[FFmpeg-devel] [PATCH] Unconditionally run emms on calls to emms_c() if HAVE_MMX is defined

[Dominik 'Rathann' Mierzejewski]

On Sunday, 04 July 2010 at 21:50, M?ns Rullg?rd wrote:
> Dominik 'Rathann' Mierzejewski <dominik at rangers.eu.org> writes:
> 
> > On Sunday, 04 July 2010 at 20:02, M?ns Rullg?rd wrote:
> >> Dominik 'Rathann' Mierzejewski <dominik at rangers.eu.org> writes:
> >> 
> >> > On Sunday, 04 July 2010 at 17:05, M?ns Rullg?rd wrote:
> >> >> Eli Friedman <eli.friedman at gmail.com> writes:
> >> >> 
> >> >> > 2010/7/4 M?ns Rullg?rd <mans at mansr.com>:
> >> >> >> Eli Friedman <eli.friedman at gmail.com> writes:
> >> >> >>
> >> >> >>> On Sat, Jul 3, 2010 at 11:50 PM, Eli Friedman <eli.friedman at gmail.com> wrote:
> >> >> >>>> Patch attached. ?We already assume HAVE_MMX implies MMX is available
> >> >> >>>> at runtime, so this seems like it should be OK.
> >> >> >>>
> >> >> >>> Actually, that's wrong... I think this breaks distros that want to
> >> >> >>> support Pentium Pro and earlier in the same binary for modern
> >> >> >>> computers.
> >> >> >>
> >> >> >> A binary built for i586 or earlier will be quite crippled even in
> >> >> >> plain C code. ?The only sane thing to do as a distro to provide two
> >> >> >> packages (or more).
> >> >> >
> >> >> > So you think this patch is okay?
> >> >> 
> >> >> _I_ think the idea is OK, but your patch isn't quite what I intended.
> >> >> I'm waiting for Reinhard to voice his opinion.  He knows what distros
> >> >> want, can, and can't.
> >> >
> >> > Speaking from Fedora side, the current minimum hw requirement for CPU
> >> > is Pentium Pro (i686). MMX is not required, so the basic package should
> >> > work even if MMX is not available.
> >> 
> >> Do you have any mechanism for providing multiple packages of the same
> >> software with different optimisations?  Allowing mmx/sse in
> >> non-pointered code has real performance advantages.  Do you want to
> >> deprive your users of those?
> >
> > Yes, we have such mechanism and no, I don't want to deprive users
> > of the optimizations.
> 
> So you wouldn't be screaming bloody murder if we made mmx-enabled
> builds use a few mmx instructions unconditionally?

No, not at all. I doubt there are (m)any Fedora users with Pentium Pro
who want to use FFmpeg.

Regards,
R.
-- 
Fedora Developer http://fedoraproject.org/wiki/User:Rathann
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