Hint Rewrite beq_int_refl : expr_beq.
Definition beq_long (i1 i2 : int64) : bool :=
Zeq_bool (Int64.intval i1) (Int64.intval i2).

(* Specifications: *)
Lemma beq_long_true : forall a b, beq_long a b = true -> a = b.
Lemma beq_long_refl : forall i, beq_long i i = true.
Hint Resolve beq_long_refl : expr_beq.