On 11/27/2017 1:50 PM, Henrik Gramner wrote: > On Sun, Nov 26, 2017 at 11:51 PM, James Darnley <james.darn...@gmail.com> > wrote: >> -pd_0_int_min: times 2 dd 0, -2147483648 >> -pq_int_min: times 2 dq -2147483648 >> -pq_int_max: times 2 dq 2147483647 >> +pd_0_int_min: times 4 dd 0, -2147483648 >> +pq_int_min: times 4 dq -2147483648 >> +pq_int_max: times 4 dq 2147483647 > > Using 128-bit broadcasts is preferable over duplicating the constants > to 256-bit unless there's a good reason for doing so since it wastes > less cache and is faster on AMD CPU:s.
What would that reason be? Afaik broadcasts are expensive, since they both load from memory then splat data across lanes. Using them inside loops doesn't sound like a good idea. But i guess you have more experience testing with more varied chips than i do. Also, by AMD cpus you mean Ryzen? Because on Bulldozer-based CPUs we purposely disabled functions using ymm regs. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
