diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Target/X86/X86ISelLowering.cpp | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp index 8125b4c1ad6..d70cdb8a762 100644 --- a/llvm/lib/Target/X86/X86ISelLowering.cpp +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp @@ -8741,6 +8741,16 @@ static bool isAllOnes(SDValue V) { return C && C->isAllOnesValue(); } +static bool isTruncWithZeroHighBitsInput(SDValue V, SelectionDAG &DAG) { + if (V.getOpcode() != ISD::TRUNCATE) + return false; + + SDValue VOp0 = V.getOperand(0); + unsigned InBits = VOp0.getValueSizeInBits(); + unsigned Bits = V.getValueSizeInBits(); + return DAG.MaskedValueIsZero(VOp0, APInt::getHighBitsSet(InBits,InBits-Bits)); +} + SDValue X86TargetLowering::LowerSELECT(SDValue Op, SelectionDAG &DAG) const { bool addTest = true; SDValue Cond = Op.getOperand(0); @@ -8910,9 +8920,9 @@ SDValue X86TargetLowering::LowerSELECT(SDValue Op, SelectionDAG &DAG) const { } if (addTest) { - // Look pass the truncate. - if (Cond.getOpcode() == ISD::TRUNCATE) - Cond = Cond.getOperand(0); + // Look pass the truncate if the high bits are known zero. + if (isTruncWithZeroHighBitsInput(Cond, DAG)) + Cond = Cond.getOperand(0); // We know the result of AND is compared against zero. Try to match // it to BT. @@ -9219,9 +9229,9 @@ SDValue X86TargetLowering::LowerBRCOND(SDValue Op, SelectionDAG &DAG) const { } if (addTest) { - // Look pass the truncate. - if (Cond.getOpcode() == ISD::TRUNCATE) - Cond = Cond.getOperand(0); + // Look pass the truncate if the high bits are known zero. + if (isTruncWithZeroHighBitsInput(Cond, DAG)) + Cond = Cond.getOperand(0); // We know the result of AND is compared against zero. Try to match // it to BT. |
