https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123212
--- Comment #1 from Sam James <sjames at gcc dot gnu.org> --- The algorithm was changed for switch conversion in 15 and then in r15-4756-g06bc3a734e8890, it was made to only be at >= -O1 (but not -Og) because of it being too expensive at -O0.
