On Mon, Oct 24, 2016 at 10:31 PM, Ronald S. Bultje <rsbul...@gmail.com> wrote: > Hi, > > On Mon, Oct 24, 2016 at 4:26 PM, Henrik Gramner <hen...@gramner.com> wrote: > >> On Mon, Oct 24, 2016 at 9:59 PM, Ronald S. Bultje <rsbul...@gmail.com> >> wrote: >> > Good idea to reference Hendrik Gramner here, who keeps insisting we get >> rid >> > of all MMX code in ffmpeg (at least as an option) for future Intel CPUs >> in >> > which MMX will be deprecated. >> >> Replacing MMX with SSE2 is indeed the most "proper" fix in my opinion, >> but it's a fair amount of work and not done in an evening. >> >> The fact that a lot of assembly lacks unit tests is certainly not >> helping in that regard. >> >> Some MMX instructions are slower than the equivalent SSE2 code on >> Skylake. Intel hasn't officially commented on (as far as I know at >> least) if we should expect this trend to continue, but they certainly >> seem to treat MMX as legacy. >> >> I doubt they would completely remove support for it though, backwards >> compatibility is a big selling-point for x86. > > > Well, it gives us another way of fixing this issue (on x86-64 only): have > sse2 implementations for all code that has a mmx (register) path right now. >
I don't think the argument for pre-sse2 CPUs is that strong on 32-bit systems, either. I wouldn't necessarily limit this to x86-64 at that, considering its probably another half year at least, probably longer, until such a conversion could be completed. - Hendrik _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
