[FFmpeg-devel] [PATCH] VP8 luma(16) inner-MB H/V loopfilter MMX/SSE2

[Eli Friedman]

On Sun, Jul 11, 2010 at 4:02 PM, Ronald S. Bultje <rsbultje at gmail.com> wrote:
> Hi Eli,
>
> On Sun, Jul 11, 2010 at 2:20 PM, Eli Friedman <eli.friedman at gmail.com> wrote:
>> + ? ?mova ? ? ? ? ? ? m4, m1
>> + ? ?SWAP ? ? ? ? ? ? ?4, 1
>>
>> This pattern seems to be repeated a lot... I fail to see the point.
>> Swapping two registers with the same contents doesn't do anything
>> significant.
>
> What I've been told is that for a mova x, y, the x (dest) is available
> one cycle after the source, so using y (src) directly after is
> preferred over using x directly after. In this function, I'm trying to
> organize it such that m2-m5 are (at least in the source) consistently
> referring to p1/p0/q0/q1, hence the SWAP.

Oh, okay, that makes sense.

-Eli