[Bug tree-optimization/21636] New: Missed ccp optimization

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

The following code we miss one ccp optimization:
struct f
{
  int i;
};
int g()throw()
{
  f a;
  a.i = 1;
  f *a1 = &a;
  int *i = &a1->i;
  return *i;  /* This should be turned into a.i */
}

We get right now:
Visiting statement:
a1_3 = &a;

Lattice value changed to CONSTANT &a.  Adding SSA edges to worklist.

Visiting statement:
i_4 = &a1_3->i;

Lattice value changed to VARYING.  Adding SSA edges to worklist.
Adding Destination of edge (0 -> 2) to worklist


we should see that the lattice value for &a1_3->i is really constant if a1_3 is constant.

-- 
           Summary: Missed ccp optimization
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21636