https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118362
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> --- gcc/machmode.def doesn't contain any VECTOR_MODE/VECTOR_MODES. And, even vector modes defined in the backend don't appear anywhere without any reason, the V8SImode in this case is because the *vmrhf and *vmrlf insns actually use those and combine just attempted to simplify that.
