acq/rel remains efficient on a platform that doesn't need barriers to implement it (ie, x86).
consume remains efficient on a platform that doesn't need barriers to enforce a dataflow dependency (ie, ARMv7).
acq/rel remains efficient on a platform that doesn't need barriers to implement it (ie, x86).
consume remains efficient on a platform that doesn't need barriers to enforce a dataflow dependency (ie, ARMv7).