(** Invariance by external call *)

Lemma match_envs_extcall:
forall f cenv e le m lo hi te tle tlo thi tm f' m',
match_envs f cenv e le m lo hi te tle tlo thi ->
Mem.unchanged_on (loc_unmapped f) m m' ->
inject_incr f f' ->
inject_separated f f' m tm ->
Ple hi (Mem.nextblock m) -> Ple thi (Mem.nextblock tm) ->
match_envs f' cenv e le m' lo hi te tle tlo thi.