;
+ auto *CatchPad = cast<CatchPadInst>(HandlerBlock->getFirstNonPHI());
+ for (User *Child : CatchPad->users()) {
+ // Intentionally ignore invokes here -- since the catchswitch is
+ // marked "unwind to caller", it would be a verifier error if it
+ // contained an invoke which unwinds out of it, so any invoke we'd
+ // encounter must unwind to some child of the catch.
+ if (!isa<CleanupPadInst>(Child) && !isa<CatchSwitchInst>(Child))
+ continue;
+
+ Instruction *ChildPad = cast<Instruction>(Child);
+ auto Memo = MemoMap.find(ChildPad);
+ if (Memo == MemoMap.end()) {
+ // Haven't figure out this child pad yet; queue it.
+ Worklist.push_back(ChildPad);
+ continue;
+ }
+ // We've already checked this child, but might have found that
+ // it offers no proof either way.
+ Value *ChildUnwindDestToken = Memo->second;
+ if (!ChildUnwindDestToken)
+ continue;
+ // We already know the child's unwind dest, which can either
+ // be ConstantTokenNone to indicate unwind to caller, or can
+ // be another child of the catchpad. Only the former indicates
+ // the unwind dest of the catchswitch.
+ if (isa<ConstantTokenNone>(ChildUnwindDestToken)) {
+ UnwindDestToken = ChildUnwindDestToken;
+ break;
+ }
+ assert(getParentPad(ChildUnwindDestToken) == CatchPad);
+ }
+ }
+ }
+ } else {
+ auto *CleanupPad = cast<CleanupPadInst>(CurrentPad);
+ for (User *U : CleanupPad->users()) {
+ if (auto *CleanupRet = dyn_cast<CleanupReturnInst>(U)) {
+ if (BasicBlock *RetUnwindDest = CleanupRet->getUnwindDest())
+ UnwindDestToken = RetUnwindDest->getFirstNonPHI();
+ else
+ UnwindDestToken = ConstantTokenNone::get(CleanupPad->getContext());
+ break;
+ }
+ Value *ChildUnwindDestToken;
+ if (auto *Invoke = dyn_cast<InvokeInst>(U)) {
+ ChildUnwindDestToken = Invoke->getUnwindDest()->getFirstNonPHI();
+ } else if (isa<CleanupPadInst>(U) || isa<CatchSwitchInst>(U)) {
+ Instruction *ChildPad = cast<Instruction>(U);
+ auto Memo = MemoMap.find(ChildPad);
+ if (Memo == MemoMap.end()) {
+ // Haven't resolved this child yet; queue it and keep searching.
+ Worklist.push_back(ChildPad);
+ continue;
+ }
+ // We've checked this child, but still need to ignore it if it
+ // had no proof either way.
+ ChildUnwindDestToken = Memo->second;
+ if (!ChildUnwindDestToken)
+ continue;
+ } else {
+ // Not a relevant user of the cleanuppad
+ continue;
+ }
+ // In a well-formed program, the child/invoke must either unwind to
+ // an(other) child of the cleanup, or exit the cleanup. In the
+ // first case, continue searching.
+ if (isa<Instruction>(ChildUnwindDestToken) &&
+ getParentPad(ChildUnwindDestToken) == CleanupPad)
+ continue;
+ UnwindDestToken = ChildUnwindDestToken;
+ break;
+ }
+ }
+ // If we haven't found an unwind dest for CurrentPad, we may have queued its
+ // children, so move on to the next in the worklist.
+ if (!UnwindDestToken)
+ continue;
+
+ // Now we know that CurrentPad unwinds to UnwindDestToken. It also exits
+ // any ancestors of CurrentPad up to but not including UnwindDestToken's
+ // parent pad. Record this in the memo map, and check to see if the
+ // original EHPad being queried is one of the ones exited.
+ Value *UnwindParent;
+ if (auto *UnwindPad = dyn_cast<Instruction>(UnwindDestToken))
+ UnwindParent = getParentPad(UnwindPad);
+ else
+ UnwindParent = nullptr;
+ bool ExitedOriginalPad = false;
+ for (Instruction *ExitedPad = CurrentPad;
+ ExitedPad && ExitedPad != UnwindParent;
+ ExitedPad = dyn_cast<Instruction>(getParentPad(ExitedPad))) {
+ // Skip over catchpads since they just follow their catchswitches.
+ if (isa<CatchPadInst>(ExitedPad))
+ continue;
+ MemoMap[ExitedPad] = UnwindDestToken;
+ ExitedOriginalPad |= (ExitedPad == EHPad);
+ }
+
+ if (ExitedOriginalPad)
+ return UnwindDestToken;
+
+ // Continue the search.
+ }
+
+ // No definitive information is contained within this funclet.
+ return nullptr;
+}
+
+/// Given an EH pad, find where it unwinds. If it unwinds to an EH pad,
+/// return that pad instruction. If it unwinds to caller, return
+/// ConstantTokenNone. If it does not have a definitive unwind destination,
+/// return nullptr.
+///
+/// This routine gets invoked for calls in funclets in inlinees when inlining
+/// an invoke. Since many funclets don't have calls inside them, it's queried
+/// on-demand rather than building a map of pads to unwind dests up front.
+/// Determining a funclet's unwind dest may require recursively searching its
+/// descendants, and also ancestors and cousins if the descendants don't provide
+/// an answer. Since most funclets will have their unwind dest immediately
+/// available as the unwind dest of a catchswitch or cleanupret, this routine
+/// searches top-down from the given pad and then up. To avoid worst-case
+/// quadratic run-time given that approach, it uses a memo map to avoid
+/// re-processing funclet trees. The callers that rewrite the IR as they go
+/// take advantage of this, for correctness, by checking/forcing rewritten
+/// pads' entries to match the original callee view.
+static Value *getUnwindDestToken(Instruction *EHPad,
+ UnwindDestMemoTy &MemoMap) {
+ // Catchpads unwind to the same place as their catchswitch;
+ // redirct any queries on catchpads so the code below can
+ // deal with just catchswitches and cleanuppads.
+ if (auto *CPI = dyn_cast<CatchPadInst>(EHPad))
+ EHPad = CPI->getCatchSwitch();
+
+ // Check if we've already determined the unwind dest for this pad.
+ auto Memo = MemoMap.find(EHPad);
+ if (Memo != MemoMap.end())
+ return Memo->second;
+
+ // Search EHPad and, if necessary, its descendants.
+ Value *UnwindDestToken = getUnwindDestTokenHelper(EHPad, MemoMap);
+ assert((UnwindDestToken == nullptr) != (MemoMap.count(EHPad) != 0));
+ if (UnwindDestToken)
+ return UnwindDestToken;
+
+ // No information is available for this EHPad from itself or any of its
+ // descendants. An unwind all the way out to a pad in the caller would
+ // need also to agree with the unwind dest of the parent funclet, so
+ // search up the chain to try to find a funclet with information. Put
+ // null entries in the memo map to avoid re-processing as we go up.
+ MemoMap[EHPad] = nullptr;
+ Instruction *LastUselessPad = EHPad;
+ Value *AncestorToken;
+ for (AncestorToken = getParentPad(EHPad);
+ auto *AncestorPad = dyn_cast<Instruction>(AncestorToken);
+ AncestorToken = getParentPad(AncestorToken)) {
+ // Skip over catchpads since they just follow their catchswitches.
+ if (isa<CatchPadInst>(AncestorPad))
+ continue;
+ assert(!MemoMap.count(AncestorPad) || MemoMap[AncestorPad]);
+ auto AncestorMemo = MemoMap.find(AncestorPad);
+ if (AncestorMemo == MemoMap.end()) {
+ UnwindDestToken = getUnwindDestTokenHelper(AncestorPad, MemoMap);
+ } else {
+ UnwindDestToken = AncestorMemo->second;
+ }
+ if (UnwindDestToken)
+ break;
+ LastUselessPad = AncestorPad;
+ }
+
+ // Since the whole tree under LastUselessPad has no information, it all must
+ // match UnwindDestToken; record that to avoid repeating the search.
+ SmallVector<Instruction *, 8> Worklist(1, LastUselessPad);
+ while (!Worklist.empty()) {
+ Instruction *UselessPad = Worklist.pop_back_val();
+ assert(!MemoMap.count(UselessPad) || MemoMap[UselessPad] == nullptr);
+ MemoMap[UselessPad] = UnwindDestToken;
+ if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(UselessPad)) {
+ for (BasicBlock *HandlerBlock : CatchSwitch->handlers())
+ for (User *U : HandlerBlock->getFirstNonPHI()->users())
+ if (isa<CatchSwitchInst>(U) || isa<CleanupPadInst>(U))
+ Worklist.push_back(cast<Instruction>(U));
+ } else {
+ assert(isa<CleanupPadInst>(UselessPad));
+ for (User *U : UselessPad->users())
+ if (isa<CatchSwitchInst>(U) || isa<CleanupPadInst>(U))
+ Worklist.push_back(cast<Instruction>(U));
+ }
+ }
+
+ return UnwindDestToken;
+}
+
/// When we inline a basic block into an invoke,
/// we have to turn all of the calls that can throw into invokes.
/// This function analyze BB to see if there are any calls, and if so,
/// it rewrites them to be invokes that jump to InvokeDest and fills in the PHI
/// nodes in that block with the values specified in InvokeDestPHIValues.
-static BasicBlock *
-HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB, BasicBlock *UnwindEdge) {
+static BasicBlock *HandleCallsInBlockInlinedThroughInvoke(
+ BasicBlock *BB, BasicBlock *UnwindEdge,
+ UnwindDestMemoTy *FuncletUnwindMap = nullptr) {
for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
Instruction *I = &*BBI++;
@@ -196,6 +427,31 @@ HandleCallsInBlockInlinedThroughInvoke(BasicBlock *BB, BasicBlock *UnwindEdge) {
if (!CI || CI->doesNotThrow() || isa<InlineAsm>(CI->getCalledValue()))
continue;
+ if (auto FuncletBundle = CI->getOperandBundle(LLVMContext::OB_funclet)) {
+ // This call is nested inside a funclet. If that funclet has an unwind
+ // destination within the inlinee, then unwinding out of this call would
+ // be UB. Rewriting this call to an invoke which targets the inlined
+ // invoke's unwind dest would give the call's parent funclet multiple
+ // unwind destinations, which is something that subsequent EH table
+ // generation can't handle and that the veirifer rejects. So when we
+ // see such a call, leave it as a call.
+ auto *FuncletPad = cast<Instruction>(FuncletBundle->Inputs[0]);
+ Value *UnwindDestToken =
+ getUnwindDestToken(FuncletPad, *FuncletUnwindMap);
+ if (UnwindDestToken && !isa<ConstantTokenNone>(UnwindDestToken))
+ continue;
+#ifndef NDEBUG
+ Instruction *MemoKey;
+ if (auto *CatchPad = dyn_cast<CatchPadInst>(FuncletPad))
+ MemoKey = CatchPad->getCatchSwitch();
+ else
+ MemoKey = FuncletPad;
+ assert(FuncletUnwindMap->count(MemoKey) &&
+ (*FuncletUnwindMap)[MemoKey] == UnwindDestToken &&
+ "must get memoized to avoid confusing later searches");
+#endif // NDEBUG
+ }
+
// Convert this function call into an invoke instruction. First, split the
// basic block.
BasicBlock *Split =
@@ -328,13 +584,23 @@ static void HandleInlinedEHPad(InvokeInst *II, BasicBlock *FirstNewBlock,
// This connects all the instructions which 'unwind to caller' to the invoke
// destination.
+ UnwindDestMemoTy FuncletUnwindMap;
for (Function::iterator BB = FirstNewBlock->getIterator(), E = Caller->end();
BB != E; ++BB) {
if (auto *CRI = dyn_cast<CleanupReturnInst>(BB->getTerminator())) {
if (CRI->unwindsToCaller()) {
- CleanupReturnInst::Create(CRI->getCleanupPad(), UnwindDest, CRI);
+ auto *CleanupPad = CRI->getCleanupPad();
+ CleanupReturnInst::Create(CleanupPad, UnwindDest, CRI);
CRI->eraseFromParent();
UpdatePHINodes(&*BB);
+ // Finding a cleanupret with an unwind destination would confuse
+ // subsequent calls to getUnwindDestToken, so map the cleanuppad
+ // to short-circuit any such calls and recognize this as an "unwind
+ // to caller" cleanup.
+ assert(!FuncletUnwindMap.count(CleanupPad) ||
+ isa<ConstantTokenNone>(FuncletUnwindMap[CleanupPad]));
+ FuncletUnwindMap[CleanupPad] =
+ ConstantTokenNone::get(Caller->getContext());
}
}
@@ -345,12 +611,41 @@ static void HandleInlinedEHPad(InvokeInst *II, BasicBlock *FirstNewBlock,
Instruction *Replacement = nullptr;
if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(I)) {
if (CatchSwitch->unwindsToCaller()) {
+ Value *UnwindDestToken;
+ if (auto *ParentPad =
+ dyn_cast<Instruction>(CatchSwitch->getParentPad())) {
+ // This catchswitch is nested inside another funclet. If that
+ // funclet has an unwind destination within the inlinee, then
+ // unwinding out of this catchswitch would be UB. Rewriting this
+ // catchswitch to unwind to the inlined invoke's unwind dest would
+ // give the parent funclet multiple unwind destinations, which is
+ // something that subsequent EH table generation can't handle and
+ // that the veirifer rejects. So when we see such a call, leave it
+ // as "unwind to caller".
+ UnwindDestToken = getUnwindDestToken(ParentPad, FuncletUnwindMap);
+ if (UnwindDestToken && !isa<ConstantTokenNone>(UnwindDestToken))
+ continue;
+ } else {
+ // This catchswitch has no parent to inherit constraints from, and
+ // none of its descendants can have an unwind edge that exits it and
+ // targets another funclet in the inlinee. It may or may not have a
+ // descendant that definitively has an unwind to caller. In either
+ // case, we'll have to assume that any unwinds out of it may need to
+ // be routed to the caller, so treat it as though it has a definitive
+ // unwind to caller.
+ UnwindDestToken = ConstantTokenNone::get(Caller->getContext());
+ }
auto *NewCatchSwitch = CatchSwitchInst::Create(
CatchSwitch->getParentPad(), UnwindDest,
CatchSwitch->getNumHandlers(), CatchSwitch->getName(),
CatchSwitch);
for (BasicBlock *PadBB : CatchSwitch->handlers())
NewCatchSwitch->addHandler(PadBB);
+ // Propagate info for the old catchswitch over to the new one in
+ // the unwind map. This also serves to short-circuit any subsequent
+ // checks for the unwind dest of this catchswitch, which would get
+ // confused if they found the outer handler in the callee.
+ FuncletUnwindMap[NewCatchSwitch] = UnwindDestToken;
Replacement = NewCatchSwitch;
}
} else if (!isa<FuncletPadInst>(I)) {
@@ -369,8 +664,8 @@ static void HandleInlinedEHPad(InvokeInst *II, BasicBlock *FirstNewBlock,
for (Function::iterator BB = FirstNewBlock->getIterator(),
E = Caller->end();
BB != E; ++BB)
- if (BasicBlock *NewBB =
- HandleCallsInBlockInlinedThroughInvoke(&*BB, UnwindDest))
+ if (BasicBlock *NewBB = HandleCallsInBlockInlinedThroughInvoke(
+ &*BB, UnwindDest, &FuncletUnwindMap))
// Update any PHI nodes in the exceptional block to indicate that there
// is now a new entry in them.
UpdatePHINodes(NewBB);
@@ -1413,6 +1708,20 @@ bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
}
}
+ // If we are inlining for an invoke instruction, we must make sure to rewrite
+ // any call instructions into invoke instructions. This is sensitive to which
+ // funclet pads were top-level in the inlinee, so must be done before
+ // rewriting the "parent pad" links.
+ if (auto *II = dyn_cast<InvokeInst>(TheCall)) {
+ BasicBlock *UnwindDest = II->getUnwindDest();
+ Instruction *FirstNonPHI = UnwindDest->getFirstNonPHI();
+ if (isa<LandingPadInst>(FirstNonPHI)) {
+ HandleInlinedLandingPad(II, &*FirstNewBlock, InlinedFunctionInfo);
+ } else {
+ HandleInlinedEHPad(II, &*FirstNewBlock, InlinedFunctionInfo);
+ }
+ }
+
// Update the lexical scopes of the new funclets and callsites.
// Anything that had 'none' as its parent is now nested inside the callsite's
// EHPad.
@@ -1469,18 +1778,6 @@ bool llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
}
}
- // If we are inlining for an invoke instruction, we must make sure to rewrite
- // any call instructions into invoke instructions.
- if (auto *II = dyn_cast<InvokeInst>(TheCall)) {
- BasicBlock *UnwindDest = II->getUnwindDest();
- Instruction *FirstNonPHI = UnwindDest->getFirstNonPHI();
- if (isa<LandingPadInst>(FirstNonPHI)) {
- HandleInlinedLandingPad(II, &*FirstNewBlock, InlinedFunctionInfo);
- } else {
- HandleInlinedEHPad(II, &*FirstNewBlock, InlinedFunctionInfo);
- }
- }
-
// Handle any inlined musttail call sites. In order for a new call site to be
// musttail, the source of the clone and the inlined call site must have been
// musttail. Therefore it's safe to return without merging control into the
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