https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118131
--- Comment #1 from Christophe Lyon <clyon at gcc dot gnu.org> --- This is because arm.cc:arm_attr_length_move_neon() does not handle the new MVE struct modes, which correspond to OImode and XImode. Adding them leads to a crash later because in neon.md we have (define_split [(set (match_operand:OI 0 "s_register_operand" "") (match_operand:OI 1 "s_register_operand" ""))] which does not support the new modes either.