doubt related to O3 optimization

[Ezhil P]

hi,
came across this in website

*https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html*
<https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html>

.............................................................................................................

-fprofile-use

-fprofile-use=*path*

Enable profile feedback-directed optimizations, and the following
optimizations, *many of which are generally profitable only with profile
feedback available: *

-fbranch-probabilities  -fprofile-values

-funroll-loops  -fpeel-loops  -ftracer  -fvpt

-finline-functions  -fipa-cp  -fipa-cp-clone  -fipa-bit-cp

-fpredictive-commoning  -fsplit-loops  -funswitch-loops

-fgcse-after-reload  -ftree-loop-vectorize  -ftree-slp-vectorize

-fvect-cost-model=dynamic  -ftree-loop-distribute-patterns

-fprofile-reorder-functions

.........................................................................................................


O3 optimization uses most of these flags.


Since it has been mentioned as above I assumed that some optimization flags
specified here cannot function without profile info.


Can you please clarify whether the flags mentioned above can function
without using profile information by just specifying O3?


Thank you





-- 
P.Ezhil,
Asst Prof,
L.N GOVERNMENT COLLEGE,
PONNERI - 601204