Definition option_list_to_list {A} (x: option (list A)) : list A :=
 match x with Some al => al | None => nil end.

(* Specifications: *)
Lemma Vptrofs_inj : forall o1 o2, Vptrofs o1 = Vptrofs o2 -> Ptrofs.unsigned o1 = Ptrofs.unsigned o2.
Lemma builtin_event_determ ef m vargs T1 (BE1: builtin_event ef m vargs T1) T2 (BE2: builtin_event ef m vargs T2): T1=T2.