On Wed, 10 Feb 2021, Uecker, Martin via Liaison wrote:

> > You need the various *operations* from stdatomic.h in forms that can be
> > applied to non-atomic data.
>
> I am not sure I understand what you mean.
>
> On a fundamental level on architectures supported by C there
> is no atomic or non-atomic memory. Only accesses are atomic or
> not (this is why a qualifier is a natural choice for "lockless"
> accesses). So having the qualifier would imply atomic accesses
> and not having the qualifier would imply accesses which may
> be not atomic. We support atomic for all types, so we need
> a fallback mechanism if the hardware can not do a "lockless"
> access.

My point is that you could allow atomic_store, atomic_compare_exchange
etc. generic functions from stdatomic.h to be called where the type shown
as A is not an atomic type, so allowing a mixture of atomic and non-atomic
operations on the same object, without having an atomic qualifier at all.
Or you could have new generic functions that do the same as the existing
ones but on non-atomic types, again without needing an atomic qualifier.

-- 
Joseph S. Myers
joseph_at_[hidden]