How do they avoid the subsequent bugs O3 tends to produce?
First time I’m hearing of this. Do you have some more details?
They don’t.
Gentoo users in shambles
Bah, they’ll never have my precious
-march=native!Jokes on you, my system is (mostly) -O3
too fancy for -O2? lol
Yes
Not like Ubuntu works very well on old hardware but hopefully O2 support will still be there. Many people need it.
-O2 vs -O3 adds
-fgcse-after-reload -fipa-cp-clone -floop-interchange -floop-unroll-and-jam -fpeel-loops -fpredictive-commoning -fsplit-loops -fsplit-paths -ftree-loop-distribution -ftree-partial-pre -funswitch-loops -fvect-cost-model=dynamic -fversion-loops-for-stridesI don’t think any of these optimizations require more modern hardware?
Right. GCC -f optimizations are basically like “how hard are we going to try to be clever” and are, I believe, orthogonal to the actual instructions used. Machine dependent args start with -m, like -march or -mavx etc.
op-ti-mize [verb (trans.)]* … (gcc) to modify executable code so that it fails more quickly.
