RE: [PATCH]middle-end match.pd: optimize fneg (fabs (x)) to x | (1 << signbit(x)) [PR109154]

[Tamar Christina <Tamar.Christina@arm.com>]

> > b17e1136600a 100644
> > --- a/gcc/match.pd
> > +++ b/gcc/match.pd
> > @@ -9476,3 +9476,57 @@ and,
> >         }
> >         (if (full_perm_p)
> >   	(vec_perm (op@3 @0 @1) @3 @2))))))
> > +
> > +/* Transform fneg (fabs (X)) -> X | 1 << signbit (X).  */
> > +
> > +(simplify
> > + (negate (abs @0))
> > + (if (FLOAT_TYPE_P (type)
> > +      /* We have to delay this rewriting till after forward prop because
> otherwise
> > +	 it's harder to do trigonometry optimizations. e.g. cos(-fabs(x)) is not
> > +	 matched in one go.  Instead cos (-x) is matched first followed by
> cos(|x|).
> > +	 The bottom op approach makes this rule match first and it's not untill
> > +	 fwdprop that we match top down.  There are manu such
> simplications
> > +so we
> Multiple typos this line.  fwdprop->fwprop manu->many
> simplications->simplifications.
> 
> OK with the typos fixed.

Ah I think you missed the previous emails from Richi whom wanted this canonicalized to
copysign instead. I've just finished doing so and will send the updated patch 😊

> 
> Thanks.  I meant to say hi at the Cauldron, but never seemed to get away long
> enough to find you..

Hehehe Indeed, I think I only saw you once and then *poof* like a ninja you were gone!

Next time 😊

Cheers,
Tamar

> 
> jeff