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FYI - flags included by -O options in gcc 3.1
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slik
n00b
n00b


Joined: 18 Apr 2002
Posts: 48
Location: Alberta, Canada

PostPosted: Fri Jun 28, 2002 1:01 am    Post subject: FYI - flags included by -O options in gcc 3.1 Reply with quote

-mcpu and -march will differ per your cpu of course, this is from a newish duron with -march=athlon passed in.
I've seen people putting flags in thier setups that are already included with a given -O flag, so..
Also notice that -fomit-frame-pointer isn't included with this processor.
options are added to previous optimization level.

no -O option passed, same as -O0
options enabled: -fpeephole -ffunction-cse -fkeep-static-consts -fpcc-struct-return -fgcse-lm -fgcse-sm -fsched-interblock -fsched-spec -fbranch-count-reg -fcommon -fgnu-linker -fargument-alias -fident -fmath-errno -ftrapping-math -m80387 -mhard-float -mno-soft-float -mieee-fp -mfp-ret-in-387 -mcpu=athlon -march=athlon

-O1 same as -O adds best for debugging
-fdefer-pop -fthread-jumps -fcprop-registers -fmerge-constants -fguess-branch-probability

-O2 adds
-foptimize-sibling-calls -fcse-follow-jumps -fcse-skip-blocks -fexpensive-optimizations -fstrength-reduce -fforce-mem -fcaller-saves -fgcse -frerun-cse-after-loop -frerun-loop-opt -fdelete-null-pointer-checks -fschedule-insns2 -freorder-blocks -fregmove -foptimize-register-move -fstrict-aliasing -fpeephole2

-O3 adds
-frename-registers

-Os is the same as for -O2 but also preforms further optimization to reduce size of executable.
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fghellar
Bodhisattva
Bodhisattva


Joined: 10 Apr 2002
Posts: 856
Location: Porto Alegre, BR

PostPosted: Fri Jun 28, 2002 3:39 am    Post subject: Reply with quote

I believe this is interesting enough to deserve a place in Tips&Tricks:
http://forums.gentoo.org/viewtopic.php?p=31471
:wink:
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