[Bug other/49244] no intrinsics to emit 'lock bts' and 'lock btc'

[desrt at desrt dot ca]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49244

--- Comment #2 from Ryan Lortie <desrt at desrt dot ca> 2011-06-02 23:05:58 UTC ---
I'd be happy enough if GCC published a "recommended sequence" or something so
that it would be easier to check for this exact sequence...

A new user-accessible builtin would also make me happy.