Re: [FFmpeg-devel] [PATCH 1/2] avcodec/vvc: Remove NOP condition check in alf_filter_luma

[Nuo Mi <nuomi2021@gmail.com>]

On Wed, Jul 17, 2024 at 12:17 AM Zhao Zhili <quinkblack@foxmail.com> wrote:

>
>
> > On Jul 17, 2024, at 00:07, Zhao Zhili <quinkblack@foxmail.com> wrote:
> >
> >
> >
> >> On Jul 16, 2024, at 20:31, Nuo Mi <nuomi2021@gmail.com> wrote:
> >>
> >> On Tue, Jul 16, 2024 at 10:50 AM Zhao Zhili <quinkblack@foxmail.com
> <mailto:quinkblack@foxmail.com>> wrote:
> >>
> >>> From: Zhao Zhili <zhilizhao@tencent.com <mailto:zhilizhao@tencent.com
> >>
> >>>
> >>> If (y + i == vb_above) or (y + i == vb_below), the if body has no
> >>> operation.
> >>>
> >> 👍, How did you find this? From a compiler warning or by reading the
> code?
> >
> > There is compiler warning. I found this issue when trying to simplify
> the logic
> > before rewrite in ARM assembly.
>
> Oops, I mean there is “no" compiler warning.
>
Good catch!
Applied.
Thank you


>
> >
> >>
> >>
> >>> ---
> >>> libavcodec/vvc/filter_template.c | 4 ++--
> >>> 1 file changed, 2 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/libavcodec/vvc/filter_template.c
> >>> b/libavcodec/vvc/filter_template.c
> >>> index 9b3a0e46f7..32777452b7 100644
> >>> --- a/libavcodec/vvc/filter_template.c
> >>> +++ b/libavcodec/vvc/filter_template.c
> >>> @@ -77,7 +77,7 @@ static void FUNC(alf_filter_luma)(uint8_t *_dst,
> >>> ptrdiff_t dst_stride, const uin
> >>>                const int is_near_vb_below = (y + i >= vb_pos) && (y + i
> >>> <= vb_pos);
> >>>                const int is_near_vb = is_near_vb_above ||
> >>> is_near_vb_below;
> >>>
> >>> -                if ((y + i < vb_pos) && ((y + i) >= vb_above)) {
> >>> +                if ((y + i < vb_pos) && ((y + i) > vb_above)) {
> >>>                    p1 = (y + i == vb_pos - 1) ? p0 : p1;
> >>>                    p3 = (y + i >= vb_pos - 2) ? p1 : p3;
> >>>                    p5 = (y + i >= vb_pos - 3) ? p3 : p5;
> >>> @@ -85,7 +85,7 @@ static void FUNC(alf_filter_luma)(uint8_t *_dst,
> >>> ptrdiff_t dst_stride, const uin
> >>>                    p2 = (y + i == vb_pos - 1) ? p0 : p2;
> >>>                    p4 = (y + i >= vb_pos - 2) ? p2 : p4;
> >>>                    p6 = (y + i >= vb_pos - 3) ? p4 : p6;
> >>> -                } else if ((y + i >= vb_pos) && ((y + i) <=
> vb_below)) {
> >>> +                } else if ((y + i >= vb_pos) && ((y + i) < vb_below))
> {
> >>>                    p2 = (y + i == vb_pos    ) ? p0 : p2;
> >>>                    p4 = (y + i <= vb_pos + 1) ? p2 : p4;
> >>>                    p6 = (y + i <= vb_pos + 2) ? p4 : p6;
> >>> --
> >>> 2.42.0
> >>>
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