[FFmpeg-devel] [PATCH] huffyuvencdsp: Add ff_diff_bytes_{sse2, avx2}

[James Almer]

On 10/20/2015 10:32 PM, Timothy Gu wrote:
> SSE2 version 4%-35% faster than MMX depending on the width.
> AVX2 version 1%-13% faster than SSE2 depending on the width.
> ---
> 
> Addressed James's and Henrik's advices. Removed heuristics based on width.
> Made available both aligned and unaligned versions. For AVX2 version,
> gracefully fall back on SSE2.
> 
> ---
>  libavcodec/huffyuvenc.c            |   4 +-
>  libavcodec/x86/huffyuvencdsp.asm   | 110 +++++++++++++++++++++++++++++++------
>  libavcodec/x86/huffyuvencdsp_mmx.c |  14 ++++-
>  3 files changed, 107 insertions(+), 21 deletions(-)
> 
> diff --git a/libavcodec/huffyuvenc.c b/libavcodec/huffyuvenc.c
> index 49d711a..e080cd9 100644
> --- a/libavcodec/huffyuvenc.c
> +++ b/libavcodec/huffyuvenc.c
> @@ -60,12 +60,12 @@ static inline int sub_left_prediction(HYuvContext *s, uint8_t *dst,
>              }
>              return left;
>          } else {
> -            for (i = 0; i < 16; i++) {
> +            for (i = 0; i < 32; i++) {
>                  const int temp = src[i];
>                  dst[i] = temp - left;
>                  left   = temp;
>              }
> -            s->hencdsp.diff_bytes(dst + 16, src + 16, src + 15, w - 16);
> +            s->hencdsp.diff_bytes(dst + 32, src + 32, src + 31, w - 32);
>              return src[w-1];
>          }
>      } else {
> diff --git a/libavcodec/x86/huffyuvencdsp.asm b/libavcodec/x86/huffyuvencdsp.asm
> index e001906..699fd38 100644
> --- a/libavcodec/x86/huffyuvencdsp.asm
> +++ b/libavcodec/x86/huffyuvencdsp.asm
> @@ -27,9 +27,9 @@
>  
>  section .text
>  
> -INIT_MMX mmx
>  ; void ff_diff_bytes_mmx(uint8_t *dst, const uint8_t *src1, const uint8_t *src2,
>  ;                        intptr_t w);
> +%macro DIFF_BYTES_PROLOGUE 0
>  %if ARCH_X86_32
>  cglobal diff_bytes, 3,5,2, dst, src1, src2
>  %define wq r4q
> @@ -40,34 +40,108 @@ cglobal diff_bytes, 4,5,2, dst, src1, src2, w
>      DECLARE_REG_TMP 4
>  %endif ; ARCH_X86_32
>  %define i t0q
> +%endmacro
> +
> +; label to jump to if w < regsize
> +%macro DIFF_BYTES_LOOP_PREP 1
>      mov                i, wq
> -    and                i, -2 * mmsize
> -        jz  .setup_loop2
> +    and                i, -2 * regsize
> +        jz            %1
>      add             dstq, i
>      add            src1q, i
>      add            src2q, i
>      neg                i
> -.loop:
> -    mova              m0, [src1q + i]
> -    mova              m1, [src1q + i + mmsize]
> -    psubb             m0, [src2q + i]
> -    psubb             m1, [src2q + i + mmsize]
> -    mova          [dstq + i], m0
> -    mova [mmsize + dstq + i], m1
> -    add                i, 2 * mmsize
> -        jl         .loop
> -.setup_loop2:
> -    and               wq, 2 * mmsize - 1
> -        jz          .end
> +%endmacro
> +
> +; mov type used for src1q, dstq, first reg, second reg
> +%macro DIFF_BYTES_LOOP_CORE 4
> +%if regsize != 16

%if mmsize != 16

By checking regsize you're using the SSE2 version in the AVX2 xmm loop. Check
for mmsize instead, which it's always 32 since you used INIT_YMM.

Should be good otherwise, but wait for Hendrik in case he wants to comment.