https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108149
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> --- https://gcc.gnu.org/pipermail/gcc-patches/2009-November/273251.html was when it was added. See also https://patchwork.ozlabs.org/project/linuxppc-dev/patch/1384936551-8494-1-git-send-email-tiejun.c...@windriver.com/ which mentions about e500mc64 not allowing altivec ...
