diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp index c26766a95ac..f0c96bdf768 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp @@ -44,12 +44,18 @@ static bool ShrinkDemandedConstant(Instruction *I, unsigned OpNo, Demanded &= OpC->getValue(); I->setOperand(OpNo, ConstantInt::get(OpC->getType(), Demanded)); - // If 'nsw' is set and the constant is negative, removing *any* bits from the - // constant could make overflow occur. Remove 'nsw' from the instruction in - // this case. - if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(I)) - if (OBO->hasNoSignedWrap() && OpC->getValue().isNegative()) - cast<BinaryOperator>(OBO)->setHasNoSignedWrap(false); + // If either 'nsw' or 'nuw' is set and the constant is negative, + // removing *any* bits from the constant could make overflow occur. + // Remove 'nsw' and 'nuw' from the instruction in this case. + if (auto *OBO = dyn_cast<OverflowingBinaryOperator>(I)) { + assert(OBO->getOpcode() == Instruction::Add); + if (OBO->hasNoSignedWrap() || OBO->hasNoUnsignedWrap()) { + if (OpC->getValue().isNegative()) { + cast<BinaryOperator>(OBO)->setHasNoSignedWrap(false); + cast<BinaryOperator>(OBO)->setHasNoUnsignedWrap(false); + } + } + } return true; } |
