Definition shru (v w: aval) :=
match w with
| I amount =>
if Int.ltu amount Int.iwordsize then
match v with
| I i => I (Int.shru i amount)
| Uns p n => uns p (n - Int.unsigned amount)
| _ => uns (provenance v) (Int.zwordsize - Int.unsigned amount)
end
else ntop1 v
| _ => ntop1 v
end.

Lemma shru_sound:
forall v w x y, vmatch v x -> vmatch w y -> vmatch (Val.shru v w) (shru x y).