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Re: C provenance semantics proposal
Am Donnerstag, den 18.04.2019, 15:49 +0100 schrieb Peter Sewell:
> On Thu, 18 Apr 2019 at 14:54, Uecker, Martin
> <Martin.Uecker@med.uni-goettingen.de> wrote:
> >
> > Am Donnerstag, den 18.04.2019, 07:42 -0600 schrieb Jeff Law:
> > > On 4/18/19 6:20 AM, Uecker, Martin wrote:
> > > > Am Donnerstag, den 18.04.2019, 11:45 +0100 schrieb Peter Sewell:
> > > > > On Thu, 18 Apr 2019 at 10:32, Richard Biener <richard.guenther@gmail.com> wrote:
> >
> > ...
> > > > 4.) Compilers make sure that exposed objects never
> > > > are allocated next to each other (as Jens proposed).
> > >
> > > Ugh. Not sure how you enforce that. Consider that the compiler may
> > > ultimately have no control over layout of data in static storage.
> >
> > One maybe only where it matters? I assume the biggest benefit
> > is for local variables and there the compiler has full control.
> >
> > For arbitrary pointer coming from somewhere, one has no provenance
> > information anyway.
>
> that's not quite true - one does know that it can't have the same provenance
> as anything created more recently than the incoming pointer
Good point. But then the objects can not be next to each other anyway.
Best,
Martin