Fedora development switch to GCC 4.1.0-RH prerelease
Jesse Barnes
jbarnes at virtuousgeek.org
Thu Dec 8 19:14:09 UTC 2005
On Thursday, December 8, 2005 11:00 am, Alan Cox wrote:
> On Thu, Dec 08, 2005 at 10:09:36AM -0800, Jesse Barnes wrote:
> > FYI, on my system, the only package that seems to make use
> > of /usr/lib/(3dnow|sse2|sse3) seems to be gmp, the GNU MP math
> > library.
>
> Some other libraries handle it internally because they need to be
> cross platform - mesa is a good example here.
Right, those libraries are already good to go; I'm thinking of things
like libjpeg or libtheora (in fact, I tried the new vectorizer on
libjpeg and it was able to vectorize quite a few loops, so I'm hopeful
that other libraries will be similarly optimized). I don't think they
include SSE or 3dnow specific loops with runtime detection. And rather
than going through the process of hand tuning them with assembly, it
seems worthwhile to tweak their critical loops such that they can be
autovectorized by gcc, that way any platform with a gcc
autovectorization target can benefit.
Jesse
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