[Bug tree-optimization/21658] New: CCP does not propagate ADDR_EXPR far enough.

[kazu at cs dot umass dot edu]

Consider:

void
f (void)
{
  int *p, *q, *r;
  int a[10];
  p = &a[5];
  q = p - 1;
  r = q - 1;
  *r = 1;
}

Here is what I get from the first CCP.

f ()
{
  int a[10];
  int * r;
  int * q;
  int * p;

<bb 0>:
  p_1 = &a[5];
  q_2 = &a[4];
  r_3 = q_2 - 4B;
  *r_3 = 1;
  return;

}

Note that p_1 and q_2 are of the form &a[CST], but r_3 is not.

-- 
           Summary: CCP does not propagate ADDR_EXPR far enough.
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: enhancement
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: kazu at cs dot umass dot edu
                CC: dnovillo at redhat dot com,gcc-bugs at gcc dot gnu dot
                    org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21658