The debate about whether further reordering is possible is an interesting one. I think it's evidence that it's basically not possible for humans to reason about

The debate about whether further reordering is possible is an interesting one. I think it's evidence that it's basically not possible for humans to reason about the memory model. The best way to resolve it is to use an automated checking tool based on a formal model. Good choices are CDSChecker[1] or the newer CppMem[2]. [1]: http://plrg.ics.uci.edu/software_page/42-2/ http://plrg.ics.uci.edu/software_page/42-2/ [2]: http://svr-pes20-cppmem.cl.cam.ac.uk/cppmem/help.html http://svr-pes20-cppmem.cl.cam.ac.uk/cppmem/help.html