-O3 optimization

Rodolfo Lima rodolfo at rodsoft.org
Wed Apr 9 04:52:28 PDT 2003

Why you guys don't use -O3 optimization throughout the building of packages?

>From gcc's man:

   -O2 Optimize even more.  GCC performs nearly all supported optimiza-
           tions that do not involve a space-speed tradeoff.  The compiler
           does not perform loop unrolling or function inlining when you
           ify -O2.  As compared to -O, this option increases both
           time and the performance of the generated code.

           -O2 turns on all optional optimizations except for loop
           function inlining, and register renaming.  It also turns on the
           -fforce-mem option on all machines and frame pointer elimination
           machines where doing so does not interfere with debugging.

           Please note the warning under -fgcse about invoking -O2 on
           that use computed gotos.

   -O3 Optimize yet more.  -O3 turns on all optimizations specified by -O2
           and also turns on the -finline-functions and -frename-registers

I think loop unrolling and inline functions can do a lot for performance...


Unsubscribe: send email to listar at linuxfromscratch.org
and put 'unsubscribe lfs-dev' in the subject header of the message

More information about the lfs-dev mailing list