let ptr_rel op l1 l2 =
match op with
| Lt -> D.lt_pointer l1 l2
| Gt -> D.lt_pointer l2 l1
| Le -> D.le_pointer l1 l2
| Ge -> D.le_pointer l2 l1
| Eq -> F.p_eq l1 l2
| Ne -> F.p_neq l1 l2
| _ -> assert false