TLO.DAG.getNode(ISD::ANY_EXTEND, dl, Op.getValueType(),
NarrowShl));
}
+ // Repeat the SHL optimization above in cases where an extension
+ // intervenes: (shl (anyext (shr x, c1)), c2) to
+ // (shl (anyext x), c2-c1). This requires that the bottom c1 bits
+ // aren't demanded (as above) and that the shifted upper c1 bits of
+ // x aren't demanded.
+ if (InOp.hasOneUse() &&
+ InnerOp.getOpcode() == ISD::SRL &&
+ InnerOp.hasOneUse() &&
+ isa<ConstantSDNode>(InnerOp.getOperand(1))) {
+ uint64_t InnerShAmt = cast<ConstantSDNode>(InnerOp.getOperand(1))
+ ->getZExtValue();
+ if (InnerShAmt < ShAmt &&
+ InnerShAmt < InnerBits &&
+ NewMask.lshr(InnerBits - InnerShAmt + ShAmt) == 0 &&
+ NewMask.trunc(ShAmt) == 0) {
+ SDValue NewSA =
+ TLO.DAG.getConstant(ShAmt - InnerShAmt,
+ Op.getOperand(1).getValueType());
+ EVT VT = Op.getValueType();
+ SDValue NewExt = TLO.DAG.getNode(ISD::ANY_EXTEND, dl, VT,
+ InnerOp.getOperand(0));
+ return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::SHL, dl, VT,
+ NewExt, NewSA));
+ }
+ }
}
KnownZero <<= SA->getZExtValue();