Proof with eauto with val_renamings.
intros;
destruct vhi; inversion Hobs_hi; subst; simpl...
destruct vlo; inversion Hobs_lo...
Qed.

Lemma val_obs_load_result:
forall f v v' chunk
(Hval_obs: val_obs f v v'),
val_obs f (Val.load_result chunk v) (Val.load_result chunk v').