include "ASM/Util.ma".
include "ERTL/ERTL.ma".
include "utilities/adt/set_adt.ma".

definition statement_successors ≝
  λglobals: list ident.
  λs: ertl_statement globals.
  match s with
  [ sequential seq l ⇒
    match seq with
    [ COND acc_a_reg lbl_true ⇒
        set_insert … lbl_true (set_singleton … l)
    | _ ⇒ set_singleton … l ]
  | GOTO l ⇒ set_singleton … l
  | RETURN ⇒ set_empty ?
  ].

definition register_lattice ≝ (set register) × (set Register).
definition lattice_property ≝ register_lattice.
definition lattice_bottom: register_lattice ≝ 〈set_empty register, set_empty Register〉.
definition lattice_psingleton: register → register_lattice ≝
  λr.
    〈set_singleton … r, set_empty …〉.
definition lattice_hsingleton: Register → register_lattice ≝
  λr.
    〈set_empty …, set_singleton … r〉.

definition lattice_join: register_lattice → register_lattice → register_lattice ≝
  λleft.
  λright.
  let 〈lp, lh〉 ≝ left in
  let 〈rp, rh〉 ≝ right in
    〈set_union … lp rp, set_union … lh rh〉.

definition lattice_diff: register_lattice → register_lattice → register_lattice ≝
  λleft.
  λright.
  let 〈lp, lh〉 ≝ left in
  let 〈rp, rh〉 ≝ right in
    〈set_diff … lp rp, set_diff … lh rh〉.

definition lattice_equal: register_lattice → register_lattice → bool ≝
  λleft.
  λright.
  let 〈lp, lh〉 ≝ left in
  let 〈rp, rh〉 ≝ right in
    andb (set_equal … (eq_identifier …) lp rp) (set_equal … eq_Register lh rh).

definition lattice_is_maximal: register_lattice → bool ≝ λl. false.

record lattice_property_sig: Type[1] ≝
{
  lp_type      : Type[0];
  lp_property  : Type[0];
  lp_bottom    : lp_type;
  lp_psingleton: register → lp_type;
  lp_hsingleton: Register → lp_type;
  lp_join      : lp_type → lp_type → lp_type;
  lp_diff      : lp_type → lp_type → lp_type;
  lp_equal     : lp_type → lp_type → bool;
  lp_is_maximal: lp_type → bool
}.

definition property ≝
  mk_lattice_property_sig
    ((set register) × (set Register))
    lattice_property
    lattice_bottom
    lattice_psingleton
    lattice_hsingleton
    lattice_join
    lattice_diff
    lattice_equal
    lattice_is_maximal.

definition defined ≝
  λglobals: list ident.
  λs: ertl_statement globals.
  match s with
  [ sequential seq l ⇒
    match seq with
    [ OP2 op2 r1 r2 _ ⇒
      match op2 with
      [ Add ⇒ lattice_join (lattice_hsingleton RegisterCarry) (lattice_psingleton r1)
      | Addc ⇒ lattice_join (lattice_hsingleton RegisterCarry) (lattice_psingleton r1)
      | Sub ⇒ lattice_join (lattice_hsingleton RegisterCarry)  (lattice_psingleton r1)
      | _ ⇒ lattice_psingleton r1
      ]
    | CLEAR_CARRY ⇒ lattice_hsingleton RegisterCarry
    | SET_CARRY ⇒ lattice_hsingleton RegisterCarry
    | OPACCS opaccs dr1 dr2 sr1 sr2 ⇒
       lattice_join (lattice_psingleton dr1) (lattice_psingleton dr2)
    | OP1 op1 r1 r2 ⇒ lattice_join (lattice_psingleton r1) (lattice_psingleton r2)
    | POP r ⇒ lattice_psingleton r
    | INT r _ ⇒ lattice_psingleton r
    | ADDRESS _ _ r1 r2 ⇒ lattice_join (lattice_psingleton r1) (lattice_psingleton r2)
    | LOAD r _ _ ⇒ lattice_psingleton r
    (* Potentially destroys all caller-save hardware registers. *)
    | CALL_ID id _ _ ⇒ 〈set_empty …, set_from_list … RegisterCallerSaved〉
    | COMMENT c ⇒ lattice_bottom
    | COND r lbl_true ⇒ lattice_bottom
    | STORE acc_a dpl dph ⇒ lattice_bottom
    | COST_LABEL clabel ⇒ lattice_bottom
    | PUSH r ⇒ lattice_bottom
    | MOVE pair_reg ⇒
      (* first register relevant only *)
      let r1 ≝ \fst pair_reg in
      match r1 with
      [ pseudo p ⇒ lattice_psingleton p
      | hardware h ⇒ lattice_hsingleton h
      ]
    | extension ext ⇒
      match ext with
      [ ertl_st_ext_new_frame ⇒ lattice_join (lattice_hsingleton RegisterSPL) (lattice_hsingleton RegisterSPH)
      | ertl_st_ext_del_frame ⇒ lattice_join (lattice_hsingleton RegisterSPL) (lattice_hsingleton RegisterSPH)
      | ertl_st_ext_frame_size r ⇒ lattice_psingleton r]]
  | RETURN ⇒ lattice_bottom
  | GOTO l ⇒ lattice_bottom
  ].

definition ret_regs ≝ set_from_list … RegisterRets.

definition used ≝
  λglobals: list ident.
  λs: ertl_statement globals.
  match s with
  [ sequential seq l ⇒
    match seq with
    [ OP2 op2 acc_a r1 r2 ⇒
      match op2 with
      [ Addc ⇒
        lattice_join (lattice_join (lattice_psingleton r1) (lattice_psingleton r2)) (lattice_hsingleton RegisterCarry)
      | _ ⇒ lattice_join (lattice_psingleton r1) (lattice_psingleton r2)
      ]
    | CLEAR_CARRY ⇒ lattice_bottom
    | SET_CARRY ⇒ lattice_bottom
    (* acc_a and acc_b *)
    | OPACCS opaccs dr1 dr2 sr1 sr2 ⇒
       lattice_join (lattice_psingleton sr1) (lattice_psingleton sr2)
    | OP1 op1 r1 r2 ⇒ lattice_psingleton r2
    | POP r ⇒ lattice_bottom
    | INT r _ ⇒ lattice_bottom
    | ADDRESS _ _ r1 r2 ⇒ lattice_bottom
    | LOAD acc_a dpl dph ⇒ lattice_join (lattice_psingleton dpl) (lattice_psingleton dph)
    (* Reads the hardware registers that are used to pass parameters. *)
    | CALL_ID _ nparams _ ⇒ 〈set_empty …, set_from_list … (prefix ? nparams RegisterParams)〉
    | COMMENT c ⇒ lattice_bottom
    | COND r lbl_true ⇒ lattice_psingleton r
    | STORE acc_a dpl dph ⇒
      lattice_join (lattice_join (lattice_psingleton acc_a) (lattice_psingleton dpl)) (lattice_psingleton dph)
    | COST_LABEL clabel ⇒ lattice_bottom
    | PUSH r ⇒ lattice_psingleton r
    | MOVE pair_reg ⇒
      (* only second reg in pair relevant *)
      let r2 ≝ \snd pair_reg in
      match r2 with
      [ pseudo p ⇒ lattice_psingleton p
      | hardware h ⇒ lattice_hsingleton h
      ]
  | extension ext ⇒
    match ext with
    [ ertl_st_ext_new_frame ⇒ lattice_join (lattice_hsingleton RegisterSPL) (lattice_hsingleton RegisterSPH)
    | ertl_st_ext_del_frame ⇒ lattice_join (lattice_hsingleton RegisterSPL) (lattice_hsingleton RegisterSPH)
    | ertl_st_ext_frame_size r ⇒ lattice_bottom]]
  | RETURN ⇒ 〈set_empty …, set_union … (set_from_list … RegisterCalleeSaved) ret_regs〉
  | GOTO l ⇒ lattice_bottom
  ].

definition eliminable ≝
  λglobals: list ident.
  λl: register_lattice.
  λs: ertl_statement globals.
  let 〈pliveafter, hliveafter〉 ≝ l in
  match s with
  [ sequential seq l ⇒
    match seq with
    [ OP2 op2 r1 r2 r3 ⇒
      if set_member … (eq_identifier …) r1 pliveafter ∨
         set_member … eq_Register RegisterCarry hliveafter then
        None ?
      else
        Some ? l
    | CLEAR_CARRY ⇒ None ?
    | SET_CARRY ⇒ None ?
    | OPACCS opaccs dr1 dr2 sr1 sr2 ⇒
      if set_member … (eq_identifier …) dr1 pliveafter ∨
         set_member … (eq_identifier …) dr2 pliveafter ∨
         set_member … eq_Register RegisterCarry hliveafter then
        None ?
      else
        Some ? l
    | OP1 op1 r1 r2 ⇒
      if set_member … (eq_identifier …) r1 pliveafter ∨
         set_member … eq_Register RegisterCarry hliveafter then
        None ?
      else
        Some ? l
    | POP r ⇒ None ?
    | INT r _ ⇒
      if set_member … (eq_identifier …) r pliveafter ∨
         set_member … eq_Register RegisterCarry hliveafter then
        None ?
      else
        Some ? l
    | ADDRESS _ _ r1 r2 ⇒
      if set_member … (eq_identifier …) r1 pliveafter ∨
         set_member … (eq_identifier …) r2 pliveafter ∨
         set_member … eq_Register RegisterCarry hliveafter then
        None ?
      else
        Some ? l
    | LOAD acc_a dpl dph ⇒
      if set_member ? (eq_identifier …) acc_a pliveafter ∨
         set_member … eq_Register RegisterCarry hliveafter then
        None ?
      else
        Some ? l
    | CALL_ID _ nparams _ ⇒ None ?
    | COMMENT c ⇒ None ?
    | COND r lbl_true ⇒ None ?
    | STORE acc_a dpl dph ⇒ None ?
    | COST_LABEL clabel ⇒ None ?
    | PUSH r ⇒ None ?
    | MOVE pair_reg ⇒
      let r1 ≝ \fst pair_reg in
      let r2 ≝ \snd pair_reg in
      match r1 with
      [ pseudo p1 ⇒
        if set_member … (eq_identifier …) p1 pliveafter ∨
           set_member … eq_Register RegisterCarry hliveafter then
          None ?
        else
          Some ? l
      | hardware h1 ⇒
        if set_member … eq_Register h1 hliveafter then
          None ?
        else
          Some ? l]
    | extension ext ⇒
      match ext with
      [ ertl_st_ext_new_frame ⇒ None ?
      | ertl_st_ext_del_frame ⇒ None ?
      | ertl_st_ext_frame_size r ⇒
        if set_member ? (eq_identifier RegisterTag) r pliveafter ∨
           set_member ? eq_Register RegisterCarry hliveafter then
          None ?
        else
          Some ? l]]
  | GOTO l ⇒ None ?
  | RETURN ⇒ None ?
  ].

definition statement_semantics: ∀globals: list ident. ertl_statement globals → register_lattice → register_lattice ≝
  λglobals.
  λstmt.
  λliveafter.
  match eliminable globals liveafter stmt with
  [ None ⇒ lattice_join (lattice_diff liveafter (defined globals stmt)) (used globals stmt)
  | Some l ⇒ liveafter
  ].

definition valuation ≝ label → register_lattice.
definition rhs ≝ valuation → lattice_property.
definition equations ≝ label → rhs.

axiom fix_lfp: equations → valuation.

definition livebefore ≝
  λglobals: list ident.
  λint_fun: ertl_internal_function globals.
  λlabel.
  λliveafter: valuation.
  match lookup … (joint_if_code … int_fun) label with
  [ None      ⇒ ?
  | Some stmt ⇒ statement_semantics globals stmt (liveafter label)
  ].
  cases not_implemented (* XXX *)
qed.

definition liveafter ≝
  λglobals: list ident.
  λint_fun: ertl_internal_function globals.
  λlivebefore: label → ?.
  λlabel.
  λliveafter: valuation.
  match lookup … (joint_if_code … int_fun) label with
  [ None      ⇒ ?
  | Some stmt ⇒ set_fold ? ? (λsuccessor. λaccu: register_lattice.
      lattice_join (livebefore successor liveafter) accu)
      (statement_successors globals stmt) lattice_bottom
  ].
  cases not_implemented (* XXX *)
qed.

definition analyse ≝
  λglobals.
  λint_fun.
    fix_lfp (liveafter globals int_fun (livebefore globals int_fun)).