diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Target/X86/X86ISelDAGToDAG.cpp | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp b/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp index dadce7a09a2..acd6e23a10c 100644 --- a/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp +++ b/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp @@ -1378,7 +1378,6 @@ static bool foldMaskAndShiftToExtract(SelectionDAG &DAG, SDValue N, // allows us to fold the shift into this addressing mode. Returns false if the // transform succeeded. static bool foldMaskedShiftToScaledMask(SelectionDAG &DAG, SDValue N, - uint64_t Mask, SDValue Shift, SDValue X, X86ISelAddressMode &AM) { if (Shift.getOpcode() != ISD::SHL || @@ -1396,6 +1395,11 @@ static bool foldMaskedShiftToScaledMask(SelectionDAG &DAG, SDValue N, if (ShiftAmt != 1 && ShiftAmt != 2 && ShiftAmt != 3) return true; + // Use a signed mask so that shifting right will insert sign bits. These + // bits will be removed when we shift the result left so it doesn't matter + // what we use. This might allow a smaller immediate encoding. + int64_t Mask = cast<ConstantSDNode>(N->getOperand(1))->getSExtValue(); + MVT VT = N.getSimpleValueType(); SDLoc DL(N); SDValue NewMask = DAG.getConstant(Mask >> ShiftAmt, DL, VT); @@ -1863,7 +1867,7 @@ bool X86DAGToDAGISel::matchAddressRecursively(SDValue N, X86ISelAddressMode &AM, // Try to swap the mask and shift to place shifts which can be done as // a scale on the outside of the mask. - if (!foldMaskedShiftToScaledMask(*CurDAG, N, Mask, Shift, X, AM)) + if (!foldMaskedShiftToScaledMask(*CurDAG, N, Shift, X, AM)) return false; // Try to fold the mask and shift into BEXTR and scale. |
