[FFmpeg-devel] [PATCH v4] libswscale/ppc: VSX-optimize 9-16 bit yuv2planeX

Lauri Kasanen cand at gmx.com
Sat Jan 12 10:38:51 EET 2019


On Sat, 12 Jan 2019 01:03:09 +0100
Michael Niedermayer <michael at niedermayer.cc> wrote:

> On Fri, Jan 11, 2019 at 11:16:20AM +0200, Lauri Kasanen wrote:
> > On Fri, 11 Jan 2019 09:56:15 +0100
> > Michael Niedermayer <michael at niedermayer.cc> wrote:
> > 
> > > > +#ifdef __GNUC__
> > > > +            // GCC does not support vmuluwm yet. Bug open.
> > > 
> > > this should probably be tested by configure similar to how other
> > > compiler limitations are tested
> > 
> > We can't really test for it, because there is no standard name for it. I
> > don't know what name the gcc devs will pick for it, it could be vec_mul,
> > vec_vmuluwm or something different.
> 
> the code contains a #if and a #else case
> so i thought there was something else than the __GNUC__ case and gcc
> would follow that

It's second-hand info from libsimdpp. I don't know where they got it.

However, I found out yesterday that gcc docs are wrong, and vec_mul for
gcc does use the correct instruction on power8. Respinning.

- Lauri


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