Definition floatofwords (x y: aval) :=
match x, y with
| I i, I j => F(Float.from_words i j)
| _, _     => ntop2 x y
end.

Lemma floatofwords_sound:
forall v w x y, vmatch v x -> vmatch w y -> vmatch (Val.floatofwords v w) (floatofwords x y).