diff options
Diffstat (limited to 'llvm/lib/Target/X86/X86ISelLowering.cpp')
| -rw-r--r-- | llvm/lib/Target/X86/X86ISelLowering.cpp | 22 |
1 files changed, 12 insertions, 10 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp index ef8a6d68395..12f6d409a60 100644 --- a/llvm/lib/Target/X86/X86ISelLowering.cpp +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp @@ -33922,14 +33922,20 @@ static SDValue combineMul(SDNode *N, SelectionDAG &DAG, DAG.getNode(ISD::SHL, DL, VT, N->getOperand(0), DAG.getConstant(Log2_64(NumSign * SignMulAmt - 1), DL, MVT::i8))); + // To negate, subtract the number from zero + if (SignMulAmt < 0) + NewMul = DAG.getNode(ISD::SUB, DL, VT, + DAG.getConstant(0, DL, VT), NewMul); } else if (IsPowerOf2_64MinusOne) { // (mul x, 2^N - 1) => (sub (shl x, N), x) - NewMul = DAG.getNode( - ISD::SUB, DL, VT, - DAG.getNode(ISD::SHL, DL, VT, N->getOperand(0), - DAG.getConstant(Log2_64(NumSign * SignMulAmt + 1), DL, - MVT::i8)), - N->getOperand(0)); + NewMul = DAG.getNode(ISD::SHL, DL, VT, N->getOperand(0), + DAG.getConstant(Log2_64(NumSign * SignMulAmt + 1), + DL, MVT::i8)); + // To negate, reverse the operands of the subtract. + if (SignMulAmt < 0) + NewMul = DAG.getNode(ISD::SUB, DL, VT, N->getOperand(0), NewMul); + else + NewMul = DAG.getNode(ISD::SUB, DL, VT, NewMul, N->getOperand(0)); } else if (IsPowerOf2_64MinusTwo && NumSign == 1) { // (mul x, 2^N - 1) => (sub (shl x, N), x) NewMul = DAG.getNode(ISD::SHL, DL, VT, N->getOperand(0), @@ -33938,10 +33944,6 @@ static SDValue combineMul(SDNode *N, SelectionDAG &DAG, NewMul = DAG.getNode(ISD::SUB, DL, VT, NewMul, N->getOperand(0)); NewMul = DAG.getNode(ISD::SUB, DL, VT, NewMul, N->getOperand(0)); } - // To negate, subtract the number from zero - if (NewMul && NumSign == -1) - NewMul = - DAG.getNode(ISD::SUB, DL, VT, DAG.getConstant(0, DL, VT), NewMul); } } |
