diff options
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp | 32 |
1 files changed, 17 insertions, 15 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp index 8006b804597..800c262266c 100644 --- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp @@ -1205,21 +1205,23 @@ bool TargetLowering::SimplifyDemandedBits(SDValue Op, getShiftAmountTy(Op.getValueType(), DL)); } - APInt HighBits = APInt::getHighBitsSet(OperandBitWidth, - OperandBitWidth - BitWidth); - HighBits.lshrInPlace(ShAmt->getZExtValue()); - HighBits = HighBits.trunc(BitWidth); - - if (ShAmt->getZExtValue() < BitWidth && !(HighBits & NewMask)) { - // None of the shifted in bits are needed. Add a truncate of the - // shift input, then shift it. - SDValue NewTrunc = TLO.DAG.getNode(ISD::TRUNCATE, dl, - Op.getValueType(), - In.getOperand(0)); - return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SRL, dl, - Op.getValueType(), - NewTrunc, - Shift)); + if (ShAmt->getZExtValue() < BitWidth) { + APInt HighBits = APInt::getHighBitsSet(OperandBitWidth, + OperandBitWidth - BitWidth); + HighBits.lshrInPlace(ShAmt->getZExtValue()); + HighBits = HighBits.trunc(BitWidth); + + if (!(HighBits & NewMask)) { + // None of the shifted in bits are needed. Add a truncate of the + // shift input, then shift it. + SDValue NewTrunc = TLO.DAG.getNode(ISD::TRUNCATE, dl, + Op.getValueType(), + In.getOperand(0)); + return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SRL, dl, + Op.getValueType(), + NewTrunc, + Shift)); + } } break; } |
