https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112415
--- Comment #19 from Jeffrey A. Law <law at gcc dot gnu.org> --- f-m-o runs post-allocation, so the scope of where it's behavior can change things is narrower. So testing with -fno-schedule-insns isn't going to be useful, but -fno-schedule-insns2 might. I'm a bit concerned that we can't turn off f-m-o with an attribute. That would indicating something isn't wired up right in the options handling.