[Pixman] [PATCH 1/3] mmx: use MMX inline assembly only when USE_MMX

Soeren Sandmann sandmann at cs.au.dk
Wed Jul 27 09:59:20 PDT 2011

Matt Turner <mattst88 at gmail.com> writes:

> On Wed, Jul 20, 2011 at 3:29 PM,  <mattst88 at gmail.com> wrote:
>> +       memcpy(d, s, w);
> I'm not sure if this change should be made, or whether I should do
> like the other two hunks and only emit movq instructions for #if
> defined USE_MMX.
> memcpy should be optimized in libc, or perhaps the C compiler itself,
> so.

Well, if you remove all the MMX instructions from the function, then it
isn't really MMX specific anymore and could just as well be moved to
pixman-general.c. I'm not convinced that memcpy() is necessarily
optimized for MMX in glibc, though.

On the other hand, at this point, the main use for MMX on x86 is the
first version of the OLPC, which had a Geode chip without SSE2 support.
If you know that the OLPC developers are fine with eliminating the MMX
support for blt, I'm fine with that too.


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