On Fri, Jan 26, 2024 at 9:45 PM Martin Storsjö <mar...@martin.st> wrote:
> On Fri, 26 Jan 2024, Martin Storsjö wrote: > > > These inline implementations of AV_COPY64, AV_SWAP64 and AV_ZERO64 > > are known to clobber the FPU state - which has to be restored > > with the 'emms' instruction afterwards. > > > > This was known and signaled with the FF_COPY_SWAP_ZERO_USES_MMX > > define, which calling code seems to have been supposed to check, > > in order to call emms_c() after using them. See > > 0b1972d4096df5879038f0af776f87f41e90ebd4, > > 29c4c0886d143790fcbeddbe40a23dfc6f56345c and > > df215e575850e41b19aeb1fd99e53372a6b3d537 for history on earlier > > fixes in the same area. > > > > However, new code can use these AV_*64() macros without knowing > > about the need to call emms_c(). > > > > Just get rid of these dangerous inline assembly snippets; this > > doesn't make any difference for 64 bit architectures anyway. > > > > Signed-off-by: Martin Storsjö <mar...@martin.st> > > --- > > libavcodec/dca_core.c | 16 ---------------- > > libavutil/x86/intreadwrite.h | 36 ------------------------------------ > > 2 files changed, 52 deletions(-) > > I forgot to add some more context here; the VVC tests fail on i386 in some > cases. > > https://patchwork.ffmpeg.org/project/ffmpeg/patch/20240125170518.61211-1-p...@frankplowman.com/ > fixes this, by using av_log2() instead of the float log2() in the VVC > decoder. This patch fixes the same issue as well, by eliminating the FPU > state clobbering (so that float math functions anywhere in decoders work > as expected). > 👍 > > // Martin > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
