Proof with eauto with val_erasure.
intros.
destruct v, chunk; simpl; unfold inj_value; simpl;
repeat econstructor...
Qed.

(*TODO: move to other file *)
Lemma val_erasure_offset_ptr:
forall v v' z
(Hval_erasure: val_erasure v v'),
val_erasure (Val.offset_ptr v z) (Val.offset_ptr v' z).