[PATCH] D72600: Analysis: Add max recursison to isDereferenceableAndAlignedPointer
Matt Arsenault via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Mon Jan 13 05:20:24 PST 2020
arsenm created this revision.
arsenm added reviewers: reames, apilipenko, sanjoy.
Herald added subscribers: hiraditya, wdng.
Herald added a project: LLVM.
Fixes stack overflow in test/CodeGen/X86/large-gep-chain.ll when store
lowering starts adding dereferenceable flags.
https://reviews.llvm.org/D72600
Files:
llvm/lib/Analysis/Loads.cpp
Index: llvm/lib/Analysis/Loads.cpp
===================================================================
--- llvm/lib/Analysis/Loads.cpp
+++ llvm/lib/Analysis/Loads.cpp
@@ -52,7 +52,12 @@
static bool isDereferenceableAndAlignedPointer(
const Value *V, Align Alignment, const APInt &Size, const DataLayout &DL,
const Instruction *CtxI, const DominatorTree *DT,
- SmallPtrSetImpl<const Value *> &Visited) {
+ SmallPtrSetImpl<const Value *> &Visited, unsigned MaxDepth) {
+
+ // Recursion limit.
+ if (MaxDepth-- == 0)
+ return false;
+
// Already visited? Bail out, we've likely hit unreachable code.
if (!Visited.insert(V).second)
return false;
@@ -63,7 +68,8 @@
// bitcast instructions are no-ops as far as dereferenceability is concerned.
if (const BitCastOperator *BC = dyn_cast<BitCastOperator>(V))
return isDereferenceableAndAlignedPointer(BC->getOperand(0), Alignment,
- Size, DL, CtxI, DT, Visited);
+ Size, DL, CtxI, DT, Visited,
+ MaxDepth);
bool CheckForNonNull = false;
APInt KnownDerefBytes(Size.getBitWidth(),
@@ -99,22 +105,22 @@
// addrspacecast, so we can't do arithmetic directly on the APInt values.
return isDereferenceableAndAlignedPointer(
Base, Alignment, Offset + Size.sextOrTrunc(Offset.getBitWidth()), DL,
- CtxI, DT, Visited);
+ CtxI, DT, Visited, MaxDepth);
}
// For gc.relocate, look through relocations
if (const GCRelocateInst *RelocateInst = dyn_cast<GCRelocateInst>(V))
return isDereferenceableAndAlignedPointer(
- RelocateInst->getDerivedPtr(), Alignment, Size, DL, CtxI, DT, Visited);
+ RelocateInst->getDerivedPtr(), Alignment, Size, DL, CtxI, DT, Visited, MaxDepth);
if (const AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(V))
return isDereferenceableAndAlignedPointer(ASC->getOperand(0), Alignment,
- Size, DL, CtxI, DT, Visited);
+ Size, DL, CtxI, DT, Visited, MaxDepth);
if (const auto *Call = dyn_cast<CallBase>(V))
if (auto *RP = getArgumentAliasingToReturnedPointer(Call, true))
return isDereferenceableAndAlignedPointer(RP, Alignment, Size, DL, CtxI,
- DT, Visited);
+ DT, Visited, MaxDepth);
// If we don't know, assume the worst.
return false;
@@ -128,11 +134,11 @@
// Note: At the moment, Size can be zero. This ends up being interpreted as
// a query of whether [Base, V] is dereferenceable and V is aligned (since
// that's what the implementation happened to do). It's unclear if this is
- // the desired semantic, but at least SelectionDAG does exercise this case.
-
+ // the desired semantic, but at least SelectionDAG does exercise this case.
+
SmallPtrSet<const Value *, 32> Visited;
return ::isDereferenceableAndAlignedPointer(V, Alignment, Size, DL, CtxI, DT,
- Visited);
+ Visited, 16);
}
bool llvm::isDereferenceableAndAlignedPointer(const Value *V, Type *Ty,
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