[Bug tree-optimization/67323] Use non-unit stride loads by preference when applicable

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67323

--- Comment #3 from rguenther at suse dot de <rguenther at suse dot de> ---
On Tue, 25 Aug 2015, michael.collison at linaro dot org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67323
> 
> --- Comment #2 from Michael Collison <michael.collison at linaro dot org> ---
> Richard,
> 
> Should I create a test case that fails until you resolve this in GCC 6?

If you can provide one that I can check in together with a fix that
would be nice.  Having it in the tree now and FAILing isn't according
to our policies.

> On 08/25/2015 02:14 AM, rguenth at gcc dot gnu.org wrote:
> > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67323
> >
> > Richard Biener <rguenth at gcc dot gnu.org> changed:
> >
> >             What    |Removed                     |Added
> > ----------------------------------------------------------------------------
> >               Status|UNCONFIRMED                 |ASSIGNED
> >     Last reconfirmed|                            |2015-08-25
> >                   CC|richard.guenther at gmail dot com  |rguenth at gcc dot gnu.org
> >           Depends on|                            |66721
> >             Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org
> >       Ever confirmed|0                           |1
> >
> > --- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
> > Confirmed.  We go down the SLP path here because the vectorizer thinks that
> > SLP is always cheaper than using interleaving (which generally is true
> > if there were not targets which can do the load plus interleave with
> > load-lanes ...).
> >
> > I think this may be a regression as well because I enhanced SLP to apply
> > to way more cases.
> >
> > Note that my plan is to make the vectorizer consider both (well, not really,
> > but this bug shows I maybe should try), SLP and non-SLP, and evaluate based
> > on costs which route to go.
> >
> >
> > Referenced Bugs:
> >
> > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66721
> > [Bug 66721] [6 regression] gcc.target/i386/pr61403.c FAILs
> 
>