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

Guillaume Poirier gpoirier
Fri Oct 13 11:46:41 CEST 2006


Zuxy Meng wrote:
> Hi,
> 2006/10/13, Guillaume Poirier <gpoirier at mplayerhq.hu>:
>> Hi,
>> The attached patch (hopefully) allows to test for the presence of CMOV
>> instruction, introduced in _real_ i686 CPUs.
>> It's needed for latest and greatest CABAC code, as some cpus that
>> claim to be i686 do not support cmov (such as VIA C3).
>> This patch creates #define HAVE_CMOV 1 for config.h and
>> TARGET_CMOV=yes for config.mak.
>> I don't know if the name is too wise, maybe it would be better to have
>>  HAVE_X86_CMOV to specify that were are talking about x86 in
>> particular (other CPU support conditional move too, sadly, PPC doesn't).
> Why not detect it at run-time in cputest.c, just like what we've done
> for 3DNow!, SSE, etc.?

Well this _could_ be done, it's just that I'm not sure what it would
mean in terms of performance. This would have to be benchmarked.


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