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Re: Fedora development switch to GCC 4.1.0-RH prerelease



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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