https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107563
--- Comment #6 from Hongtao.liu <crazylht at gmail dot com> --- Shufd only handles void foo1(temp_vec_type& v) noexcept { v=__builtin_shufflevector(v,v,12,13,14,15,8,9,10,11,4,5,6,7,0,1,2,3); } Not the case in #c0.