[FFmpeg-devel] [PATCH] Remove global mm_flags variable

[Måns Rullgård]

Michael Niedermayer <michaelni at gmx.at> writes:

> On Tue, Aug 24, 2010 at 10:39:30PM +0300, Ivan Kalvachev wrote:
>> On 8/24/10, Mans Rullgard <mans at mansr.com> wrote:
>> > -
>> > -#define emms_c() \
>> > -{\
>> > -    if (mm_flags & FF_MM_MMX)\
>> > -        emms();\
>> > -}
>> > +#define emms_c() emms()
>> 
>> Michael, are you really OK with that change?
>> The result would be illegal instruction on all pre-MMX CPUs.
>
> who still uses these?
> and how much pre mmx x86 asm do we have? and how much faster is
> that on pre mmx cpus?

--disable-mmx still allows non-mmx asm.  Nothing is lost.

> and dont forget disabling asm disables emms and thus this issue
> also being able to use mmx without conditionals should allow some
> speedups if we dont already use that somewhere, i remember it being
> discussed ...

There is some such code in intreadwrite.h.  I don't remember what
conditions it is under.  Perhaps it should be revisited.

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