On Mon, 2014-02-17 at 12:23 -0800, Paul E. McKenney wrote: > On Mon, Feb 17, 2014 at 08:55:47PM +0100, Torvald Riegel wrote: > > On Sat, 2014-02-15 at 10:49 -0800, Linus Torvalds wrote: > > > On Sat, Feb 15, 2014 at 9:45 AM, Torvald Riegel <triegel@xxxxxxxxxx> wrote: > > > > > > > > I think a major benefit of C11's memory model is that it gives a > > > > *precise* specification for how a compiler is allowed to optimize. > > > > > > Clearly it does *not*. This whole discussion is proof of that. It's > > > not at all clear, > > > > It might not be an easy-to-understand specification, but as far as I'm > > aware it is precise. The Cambridge group's formalization certainly is > > precise. From that, one can derive (together with the usual rules for > > as-if etc.) what a compiler is allowed to do (assuming that the standard > > is indeed precise). My replies in this discussion have been based on > > reasoning about the standard, and not secret knowledge (with the > > exception of no-out-of-thin-air, which is required in the standard's > > prose but not yet formalized). > > > > I agree that I'm using the formalization as a kind of placeholder for > > the standard's prose (which isn't all that easy to follow for me > > either), but I guess there's no way around an ISO standard using prose. > > > > If you see a case in which the standard isn't precise, please bring it > > up or open a C++ CWG issue for it. > > I suggest that I go through the Linux kernel's requirements for atomics > and memory barriers and see how they map to C11 atomics. With that done, > we would have very specific examples to go over. Without that done, the > discussion won't converge very well. > > Seem reasonable? Sounds good! -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
