InnerShift.getOperand(0), NewShiftAmt);
return DAG.getNode(ISD::TRUNCATE, DL, VT, NewShift);
}
- // In the more general case, we can clear the high bits after the shift:
- // srl (trunc (srl x, c1)), c2 --> trunc (and (srl x, (c1+c2)), Mask)
- if (N0.hasOneUse() && InnerShift.hasOneUse() && c1 + c2 <= OpSizeInBits) {
- SDLoc DL(N);
- SDValue NewShiftAmt = DAG.getConstant(c1 + c2, DL, ShiftAmtVT);
- SDValue NewShift = DAG.getNode(ISD::SRL, DL, InnerShiftVT,
- InnerShift.getOperand(0), NewShiftAmt);
- SDValue Mask = DAG.getConstant((1 << (InnerShiftSize - c2)) - 1, DL,
- InnerShiftVT);
- SDValue And = DAG.getNode(ISD::AND, DL, InnerShiftVT, NewShift, Mask);
- return DAG.getNode(ISD::TRUNCATE, DL, VT, And);
- }
}
}
define i32 @t(i64 %x) {
; CHECK-LABEL: t:
; CHECK: // %bb.0:
-; CHECK-NEXT: ubfx x0, x0, #17, #28
+; CHECK-NEXT: lsr x8, x0, #13
+; CHECK-NEXT: ubfx x0, x8, #4, #28
; CHECK-NEXT: // kill: def $w0 killed $w0 killed $x0
; CHECK-NEXT: ret
%s = lshr i64 %x, 13
define i32 @sh_trunc_sh(i64 %x) {
; CHECK-LABEL: sh_trunc_sh:
; CHECK: # %bb.0:
-; CHECK-NEXT: rldicl 3, 3, 47, 36
+; CHECK-NEXT: rldicl 3, 3, 51, 13
+; CHECK-NEXT: srwi 3, 3, 4
; CHECK-NEXT: blr
%s = lshr i64 %x, 13
%t = trunc i64 %s to i32