Re: must_alias question

[Jan Hubicka <jh at suse dot cz>]

> On Thu, 2003-11-20 at 05:04, Jan Hubicka wrote:
> 
> > One thing that looks strange to me is clearing of
> > may_point_to_global_mem for variable whose address is taken.  Isn't this
> > the other way around?  (ie we can look for pointers that are never
> > assigned to global memory addresses or other pointers with this flag).
> > 
> I'm not sure I understand what problem you're running into, here.  Give
> me an example?

I am not running into any problem, except that reordering tailcall and
mustalias passes triggers the bootstrap failure, so I am trying to
understand things better.

But for foloowing code:

char global;
t()
{
  char *a=global;
  char **b=&a;
  return *a;
}
must_alias clears may_point_to_global_mem for variable a based on fact
that it's address is no longer taken.  This looks just wrong.
the fact that we don't take address of pointer has nothing to do about
the fact whehtehr it points to global memory or not.
Or am I missunderstanding semantics of the flag?

Honza
> 
> 
> Diego.