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

Lemma valid_val_compare_ints:
forall f rs m v1 v2 r,
regset_wd f rs ->
valid_val f (compare_ints v1 v2 rs m r).