FreeBSD Port: subversion-1.1.3
davidxu at freebsd.org
Fri Apr 8 00:15:54 PDT 2005
Francois Tigeot wrote:
>On Fri, Apr 08, 2005 at 09:54:04AM +0800, David Xu wrote:
>>I heard only -O works, -O2 does not work, -Os sometimes is a higher
>>level than -O2.
>AFAIK, -Os is only a subset of -O2.
>-Os only includes the -O2 optimisations which don't increase code size;
>it gives generally better performance than -O2 due to a better cache
>I have found this particularly true when using VIA C3 processors.
According to gcc manual:
-Os Optimize for size. This enables all -O2 optimizations that do
not typically increase code size. It also performs
timizations designed to reduce code size.
So the options are overlapped, and also each option has its own
optimizations, it should
be treated that both -Os and -O2 have dangerous optimizations.
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