[FFmpeg-devel] [PATCH 1/2] x86: Don't hardcode the height to 8 in sad8_xy2_mmx

[Martin Storsjö]

On Wed, 13 Jul 2022, Martin Storsjö wrote:

> The height is hardcoded in some of the me_cmp functions, but not
> in all of them. But in the case of all other functions, it's hardcoded
> in the same place in SIMD functions as in the C reference functions,
> while this one function differs from the behaviour of the C code.
>
> (Before 542765ce3eccbca587d54262a512cbdb1407230d, there were a
> couple other sad8_*_mmx functions with similar hardcoded height.)
> ---
> libavcodec/x86/me_cmp_init.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/libavcodec/x86/me_cmp_init.c b/libavcodec/x86/me_cmp_init.c
> index 61e9396b8f..dcc2621276 100644
> --- a/libavcodec/x86/me_cmp_init.c
> +++ b/libavcodec/x86/me_cmp_init.c
> @@ -202,13 +202,12 @@ static inline int sum_mmx(void)
> static int sad8_xy2_ ## suf(MpegEncContext *v, uint8_t *blk2,           \
>                             uint8_t *blk1, ptrdiff_t stride, int h)     \
> {                                                                       \
> -    av_assert2(h == 8);                                                     \
>     __asm__ volatile (                                                  \
>         "pxor %%mm7, %%mm7     \n\t"                                    \
>         "pxor %%mm6, %%mm6     \n\t"                                    \
>         ::);                                                            \
>                                                                         \
> -    sad8_4_ ## suf(blk1, blk2, stride, 8);                              \
> +    sad8_4_ ## suf(blk1, blk2, stride, h);                              \
>                                                                         \
>     return sum_ ## suf();                                               \
> }                                                                       \
> -- 
> 2.25.1

Ping, does this seem reasonable? Michael indicated a desire to make the 
me_cmp functions more general and flexible than what they are today, and 
this would be a first step to making checkasm test such cases.

// Martin