Fixpoint freelist_no_overlap (l: list (block * Z * Z)) : Prop :=
  match l with
  | nil => True
  | (b, lo, hi) :: l' =>
      freelist_no_overlap l' /\
      (forall b' lo' hi', In (b', lo', hi') l' ->
       b' <> b \/ hi' <= lo \/ hi <= lo')
  end.

Theorem match_envs_free_blocks: forall j cenv e le m lo hi te tle tlo thi m' tm, match_envs j cenv e le m lo hi te tle tlo thi -> Mem.inject j m tm -> Mem.free_list m (blocks_of_env ge e) = Some m' -> exists tm', Mem.free_list tm (blocks_of_env tge te) = Some tm' /\ Mem.inject j m' tm'.