Definition advance_next (gl: list (ident * globdef F V)) (x: positive) :=
List.fold_left (fun n g => Pos.succ n) gl x.
Remark genv_next_add_globals:
forall gl ge,
genv_next (add_globals ge gl) = advance_next gl (genv_next ge).
Remark genv_public_add_globals:
forall gl ge,
genv_public (add_globals ge gl) = genv_public ge.

Theorem block_is_volatile_below:
forall ge b, block_is_volatile ge b = true ->  Plt b ge.(genv_next).