https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83964
--- Comment #20 from Segher Boessenkool <segher at gcc dot gnu.org> --- There were various issues with the builtins. We could have made them work for just (say) power8 and up, in time for GCC 8, but then for a long time no one would be able to use __builtin_fcti[wd] on other configs without first doing some configure check for it. While the instructions exist on *any* PowerPC (with hard float) (and fctid is illegal in ISA 1.xx on 32-bit implementations). Since nothing uses the builtins yet, we are dropping them for GCC 8. They will be added back in GCC 9, or a generic implementation sounds even better, indeed :-)
