FreeBSD Port: subversion-1.1.3
David Xu
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
>>optimization
>>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
>footprint.
>
>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
further op-
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.
David Xu
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