[FFmpeg-devel] [PATCH] avcodec/x86/hevc: fix luma 12b overflow

[Ronald S. Bultje]

Hi,

On Sun, Feb 25, 2024 at 5:30 PM Henrik Gramner via ffmpeg-devel <
ffmpeg-devel at ffmpeg.org> wrote:

> On Sun, Feb 25, 2024 at 5:42 PM Ronald S. Bultje <rsbultje at gmail.com>
> wrote:
> > +    mova            m13, [pw_8]
> > +    paddw           m10, m12, m12
> > +    paddw           m12, m10 ; 9 * (q0 - p0) - 3 * ( q1 - p1 )
> >      paddw           m12, m13; + 8
>
> Memory operand
>
> > +    paddw           m10, m13, m13
> > +    paddw           m13, m10 ; abs(9 * (q0 - p0) - 3 * ( q1 - p1 ))
> > +    paddw           m13, [pw_8]
> [...]
> > +    paddw           m13, m12, m12
> > +    paddw           m13, m12 ; 3*abs(m12)
> > +    paddw           m13, [pw_8]
>
> Another minor improvement would be to reorder the adds like (x + x) +
> (x + 8) instead of ((x + x) + x) + 8 to allow for more
> instruction-level parallelism.
>

New version attached.

Ronald
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