http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56298
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-02-12 14:08:05 UTC --- Headers are one thing, but you certainly can't use AES builtins in code not compiled with -maes or functions not using __attribute__((target ("aes"))) or similar. That just can't work, the insns the intrinsics want to use just aren't enabled in those ISA selections, and in other cases (think say just SSE2 ISA code, using AVX intrinsics) neither are the registers, nor modes available, in addition to the instructions.