Definition weak_mapsto_ sh e rho :=
match (eval_expr e rho) with
| Vptr b o => (mapsto_ sh (typeof e) (Vptr b o)) ||
              (mapsto_ sh (typeof e) (Vptr b o))
| _ => FF
end.

Lemma extend_sepcon_TT {A} {JA: Join A} {PA: Perm_alg A}{SA: Sep_alg A} {AG: ageable A} {Aga: Age_alg A}: forall P, boxy extendM (P * TT).