On Fri, 2014-12-26 at 23:19 +0000, Andrew Haley wrote: > On 26/12/14 22:49, Matt Godbolt wrote: > > At the moment I think the best I can do is to use an inline assembly > > version of the increment which prevents GCC from doing any > > optimisation upon it. That seems rather ugly though, and if anyone has > > any better suggestions I'd be very grateful. > > Well, that's the problem: do you want a barrier or not? With no > barrier there is no guarantee that the data will ever be written to > memory. Do you only care about x86 processors?
The C++11 memory model guarantees the following though (1.10p25): An implementation should ensure that the last value (in modification order) assigned by an atomic or synchronization operation will become visible to all other threads in a finite period of time.