LLVMAtomicOrderingNotAtomic

< A load or store which is not atomic

< Lowest level of atomicity, guarantees somewhat sane results, lock free.

< guarantees that if you take all the operations affecting a specific address, a consistent ordering exists

< Acquire provides a barrier of the sort necessary to acquire a lock to access other memory with normal loads and stores.

< Release is similar to Acquire, but with a barrier of the sort necessary to release a lock.

< provides both an Acquire and a Release barrier (for fences and operations which both read and write memory).

< provides Acquire semantics for loads and Release semantics for stores. Additionally, it guarantees that a total ordering exists between all SequentiallyConsistent operations.