Date: Thu, 2 May 2024 20:47:06 +0300
On Thu, 2 May 2024 at 20:44, Martin Uecker via Liaison
<liaison_at_[hidden]> wrote:
> The two problems we discussed for C were
>
> 1. even when we require those stores (I see no problem there),
> it is difficult to make sure that the information does not
> leak in a different way, e.g. because registers or other
> stack area are not cleared. WG14 was content with making the
> intent clear.
We have Recommended Practice that we can use for the intent.
> 2. if there is UB afterwards then the extreme interpretation
> of UB (which WG14 later rejected) makes the complete program have
> no meaning.
That's a separable problem (because we have a separate proposal for an
optimization barrier),
but if it's a volatile write, it's an optimization barrier because the
volatile write is an observable effect.
So I don't think this is a problem.
<liaison_at_[hidden]> wrote:
> The two problems we discussed for C were
>
> 1. even when we require those stores (I see no problem there),
> it is difficult to make sure that the information does not
> leak in a different way, e.g. because registers or other
> stack area are not cleared. WG14 was content with making the
> intent clear.
We have Recommended Practice that we can use for the intent.
> 2. if there is UB afterwards then the extreme interpretation
> of UB (which WG14 later rejected) makes the complete program have
> no meaning.
That's a separable problem (because we have a separate proposal for an
optimization barrier),
but if it's a volatile write, it's an optimization barrier because the
volatile write is an observable effect.
So I don't think this is a problem.
Received on 2024-05-02 17:47:20