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Re: Loop unrolling-related SPEC regressions?


> Jan Hubicka <jh@suse.cz> writes:
> 
> > I am playing with the idea of making -O behaving like -f and allowing -Ospeed
> > "optimize for maximal speed for common circmuatens" and -Osize.  We can also
> > invent -O[no]debug "prohibit optimizations that make debugging dificult, like
> > tail call optimization, frame pointer ellimination, or (currently) register
> > renaming", 
> 
> Don't we already have these?  -O3 is what you call 'Ospeed', -Os is
> what you call 'Osize', '-O0' is Odebug.

Yes and no. Defnitly to get best perofrmance you don't need to enable
just -march=mymodel -O3

We disable some options at higher optimizations levels just to allow debugging
(like -fomit-frame-pointer, register renaming, loop unrolling).

It is somewhat dificult to orientate in the optimization levels for users
and I am not sure what exactly can we do with the situation.

Honza
> 
> -- 
> - Geoffrey Keating <geoffk@geoffk.org> <geoffk@redhat.com>


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