diff --git a/llvm/lib/Analysis/Loads.cpp b/llvm/lib/Analysis/Loads.cpp index 4ee2d7c52927a..218fc3e0030dd 100644 --- a/llvm/lib/Analysis/Loads.cpp +++ b/llvm/lib/Analysis/Loads.cpp @@ -52,7 +52,12 @@ static bool isAligned(const Value *Base, const APInt &Offset, Align Alignment, static bool isDereferenceableAndAlignedPointer( const Value *V, Align Alignment, const APInt &Size, const DataLayout &DL, const Instruction *CtxI, const DominatorTree *DT, - SmallPtrSetImpl &Visited) { + SmallPtrSetImpl &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 @@ static bool isDereferenceableAndAlignedPointer( // bitcast instructions are no-ops as far as dereferenceability is concerned. if (const BitCastOperator *BC = dyn_cast(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 @@ static bool isDereferenceableAndAlignedPointer( // 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(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(V)) return isDereferenceableAndAlignedPointer(ASC->getOperand(0), Alignment, - Size, DL, CtxI, DT, Visited); + Size, DL, CtxI, DT, Visited, MaxDepth); if (const auto *Call = dyn_cast(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 @@ bool llvm::isDereferenceableAndAlignedPointer(const Value *V, Align Alignment, // 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 Visited; return ::isDereferenceableAndAlignedPointer(V, Alignment, Size, DL, CtxI, DT, - Visited); + Visited, 16); } bool llvm::isDereferenceableAndAlignedPointer(const Value *V, Type *Ty,