[Bug tree-optimization/29145] unsafe use of restrict qualifier

["dberlin at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #5 from dberlin at gcc dot gnu dot org  2006-11-04 04:15 -------
This was something that slipped in, IIRC. I was of Ian's viewpoint, that
may_alias_p should handle it, and it shouldn't be special to data-references.
But it can't, at least in it's current state, because it somehow gets stripped.

I forget the exact details, but diego has explained this to me before :).

Diego, what was the deal with restrict and stripping qualifications that caused
us to not see restrict when it comes time for may_alias_p? 

Anyway, what exactly does "based on" mean?

is the following legal?

int *whee(int *__restrict a)
{
return a - 2;
}
void with_restrict(int * __restrict p)
{
  int i;
  int *q = whee(p);

  for (i = 0; i < 1000; ++i) {
    p[i] = q[i];
  }


If so, we'll never be able to get restrict right on a intraprocedural basis,
and it makes restrict completely useless for almost all cases that restricted
pointers escape :)


-- 

dberlin at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dnovillo at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29145