On Tue, Oct 31, 2017 at 03:52:14PM +0000, Thomas Köppe wrote: > +Teresa, who drafted the patch initially. > > On 31 October 2017 at 15:38, Michael Niedermayer <mich...@niedermayer.cc> > wrote: > > > On Tue, Oct 31, 2017 at 12:16:18PM +0000, Thomas Köppe wrote: > > > Variables used in inline assembly need to be marked with > > attribute((used)). > > > > This should not be the case. > > Variables referenced through in/out operands should not need that. > > Only ones accessed directly bypassing operands should need this > > > > I've added Teresa to the thread, who initially analyzed the problem. (For > background on ThinLTO, see here cppcon talk: > https://www.youtube.com/watch?v=p9nH2vZ2mNo.) > > [...] > > > - #define DECLARE_ALIGNED(n,t,v) t __attribute__ ((aligned (n))) > > v > > > + #define DECLARE_ALIGNED(n,t,v) t av_used __attribute__ > > ((aligned (n))) v > > > > which variables actually are affected/ need this ? > > > > Without this annotation, and when compiling and linking with ThinLTO, I get > an undefined reference to "ff_h264_cabac_tables", and also to > "ff_pw_96", "ff_pw_53", > "ff_pw_42", "ff_w1111" and many more.
i guess these are all accessed directly, like through MANGLE() > > > > Marking all aligned variables as used makes it harder to spot unused > > variables leading to accumulation of cruft > > > > I see. Maybe we can annotate only the affected variables more granularly? > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Avoid a single point of failure, be that a person or equipment.
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