Module ConseqFacts :=
SeparationLogicFacts.GenConseqFacts
(SeparationLogicAsLogicSoundness.MainTheorem.CSHL_PracticalLogic.CSHL_MinimumLogic.CSHL_Def)
(Conseq).
(* OLD VERSION: Lemma semax_post': forall R' Espec {cs: compspecs} Delta R P c, R' |-- R -> @semax cs Espec Delta P c (normal_ret_assert R') -> @semax cs Espec Delta P c (normal_ret_assert R). *)
intros.
destruct Q as [?Q ?Q ?Q ?Q].
eapply semax_post; eauto; intros; apply andp_left2; simpl; auto; normalize.
Qed.
Ltac frame_SEP' L :=  (* this should be generalized to permit framing on LOCAL part too *)
grab_indexes_SEP L;
match goal with
| |- @semax _ _ (PROPx _ (LOCALx _ (SEPx ?R))) _ _ =>
rewrite <- (firstn_skipn (length L) R);
simpl length; unfold firstn, skipn;
eapply (semax_frame_PQR nil);
[ unfold closed_wrt_modvars;  auto 50 with closed
| ]
| |- ENTAIL _ , (PROPx _ (LOCALx _ (SEPx ?R))) |-- _ =>
rewrite <- (firstn_skipn (length L) R);
simpl length; unfold firstn, skipn;
apply derives_frame_PQR
end.
Tactic Notation "frame_SEP" constr(a) :=
frame_SEP' (a::nil).
Tactic Notation "frame_SEP" constr(a) constr(b) :=
frame_SEP' (a::b::nil).
Tactic Notation "frame_SEP" constr(a) constr(b) constr(c) :=
frame_SEP' (a::b::c::nil).
Tactic Notation "frame_SEP" constr(a) constr(b) constr(c) constr(d) :=
frame_SEP' (a::b::c::d::nil).
Tactic Notation "frame_SEP" constr(a) constr(b) constr(c) constr(d) constr(e) :=
frame_SEP' (a::b::c::d::e::nil).
Tactic Notation "frame_SEP" constr(a) constr(b) constr(c) constr(d) constr(e) constr(f) :=
frame_SEP' (a::b::c::d::e::f::nil).
Tactic Notation "frame_SEP" constr(a) constr(b) constr(c) constr(d) constr(e) constr(f) constr(g) :=
frame_SEP' (a::b::c::d::e::f::g::nil).
Tactic Notation "frame_SEP" constr(a) constr(b) constr(c) constr(d) constr(e) constr(f) constr(g) constr(h) :=
frame_SEP' (a::b::c::d::e::f::g::h::nil).
Tactic Notation "frame_SEP" constr(a) constr(b) constr(c) constr(d) constr(e) constr(f) constr(g) constr(h) constr(i) :=
frame_SEP' (a::b::c::d::e::f::g::h::i::nil).
Tactic Notation "frame_SEP" constr(a) constr(b) constr(c) constr(d) constr(e) constr(f) constr(g) constr(h) constr(i) constr(j) :=
frame_SEP' (a::b::c::d::e::f::g::h::i::j::nil).
Ltac gather_SEP' L :=
grab_indexes_SEP L;
match goal with |- context [SEPx ?R] =>
let r := fresh "R" in
set (r := (SEPx R));
revert r;
rewrite <- (firstn_skipn (length L) R);
unfold length at 1 2;
unfold firstn at 1; unfold skipn at 1;
rewrite gather_SEP;
unfold fold_right at 1; try  rewrite sepcon_emp;
try (intro r; unfold r; clear r)
end.
(* replaced by the new gather_SEP in freezer.v ... Tactic Notation "gather_SEP" constr(a) := gather_SEP' (a::nil). Tactic Notation "gather_SEP" constr(a) constr(b) := gather_SEP' (a::b::nil). Tactic Notation "gather_SEP" constr(a) constr(b) constr(c) := gather_SEP' (a::b::c::nil). Tactic Notation "gather_SEP" constr(a) constr(b) constr(c) constr(d) := gather_SEP' (a::b::c::d::nil). Tactic Notation "gather_SEP" constr(a) constr(b) constr(c) constr(d) constr(e) := gather_SEP' (a::b::c::d::e::nil). Tactic Notation "gather_SEP" constr(a) constr(b) constr(c) constr(d) constr(e) constr(f) := gather_SEP' (a::b::c::d::e::f::nil). Tactic Notation "gather_SEP" constr(a) constr(b) constr(c) constr(d) constr(e) constr(f) constr(g) := gather_SEP' (a::b::c::d::e::f::g::nil). Tactic Notation "gather_SEP" constr(a) constr(b) constr(c) constr(d) constr(e) constr(f) constr(g) constr(h) := gather_SEP' (a::b::c::d::e::f::g::h::nil). Tactic Notation "gather_SEP" constr(a) constr(b) constr(c) constr(d) constr(e) constr(f) constr(g) constr(h) constr(i) := gather_SEP' (a::b::c::d::e::f::g::h::i::nil). Tactic Notation "gather_SEP" constr(a) constr(b) constr(c) constr(d) constr(e) constr(f) constr(g) constr(h) constr(i) constr(j) := gather_SEP' (a::b::c::d::e::f::g::h::i::j::nil). *)
Fixpoint replace_nth {A} (n: nat) (al: list A) (x: A) {struct n}: list A :=
match n, al with
| O , a::al => x::al
| S n', a::al' => a :: replace_nth n' al' x
| _, nil => nil
end.
Fixpoint my_nth{A} (n: nat) (al: list A) (default: A) {struct n} : A :=
(* just like nth; make a new copy, for better control of unfolding *)
match n, al with
| O, a::al' => a
| S n', a::al' => my_nth n' al' default
| _, nil => default
end.

Lemma replace_nth_commute:
forall {A} i j R (a b: A),
i <> j ->
replace_nth i (replace_nth j R b) a =
replace_nth j (replace_nth i R a) b.