https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80878
--- Comment #17 from andysem at mail dot ru --- I'll clarify why I think load() should be allowed to issue writes on the memory. According to [atomics.types.operations]/18 in N4713, compare_exchange_*() is a load operation if the comparison fails, yet we know cmpxchg (even the ones more narrow than cmpxchg16b) always writes, so we must assume a load operation may write. I do not find a definition of a "load operation" in the standard and [atomics.types.operations]/12 and 13 avoid this term, saying that load() "Atomically returns the value pointed to by this." Again, it doesn't say anything about writes to the memory. So, if compare_exchange_*() is allowed to write on failure, why load() shouldn't be? Either compare_exchange_*() issuing writes is a bug (in which case a lock-free CAS can't be implemented on x86 at all) or writes in load() should be allowed and the change wrt. cmpxchg16b should be reverted.
