[FFmpeg-devel] [PATCH 07/10] avfilter/vf_nlmeans: Move ff_nlmeans_init into a header

[Soft Works]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> Hendrik Leppkes
> Sent: Friday, May 13, 2022 11:27 AM
> To: FFmpeg development discussions and patches <ffmpeg-
> devel at ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH 07/10] avfilter/vf_nlmeans: Move
> ff_nlmeans_init into a header
> 
> On Fri, May 13, 2022 at 11:26 AM Andreas Rheinhardt
> <andreas.rheinhardt at outlook.com> wrote:
> >
> > Soft Works:
> > >
> > >
> > >> -----Original Message-----
> > >> From: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> > >> Sent: Friday, May 13, 2022 10:27 AM
> > >> To: Soft Works <softworkz at hotmail.com>; FFmpeg development
> discussions
> > >> and patches <ffmpeg-devel at ffmpeg.org>
> > >> Subject: Re: [FFmpeg-devel] [PATCH 07/10] avfilter/vf_nlmeans:
> Move
> > >> ff_nlmeans_init into a header
> > >>
> > >> Soft Works:
> > >>>
> > >>>
> > >>>> -----Original Message-----
> > >>>> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf
> Of
> > >>>> Andreas Rheinhardt
> > >>>> Sent: Tuesday, May 3, 2022 8:38 AM
> > >>>> To: ffmpeg-devel at ffmpeg.org
> > >>>> Cc: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> > >>>> Subject: [FFmpeg-devel] [PATCH 07/10] avfilter/vf_nlmeans: Move
> > >>>> ff_nlmeans_init into a header
> > >>>>
> > >>>> This removes a dependency of checkasm on lavfi/vf_nlmeans.o
> > >>>> and also allows to inline ff_nlmeans_init() irrespectively of
> > >>>> interposing.
> > >>>>
> > >>>> Signed-off-by: Andreas Rheinhardt
> <andreas.rheinhardt at outlook.com>
> > >>>> ---
> > >>>
> > >>> [..]
> > >>>
> > >>>> +
> > >>>> +static av_unused void ff_nlmeans_init(NLMeansDSPContext *dsp)
> > >>>> +{
> > >>>> +    dsp->compute_safe_ssd_integral_image =
> > >>>> compute_safe_ssd_integral_image_c;
> > >>>> +    dsp->compute_weights_line = compute_weights_line_c;
> > >>>> +
> > >>>> +    if (ARCH_AARCH64)
> > >>>> +        ff_nlmeans_init_aarch64(dsp);
> > >>>
> > >>> Hi Andreas,
> > >>>
> > >>> the above breaks compilation for me:
> > >>>
> > >>> 1>libavfilterd.lib(libavfilter_vf_nlmeans.obj) : error LNK2019:
> > >> unresolved external symbol ff_nlmeans_init_aarch64 referenced in
> > >> function ff_nlmeans_init
> > >>>
> > >>> The reason is that I'm (obviously) not compiling stuff from the
> > >>> libavfilter\aarch64 subfolder.
> > >>>
> > >>> It might need an #ifdef ?
> > >>>
> > >>> I haven't taken a deeper look at it, though.
> > >>>
> > >>> Thanks,
> > >>> softworkz
> > >>>
> > >>>
> > >>
> > >> That surprises me: The earlier code did exactly the same; in
> fact,
> > >> using
> > >> if (ARCH_*) is our typical check for arches in dsp-init code.
> > >
> > > I looked at this a bit further. It seems that the VS project
> > > generation tool that I'm using is creating dummy definitions
> > > for such cases. In the previous workspace it had generated
> > >
> > > void ff_nlmeans_init_aarch64(NLMeansDSPContext *dsp) {return;}
> > >
> > > in a separate code file for being able to work with the ffmpeg
> > > code in VS without modifying any of the code.
> > >
> > > Now that you have moved that code to a header file, this logic
> > > doesn't work anymore.
> > >
> >
> > Why does your compiler not just eliminate dead code like all the
> others?
> > Is this MSVC -O0 behaviour?
> 
> 
> MSVC does not do DCE when optimizations are disabled, yes. So this is
> where this is coming from.
> 
> > I just sent the patch
> > https://ffmpeg.org/pipermail/ffmpeg-devel/2022-May/296380.html, but
> now
> > that I read this I have to agree with Hendrik: Why not update your
> tool
> > instead?
> >
> 
> Actually looking at the tool, it seems like it handles header files.
> Did you actually re-run the generation tool after applying this patch?

Today I pulled HEAD and ran the tool (after I had pulled the latest 
version of the tool and compiled it). It didn't detect the header 
definition. That's why I wrote to Andreas.

Thanks a lot for your help!

softworkz