* Zbigniew Jędrzejewski-Szmek:
And -Ofast is not something that can be enabled as a default build flag, because it leads to surprising and unpredictable behaviour in some cases. (*)
I assume (*) refers to the the strange-action-at-distance issue. It was recently fixed in GCC:
--funsafe-math-optimizations is unexpectedly harmful, especially w/ -shared https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55522
Thanks, Florian