Definition val_inject_opt (j: meminj) (v1 v2: option val) :=
  match v1, v2 with Some v1', Some v2' => val_inject j v1' v2'
  | None, None => True
  | _, _ => False
  end.

Lemma loadbytes_D: forall m b ofs n bytes (LD: Mem.loadbytes m b ofs n = Some bytes), Mem.range_perm m b ofs (ofs + n) Cur Readable /\ bytes = Mem.getN (nat_of_Z n) ofs (PMap.get b (Mem.mem_contents m)).