Definition modu (v w: aval) :=
match w, v with
| I i2, I i1 =>
if Int.eq i2 Int.zero
then if va_strict tt then Vbot else ntop
else I (Int.modu i1 i2)
| I i2, _ => uns (provenance v) (usize i2)
| _, _ => ntop2 v w
end.

Lemma modu_sound:
forall v w u x y, vmatch v x -> vmatch w y -> Val.modu v w = Some u -> vmatch u (modu x y).