[FFmpeg-devel] [PATCH] The definition of av_always_inline with --enable-small or --disable-optimizations

Michael Niedermayer michaelni
Tue Dec 14 21:57:38 CET 2010


On Tue, Dec 14, 2010 at 10:48:49PM +0200, Martin Storsj? wrote:
> On Tue, 14 Dec 2010, Michael Niedermayer wrote:
> 
> > On Tue, Dec 14, 2010 at 11:28:36AM +0200, Martin Storsj? wrote:
> > > Hi,
> > > 
> > > At the end of the configure script, we currently do this:
> > > 
> > > if enabled small || disabled optimizations; then
> > >     echo "#undef  av_always_inline"  >> $TMPH
> > >     echo "#define av_always_inline"  >> $TMPH
> > > fi
> > > 
> > > This causes a lot of warnings when building with either of these 
> > > configurations, warnings like this one:
> > > 
> > > ./libavutil/x86/bswap.h:32: warning: ?av_bswap16? defined but not used
> > > 
> > > These warnings can be silenced either by adding -Wno-unused-function to 
> > > the cflags, or by changing the definition of av_always_inline for this 
> > > case. Possible options are:
> > > 
> > > - empty, as currently, spewing lots of warnings
> > > - inline (as opposed to the __attribute__((always_inline) used otherwise), 
> > >   but that won't avoid all inlineing even if the user requested 
> > >   --disable-optimizations
> > 
> > > - __attribute__((unused)), which seems to be supported since gcc 2.95
> > 
> > This would suppress unused warnings incorrectly
> 
> Only for builds with --disable-optimizations or for --enable-small. 
> Currently, in those build configurations, it's really hard to see the 
> relevant warnings since the console is totally spammed with the warnings 
> for all the defined but unused static av_always_inline functions.
> 
> For all occurrances of av_always_inline functions in headers, I see no 
> issue with __attribute__((unused)).
> 
> Would you prefer the version where av_always_inline is redefined as 
> "inline" for --enable-small builds (but as __attribute__((unused)) for 
> --disable-optimizations)?

I would slightly prefer this unless it makes small bigger by a non trivial
amount

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

There will always be a question for which you do not know the correct awnser.
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