[Libav-user] a little performance/optimisation headbreaker :)

"René J.V. Bertin" rjvbertin at gmail.com
Fri Feb 15 17:12:17 CET 2013

On Feb 15, 2013, at 17:08, Claudio Freire wrote:

> SSE intrinsics (and automatic vectorization in fact) perform a lot
> more poorly if you don't use __builtin_assume_aligned[0]
> [0] http://gcc.gnu.org/projects/tree-ssa/vectorization.html#assume-aligned

Ah, of course ... but OS X memory allocators are guaranteed to return pointers that are aligned properly for SSE intrinsics, IIRC. And I presume that since FFmpeg uses intrinsics quite extensively, its allocators also do this (on platforms where it's not already the case)...
Thanks for the link!


More information about the Libav-user mailing list