I think the new memory model does not guarantee this program always prints 1:
1. There is no synchronization guarantee between line 13 and line 14 as these atomic operations are manipulated on the different memory locations. 2. It is *not* prohibited for the compiler to switch line 13 and line 14 (as I read from section https://go.dev/ref/mem#badcompiler) because of the above reason, and also, there is no order between line 13 and line 20. So this is possible: line 14 < line 18 < line 20 < line 13. 3. Depending on the memory layout of a and b, if they are on the same cache line, then the program will always print 1. On Mon, Aug 15, 2022 at 8:48 AM 'Axel Wagner' via golang-nuts <golang-nuts@googlegroups.com> wrote: > > Why wouldn't it? >> >> If the effect of an atomic operation A is observed by atomic operation B, >> then A is synchronized before B. > > To me, it seems pretty clear that it will. Line 13 is synchronized before > line 14, which is synchronized before any load observing its effects (i.e. > any execution of line 18 which runs into the branch) - and such a load is > synchronized before the load in line 20. > > Therefore, the store in Line 13 is synchronized before the load in line 20. > > > On Mon, Aug 15, 2022 at 8:37 AM tapi...@gmail.com <tapir....@gmail.com> wrote: >> >> By the latest version of Go Memory Model article: https://go.dev/ref/mem, >> will the following program always print 1? >> >> https://go.dev/play/p/RICYGip5y8M >> >> -- >> You received this message because you are subscribed to the Google Groups >> "golang-nuts" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to golang-nuts+unsubscr...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/4d9b8130-d06c-4519-9b99-d161e922d8f6n%40googlegroups.com. > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/CAEkBMfHpwchwjAMtXNtpVmhb42Ncw9ENKhz5xH9Sv1z_-DMrRA%40mail.gmail.com. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAGrj7%2B%2BRZeMdnspKHK4yOKJ9eHka-B6jk_bhM5M95XbyamVC%3Dg%40mail.gmail.com.
