(** Preservation of [match_callstack] by external calls. *)

Lemma match_callstack_external_call:
forall f1 f2 m1 m2 m1' m2',
Mem.unchanged_on (loc_unmapped f1) m1 m2 ->
Mem.unchanged_on (loc_out_of_reach f1 m1) m1' m2' ->
inject_incr f1 f2 ->
inject_separated f1 f2 m1 m1' ->
(forall b ofs p, Mem.valid_block m1 b -> Mem.perm m2 b ofs Max p -> Mem.perm m1 b ofs Max p) ->
forall cs bound tbound,
match_callstack f1 m1 m1' cs bound tbound ->
Ple bound (Mem.nextblock m1) -> Ple tbound (Mem.nextblock m1') ->
match_callstack f2 m2 m2' cs bound tbound.