Re: [Bug-gnubg] compiling with optimization

[Holger]

At 22:09 18.11.2003, Achim Mueller wrote:
> I just did a small test with different optimization flags.
>
> machine:toshiba satellite 2430-101, 512mb RAM, 2,5 ghz pentium4
> os:     SuSE-Linux 9.0, glibc-2.3.2-88, gcc-3.3.1
>
> without opt:    CFLAGS=""
> i686:           CFLAGS="-march=i686 -mcpu=i686"
> i686-O2:        same + O2
> i686-O3:        same + O3
> pentium4:       CFLAGS="-march=pentium4 -mcpu=pentium4"
> pentium4-O2:    same + O2
> pentium4-O3:    same + O3
> pentium4-all:   same + -pipe -fomit-frame-pointer -fforce-addr
>                        -falign-functions=4 -ffast-math
>
> Results (gnubg -t "calibrate"):
>
> without opt:    10954   12642
> i686:           10985   11272
> i686-O2:        22119   22125
> i686-O3:        22386   22438
> pentium4:       10996   11186
> pentium4-O2:    23307   23255
> pentium4-O3:    22849   22783
> pentium4-all:   22815   22852
>
> Interesting: If you don't use "-O" you get only half of the maximum.
>
> Comments?

Same like we got in former tests. See e.g. 
http://mail.gnu.org/archive/html/bug-gnubg/2003-01/msg00424.html . However 
it's a bit strange that pentium4-O3 does worse than pentium4-O2. In my 
experience it's most important to switch on -O2 (or -O3). All processor 
specific features (like MMX or SSE) hardly make a difference.

Regards,

        Holger