Commit a9af1dc3 authored by Matt Arsenault's avatar Matt Arsenault
Browse files

Analysis: Add max recursison to isDereferenceableAndAlignedPointer 

Fixes stack overflow in test/CodeGen/X86/large-gep-chain.ll when store
lowering starts adding dereferenceable flags.
parent c5c1bb33

llvm/lib/Analysis/Loads.cpp

+15 −9
Original line number Diff line number Diff line
@@ -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<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 @@ static bool isDereferenceableAndAlignedPointer( 
  // 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 @@ 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<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;
@@ -132,7 +138,7 @@ bool llvm::isDereferenceableAndAlignedPointer(const Value *V, Align Alignment, 


  SmallPtrSet<const Value *, 32> Visited;

  return ::isDereferenceableAndAlignedPointer(V, Alignment, Size, DL, CtxI, DT,

                                              Visited);

                                              Visited, 16);

}



bool llvm::isDereferenceableAndAlignedPointer(const Value *V, Type *Ty,