Definition intoffloat (x: aval) :=
  match x with
  | F f =>
      match Float.to_int f with
      | Some i => I i
      | None => if va_strict tt then Vbot else ntop
      end
  | _ => ntop1 x
  end.

(* Specifications: *)
Lemma intoffloat_sound: forall v x w, vmatch v x -> Val.intoffloat v = Some w -> vmatch w (intoffloat x).