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Re: [MiNT] Why not O3


> > Die 30.03.01 (20:09) owner-mint@fishpool.com scripsit:
> >> Question: why Mint kernel is compiled with O2 and not 03? 
> > Because -O3 is the same as -O2 -funroll-loops, IIRC, which produces larger
> > binaries not gaining any significant speedup.
> You should compile -O1, that is, as far as I know, optimisation
> for space (executable size). There is a paradox : I found that
> -O1 compilations are faster than -O3. I made my opinion on that.

Perhaps you are right, but the question was about the selection between
-O2 and -O3 :-) Sure, I didn't try -O1.

> In facts, Atari machines have very tiny cache memory, and there's
> no L2 caches. So, optimisations for speed (-O3) that generate
> supposed faster code, by the way of unrolling loops and others
> expensive optimisations etc ... are not efficient on our
> platforms. The compacity of executable's code is much more
> efficient.

Exactly that's why it was changed from -O3 to -O2.


Konrad M.Kokoszkiewicz
mail: draco@atari.org

** Ea natura multitudinis est,
** aut servit humiliter, aut superbe dominatur (Liv. XXIV,25)
** Taka to juz natura pospolstwa, ze albo sluzy ono unizenie,
** albo bezczelnie sie panoszy.