Definition loword (x: aval) :=
match x with
| L i => I(Int64.loword i)
| _   => ntop1 x
end.

Lemma loword_sound: forall v x, vmatch v x -> vmatch (Val.loword v) (loword x).
Definition hiword (x: aval) :=
match x with
| L i => I(Int64.hiword i)
| _   => ntop1 x
end.