http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56028
--- Comment #5 from Evgeniy Stepanov <eugeni.stepanov at gmail dot com> 2013-01-18 16:38:11 UTC --- Well, it's true that classes have assignment operators, and basic types don't. But this does not have anything to do with how the assignment could (or could not) be implemented at the machine level. AFAIU, the main point here is that a valid, data-race-free program can't observe the non-atomicity of a 64-bit store. And there is no special clause for volatile stores in this regard, either. I agree that in practice volatile stores of reasonably-sized basic types must be atomic, or a lot of legacy code will break.
