[voidstarcpp]

>GCC is actually good at that, -O3 has no issue recognizing it.

imo, if you have to go to O3 or enable a pragma to get an "obvious" optimization then this is undesirable and probably something the programmer still needs to be conscious of, especially since we spend so much time doing development builds that are not at the maximum release optimization level.

[lifthrasiir]

"Misaligned" would be a better word than "obvious". It is well known and understood that a higher optimization level means more compilation time, potential speed gain and more subtle breakage in case of presence of UB, and being the maximum level, -O3 also implies potential binary size increase as well. In this understanding I believe `-funswitch-loops` is correctly placed on -O3. But ideally we want less compilation time, potential speed gain, less subtle breakage and insignificant binary size increase at once, and you can argue that all existing optimization levels are too far from that ideal.