Proof with eauto with wd.
intros.
destruct v1,v2; simpl; auto;
unfold Val.cmpu, Val.cmpu_bool...
Qed.
Hint Immediate valid_val_cmpu :wd.

(* Specifications: *)
Lemma valid_val_cmplu:
forall f ptr c v1 v2,
valid_val f (Val.maketotal (Val.cmplu ptr c v1 v2)).