[FFmpeg-devel] [PATCH] Get rid of unused PREFETCHW and prefer MMX2 over 3DNow!

[Michael Niedermayer]

On Sat, Jan 09, 2010 at 10:47:31PM +0800, Zuxy Meng wrote:
> 2010/1/9 Michael Niedermayer <michaelni at gmx.at>:
> > On Sat, Jan 09, 2010 at 10:22:59PM +0800, Zuxy Meng wrote:
> >> 2010/1/8 Michael Niedermayer <michaelni at gmx.at>:
> >> > On Fri, Jan 08, 2010 at 11:37:17AM +0800, Zuxy Meng wrote:
> >> >> Hi,
> >> >>
> >> >> We never used PREFETCHW in libswscale, and MMX2's prefetchnta is
> >> >> preferrable than 3DNow!'s prefetch due to the former's non temporal
> >> >> hint.
> >> >>
> >> >> --
> >> >> Zuxy
> >> >> Beauty is truth,
> >> >> While truth is beauty.
> >> >> PGP KeyID: E8555ED6
> >> >
> >> >> ?rgb2rgb_template.c | ? 12 ++++--------
> >> >> ?swscale_template.c | ? 10 +++-------
> >> >> ?2 files changed, 7 insertions(+), 15 deletions(-)
> >> >> 596c1966a2582e14b7eec570fd57db77da8d8386 ?prefetch.diff
> >> >> Index: libswscale/swscale_template.c
> >> >> ===================================================================
> >> >> --- libswscale/swscale_template.c ? ? (?? 30234)
> >> >> +++ libswscale/swscale_template.c ? ? (??????)
> >> >> @@ -25,17 +25,13 @@
> >> >> ?#undef MOVNTQ
> >> >> ?#undef PAVGB
> >> >> ?#undef PREFETCH
> >> >> -#undef PREFETCHW
> >> >>
> >> >> -#if COMPILE_TEMPLATE_AMD3DNOW
> >> >> -#define PREFETCH ?"prefetch"
> >> >> -#define PREFETCHW "prefetchw"
> >> >> -#elif COMPILE_TEMPLATE_MMX2
> >> >> +#if COMPILE_TEMPLATE_MMX2
> >> >> ?#define PREFETCH "prefetchnta"
> >> >> -#define PREFETCHW "prefetcht0"
> >> >> +#elif COMPILE_TEMPLATE_AMD3DNOW
> >> >> +#define PREFETCH ?"prefetch"
> >> >> ?#else
> >> >> ?#define PREFETCH ?" # nop"
> >> >> -#define PREFETCHW " # nop"
> >> >> ?#endif
> >> >
> >> > you are mixing 2 unrelated changes in one patch (which makes it unreadable)
> >>
> >> So the updated one that removes PREFETCHW only.
> >> --
> >> Zuxy
> >> Beauty is truth,
> >> While truth is beauty.
> >> PGP KeyID: E8555ED6
> >
> >> ?rgb2rgb_template.c | ? ?4 ----
> >> ?swscale_template.c | ? ?4 ----
> >> ?2 files changed, 8 deletions(-)
> >> 84258f05157cab9ee37b40695f974cc9bcf7a6cc ?prefetch.diff
> >
> > ok
> 
> Applied. Now the other part that prefers MMX2 over 3DNow! because the
> former's prefetchnta has a non temporal hint that is suitable to be
> used with movntq.

needs benchmark on a system where it makes a differences

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I do not agree with what you have to say, but I'll defend to the death your
right to say it. -- Voltaire
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