Re: [FFmpeg-devel] [PATCH] avcodec/x86/audiodsp: add scalarproduct avx2

[James Almer <jamrial@gmail.com>]

> From 55eb5a18b4bf029f52f9d9108a750c576ba780ee Mon Sep 17 00:00:00 2001
> From: Paul B Mahol <onemda@gmail.com>
> Date: Mon, 12 Sep 2022 18:53:31 +0200
> Subject: [PATCH] avcodec/x86/audiodsp: add scalarproduct avx2
> 
> Signed-off-by: Paul B Mahol <onemda@gmail.com>
> ---
>  libavcodec/x86/audiodsp.asm    | 24 ++++++++++++++++++++++++
>  libavcodec/x86/audiodsp_init.c |  6 ++++++
>  2 files changed, 30 insertions(+)
> 
> diff --git a/libavcodec/x86/audiodsp.asm b/libavcodec/x86/audiodsp.asm
> index b604b0443c..55051f6aa7 100644
> --- a/libavcodec/x86/audiodsp.asm
> +++ b/libavcodec/x86/audiodsp.asm
> @@ -44,6 +44,30 @@ cglobal scalarproduct_int16, 3,3,3, v1, v2, order
>      movd   eax, m2
>      RET
>  
> +INIT_YMM avx2
> +cglobal scalarproduct_int16, 3,4,3, v1, v2, order, offset
> +    xor offsetq, offsetq
> +    add orderd, orderd
> +    pxor    m1, m1
> +    cmp orderd, 32

This parameter needs to be multiple of 16. What will happen below if 
it's for example 48? Are both buffers padded enough to handle 16 bytes 
of overread?

> +    jl   .l16
> +.loop:
> +    movu    m0, [v1q + offsetq]
> +    pmaddwd m0, [v2q + offsetq]
> +    paddd   m1, m0
> +    add     offsetq, mmsize
> +    cmp     offsetq, orderq

You should use the neg trick from the sse2 version so you can remove the 
cmp from this loop.

> +    jl .loop
> +    HADDD   m1, m0
> +    movd   eax, xm1
> +    RET
> +.l16:
> +    movu    xm0, [v1q + offsetq]
> +    pmaddwd xm0, [v2q + offsetq]
> +    paddd   xm1, xm0
> +    HADDD  xm1, xm0
> +    movd   eax, xm1
> +    RET
>  
>  ;-----------------------------------------------------------------------------
>  ; void ff_vector_clip_int32(int32_t *dst, const int32_t *src, int32_t min,
> diff --git a/libavcodec/x86/audiodsp_init.c b/libavcodec/x86/audiodsp_init.c
> index aa5e43e570..77d5948442 100644
> --- a/libavcodec/x86/audiodsp_init.c
> +++ b/libavcodec/x86/audiodsp_init.c
> @@ -24,6 +24,9 @@
>  #include "libavutil/x86/cpu.h"
>  #include "libavcodec/audiodsp.h"
>  
> +int32_t ff_scalarproduct_int16_avx2(const int16_t *v1, const int16_t *v2,
> +                                    int order);
> +
>  int32_t ff_scalarproduct_int16_sse2(const int16_t *v1, const int16_t *v2,
>                                      int order);
>  
> @@ -53,4 +56,7 @@ av_cold void ff_audiodsp_init_x86(AudioDSPContext *c)
>  
>      if (EXTERNAL_SSE4(cpu_flags))
>          c->vector_clip_int32 = ff_vector_clip_int32_sse4;
> +
> +    if (EXTERNAL_AVX2(cpu_flags))
> +        c->scalarproduct_int16 = ff_scalarproduct_int16_avx2;
>  }
> -- 
> 2.37.2
> 
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