Ltac prove_signed_range :=
match goal with
| |- Int.min_signed <= _ <= Int.max_signed =>
normalize; rep_omega
| |- Int64.min_signed <= _ <= Int64.max_signed =>
normalize; rep_omega
end.

Lemma ptr_eq_nullval: ptr_eq nullval nullval.
Hint Resolve ptr_eq_nullval : prove_it_now.