Definition force_valid_pointers m v1 v2 :=
match v1, v2 with
| Vptr b1 ofs1, Vptr b2 ofs2 =>
    (Mem.valid_pointer m b1 (Ptrofs.unsigned ofs1) &&
    Mem.valid_pointer m b2 (Ptrofs.unsigned ofs2))%bool
| _, _ => false
end.Definition blocks_match op v1 v2 :=
match op with Cop.Olt | Cop.Ogt | Cop.Ole | Cop.Oge =>
  match v1, v2 with
    Vptr b _, Vptr b2 _ => b=b2
    | _, _ => False
  end
| _ => True
end.

Lemma mapsto_valid_pointer : forall b o sh t jm, nonidentity sh -> (mapsto_ sh (t) (Vptr b o) * TT)%pred (m_phi jm) -> Mem.valid_pointer (m_dry jm) b (Ptrofs.unsigned o) = true.