Hi, On Sun, Nov 13, 2022 at 8:47 AM Nomis101 <nomis...@web.de> wrote:
> Am 12.11.22 um 23:09 schrieb Ronald S. Bultje: > > Hi, > > > > On Sat, Nov 12, 2022 at 1:57 PM Nomis101 <nomis...@web.de> wrote: > > > >> Hi.If building FFmpeg, configure does set a value for mstack-alignment, > >> for example on macOS > >> -mstack-alignment=16. On HandBrake we found there is an issue with > current > >> Clang in Xcode about > >> conflicting 'override-stack-alignment' values if we build with ThinLTO. > >> > >> "ld: linking module flags 'override-stack-alignment': IDs have > conflicting > >> values" > >> > >> I found out why this is. x264 does set -mstack-alignment=64 in > configure, > >> FFmpeg does set > >> -mstack-alignment=16 and this seems to be a conflict when linking. If I > >> modify both configure files > >> and remove the mstack-alignment part, then the build does finish with no > >> error. > >> > >> And here comes my questions. I was wondering, about the technical reason > >> why FFmpeg does set > >> mstack-alignment? And if it would be safe to disable it in case FFmpeg > is > >> compiled with ThinLTO (for > >> HandBrake)? > >> > > > > It can safely be set to the higher of the two values, it has the same > > meaning. Alignment of 64 implies alignment of 16. > Thanks. I found out, that its enough to disable the mstack-alignment part > for x264 in case of > ThinLTO. This will also fix the error. > For people looking at this in the archives after a google search, trying this out and wondering why their x264 crashes, please see the following reference: https://mailman.videolan.org/pipermail/x264-devel/2022-November/012963.html (Summary: if you remove the stack alignment in x264, please also remove the assumption in x264's build that the stack *is* in fact aligned, and then everything will work fine (although a few instructions slower).) Ronald _______________________________________________ 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".
