Le 10 juin 2024 16:07:14 GMT+03:00, Andreas Rheinhardt <andreas.rheinha...@outlook.com> a écrit : >Rémi Denis-Courmont: >> >> >> Le 10 juin 2024 14:57:29 GMT+03:00, Michael Niedermayer >> <mich...@niedermayer.cc> a écrit : >>> Also we have alpha fate clients: >>> https://fate.ffmpeg.org/?query=subarch:alpha%2F%2F >> >> Are there? I only see Ubuntu 22.04 builds which must be cross-compiled since >> Ubuntu 22.04 doesn't support DEC Alpha, not even as a port. >> >> So I guess the tests are run on user-mode QEMU? For the sake of the argument >> and to answer your performance question, SIMD on QEMU is in my experience >> much *slower* than scalar C, due to limitations of TCG. So if that's the >> goal post, then removing the optimisations is actually a performance win. >> > >I doubt that the same can be said about removing the fast 64bit and clz >flags.
Sure. TCG has express support for CLZ and CTZ. We could default to the GCC built-ins on Clang and GCC regardless of fast CLZ though. IMO the fast 64-bit detection should use some default heuristic for unknown platforms though. We could at least check if UINTPTR_MAX is larger or equal to UINT64_MAX (won't work for 64-bit ILP32 ABIs, but I don't think Alpha has ever had one). In any case, this may be relevant for some platforms but probably not for Alpha as of 2024. _______________________________________________ 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".
