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...
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