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

[Martin Storsjö]

On Tue, 14 Dec 2010, Michael Niedermayer wrote:

> 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

This version is attached now.

It doesn't seem to make it bigger at all in a normal build with 
--enable-small, probably since gcc doesn't choose to inline any of those 
functions when -Os is specified.

// Martin
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-configure-Avoid-warnings-if-av_always_inline-is-disa.patch
Type: text/x-diff
Size: 1708 bytes
Desc: 
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20101215/59eb1f9f/attachment.patch>