Hint Resolve node_precise.

Lemma node_contents_eq : forall sh1 sh2 e1 e2 n1 n2 l1 l2 p, readable_share sh1 -> readable_share sh2 ->
repable_signed e1 -> repable_signed e2 -> n1 <> Vundef -> n2 <> Vundef -> l1 <> Vundef -> l2 <> Vundef ->
data_at sh1 tnode (vint e1, (n1, l1)) p * data_at sh2 tnode (vint e2, (n2, l2)) p |--
!!(e1 = e2 /\ n1 = n2 /\ l1 = l2).