I have found lock inc addr but that doesn't keep a copy of the stored value around and even a read immediately after it in the same thread could come after a competing write.
The best solution I have found is a load/inc/cas loop.
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In C++11 std::atomic, [`fetch_add`](http://en.cppreference.com/w/cpp/atomic/atomic/fetch_add) `+ 1` does what you want. Or more simply, [`operator++`](http://en.cppreference.com/w/cpp/atomic/atomic/operator_arith), but then you can't use a weaker `memory_order_relaxed` to make it faster on non-x86 if you don't need a barrier. (`lock xadd` implements `fetch_add`, returning the old value). – Peter Cordes Sep 02 '17 at 08:16
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[Can num++ be atomic for 'int num'?](https://stackoverflow.com/q/39393850/995714) – phuclv Jan 14 '18 at 08:37
