[FFmpeg-devel] [PATCH] SSE dct32() [Was: r23095 - in trunk/libavcodec: ...]

Måns Rullgård mans
Sun Jun 20 12:15:50 CEST 2010

Vitor Sessak <vitor1001 at gmail.com> writes:

>>> I don't remember seeing a big difference _for the dct32 code_ between in ==
>>> out and in != out.
>> now iam confused, i thought the 3% you quoted was about in ==out vs in!= out
>> ?
> No, the 3% slowdown was when converting our general code (using FFT)
> to have in != out.

And that was due to missed optimisations caused by gcc not knowing
that those pointers don't alias each other.  Marking them restrict is
not good either, since we actually want to pass the same value

M?ns Rullg?rd
mans at mansr.com

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