[Ffmpeg-devel] [PATH] test if cpu supports CMOV

[Guillaume Poirier]

Hi,
Zuxy Meng wrote:
> 2006/10/16, Diego Biurrun <diego at biurrun.de>:
> 
>> On Fri, Oct 13, 2006 at 12:03:52PM +0200, Michael Niedermayer wrote:
>> >
>> > this will break runtime cpudetect (yeah i know my crap code already
>> > broke it but thats not supposed to stay that way in svn)
>>
>> BTW, is there an ETA on this?  We've postponed MPlayer 1.0RC1 to the
>> next weekend yesterday because of the cmov issue ...
>>
>> We already have some cmov code in libavutil/common.h, which is enclosed
>> by '#if defined(ARCH_X86) && __CPU__ >= 686'.  I wanted to commit this
>> as a quick fix to libavcodec/cabac.h, but there are two problems:
>>
>> 1) Apparently there are 686 CPUs without cmov (VIA C3).
> 
> 
> IIRC mplayer's configure can detect this crap and set $iproc to 586.

That's not a bad idea, after all, ppl who chose to purchase C3 CPU are
clearly not interested in CPU power, to the possible gains obtains by
i686 instructions minus cmov WRT plain i586 instructions shouldn't be
an issue IMHO.

Guillaume