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

[Måns Rullgård]

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?

-- 
M?ns Rullg?rd
mans at mansr.com