diff options
Diffstat (limited to 'llvm/lib/Target/X86')
| -rw-r--r-- | llvm/lib/Target/X86/X86ISelLowering.cpp | 24 |
1 files changed, 13 insertions, 11 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp index 5fb3ece19f2..5f1e9ef1b03 100644 --- a/llvm/lib/Target/X86/X86ISelLowering.cpp +++ b/llvm/lib/Target/X86/X86ISelLowering.cpp @@ -22982,20 +22982,22 @@ static SDValue LowerCTTZ(SDValue Op, const X86Subtarget &Subtarget, if (VT.is256BitVector() && !Subtarget.hasInt256()) return Lower256IntUnary(Op, DAG); - // cttz_undef(x) = (width - 1) - ctlz(x & -x) - if (Op.getOpcode() == ISD::CTTZ_ZERO_UNDEF) { - SDValue WidthMinusOne = DAG.getConstant(NumBits - 1, dl, VT); - SDValue LSB = DAG.getNode(ISD::AND, dl, VT, N0, - DAG.getNode(ISD::SUB, dl, VT, Zero, N0)); - return DAG.getNode(ISD::SUB, dl, VT, WidthMinusOne, - DAG.getNode(ISD::CTLZ, dl, VT, LSB)); + // Tmp = ~x & (x - 1) + SDValue One = DAG.getConstant(1, dl, VT); + SDValue Tmp = DAG.getNode(ISD::AND, dl, VT, DAG.getNOT(dl, N0, VT), + DAG.getNode(ISD::SUB, dl, VT, N0, One)); + + // cttz(x) = width - ctlz(~x & (x - 1)) + const TargetLowering &TLI = DAG.getTargetLoweringInfo(); + if (TLI.isOperationLegal(ISD::CTLZ, VT) && + !TLI.isOperationLegal(ISD::CTPOP, VT)) { + SDValue Width = DAG.getConstant(NumBits, dl, VT); + return DAG.getNode(ISD::SUB, dl, VT, Width, + DAG.getNode(ISD::CTLZ, dl, VT, Tmp)); } // cttz(x) = ctpop(~x & (x - 1)) - SDValue One = DAG.getConstant(1, dl, VT); - return DAG.getNode(ISD::CTPOP, dl, VT, - DAG.getNode(ISD::AND, dl, VT, DAG.getNOT(dl, N0, VT), - DAG.getNode(ISD::SUB, dl, VT, N0, One))); + return DAG.getNode(ISD::CTPOP, dl, VT, Tmp); } assert(Op.getOpcode() == ISD::CTTZ && |
