https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117093
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- t_4 = BIT_FIELD_REF <r_3(D), 32, 0>; a_5 = VEC_PERM_EXPR <_1, _1, { 1, 1, 2, 3 }>; a_6 = BIT_INSERT_EXPR <a_5, t_4, 32 (32 bits)>; t_7 = BIT_FIELD_REF <r_3(D), 32, 64>; _2 = BIT_FIELD_REF <r_3(D), 32, 96>; a_8 = BIT_INSERT_EXPR <a_6, _2, 64 (32 bits)>; a_9 = BIT_INSERT_EXPR <a_8, t_7, 96 (32 bits)>; IIRC there are others like this.