On Wed, Dec 7, 2016 at 2:07 PM, James Darnley <jdarn...@obe.tv> wrote: > Because a few instructions using 3 operand form should be quicker. The > fact that it doesn't show is no doubt down to the out of order execution > managing to do the moves earlier than written.
Register-register moves are handled in the register renaming stage without consuming any execution resources and are often essentially free (on modern Intel CPUs, e.g. Haswell+ at least, I don't remember if this applied to Sandy Bridge as well). The advantage of 3-arg operands is reduced decoding pressure and slightly denser encoding which can save some cache if you have a lot of register-register moves. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
