core.stdc.stdatomic

[Richard (Rikki) Andrew Cattermole]

On 14/11/2023 9:35 PM, Walter Bright wrote:
> The fence instructions are supported by DMD's inline assembler, so they 
> can be done, too, as simple functions.
> 
> Why is this a write-off?

 From C11 spec for ``atomic_signal_fence``:

NOTE 2 Compiler optimizations and reorderings of loads and stores are 
inhibited in the same way as with
atomic_thread_fence, but the hardware fence instructions that 
atomic_thread_fence would
have inserted are not emitted.

In other words no instructions emitted, it does not map to an x86 
instruction.

I've said this before, dmd is a write off for lock-free concurrent data 
structures. Having ANY extra functions in the call stack can throw off 
the timing and end in segfaults. It MUST be inlined! This will be true 
of any use case for atomics that is beyond that of reference counting.