On Tue, Nov 14, 2023 at 10:14 PM Xi Ruoyao <xry...@xry111.site> wrote: > > On Tue, 2023-11-14 at 11:44 +0100, Richard Biener wrote: > > > diff --git a/gcc/simplify-rtx.cc b/gcc/simplify-rtx.cc > > > index 2d2e5a3c1ca..f3745d86aea 100644 > > > --- a/gcc/simplify-rtx.cc > > > +++ b/gcc/simplify-rtx.cc > > > @@ -4392,7 +4392,7 @@ simplify_ashift: > > > real_convert (&f1, mode, CONST_DOUBLE_REAL_VALUE (trueop1)); > > > rtx tmp = simplify_gen_unary (ABS, mode, op0, mode); > > > if (REAL_VALUE_NEGATIVE (f1)) > > > - tmp = simplify_gen_unary (NEG, mode, tmp, mode); > > > + tmp = simplify_unary_operation (NEG, mode, tmp, mode); > > > return tmp; > > > } > > > > shouldn't that be when either the ABS or the NEG simplify? > > Simplify (copysign x, POSTIVE_CONST) to (abs x) is an optimization. So > for a positive f1, tmp will just be (abs x) and we return it.
Ah, OK. > > And I wonder when that happens - I suppose when op0 is CONST_DOUBLE only? > > Yes, it's Andrew's intention. The patch is fine then. Richard. > -- > Xi Ruoyao <xry...@xry111.site> > School of Aerospace Science and Technology, Xidian University
