Re: [Gnu-arch-users] Re: posible issue on ia64 with va_args.

[Andrew Suffield]

On Tue, Mar 16, 2004 at 09:26:29AM -0500, Stefan Monnier wrote:
> > It happens with some debugging systems (which I believe was the
> > original intent), where they use a tagged NULL pointer so that instead
> > of "Dereferenced NULL <segfault>", you get "Dereferenced NULL from
> > foo.c:63 <segfault>", which can be very useful on occasion.
> 
> Wouldn't that tend to cause problems where
> 
>     assert (NULL
>             ==
>             NULL);
> 
> can fail?

No, it's all handled by the compiler. == on pointers is true for two
NULL pointers even if they have different tags. Usually they just
carve out a chunk of the address space for the "tag" value and do
pointer comparisons only on the other part.

-- 
  .''`.  ** Debian GNU/Linux ** | Andrew Suffield
 : :' :  http://www.debian.org/ |
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