[FFmpeg-devel] [PATCH 1/2] configure: add check for AVX inline support

Michael Niedermayer michaelni at gmx.at
Fri May 16 17:29:18 CEST 2014

On Fri, May 16, 2014 at 07:49:24AM -0400, Ronald S. Bultje wrote:
> Hi,
> On Thu, May 15, 2014 at 11:42 PM, Michael Niedermayer <michaelni at gmx.at>wrote:
> > On Thu, May 15, 2014 at 07:03:02PM -0300, James Almer wrote:
> > > Signed-off-by: James Almer <jamrial at gmail.com>
> > > ---
> > >  configure | 3 ++-
> > >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > applied
> I have big objections to this. Inline is unreadable, unportable (e.g.
> doesn't work on MSVC) and virtually nobody understands inline. It's beyond
> me that anyone wants to write avx in this atrocity of a syntax.
> Can we please revert this and rewrite patch 2/2 in yasm syntax? I would be
> greatly thankful.

James tried this with the SSE2 code already,
see: [FFmpeg-devel] [PATCH 1/2] swresample: Refactor resample asm and port it to yasm

In the best case i could reproduce in that thread yasm was 14% slower
than gcc inline for SSE2.
Was there a flaw in how i tested ?
Do you suggest that we should use yasm even if it makes the code
significantly slower?
Does someone volunteer to write the whole loop in yasm so the calling
overhead is avoided?

Other ideas that iam missing ?

about reverting, i can revert if people want, though it seems a bit
overreacting to me to revert this optimization before a similar fast
yasm implementation exists.
Thats unless it causes some regression ?


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Those who are too smart to engage in politics are punished by being
governed by those who are dumber. -- Plato 
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