Also, GCC -O3 is prone to removing too much code and reordering it, causing memory barrier issues and the like. Whoah, that's what __sync_synchronize() and vol

Also, GCC -O3 is prone to removing too much code and reordering it, causing memory barrier issues and the like. Whoah, that's what __sync_synchronize() and volatile are for. If you're trying to write order-dependent multithreaded code without those, the bug's in your code, not in compiler flag juju.