[FFmpeg-devel] [flamefest-start] A little something on MMX/SSE intrinsics
Wed Feb 27 21:29:56 CET 2008
On Wed, Feb 27, 2008 at 3:24 PM, Luca Barbato <lu_zero at gentoo.org> wrote:
> Michael Niedermayer wrote:
> > On Wed, Feb 27, 2008 at 05:42:58PM +0200, Ivan Kalvachev wrote:
> >> On Wed, Feb 27, 2008 at 4:31 PM, Reimar D?ffinger
> >> <Reimar.Doeffinger at stud.uni-karlsruhe.de> wrote:
> >>> Hello,
> >>> yet another case of someone relearning "intrinsics are still a mess and
> >>> compilers still much too stupid" ;-) :
> >>> http://www.virtualdub.org/blog/pivot/entry.php?id=188#body
> >>> Let's see if we can make today the flame-heaviest day in FFmpeg history
> >>> :-)
> >> Nice read.
> >> I'd just like to add that there is already architecture in FFmpeg that
> >> is entirely optimized on intrinsics - AltiVect. There were few
> >> fundamental problems with it and I'm not sure if they have been
> >> successfully solved. These include things like generating code that
> >> picks up processor SIMD dialect at runtime.
> > You just found us a new SOC qualification task
> > rewrite intrinsics to proper asm()
> And benchmark the result ^^;
I don't think anyone can get Altivec asm to work better than
intrinsics on more than one CPU - PPC is really, really
scheduling-sensitive, especially the G5 and Cell.
I guess you can always try, though, but don't do anything to
discourage people who know altivec from adding more. There's still a
lot missing from H.264.
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