Another obvious win is that you do not trash "user-facing" registers with rep mov, like you do with a multi-xmm-register dance. I'm pro rep mov, but an XMM duf

Another obvious win is that you do not trash "user-facing" registers with rep mov, like you do with a multi-xmm-register dance. I'm pro rep mov, but an XMM duffs device just won over rep mov where I tested. It was years ago, however, so I do not remember if I tried to run above L2 and L3. It was related to a compiler optimization debate for alternate memcpy/memmove implementations...