[MPlayer-dev-eng] [PATCH] VF Overlay

[Reimar Döffinger]

On Fri, Aug 14, 2009 at 10:10:50AM +0200, Reimar Döffinger wrote:
> Now here we have a real issue. This assumes that gcc will never use MMX,
> because that could clobber our carefully set up mm7 and mm5 registers.
> IMHO you'll have to set up these registers in the MMX code blocks where
> they are used.

Actually any MMX _or_ float code in-between will break things.

> Though as a simple solution, moving that asm block into blend_plane_MMX
> might be good enough, maybe adding a comment that it could be an issue
> in theory.

I'd be in favour of moving the emms, too.
Yes, that means overall 2 emms and 4 other instructions more per frame
but that seems acceptable to me compared to the risk of breaking
completely if gcc or some developer ever slips a simple float operation
in there.