PATCH RFC: Warn about pointer wraparound with -Wstrict-overflow

[Richard Guenther]

On Tue, Apr 8, 2008 at 11:42 PM, Mark Mitchell <mark@codesourcery.com> wrote:
> Andrew Pinski wrote:
>
> > On Tue, Apr 8, 2008 at 12:44 PM, Paul Brook <paul@codesourcery.com> wrote:
> >
> > >  On some targets (e.g. ARM) I believe base+offset addressing modes are
> > >  undefined if the calculation overflows.  So to implement -fwrapv for
> pointers
> > >  reliably you may need to disable these adressing modes.
> > >
> >
> > HPPA for sure.
> >
>
>  That seems like a pretty compelling argument.  Wrapping semantics are
> pretty easy for integers; everyone's hardware works that way.  If wrapping
> semantics are hard to implement for pointers, then maybe we shouldn't try to
> make -fwrapv work there.  In that case, the manual might be improved by
> saying "... integers (but not pointers)" so that we know that it really
> means it.  We might even have a note that mentions these kinds of hardware
> platforms.

Of course addressing mode issues only come into play if we use them for
address computation (like with lea on x86) - do we in this case?

Richard.