+SDValue SystemZTargetLowering::lowerSIGN_EXTEND(SDValue Op,
+ SelectionDAG &DAG) const {
+ // Convert (sext (ashr (shl X, C1), C2)) to
+ // (ashr (shl (anyext X), C1'), C2')), since wider shifts are as
+ // cheap as narrower ones.
+ SDValue N0 = Op.getOperand(0);
+ EVT VT = Op.getValueType();
+ if (N0.hasOneUse() && N0.getOpcode() == ISD::SRA) {
+ ConstantSDNode *SraAmt = dyn_cast<ConstantSDNode>(N0.getOperand(1));
+ SDValue Inner = N0.getOperand(0);
+ if (SraAmt && Inner.hasOneUse() && Inner.getOpcode() == ISD::SHL) {
+ ConstantSDNode *ShlAmt = dyn_cast<ConstantSDNode>(Inner.getOperand(1));
+ if (ShlAmt) {
+ unsigned Extra = (VT.getSizeInBits() -
+ N0.getValueType().getSizeInBits());
+ unsigned NewShlAmt = ShlAmt->getZExtValue() + Extra;
+ unsigned NewSraAmt = SraAmt->getZExtValue() + Extra;
+ EVT ShiftVT = N0.getOperand(1).getValueType();
+ SDValue Ext = DAG.getNode(ISD::ANY_EXTEND, SDLoc(Inner), VT,
+ Inner.getOperand(0));
+ SDValue Shl = DAG.getNode(ISD::SHL, SDLoc(Inner), VT, Ext,
+ DAG.getConstant(NewShlAmt, ShiftVT));
+ return DAG.getNode(ISD::SRA, SDLoc(N0), VT, Shl,
+ DAG.getConstant(NewSraAmt, ShiftVT));
+ }
+ }
+ }
+ return SDValue();
+}
+