diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp | 23 |
1 files changed, 8 insertions, 15 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp index d9ead9893ea..cd59366d5ee 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -3921,15 +3921,17 @@ static Instruction *processUMulZExtIdiom(ICmpInst &I, Value *MulVal, /// When performing a comparison against a constant, it is possible that not all /// the bits in the LHS are demanded. This helper method computes the mask that /// IS demanded. -static APInt getDemandedBitsLHSMask(ICmpInst &I, unsigned BitWidth, - bool isSignCheck) { - if (isSignCheck) - return APInt::getSignMask(BitWidth); - +static APInt getDemandedBitsLHSMask(ICmpInst &I, unsigned BitWidth) { const APInt *RHS; if (!match(I.getOperand(1), m_APInt(RHS))) return APInt::getAllOnesValue(BitWidth); + // If this is a normal comparison, it demands all bits. If it is a sign bit + // comparison, it only demands the sign bit. + bool UnusedBit; + if (isSignBitCheck(I.getPredicate(), *RHS, UnusedBit)) + return APInt::getSignMask(BitWidth); + switch (I.getPredicate()) { // For a UGT comparison, we don't care about any bits that // correspond to the trailing ones of the comparand. The value of these @@ -4115,20 +4117,11 @@ Instruction *InstCombiner::foldICmpUsingKnownBits(ICmpInst &I) { if (!BitWidth) return nullptr; - // If this is a normal comparison, it demands all bits. If it is a sign bit - // comparison, it only demands the sign bit. - bool IsSignBit = false; - const APInt *CmpC; - if (match(Op1, m_APInt(CmpC))) { - bool UnusedBit; - IsSignBit = isSignBitCheck(Pred, *CmpC, UnusedBit); - } - KnownBits Op0Known(BitWidth); KnownBits Op1Known(BitWidth); if (SimplifyDemandedBits(&I, 0, - getDemandedBitsLHSMask(I, BitWidth, IsSignBit), + getDemandedBitsLHSMask(I, BitWidth), Op0Known, 0)) return &I; |
