Re: [FFmpeg-devel] [PATCH] avutil/aarch64/float_dsp_neon: Refactor ff_vector_fmac_scalar_neon

[Lynne <dev@lynne.ee>]

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On 20/01/2025 00:04, Krzysztof Pyrkosz via ffmpeg-devel wrote:
> ---
>   libavutil/aarch64/float_dsp_neon.S | 13 ++++++-------
>   1 file changed, 6 insertions(+), 7 deletions(-)
> 
> diff --git a/libavutil/aarch64/float_dsp_neon.S b/libavutil/aarch64/float_dsp_neon.S
> index 35e2715b87..b21f34c084 100644
> --- a/libavutil/aarch64/float_dsp_neon.S
> +++ b/libavutil/aarch64/float_dsp_neon.S
> @@ -40,18 +40,17 @@ function ff_vector_fmul_neon, export=1
>   endfunc
>   
>   function ff_vector_fmac_scalar_neon, export=1
> -        mov             x3,  #-32
>   1:      subs            w2,  w2,  #16
> -        ld1             {v16.4s, v17.4s}, [x0], #32
> -        ld1             {v18.4s, v19.4s}, [x0], x3
> -        ld1             {v4.4s,  v5.4s},  [x1], #32
> -        ld1             {v6.4s,  v7.4s},  [x1], #32
> +        ldp             q16, q17, [x0]
> +        ldp             q4, q5, [x1], #32
>           fmla            v16.4s, v4.4s,  v0.s[0]
>           fmla            v17.4s, v5.4s,  v0.s[0]
> +        stp             q16, q17, [x0], #32
> +        ldp             q18, q19, [x0]
> +        ldp             q6, q7, [x1], #32
>           fmla            v18.4s, v6.4s,  v0.s[0]
>           fmla            v19.4s, v7.4s,  v0.s[0]
> -        st1             {v16.4s, v17.4s}, [x0], #32
> -        st1             {v18.4s, v19.4s}, [x0], #32
> +        stp             q18, q19, [x0], #32
>           b.ne            1b
>           ret
>   endfunc

LGTM.
ldp/stp are underrated instructions, they let you ignore the consecutive 
requirement of ld1/st1 when moving 2 vectors at a time.
Will push soon.

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