Am Donnerstag, 19. Oktober 2006 08:20 schrieb Vince Greg:
> Without compilation my package 80mo
> With -Os -s -fno-strict-aliasing my package 14mo
> With -O3 -Os -s -fno-strict-aliasing my package 15,2mo
> I search to have fast programms and small programms
You cannot "combine" compiler optimisation flags. It is alway the last
optimisation flag that counts. So in theory the final binaries should be
equal when using either of
-Os -s -fno-strict-aliasing
or:
-O3 -Os -s -fno-strict-aliasing
In fact the optimisation flags are only aliases and turn on other more
detailed flags.
So, what -Os in fact does is, it turns off:
-falign-functions -falign-jumps -falign-loops
-falign-labels -freorder-blocks -freorder-blocks-and-partition
-fprefetch-loop-arrays -ftree-vect-loop-version
All these pretty, but space consuming optimisation flags, which -O3 turned on
just before.
There is extensive information on CFLAGS when just googling. For example:
http://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html
http://gentoo-wiki.com/CFLAGS
Greets,
Norman
PS. Please be a bit more clear, when saying "the package x mo". What did you
do to get these numbers?
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