This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [patch] enabling vectorization by default at -O3
On Thu, Sep 13, 2007 at 11:49:51AM -0700, Mark Mitchell wrote:
> Dorit Nuzman wrote:
>
> > SpecCPU2006 on powerpc970 shows 1.5% on specINT (mostly due to a 14%
> > improvement on hmmer), and a -0.4% on specFP. This was comparing '-O3' with
> > '-O3 -ftree-vectorize -maltivec'. The costmodel wasn't on, cause it is
> > still undergoing some changes, and also it is not tuned yet for powerpc970,
> > so I hope that with the costmodel on we'll be able to get rid of the small
> > degradations we have here and there later on.
>
> I was hoping for a bit more of an overall win. The negative result on
> specFP worries me; although the overall scores are higher, it would be
> nice if we could eliminate that negative.
>
> Do any of the other optimization maintainers have a feeling about this?
> Should we turn on vectorization at -O3, or are we not quite there yet?
IMHO, the best way to getting the bugs fixed is enabling it to come on by
default. My sense is for x86 platforms, it is more of a win, but I don't have
the numbers at hand.
--
Michael Meissner, AMD
90 Central Street, MS 83-29, Boxborough, MA, 01719, USA
michael.meissner@amd.com