[MPlayer-dev-eng] Re: dsputil_mmx.c: -O2

[Vladimir Mosgalin]

Hi Carl Eugen Hoyos!

 On 2006.09.17 at 23:19:43 +0000, Carl Eugen Hoyos wrote next:

> 4.1.1:
> without my patch (best results in >10 tests):
> BENCHMARKs: VC:  64.651s VO:  17.885s A:   0.000s Sys:   2.112s =   84.648s
> BENCHMARKs: VC:  64.659s VO:  17.850s A:   0.000s Sys:   2.100s =   84.609s
> with my patch - -O2 for dsputil_mmx.c (worst results!):
> BENCHMARKs: VC:  57.822s VO:  18.448s A:   0.000s Sys:   2.181s =   78.452s
> BENCHMARKs: VC:  57.824s VO:  18.608s A:   0.000s Sys:   2.109s =   78.541s
> 
> 3.4.6:
> without my patch:
> BENCHMARKs: VC:  57.439s VO:  17.993s A:   0.000s Sys:   2.517s =   77.948s
> BENCHMARKs: VC:  57.138s VO:  17.943s A:   0.000s Sys:   2.160s =   77.242s
> with my patch - -O2 for dsputil_mmx.c:
> BENCHMARKs: VC:  56.687s VO:  17.948s A:   0.000s Sys:   2.181s =   76.816s
> BENCHMARKs: VC:  56.795s VO:  18.129s A:   0.000s Sys:   2.114s =   77.038s

You know, it looks like some buggy optimization in gcc4 (comparing to
gcc 3.4) making it almost as worse as gcc 2.95.. Maybe this should be
reported to gcc developers. Some kind of conflict between inline asm and
gcc optimizations or something like that.

Only dsputil change matters? Have you investigated whether compiling
the rest of mplayer with -O2 makes postprocessing faster? Because on
modern systems, unless to go to 1080p hdtv, more time is spent on
postprocessing than on decoding...

-- 

Vladimir