6.55 Built-in Functions for Memory Model Aware Atomic Operations

[Jonathan Wakely]

N.B. I already answered this when you sent it to the libstdc++ list,
read past the first line of my reply:
https://gcc.gnu.org/pipermail/libstdc++/2021-July/052932.html

On Wed, 21 Jul 2021 at 14:00, Amar Memic <amemic@uni-osnabrueck.de> wrote:
>
>
> Hi,6.55 Built-in Functions for Memory Model Aware Atomic Operations (https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html)  says:Note that the ‘__atomic’ builtins assume that programs will conform to the C++11 memory model. In particular, they assume that programs are free of data races. See the C++11 standard for detailed requirements.
>
> I think the second sentence is a bit misleading because atomics should handle data races.
> Especially, interleaving read/write or write/write operations should be well-defined.
> If you assume that programs are free of data races, then you could not implement spinlock based on these atomics, for example.
> I hope you can help me to interpret the paragraph in the right manner.
>
> Thanks in advance
> Amar Memic