Hint Rewrite is_pointer_force_int_ptr2 using assumption : norm1.

Lemma is_pointer_or_null_force_int_ptr2:
forall v, is_pointer_or_null (force_val
match v with
| Vint _ => Some v
| Vptr _ _ => Some v
| _ => None
end) -> (force_val
match v with
| Vint _ => Some v
| Vptr _ _ => Some v
| _ => None
end) = v.