Definition addl (x y: aval) :=
  match x, y with
  | L i, L j => L (Int64.add i j)
  | Ptr p, L i | L i, Ptr p => Ptr (if Archi.ptr64 then padd p (Ptrofs.of_int64 i) else poffset p)
  | Ptr p, _   | _, Ptr p   => Ptr (poffset p)
  | Ifptr p, L i | L i, Ifptr p => Ifptr (if Archi.ptr64 then padd p (Ptrofs.of_int64 i) else poffset p)
  | Ifptr p, Ifptr q => Ifptr (plub (poffset p) (poffset q))
  | Ifptr p, _ | _, Ifptr p => Ifptr (poffset p)
  | _, _ => ntop2 x y
  end.

Lemma addl_sound: forall v w x y, vmatch v x -> vmatch w y -> vmatch (Val.addl v w) (addl x y).