On Tue, Oct 17, 2017 at 3:17 AM, David Brown <david@xxxxxxxxxxxxxxx> wrote: > ... > If gcc cannot guarantee this, then pretty much every OS and every > embedded system programmed using gcc works by luck rather than design. > Sequences like the one in my link are very common, deep down in many > systems. Right, but its not GCC's fault. Using volatile and hoping that things works as expected has always been held together with duct tape and a prayer. Also see Ian Lance Taylor's https://www.airs.com/blog/archives/154. GCC guesses wrong on occasion. It will remove code that has value that but does not produce an output because the language does not allow us to express it. The C language lacks what we need to express what we need to do. Its a failure of the C (and C++) committees. Its not a GCC failure. Jeff
