[Bug target/63679] [5/6 Regression][AArch64] Failure to constant fold.

["rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63679

--- Comment #34 from rguenther at suse dot de <rguenther at suse dot de> ---
On Tue, 28 Jul 2015, pinskia at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63679
> 
> --- Comment #33 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
> (In reply to alalaw01 from comment #32)
> > and the optimized tree is:
> > 
> > foo ()
> > {
> >   int vect_sum_9.6;
> >   int stmp_sum_9.5;
> >   vector(4) int vect_sum_9.4;
> >   const vector(4) int vect__8.3;
> >   const int a[8];
> > 
> >   <bb 2>:
> >   MEM[(int[8] *)&a] = { 0, 1, 2, 3 };
> >   MEM[(int[8] *)&a + 16B] = { 4, 5, 6, 7 };
> >   vect__8.3_20 = MEM[(int *)&a];
> >   vect__8.3_18 = MEM[(int *)&a + 16B];
> 
> So a missing constant prop here.

Yes, but DOM should have handled this.

> 
> >   vect_sum_9.4_23 = vect__8.3_18 + vect__8.3_20;
> 
> Also most likely we don't have much constant folding for this.

We do.

> >   stmp_sum_9.5_25 = [reduc_plus_expr] vect_sum_9.4_23;
> 
> Or even this.

Likewise.

> But once those are resolved, this whole function will resolve itself :).

RTL CSE should catch the constant prop I think but I doubt we have
much vector op simplify_rtx support.