Module Lineartyping

Require Import Coqlib.
Require Import AST.
Require Import Integers.
Require Import Values.
Require Import Globalenvs.
Require Import Memory.
Require Import Events.
Require Import Op.
Require Import Machregs.
Require Import Locations.
Require Import Conventions.
Require Import LTL.
Require Import Linear.


Section WT_INSTR.

Variable funct: function.

Definition slot_valid (sl: slot) (ofs: Z) (ty: typ): bool :=
  match sl with
  | Local => zle 0 ofs
  | Outgoing => zle 0 ofs
  | Incoming => In_dec Loc.eq (S Incoming ofs ty) (regs_of_rpairs (loc_parameters funct.(fn_sig)))
  end
  && Zdivide_dec (typealign ty) ofs.

Definition slot_writable (sl: slot) : bool :=
  match sl with
  | Local => true
  | Outgoing => true
  | Incoming => false
  end.

Definition loc_valid (l: loc) : bool :=
  match l with
  | R r => true
  | S Local ofs ty => slot_valid Local ofs ty
  | S _ _ _ => false
  end.

Fixpoint wt_builtin_res (ty: typ) (res: builtin_res mreg) : bool :=
  match res with
  | BR r => subtype ty (mreg_type r)
  | BR_none => true
  | BR_splitlong hi lo => wt_builtin_res Tint hi && wt_builtin_res Tint lo
  end.

Definition wt_instr (i: instruction) : bool :=
  match i with
  | Lgetstack sl ofs ty r =>
      subtype ty (mreg_type r) && slot_valid sl ofs ty
  | Lsetstack r sl ofs ty =>
      slot_valid sl ofs ty && slot_writable sl
  | Lop op args res =>
      match is_move_operation op args with
      | Some arg =>
          subtype (mreg_type arg) (mreg_type res)
      | None =>
          let (targs, tres) := type_of_operation op in
          subtype tres (mreg_type res)
      end
  | Lload chunk addr args dst =>
      subtype (type_of_chunk chunk) (mreg_type dst)
  | Ltailcall sg ros =>
      zeq (size_arguments sg) 0
  | Lbuiltin ef args res =>
      wt_builtin_res (proj_sig_res (ef_sig ef)) res
      && forallb loc_valid (params_of_builtin_args args)
  | _ =>
      true
  end.

End WT_INSTR.

Definition wt_code (f: function) (c: code) : bool :=
  forallb (wt_instr f) c.

Definition wt_function (f: function) : bool :=
  wt_code f f.(fn_code).


Definition wt_locset (ls: locset) : Prop :=
  forall l, Val.has_type (ls l) (Loc.type l).

Lemma wt_setreg:
  forall ls r v,
  Val.has_type v (mreg_type r) -> wt_locset ls -> wt_locset (Locmap.set (R r) v ls).

Lemma wt_setstack:
  forall ls sl ofs ty v,
  wt_locset ls -> wt_locset (Locmap.set (S sl ofs ty) v ls).

Lemma wt_undef_regs:
  forall rs ls, wt_locset ls -> wt_locset (undef_regs rs ls).

Lemma wt_call_regs:
  forall ls, wt_locset ls -> wt_locset (call_regs ls).

Lemma wt_return_regs:
  forall caller callee,
  wt_locset caller -> wt_locset callee -> wt_locset (return_regs caller callee).

Lemma wt_undef_caller_save_regs:
  forall ls, wt_locset ls -> wt_locset (undef_caller_save_regs ls).

Lemma wt_init:
  wt_locset (Locmap.init Vundef).

Lemma wt_setpair:
  forall sg v rs,
  Val.has_type v (proj_sig_res sg) ->
  wt_locset rs ->
  wt_locset (Locmap.setpair (loc_result sg) v rs).

Lemma wt_setres:
  forall res ty v rs,
  wt_builtin_res ty res = true ->
  Val.has_type v ty ->
  wt_locset rs ->
  wt_locset (Locmap.setres res v rs).

Lemma wt_find_label:
  forall f lbl c,
  wt_function f = true ->
  find_label lbl f.(fn_code) = Some c ->
  wt_code f c = true.


Definition agree_outgoing_arguments (sg: signature) (ls pls: locset) : Prop :=
  forall ty ofs,
  In (S Outgoing ofs ty) (regs_of_rpairs (loc_arguments sg)) ->
  ls (S Outgoing ofs ty) = pls (S Outgoing ofs ty).


Definition outgoing_undef (ls: locset) : Prop :=
  forall ty ofs, ls (S Outgoing ofs ty) = Vundef.


Definition wt_fundef (fd: fundef) :=
  match fd with
  | Internal f => wt_function f = true
  | External ef => True
  end.

Inductive wt_callstack: list stackframe -> Prop :=
  | wt_callstack_nil:
      wt_callstack nil
  | wt_callstack_cons: forall f sp rs c s
        (WTSTK: wt_callstack s)
        (WTF: wt_function f = true)
        (WTC: wt_code f c = true)
        (WTRS: wt_locset rs),
      wt_callstack (Stackframe f sp rs c :: s).

Lemma wt_parent_locset:
  forall s, wt_callstack s -> wt_locset (parent_locset s).

Inductive wt_state: state -> Prop :=
  | wt_regular_state: forall s f sp c rs m
        (WTSTK: wt_callstack s )
        (WTF: wt_function f = true)
        (WTC: wt_code f c = true)
        (WTRS: wt_locset rs),
      wt_state (State s f sp c rs m)
  | wt_call_state: forall s fd rs m
        (WTSTK: wt_callstack s)
        (WTFD: wt_fundef fd)
        (WTRS: wt_locset rs)
        (AGCS: agree_callee_save rs (parent_locset s))
        (AGARGS: agree_outgoing_arguments (funsig fd) rs (parent_locset s)),
      wt_state (Callstate s fd rs m)
  | wt_return_state: forall s rs m
        (WTSTK: wt_callstack s)
        (WTRS: wt_locset rs)
        (AGCS: agree_callee_save rs (parent_locset s))
        (UOUT: outgoing_undef rs),
      wt_state (Returnstate s rs m).


Section SOUNDNESS.

Variable prog: program.
Let ge := Genv.globalenv prog.

Hypothesis wt_prog:
  forall i fd, In (i, Gfun fd) prog.(prog_defs) -> wt_fundef fd.

Lemma wt_find_function:
  forall ros rs f, find_function ge ros rs = Some f -> wt_fundef f.

Theorem step_type_preservation:
  forall S1 t S2, step ge S1 t S2 -> wt_state S1 -> wt_state S2.

Theorem wt_initial_state:
  forall S, initial_state prog S -> wt_state S.

End SOUNDNESS.


Lemma wt_state_getstack:
  forall s f sp sl ofs ty rd c rs m,
  wt_state (State s f sp (Lgetstack sl ofs ty rd :: c) rs m) ->
  slot_valid f sl ofs ty = true.

Lemma wt_state_setstack:
  forall s f sp sl ofs ty r c rs m,
  wt_state (State s f sp (Lsetstack r sl ofs ty :: c) rs m) ->
  slot_valid f sl ofs ty = true /\ slot_writable sl = true.

Lemma wt_state_tailcall:
  forall s f sp sg ros c rs m,
  wt_state (State s f sp (Ltailcall sg ros :: c) rs m) ->
  size_arguments sg = 0.

Lemma wt_state_builtin:
  forall s f sp ef args res c rs m,
  wt_state (State s f sp (Lbuiltin ef args res :: c) rs m) ->
  forallb (loc_valid f) (params_of_builtin_args args) = true.

Lemma wt_callstate_wt_regs:
  forall s f rs m,
  wt_state (Callstate s f rs m) ->
  forall r, Val.has_type (rs (R r)) (mreg_type r).

Lemma wt_callstate_agree:
  forall s f rs m,
  wt_state (Callstate s f rs m) ->
  agree_callee_save rs (parent_locset s) /\ agree_outgoing_arguments (funsig f) rs (parent_locset s).

Lemma wt_returnstate_agree:
  forall s rs m,
  wt_state (Returnstate s rs m) ->
  agree_callee_save rs (parent_locset s) /\ outgoing_undef rs.