| Ramine <toto@toto.net>: Mar 18 10:44PM -0400 Hello... I have just read this about the C++11 Memory Model: Some programming languages offer SC in multiprocessor environment. In C++11, you can declare all shared variables as C++11 atomic types with default memory ordering constraints. In Java, you can mark all shared variables as volatile [1] [2]. Because the C++11 atomic types guarantee sequential consistency, the outcome r1 = r2 = 0 is impossible. To achieve this, the compiler outputs additional instructions behind the scenes – typically memory fences and/or RMW operations. Those additional instructions may make the implementation less efficient compared to one where the programmer has dealt with memory ordering directly. Read here: https://people.cs.pitt.edu/~xianeizhang/notes/cpp11_mem.html So, there is still a problem with C++, because so it is still error prone if you forget C++11 atomic types to ensure sequential consistency and it is less efficient with atomic types. So i still prefer Delphi and FreePascal that don't reorder loads and stores. Thank you, Amine Moulay Ramdane. |
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