http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46096
--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> 2010-10-20 14:40:21 UTC --- I don't recommend people use volatile to avoid multithreading races, it only prevents compiler optimisations, not hardware reordering. Using proper atomics, memory barriers or other explicit synchronisation is better. But for this testcase, yes, volatile will "fix" it. Danilo, you might like to read these http://www.drdobbs.com/cpp/201804238 http://www.drdobbs.com/high-performance-computing/212701484
