[FFmpeg-devel] [FFmpeg-cvslog] r12171 - trunk/doc/optimization.txt

[İsmail Dönmez]

Hi,

On Thu, Feb 21, 2008 at 10:19 PM, Mike Melanson <mike at multimedia.cx> wrote:
> ?smail D?nmez wrote:
>  > Hi,
>  >
>  > On Thu, Feb 21, 2008 at 9:57 PM, Uoti Urpala <uoti.urpala at pp1.inet.fi> wrote:
>  >> On Thu, 2008-02-21 at 20:11 +0100, Michael Niedermayer wrote:
>  >>  > As you can see gcc injects 2 unneeded lea instructions in the innermost loop.
>  >>
>  >>  It'd need at least one other instruction instead though. Anyway I do not
>  >>  see that behavior with Debian's gcc-4.3, gcc always uses 3 instructions
>  >>  for the adds (same as the handwritten asm).
>  >
>  > That supports my theory that gcc 4.3 is a big improvement optimization wise.
>
>  According to the data FATE has been collecting, FFmpeg binaries built
>  using gcc out of SVN are not performing as well as gcc <= 4.2.x. Much
>  worse in fact. This only seems to be an issue on x86_32.

Well that requires further investigation, is it a general slow down or
some specific part like h264 decoding?

Regards,
ismail


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