diff options
Diffstat (limited to 'llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp index 36d9b80eea2..ec976a971e3 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -1585,7 +1585,7 @@ Instruction *InstCombiner::visitFAdd(BinaryOperator &I) { /// &A[10] - &A[0]: we should compile this to "10". LHS/RHS are the pointer /// operands to the ptrtoint instructions for the LHS/RHS of the subtract. Value *InstCombiner::OptimizePointerDifference(Value *LHS, Value *RHS, - Type *Ty) { + Type *Ty, bool IsNUW) { // If LHS is a gep based on RHS or RHS is a gep based on LHS, we can optimize // this. bool Swapped = false; @@ -1653,6 +1653,15 @@ Value *InstCombiner::OptimizePointerDifference(Value *LHS, Value *RHS, // Emit the offset of the GEP and an intptr_t. Value *Result = EmitGEPOffset(GEP1); + // If this is a single inbounds GEP and the original sub was nuw, + // then the final multiplication is also nuw. We match an extra add zero + // here, because that's what EmitGEPOffset() generates. + Instruction *I; + if (IsNUW && !GEP2 && !Swapped && GEP1->isInBounds() && + match(Result, m_Add(m_Instruction(I), m_Zero())) && + I->getOpcode() == Instruction::Mul) + I->setHasNoUnsignedWrap(); + // If we had a constant expression GEP on the other side offsetting the // pointer, subtract it from the offset we have. if (GEP2) { @@ -2051,13 +2060,15 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) { Value *LHSOp, *RHSOp; if (match(Op0, m_PtrToInt(m_Value(LHSOp))) && match(Op1, m_PtrToInt(m_Value(RHSOp)))) - if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType())) + if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType(), + I.hasNoUnsignedWrap())) return replaceInstUsesWith(I, Res); // trunc(p)-trunc(q) -> trunc(p-q) if (match(Op0, m_Trunc(m_PtrToInt(m_Value(LHSOp)))) && match(Op1, m_Trunc(m_PtrToInt(m_Value(RHSOp))))) - if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType())) + if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType(), + /* IsNUW */ false)) return replaceInstUsesWith(I, Res); // Canonicalize a shifty way to code absolute value to the common pattern. |
