On 04/05/17 15:01, Jonathan Wakely wrote: > On 4 May 2017 at 13:56, Toebs Douglass <toby@xxxxxxxxxxxxxx> wrote: > Yes, to explicitly specify the memory ordering. > > x == 10 is exactly equivalent to x.load(memory_order_seq_cst) == 10. Ah! operator overloading, right? this wacky C++ stuff :-) So now I understand. > i.e. the default ordering is SC. Right. I have in fact been misreading this (and so Andrew) to mean Store Conditional, i.e I thought he was talking about LL/SC and atomic writes. > x = 1 is exactly equivalent to x.store(memory_order_seq_cst). > > http://en.cppreference.com/w/cpp/atomic/atomic/operator%3D It looks like it's doing an atomic exchange, but it's not necessarily so and where I *think* I've seen GCC only using memory barriers for stuff it called "atomic", I'm not sure. I don't code in C++, though, so we can leave it at this point.
