[Ffmpeg-devel] -fwhole-program -combine

[Måns Rullgård]

Ramiro Polla <angustia at arrozcru.no-ip.org> writes:

> Hello,
>
> Note: attached patch is for informational and archiving purposes only.
>
> With gcc 4.1.2 out, I decided to build FFmpeg with -fwhole-program
> -combine to see what happened. My previous attempts with older 4.1.1
> came accross the externally_visible bug (it was ignored, so it didn't
> link correctly).
>
> I made some changes to configure and the makefiles to echo out the
> filenames, and then when a program is being built (only ffmpeg on my
> case), it builds with all source code in the command line.

[...]

> Basically, ffmpeg_g got 9% larger, ffmpeg got 8.2% larger, and the
> benchmarks showed a slowdown of 1.3%. Way to go gcc =)
>
> Pretty frustrating... I was hoping it would be faster or smaller. Am I
> missing something to get the "agressive" optimizations to work
> properly?

My guess is that those options are mostly intended to get around
inefficiencies in C++.

-- 
M?ns Rullg?rd
mans at mansr.com