Module ValueAnalysis


Require Import Coqlib Maps Integers Floats Lattice Kildall.
Require Import Compopts AST Linking.
Require Import Values Memory Globalenvs Events.
Require Import Registers Op RTL.
Require Import ValueDomain ValueAOp Liveness.

The dataflow analysis


Definition areg (ae: aenv) (r: reg) : aval := AE.get r ae.

Definition aregs (ae: aenv) (rl: list reg) : list aval := List.map (areg ae) rl.

Analysis of function calls. We treat specially the case where neither the arguments nor the global variables point within the stack frame of the current function. In this case, no pointer within the stack frame escapes during the call.

Definition mafter_public_call : amem := mtop.

Definition mafter_private_call (am_before: amem) : amem :=
  {| am_stack := am_before.(am_stack);
     am_glob := PTree.empty _;
     am_nonstack := Nonstack;
     am_top := plub (ab_summary (am_stack am_before)) Nonstack |}.

Definition analyze_call (am: amem) (aargs: list aval) :=
  if pincl am.(am_nonstack) Nonstack
  && forallb (fun av => vpincl av Nonstack) aargs
  then (Ifptr Nonstack, mafter_private_call am)
  else (Vtop, mafter_public_call).

Definition transfer_call (ae: aenv) (am: amem) (args: list reg) (res: reg) :=
  let (av, am') := analyze_call am (aregs ae args) in
  VA.State (AE.set res av ae) am'.

Analysis of builtins.

Fixpoint abuiltin_arg (ae: aenv) (am: amem) (rm: romem) (ba: builtin_arg reg) : aval :=
  match ba with
  | BA r => areg ae r
  | BA_int n => I n
  | BA_long n => L n
  | BA_float n => F n
  | BA_single n => FS n
  | BA_loadstack chunk ofs => loadv chunk rm am (Ptr (Stk ofs))
  | BA_addrstack ofs => Ptr (Stk ofs)
  | BA_loadglobal chunk id ofs => loadv chunk rm am (Ptr (Gl id ofs))
  | BA_addrglobal id ofs => Ptr (Gl id ofs)
  | BA_splitlong hi lo => longofwords (abuiltin_arg ae am rm hi) (abuiltin_arg ae am rm lo)
  end.

Definition set_builtin_res (br: builtin_res reg) (av: aval) (ae: aenv) : aenv :=
  match br with
  | BR r => AE.set r av ae
  | _ => ae
  end.

Definition transfer_builtin_default
              (ae: aenv) (am: amem) (rm: romem)
              (args: list (builtin_arg reg)) (res: builtin_res reg) :=
  let (av, am') := analyze_call am (map (abuiltin_arg ae am rm) args) in
  VA.State (set_builtin_res res av ae) am'.

Definition transfer_builtin
              (ae: aenv) (am: amem) (rm: romem) (ef: external_function)
              (args: list (builtin_arg reg)) (res: builtin_res reg) :=
  match ef, args with
  | EF_vload chunk, addr :: nil =>
      let aaddr := abuiltin_arg ae am rm addr in
      let a :=
        if va_strict tt
        then vlub (loadv chunk rm am aaddr) (vnormalize chunk (Ifptr Glob))
        else vnormalize chunk Vtop in
      VA.State (set_builtin_res res a ae) am
  | EF_vstore chunk, addr :: v :: nil =>
      let aaddr := abuiltin_arg ae am rm addr in
      let av := abuiltin_arg ae am rm v in
      let am' := storev chunk am aaddr av in
      VA.State (set_builtin_res res ntop ae) (mlub am am')
  | EF_memcpy sz al, dst :: src :: nil =>
      let adst := abuiltin_arg ae am rm dst in
      let asrc := abuiltin_arg ae am rm src in
      let p := loadbytes am rm (aptr_of_aval asrc) in
      let am' := storebytes am (aptr_of_aval adst) sz p in
      VA.State (set_builtin_res res ntop ae) am'
  | (EF_annot _ _ | EF_debug _ _ _), _ =>
      VA.State (set_builtin_res res ntop ae) am
  | EF_annot_val _ _, v :: nil =>
      let av := abuiltin_arg ae am rm v in
      VA.State (set_builtin_res res av ae) am
  | _, _ =>
      transfer_builtin_default ae am rm args res
  end.

The transfer function for one instruction. Given the abstract state "before" the instruction, computes the abstract state "after".

Definition transfer (f: function) (rm: romem) (pc: node) (ae: aenv) (am: amem) : VA.t :=
  match f.(fn_code)!pc with
  | None =>
      VA.Bot
  | Some(Inop s) =>
      VA.State ae am
  | Some(Iop op args res s) =>
      let a := eval_static_operation op (aregs ae args) in
      VA.State (AE.set res a ae) am
  | Some(Iload chunk addr args dst s) =>
      let a := loadv chunk rm am (eval_static_addressing addr (aregs ae args)) in
      VA.State (AE.set dst a ae) am
  | Some(Istore chunk addr args src s) =>
      let am' := storev chunk am (eval_static_addressing addr (aregs ae args)) (areg ae src) in
      VA.State ae am'
  | Some(Icall sig ros args res s) =>
      transfer_call ae am args res
  | Some(Itailcall sig ros args) =>
      VA.Bot
  | Some(Ibuiltin ef args res s) =>
      transfer_builtin ae am rm ef args res
  | Some(Icond cond args s1 s2) =>
      VA.State ae am
  | Some(Ijumptable arg tbl) =>
      VA.State ae am
  | Some(Ireturn arg) =>
      VA.Bot
  end.

A wrapper on transfer that removes information associated with dead registers, so as to reduce the sizes of abstract states.

Definition transfer' (f: function) (lastuses: PTree.t (list reg)) (rm: romem)
                     (pc: node) (before: VA.t) : VA.t :=
  match before with
  | VA.Bot => VA.Bot
  | VA.State ae am =>
      match transfer f rm pc ae am with
      | VA.Bot => VA.Bot
      | VA.State ae' am' =>
          let ae'' :=
            match lastuses!pc with
            | None => ae'
            | Some regs => eforget regs ae'
            end in
          VA.State ae'' am'
     end
  end.

The forward dataflow analysis.

Module DS := Dataflow_Solver(VA)(NodeSetForward).

Definition mfunction_entry :=
  {| am_stack := ablock_init Pbot;
     am_glob := PTree.empty _;
     am_nonstack := Nonstack;
     am_top := Nonstack |}.

Definition analyze (rm: romem) (f: function): PMap.t VA.t :=
  let lu := Liveness.last_uses f in
  let entry := VA.State (einit_regs f.(fn_params)) mfunction_entry in
  match DS.fixpoint f.(fn_code) successors_instr (transfer' f lu rm)
                    f.(fn_entrypoint) entry with
  | None => PMap.init (VA.State AE.top mtop)
  | Some res => res
  end.

Constructing the approximation of read-only globals

Definition store_init_data (ab: ablock) (p: Z) (id: init_data) : ablock :=
  match id with
  | Init_int8 n => ablock_store Mint8unsigned ab p (I n)
  | Init_int16 n => ablock_store Mint16unsigned ab p (I n)
  | Init_int32 n => ablock_store Mint32 ab p (I n)
  | Init_int64 n => ablock_store Mint64 ab p (L n)
  | Init_float32 n => ablock_store Mfloat32 ab p
                        (if propagate_float_constants tt then FS n else ntop)
  | Init_float64 n => ablock_store Mfloat64 ab p
                        (if propagate_float_constants tt then F n else ntop)
  | Init_addrof symb ofs => ablock_store Mptr ab p (Ptr (Gl symb ofs))
  | Init_space n => ab
  end.

Fixpoint store_init_data_list (ab: ablock) (p: Z) (idl: list init_data)
                              {struct idl}: ablock :=
  match idl with
  | nil => ab
  | id :: idl' => store_init_data_list (store_init_data ab p id) (p + init_data_size id) idl'
  end.

When CompCert is used in separate compilation mode, the gvar_init initializer attached to a readonly global variable may not correspond to the actual initial value of this global. This occurs in two cases: In both cases, the variable can be defined and initialized in another compilation unit which is later linked with the current compilation unit.

Definition definitive_initializer (init: list init_data) : bool :=
  match init with
  | nil => false
  | Init_space _ :: nil => false
  | _ => true
  end.

Definition alloc_global (rm: romem) (idg: ident * globdef fundef unit): romem :=
  match idg with
  | (id, Gfun f) =>
      PTree.remove id rm
  | (id, Gvar v) =>
      if v.(gvar_readonly) && negb v.(gvar_volatile) && definitive_initializer v.(gvar_init)
      then PTree.set id (store_init_data_list (ablock_init Pbot) 0 v.(gvar_init)) rm
      else PTree.remove id rm
  end.

Definition romem_for (p: program) : romem :=
  List.fold_left alloc_global p.(prog_defs) (PTree.empty _).

Soundness proof


Properties of the dataflow solution.

Lemma analyze_entrypoint:
  forall rm f vl m bc,
  (forall v, In v vl -> vmatch bc v (Ifptr Nonstack)) ->
  mmatch bc m mfunction_entry ->
  exists ae am,
     (analyze rm f)!!(fn_entrypoint f) = VA.State ae am
  /\ ematch bc (init_regs vl (fn_params f)) ae
  /\ mmatch bc m am.
Proof.
  intros.
  unfold analyze.
  set (lu := Liveness.last_uses f).
  set (entry := VA.State (einit_regs f.(fn_params)) mfunction_entry).
  destruct (DS.fixpoint (fn_code f) successors_instr (transfer' f lu rm)
                        (fn_entrypoint f) entry) as [res|] eqn:FIX.
- assert (A: VA.ge res!!(fn_entrypoint f) entry) by (eapply DS.fixpoint_entry; eauto).
  destruct (res!!(fn_entrypoint f)) as [ | ae am ]; simpl in A. contradiction.
  destruct A as [A1 A2].
  exists ae, am.
  split. auto.
  split. eapply ematch_ge; eauto. apply ematch_init; auto.
  auto.
- exists AE.top, mtop.
  split. apply PMap.gi.
  split. apply ematch_ge with (einit_regs (fn_params f)).
  apply ematch_init; auto. apply AE.ge_top.
  eapply mmatch_top'; eauto.
Qed.

Lemma analyze_successor:
  forall f n ae am instr s rm ae' am',
  (analyze rm f)!!n = VA.State ae am ->
  f.(fn_code)!n = Some instr ->
  In s (successors_instr instr) ->
  transfer f rm n ae am = VA.State ae' am' ->
  VA.ge (analyze rm f)!!s (transfer f rm n ae am).
Proof.
  unfold analyze; intros.
  set (lu := Liveness.last_uses f) in *.
  set (entry := VA.State (einit_regs f.(fn_params)) mfunction_entry) in *.
  destruct (DS.fixpoint (fn_code f) successors_instr (transfer' f lu rm)
                        (fn_entrypoint f) entry) as [res|] eqn:FIX.
- assert (A: VA.ge res!!s (transfer' f lu rm n res#n)).
  { eapply DS.fixpoint_solution; eauto with coqlib.
    intros. unfold transfer'. simpl. auto. }
  rewrite H in A. unfold transfer' in A. rewrite H2 in A. rewrite H2.
  destruct lu!n.
  eapply VA.ge_trans. eauto. split; auto. apply eforget_ge.
  auto.
- rewrite H2. rewrite PMap.gi. split; intros. apply AE.ge_top. eapply mmatch_top'; eauto.
Qed.

Lemma analyze_succ:
  forall e m rm f n ae am instr s ae' am' bc,
  (analyze rm f)!!n = VA.State ae am ->
  f.(fn_code)!n = Some instr ->
  In s (successors_instr instr) ->
  transfer f rm n ae am = VA.State ae' am' ->
  ematch bc e ae' ->
  mmatch bc m am' ->
  exists ae'' am'',
     (analyze rm f)!!s = VA.State ae'' am''
  /\ ematch bc e ae''
  /\ mmatch bc m am''.
Proof.
  intros. exploit analyze_successor; eauto. rewrite H2.
  destruct (analyze rm f)#s as [ | ae'' am'']; simpl; try tauto. intros [A B].
  exists ae'', am''.
  split. auto.
  split. eapply ematch_ge; eauto. eauto.
Qed.

Analysis of registers and builtin arguments


Lemma areg_sound:
  forall bc e ae r, ematch bc e ae -> vmatch bc (e#r) (areg ae r).
Proof.
  intros. apply H.
Qed.

Lemma aregs_sound:
  forall bc e ae rl, ematch bc e ae -> list_forall2 (vmatch bc) (e##rl) (aregs ae rl).
Proof.
  induction rl; simpl; intros. constructor. constructor; auto. apply areg_sound; auto.
Qed.

Hint Resolve areg_sound aregs_sound: va.

Lemma abuiltin_arg_sound:
  forall bc ge rs sp m ae rm am,
  ematch bc rs ae ->
  romatch bc m rm ->
  mmatch bc m am ->
  genv_match bc ge ->
  bc sp = BCstack ->
  forall a v,
  eval_builtin_arg ge (fun r => rs#r) (Vptr sp Ptrofs.zero) m a v ->
  vmatch bc v (abuiltin_arg ae am rm a).
Proof.
  intros until am; intros EM RM MM GM SP.
  induction 1; simpl; eauto with va.
- eapply loadv_sound; eauto. simpl. rewrite Ptrofs.add_zero_l. auto with va.
- simpl. rewrite Ptrofs.add_zero_l. auto with va.
- eapply loadv_sound; eauto. apply symbol_address_sound; auto.
- apply symbol_address_sound; auto.
Qed.

Lemma abuiltin_args_sound:
  forall bc ge rs sp m ae rm am,
  ematch bc rs ae ->
  romatch bc m rm ->
  mmatch bc m am ->
  genv_match bc ge ->
  bc sp = BCstack ->
  forall al vl,
  eval_builtin_args ge (fun r => rs#r) (Vptr sp Ptrofs.zero) m al vl ->
  list_forall2 (vmatch bc) vl (map (abuiltin_arg ae am rm) al).
Proof.
  intros until am; intros EM RM MM GM SP.
  induction 1; simpl.
- constructor.
- constructor; auto. eapply abuiltin_arg_sound; eauto.
Qed.

Lemma set_builtin_res_sound:
  forall bc rs ae v av res,
  ematch bc rs ae ->
  vmatch bc v av ->
  ematch bc (regmap_setres res v rs) (set_builtin_res res av ae).
Proof.
  intros. destruct res; simpl; auto. apply ematch_update; auto.
Qed.

Constructing block classifications


Definition bc_nostack (bc: block_classification) : Prop :=
  forall b, bc b <> BCstack.

Section NOSTACK.

Variable bc: block_classification.
Hypothesis NOSTACK: bc_nostack bc.

Lemma pmatch_no_stack: forall b ofs p, pmatch bc b ofs p -> pmatch bc b ofs Nonstack.
Proof.
  intros. inv H; constructor; congruence.
Qed.

Lemma vmatch_no_stack: forall v x, vmatch bc v x -> vmatch bc v (Ifptr Nonstack).
Proof.
  induction 1; constructor; auto; eapply pmatch_no_stack; eauto.
Qed.

Lemma smatch_no_stack: forall m b p, smatch bc m b p -> smatch bc m b Nonstack.
Proof.
  intros. destruct H as [A B]. split; intros.
  eapply vmatch_no_stack; eauto.
  eapply pmatch_no_stack; eauto.
Qed.

Lemma mmatch_no_stack: forall m am astk,
  mmatch bc m am -> mmatch bc m {| am_stack := astk; am_glob := PTree.empty _; am_nonstack := Nonstack; am_top := Nonstack |}.
Proof.
  intros. destruct H. constructor; simpl; intros.
- elim (NOSTACK b); auto.
- rewrite PTree.gempty in H0; discriminate.
- eapply smatch_no_stack; eauto.
- eapply smatch_no_stack; eauto.
- auto.
Qed.

End NOSTACK.

Construction 1: allocating the stack frame at function entry


Ltac splitall := repeat (match goal with |- _ /\ _ => split end).

Theorem allocate_stack:
  forall m sz m' sp bc ge rm am,
  Mem.alloc m 0 sz = (m', sp) ->
  genv_match bc ge ->
  romatch bc m rm ->
  mmatch bc m am ->
  bc_nostack bc ->
  exists bc',
     bc_incr bc bc'
  /\ bc' sp = BCstack
  /\ genv_match bc' ge
  /\ romatch bc' m' rm
  /\ mmatch bc' m' mfunction_entry
  /\ (forall b, Plt b sp -> bc' b = bc b)
  /\ (forall v x, vmatch bc v x -> vmatch bc' v (Ifptr Nonstack)).
Proof.
  intros until am; intros ALLOC GENV RO MM NOSTACK.
  exploit Mem.nextblock_alloc; eauto. intros NB.
  exploit Mem.alloc_result; eauto. intros SP.
  assert (SPINVALID: bc sp = BCinvalid).
  { rewrite SP. eapply bc_below_invalid. apply Plt_strict. eapply mmatch_below; eauto. }
 Part 1: constructing bc' *)  set (f := fun b => if eq_block b sp then BCstack else bc b).
  assert (F_stack: forall b1 b2, f b1 = BCstack -> f b2 = BCstack -> b1 = b2).
  {
    assert (forall b, f b = BCstack -> b = sp).
    { unfold f; intros. destruct (eq_block b sp); auto. eelim NOSTACK; eauto. }
    intros. transitivity sp; auto. symmetry; auto.
  }
  assert (F_glob: forall b1 b2 id, f b1 = BCglob id -> f b2 = BCglob id -> b1 = b2).
  {
    assert (forall b id, f b = BCglob id -> bc b = BCglob id).
    { unfold f; intros. destruct (eq_block b sp). congruence. auto. }
    intros. eapply (bc_glob bc); eauto.
  }
  set (bc' := BC f F_stack F_glob). unfold f in bc'.
  assert (BC'EQ: forall b, bc b <> BCinvalid -> bc' b = bc b).
  { intros; simpl. apply dec_eq_false. congruence. }
  assert (INCR: bc_incr bc bc').
  { red; simpl; intros. apply BC'EQ; auto. }
 Part 2: invariance properties *)  assert (SM: forall b p, bc b <> BCinvalid -> smatch bc m b p -> smatch bc' m' b Nonstack).
  {
    intros.
    apply smatch_incr with bc; auto.
    apply smatch_inv with m.
    apply smatch_no_stack with p; auto.
    intros. eapply Mem.loadbytes_alloc_unchanged; eauto. eapply mmatch_below; eauto.
  }
  assert (SMSTACK: smatch bc' m' sp Pbot).
  {
    split; intros.
    exploit Mem.load_alloc_same; eauto. intros EQ. subst v. constructor.
    exploit Mem.loadbytes_alloc_same; eauto with coqlib. congruence.
  }
 Conclusions *)  exists bc'; splitall.
- (* incr *)
  assumption.
- (* sp is BCstack *)
  simpl; apply dec_eq_true.
- (* genv match *)
  eapply genv_match_exten; eauto.
  simpl; intros. destruct (eq_block b sp); intuition congruence.
  simpl; intros. destruct (eq_block b sp); congruence.
- (* romatch *)
  apply romatch_exten with bc.
  eapply romatch_alloc; eauto. eapply mmatch_below; eauto.
  simpl; intros. destruct (eq_block b sp); intuition.
- (* mmatch *)
  constructor; simpl; intros.
  + (* stack *)
    apply ablock_init_sound. destruct (eq_block b sp).
    subst b. apply SMSTACK.
    elim (NOSTACK b); auto.
  + (* globals *)
    rewrite PTree.gempty in H0; discriminate.
  + (* nonstack *)
    destruct (eq_block b sp). congruence. eapply SM; auto. eapply mmatch_nonstack; eauto.
  + (* top *)
    destruct (eq_block b sp).
    subst b. apply smatch_ge with Pbot. apply SMSTACK. constructor.
    eapply SM; auto. eapply mmatch_top; eauto.
  + (* below *)
    red; simpl; intros. rewrite NB. destruct (eq_block b sp).
    subst b; rewrite SP; xomega.
    exploit mmatch_below; eauto. xomega.
- (* unchanged *)
  simpl; intros. apply dec_eq_false. apply Plt_ne. auto.
- (* values *)
  intros. apply vmatch_incr with bc; auto. eapply vmatch_no_stack; eauto.
Qed.

Construction 2: turn the stack into an "other" block, at public calls or function returns

Theorem anonymize_stack:
  forall m sp bc ge rm am,
  genv_match bc ge ->
  romatch bc m rm ->
  mmatch bc m am ->
  bc sp = BCstack ->
  exists bc',
     bc_nostack bc'
  /\ bc' sp = BCother
  /\ (forall b, b <> sp -> bc' b = bc b)
  /\ (forall v x, vmatch bc v x -> vmatch bc' v Vtop)
  /\ genv_match bc' ge
  /\ romatch bc' m rm
  /\ mmatch bc' m mtop.
Proof.
  intros until am; intros GENV RO MM SP.
 Part 1: constructing bc' *)  set (f := fun b => if eq_block b sp then BCother else bc b).
  assert (F_stack: forall b1 b2, f b1 = BCstack -> f b2 = BCstack -> b1 = b2).
  {
    unfold f; intros.
    destruct (eq_block b1 sp); try discriminate.
    destruct (eq_block b2 sp); try discriminate.
    eapply bc_stack; eauto.
  }
  assert (F_glob: forall b1 b2 id, f b1 = BCglob id -> f b2 = BCglob id -> b1 = b2).
  {
    unfold f; intros.
    destruct (eq_block b1 sp); try discriminate.
    destruct (eq_block b2 sp); try discriminate.
    eapply bc_glob; eauto.
  }
  set (bc' := BC f F_stack F_glob). unfold f in bc'.

 Part 2: matching wrt bc' *)  assert (PM: forall b ofs p, pmatch bc b ofs p -> pmatch bc' b ofs Ptop).
  {
    intros. assert (pmatch bc b ofs Ptop) by (eapply pmatch_top'; eauto).
    inv H0. constructor; simpl. destruct (eq_block b sp); congruence.
  }
  assert (VM: forall v x, vmatch bc v x -> vmatch bc' v Vtop).
  {
    induction 1; constructor; eauto.
  }
  assert (SM: forall b p, smatch bc m b p -> smatch bc' m b Ptop).
  {
    intros. destruct H as [S1 S2]. split; intros.
    eapply VM. eapply S1; eauto.
    eapply PM. eapply S2; eauto.
  }
 Conclusions *)  exists bc'; splitall.
- (* nostack *)
  red; simpl; intros. destruct (eq_block b sp). congruence.
  red; intros. elim n. eapply bc_stack; eauto.
- (* bc' sp is BCother *)
  simpl; apply dec_eq_true.
- (* other blocks *)
  intros; simpl; apply dec_eq_false; auto.
- (* values *)
  auto.
- (* genv *)
  apply genv_match_exten with bc; auto.
  simpl; intros. destruct (eq_block b sp); intuition congruence.
  simpl; intros. destruct (eq_block b sp); auto.
- (* romatch *)
  apply romatch_exten with bc; auto.
  simpl; intros. destruct (eq_block b sp); intuition.
- (* mmatch top *)
  constructor; simpl; intros.
  + destruct (eq_block b sp). congruence. elim n. eapply bc_stack; eauto.
  + rewrite PTree.gempty in H0; discriminate.
  + destruct (eq_block b sp).
    subst b. eapply SM. eapply mmatch_stack; eauto.
    eapply SM. eapply mmatch_nonstack; eauto.
  + destruct (eq_block b sp).
    subst b. eapply SM. eapply mmatch_stack; eauto.
    eapply SM. eapply mmatch_top; eauto.
  + red; simpl; intros. destruct (eq_block b sp).
    subst b. eapply mmatch_below; eauto. congruence.
    eapply mmatch_below; eauto.
Qed.

Construction 3: turn the stack into an invalid block, at private calls

Theorem hide_stack:
  forall m sp bc ge rm am,
  genv_match bc ge ->
  romatch bc m rm ->
  mmatch bc m am ->
  bc sp = BCstack ->
  pge Nonstack am.(am_nonstack) ->
  exists bc',
     bc_nostack bc'
  /\ bc' sp = BCinvalid
  /\ (forall b, b <> sp -> bc' b = bc b)
  /\ (forall v x, vge (Ifptr Nonstack) x -> vmatch bc v x -> vmatch bc' v Vtop)
  /\ genv_match bc' ge
  /\ romatch bc' m rm
  /\ mmatch bc' m mtop.
Proof.
  intros until am; intros GENV RO MM SP NOLEAK.
 Part 1: constructing bc' *)  set (f := fun b => if eq_block b sp then BCinvalid else bc b).
  assert (F_stack: forall b1 b2, f b1 = BCstack -> f b2 = BCstack -> b1 = b2).
  {
    unfold f; intros.
    destruct (eq_block b1 sp); try discriminate.
    destruct (eq_block b2 sp); try discriminate.
    eapply bc_stack; eauto.
  }
  assert (F_glob: forall b1 b2 id, f b1 = BCglob id -> f b2 = BCglob id -> b1 = b2).
  {
    unfold f; intros.
    destruct (eq_block b1 sp); try discriminate.
    destruct (eq_block b2 sp); try discriminate.
    eapply bc_glob; eauto.
  }
  set (bc' := BC f F_stack F_glob). unfold f in bc'.

 Part 2: matching wrt bc' *)  assert (PM: forall b ofs p, pge Nonstack p -> pmatch bc b ofs p -> pmatch bc' b ofs Ptop).
  {
    intros. assert (pmatch bc b ofs Nonstack) by (eapply pmatch_ge; eauto).
    inv H1. constructor; simpl; destruct (eq_block b sp); congruence.
  }
  assert (VM: forall v x, vge (Ifptr Nonstack) x -> vmatch bc v x -> vmatch bc' v Vtop).
  {
    intros. apply vmatch_ifptr; intros. subst v.
    inv H0; inv H; eapply PM; eauto.
  }
  assert (SM: forall b p, pge Nonstack p -> smatch bc m b p -> smatch bc' m b Ptop).
  {
    intros. destruct H0 as [S1 S2]. split; intros.
    eapply VM with (x := Ifptr p). constructor; auto. eapply S1; eauto.
    eapply PM. eauto. eapply S2; eauto.
  }
 Conclusions *)  exists bc'; splitall.
- (* nostack *)
  red; simpl; intros. destruct (eq_block b sp). congruence.
  red; intros. elim n. eapply bc_stack; eauto.
- (* bc' sp is BCinvalid *)
  simpl; apply dec_eq_true.
- (* other blocks *)
  intros; simpl; apply dec_eq_false; auto.
- (* values *)
  auto.
- (* genv *)
  apply genv_match_exten with bc; auto.
  simpl; intros. destruct (eq_block b sp); intuition congruence.
  simpl; intros. destruct (eq_block b sp); congruence.
- (* romatch *)
  apply romatch_exten with bc; auto.
  simpl; intros. destruct (eq_block b sp); intuition.
- (* mmatch top *)
  constructor; simpl; intros.
  + destruct (eq_block b sp). congruence. elim n. eapply bc_stack; eauto.
  + rewrite PTree.gempty in H0; discriminate.
  + destruct (eq_block b sp). congruence.
    eapply SM. eauto. eapply mmatch_nonstack; eauto.
  + destruct (eq_block b sp). congruence.
    eapply SM. eauto. eapply mmatch_nonstack; eauto.
    red; intros; elim n. eapply bc_stack; eauto.
  + red; simpl; intros. destruct (eq_block b sp). congruence.
    eapply mmatch_below; eauto.
Qed.

Construction 4: restore the stack after a public call

Theorem return_from_public_call:
  forall (caller callee: block_classification) bound sp ge e ae v m rm,
  bc_below caller bound ->
  callee sp = BCother ->
  caller sp = BCstack ->
  (forall b, Plt b bound -> b <> sp -> caller b = callee b) ->
  genv_match caller ge ->
  ematch caller e ae ->
  Ple bound (Mem.nextblock m) ->
  vmatch callee v Vtop ->
  romatch callee m rm ->
  mmatch callee m mtop ->
  genv_match callee ge ->
  bc_nostack callee ->
  exists bc,
      vmatch bc v Vtop
   /\ ematch bc e ae
   /\ romatch bc m rm
   /\ mmatch bc m mafter_public_call
   /\ genv_match bc ge
   /\ bc sp = BCstack
   /\ (forall b, Plt b sp -> bc b = caller b).
Proof.
  intros until rm; intros BELOW SP1 SP2 SAME GE1 EM BOUND RESM RM MM GE2 NOSTACK.
 Constructing bc *)  set (f := fun b => if eq_block b sp then BCstack else callee b).
  assert (F_stack: forall b1 b2, f b1 = BCstack -> f b2 = BCstack -> b1 = b2).
  {
    assert (forall b, f b = BCstack -> b = sp).
    { unfold f; intros. destruct (eq_block b sp); auto. eelim NOSTACK; eauto. }
    intros. transitivity sp; auto. symmetry; auto.
  }
  assert (F_glob: forall b1 b2 id, f b1 = BCglob id -> f b2 = BCglob id -> b1 = b2).
  {
    assert (forall b id, f b = BCglob id -> callee b = BCglob id).
    { unfold f; intros. destruct (eq_block b sp). congruence. auto. }
    intros. eapply (bc_glob callee); eauto.
  }
  set (bc := BC f F_stack F_glob). unfold f in bc.
  assert (INCR: bc_incr caller bc).
  {
    red; simpl; intros. destruct (eq_block b sp). congruence.
    symmetry; apply SAME; auto.
  }
 Invariance properties *)  assert (PM: forall b ofs p, pmatch callee b ofs p -> pmatch bc b ofs Ptop).
  {
    intros. assert (pmatch callee b ofs Ptop) by (eapply pmatch_top'; eauto).
    inv H0. constructor; simpl. destruct (eq_block b sp); congruence.
  }
  assert (VM: forall v x, vmatch callee v x -> vmatch bc v Vtop).
  {
    intros. assert (vmatch callee v0 Vtop) by (eapply vmatch_top; eauto).
    inv H0; constructor; eauto.
  }
  assert (SM: forall b p, smatch callee m b p -> smatch bc m b Ptop).
  {
    intros. destruct H; split; intros. eapply VM; eauto. eapply PM; eauto.
  }
 Conclusions *)  exists bc; splitall.
- (* result value *)
  eapply VM; eauto.
- (* environment *)
  eapply ematch_incr; eauto.
- (* romem *)
  apply romatch_exten with callee; auto.
  intros; simpl. destruct (eq_block b sp); intuition.
- (* mmatch *)
  constructor; simpl; intros.
  + (* stack *)
    apply ablock_init_sound. destruct (eq_block b sp).
    subst b. eapply SM. eapply mmatch_nonstack; eauto. congruence.
    elim (NOSTACK b); auto.
  + (* globals *)
    rewrite PTree.gempty in H0; discriminate.
  + (* nonstack *)
    destruct (eq_block b sp). congruence. eapply SM; auto. eapply mmatch_nonstack; eauto.
  + (* top *)
    eapply SM. eapply mmatch_top; eauto.
    destruct (eq_block b sp); congruence.
  + (* below *)
    red; simpl; intros. destruct (eq_block b sp).
    subst b. eapply mmatch_below; eauto. congruence.
    eapply mmatch_below; eauto.
- (* genv *)
  eapply genv_match_exten with caller; eauto.
  simpl; intros. destruct (eq_block b sp). intuition congruence.
  split; intros. rewrite SAME in H by eauto with va. auto.
  apply <- (proj1 GE2) in H. apply (proj1 GE1) in H. auto.
  simpl; intros. destruct (eq_block b sp). congruence.
  rewrite <- SAME; eauto with va.
- (* sp *)
  simpl. apply dec_eq_true.
- (* unchanged *)
  simpl; intros. destruct (eq_block b sp). congruence.
  symmetry. apply SAME; auto. eapply Plt_trans. eauto. apply BELOW. congruence.
Qed.

Construction 5: restore the stack after a private call

Theorem return_from_private_call:
  forall (caller callee: block_classification) bound sp ge e ae v m rm am,
  bc_below caller bound ->
  callee sp = BCinvalid ->
  caller sp = BCstack ->
  (forall b, Plt b bound -> b <> sp -> caller b = callee b) ->
  genv_match caller ge ->
  ematch caller e ae ->
  bmatch caller m sp am.(am_stack) ->
  Ple bound (Mem.nextblock m) ->
  vmatch callee v Vtop ->
  romatch callee m rm ->
  mmatch callee m mtop ->
  genv_match callee ge ->
  bc_nostack callee ->
  exists bc,
      vmatch bc v (Ifptr Nonstack)
   /\ ematch bc e ae
   /\ romatch bc m rm
   /\ mmatch bc m (mafter_private_call am)
   /\ genv_match bc ge
   /\ bc sp = BCstack
   /\ (forall b, Plt b sp -> bc b = caller b).
Proof.
  intros until am; intros BELOW SP1 SP2 SAME GE1 EM CONTENTS BOUND RESM RM MM GE2 NOSTACK.
 Constructing bc *)  set (f := fun b => if eq_block b sp then BCstack else callee b).
  assert (F_stack: forall b1 b2, f b1 = BCstack -> f b2 = BCstack -> b1 = b2).
  {
    assert (forall b, f b = BCstack -> b = sp).
    { unfold f; intros. destruct (eq_block b sp); auto. eelim NOSTACK; eauto. }
    intros. transitivity sp; auto. symmetry; auto.
  }
  assert (F_glob: forall b1 b2 id, f b1 = BCglob id -> f b2 = BCglob id -> b1 = b2).
  {
    assert (forall b id, f b = BCglob id -> callee b = BCglob id).
    { unfold f; intros. destruct (eq_block b sp). congruence. auto. }
    intros. eapply (bc_glob callee); eauto.
  }
  set (bc := BC f F_stack F_glob). unfold f in bc.
  assert (INCR1: bc_incr caller bc).
  {
    red; simpl; intros. destruct (eq_block b sp). congruence.
    symmetry; apply SAME; auto.
  }
  assert (INCR2: bc_incr callee bc).
  {
    red; simpl; intros. destruct (eq_block b sp). congruence. auto.
  }

 Invariance properties *)  assert (PM: forall b ofs p, pmatch callee b ofs p -> pmatch bc b ofs Nonstack).
  {
    intros. assert (pmatch callee b ofs Ptop) by (eapply pmatch_top'; eauto).
    inv H0. constructor; simpl; destruct (eq_block b sp); congruence.
  }
  assert (VM: forall v x, vmatch callee v x -> vmatch bc v (Ifptr Nonstack)).
  {
    intros. assert (vmatch callee v0 Vtop) by (eapply vmatch_top; eauto).
    inv H0; constructor; eauto.
  }
  assert (SM: forall b p, smatch callee m b p -> smatch bc m b Nonstack).
  {
    intros. destruct H; split; intros. eapply VM; eauto. eapply PM; eauto.
  }
  assert (BSTK: bmatch bc m sp (am_stack am)).
  {
    apply bmatch_incr with caller; eauto.
  }
 Conclusions *)  exists bc; splitall.
- (* result value *)
  eapply VM; eauto.
- (* environment *)
  eapply ematch_incr; eauto.
- (* romem *)
  apply romatch_exten with callee; auto.
  intros; simpl. destruct (eq_block b sp); intuition.
- (* mmatch *)
  constructor; simpl; intros.
  + (* stack *)
    destruct (eq_block b sp).
    subst b. exact BSTK.
    elim (NOSTACK b); auto.
  + (* globals *)
    rewrite PTree.gempty in H0; discriminate.
  + (* nonstack *)
    destruct (eq_block b sp). congruence. eapply SM; auto. eapply mmatch_nonstack; eauto.
  + (* top *)
    destruct (eq_block b sp).
    subst. apply smatch_ge with (ab_summary (am_stack am)). apply BSTK. apply pge_lub_l.
    apply smatch_ge with Nonstack. eapply SM. eapply mmatch_top; eauto. apply pge_lub_r.
  + (* below *)
    red; simpl; intros. destruct (eq_block b sp).
    subst b. apply Plt_le_trans with bound. apply BELOW. congruence. auto.
    eapply mmatch_below; eauto.
- (* genv *)
  eapply genv_match_exten; eauto.
  simpl; intros. destruct (eq_block b sp); intuition congruence.
  simpl; intros. destruct (eq_block b sp); congruence.
- (* sp *)
  simpl. apply dec_eq_true.
- (* unchanged *)
  simpl; intros. destruct (eq_block b sp). congruence.
  symmetry. apply SAME; auto. eapply Plt_trans. eauto. apply BELOW. congruence.
Qed.

Construction 6: external call

Theorem external_call_match:
  forall ef (ge: genv) vargs m t vres m' bc rm am,
  external_call ef ge vargs m t vres m' ->
  genv_match bc ge ->
  (forall v, In v vargs -> vmatch bc v Vtop) ->
  romatch bc m rm ->
  mmatch bc m am ->
  bc_nostack bc ->
  exists bc',
     bc_incr bc bc'
  /\ (forall b, Plt b (Mem.nextblock m) -> bc' b = bc b)
  /\ vmatch bc' vres Vtop
  /\ genv_match bc' ge
  /\ romatch bc' m' rm
  /\ mmatch bc' m' mtop
  /\ bc_nostack bc'
  /\ (forall b ofs n, Mem.valid_block m b -> bc b = BCinvalid -> Mem.loadbytes m' b ofs n = Mem.loadbytes m b ofs n).
Proof.
  intros until am; intros EC GENV ARGS RO MM NOSTACK.
 Part 1: using ec_mem_inject *)  exploit (@external_call_mem_inject ef _ _ ge vargs m t vres m' (inj_of_bc bc) m vargs).
  apply inj_of_bc_preserves_globals; auto.
  exact EC.
  eapply mmatch_inj; eauto. eapply mmatch_below; eauto.
  revert ARGS. generalize vargs.
  induction vargs0; simpl; intros; constructor.
  eapply vmatch_inj; eauto. auto.
  intros (j' & vres' & m'' & EC' & IRES & IMEM & UNCH1 & UNCH2 & IINCR & ISEP).
  assert (JBELOW: forall b, Plt b (Mem.nextblock m) -> j' b = inj_of_bc bc b).
  {
    intros. destruct (inj_of_bc bc b) as [[b' delta] | ] eqn:EQ.
    eapply IINCR; eauto.
    destruct (j' b) as [[b'' delta'] | ] eqn:EQ'; auto.
    exploit ISEP; eauto. tauto.
  }
 Part 2: constructing bc' from j' *)  set (f := fun b => if plt b (Mem.nextblock m)
                     then bc b
                     else match j' b with None => BCinvalid | Some _ => BCother end).
  assert (F_stack: forall b1 b2, f b1 = BCstack -> f b2 = BCstack -> b1 = b2).
  {
    assert (forall b, f b = BCstack -> bc b = BCstack).
    { unfold f; intros. destruct (plt b (Mem.nextblock m)); auto. destruct (j' b); discriminate. }
    intros. apply (bc_stack bc); auto.
  }
  assert (F_glob: forall b1 b2 id, f b1 = BCglob id -> f b2 = BCglob id -> b1 = b2).
  {
    assert (forall b id, f b = BCglob id -> bc b = BCglob id).
    { unfold f; intros. destruct (plt b (Mem.nextblock m)); auto. destruct (j' b); discriminate. }
    intros. eapply (bc_glob bc); eauto.
  }
  set (bc' := BC f F_stack F_glob). unfold f in bc'.
  assert (INCR: bc_incr bc bc').
  {
    red; simpl; intros. apply pred_dec_true. eapply mmatch_below; eauto.
  }
  assert (BC'INV: forall b, bc' b <> BCinvalid -> exists b' delta, j' b = Some(b', delta)).
  {
    simpl; intros. destruct (plt b (Mem.nextblock m)).
    exists b, 0. rewrite JBELOW by auto. apply inj_of_bc_valid; auto.
    destruct (j' b) as [[b' delta] | ].
    exists b', delta; auto.
    congruence.
  }

 Part 3: injection wrt j' implies matching with top wrt bc' *)  assert (PMTOP: forall b b' delta ofs, j' b = Some (b', delta) -> pmatch bc' b ofs Ptop).
  {
    intros. constructor. simpl; unfold f.
    destruct (plt b (Mem.nextblock m)).
    rewrite JBELOW in H by auto. eapply inj_of_bc_inv; eauto.
    rewrite H; congruence.
  }
  assert (VMTOP: forall v v', Val.inject j' v v' -> vmatch bc' v Vtop).
  {
    intros. inv H; constructor. eapply PMTOP; eauto.
  }
  assert (SMTOP: forall b, bc' b <> BCinvalid -> smatch bc' m' b Ptop).
  {
    intros; split; intros.
  - exploit BC'INV; eauto. intros (b' & delta & J').
    exploit Mem.load_inject. eexact IMEM. eauto. eauto. intros (v' & A & B).
    eapply VMTOP; eauto.
  - exploit BC'INV; eauto. intros (b'' & delta & J').
    exploit Mem.loadbytes_inject. eexact IMEM. eauto. eauto. intros (bytes & A & B).
    inv B. inv H3. inv H7. eapply PMTOP; eauto.
  }
 Conclusions *)  exists bc'; splitall.
- (* incr *)
  exact INCR.
- (* unchanged *)
  simpl; intros. apply pred_dec_true; auto.
- (* vmatch res *)
  eapply VMTOP; eauto.
- (* genv match *)
  apply genv_match_exten with bc; auto.
  simpl; intros; split; intros.
  rewrite pred_dec_true by (eapply mmatch_below; eauto with va). auto.
  destruct (plt b (Mem.nextblock m)). auto. destruct (j' b); congruence.
  simpl; intros. rewrite pred_dec_true by (eapply mmatch_below; eauto with va). auto.
- (* romatch m' *)
  red; simpl; intros. destruct (plt b (Mem.nextblock m)).
  exploit RO; eauto. intros (R & P & Q).
  split; auto.
  split. apply bmatch_incr with bc; auto. apply bmatch_inv with m; auto.
  intros. eapply Mem.loadbytes_unchanged_on_1. eapply external_call_readonly; eauto.
  auto. intros; red. apply Q.
  intros; red; intros; elim (Q ofs).
  eapply external_call_max_perm with (m2 := m'); eauto.
  destruct (j' b); congruence.
- (* mmatch top *)
  constructor; simpl; intros.
  + apply ablock_init_sound. apply SMTOP. simpl; congruence.
  + rewrite PTree.gempty in H0; discriminate.
  + apply SMTOP; auto.
  + apply SMTOP; auto.
  + red; simpl; intros. destruct (plt b (Mem.nextblock m)).
    eapply Plt_le_trans. eauto. eapply external_call_nextblock; eauto.
    destruct (j' b) as [[bx deltax] | ] eqn:J'.
    eapply Mem.valid_block_inject_1; eauto.
    congruence.
- (* nostack *)
  red; simpl; intros. destruct (plt b (Mem.nextblock m)).
  apply NOSTACK; auto.
  destruct (j' b); congruence.
- (* unmapped blocks are invariant *)
  intros. eapply Mem.loadbytes_unchanged_on_1; auto.
  apply UNCH1; auto. intros; red. unfold inj_of_bc; rewrite H0; auto.
Qed.

Remark list_forall2_in_l:
  forall (A B: Type) (P: A -> B -> Prop) x1 l1 l2,
  list_forall2 P l1 l2 -> In x1 l1 -> exists x2, In x2 l2 /\ P x1 x2.
Proof.
  induction 1; simpl; intros.
- contradiction.
- destruct H1.
  + subst. exists b1; auto.
  + exploit IHlist_forall2; eauto. intros (x2 & U & V). exists x2; auto.
Qed.

Semantic invariant


Section SOUNDNESS.

Variable prog: program.
Variable ge: genv.

Let rm := romem_for prog.

Inductive sound_stack: block_classification -> list stackframe -> mem -> block -> Prop :=
  | sound_stack_nil: forall bc m bound,
      sound_stack bc nil m bound
  | sound_stack_public_call:
      forall (bc: block_classification) res f sp pc e stk m bound bc' bound' ae
        (STK: sound_stack bc' stk m sp)
        (INCR: Ple bound' bound)
        (BELOW: bc_below bc' bound')
        (SP: bc sp = BCother)
        (SP': bc' sp = BCstack)
        (SAME: forall b, Plt b bound' -> b <> sp -> bc b = bc' b)
        (GE: genv_match bc' ge)
        (AN: VA.ge (analyze rm f)!!pc (VA.State (AE.set res Vtop ae) mafter_public_call))
        (EM: ematch bc' e ae),
      sound_stack bc (Stackframe res f (Vptr sp Ptrofs.zero) pc e :: stk) m bound
  | sound_stack_private_call:
     forall (bc: block_classification) res f sp pc e stk m bound bc' bound' ae am
        (STK: sound_stack bc' stk m sp)
        (INCR: Ple bound' bound)
        (BELOW: bc_below bc' bound')
        (SP: bc sp = BCinvalid)
        (SP': bc' sp = BCstack)
        (SAME: forall b, Plt b bound' -> b <> sp -> bc b = bc' b)
        (GE: genv_match bc' ge)
        (AN: VA.ge (analyze rm f)!!pc (VA.State (AE.set res (Ifptr Nonstack) ae) (mafter_private_call am)))
        (EM: ematch bc' e ae)
        (CONTENTS: bmatch bc' m sp am.(am_stack)),
      sound_stack bc (Stackframe res f (Vptr sp Ptrofs.zero) pc e :: stk) m bound.

Inductive sound_state_base: state -> Prop :=
  | sound_regular_state:
      forall s f sp pc e m ae am bc
        (STK: sound_stack bc s m sp)
        (AN: (analyze rm f)!!pc = VA.State ae am)
        (EM: ematch bc e ae)
        (RO: romatch bc m rm)
        (MM: mmatch bc m am)
        (GE: genv_match bc ge)
        (SP: bc sp = BCstack),
      sound_state_base (State s f (Vptr sp Ptrofs.zero) pc e m)
  | sound_call_state:
      forall s fd args m bc
        (STK: sound_stack bc s m (Mem.nextblock m))
        (ARGS: forall v, In v args -> vmatch bc v Vtop)
        (RO: romatch bc m rm)
        (MM: mmatch bc m mtop)
        (GE: genv_match bc ge)
        (NOSTK: bc_nostack bc),
      sound_state_base (Callstate s fd args m)
  | sound_return_state:
      forall s v m bc
        (STK: sound_stack bc s m (Mem.nextblock m))
        (RES: vmatch bc v Vtop)
        (RO: romatch bc m rm)
        (MM: mmatch bc m mtop)
        (GE: genv_match bc ge)
        (NOSTK: bc_nostack bc),
      sound_state_base (Returnstate s v m).

Properties of the sound_stack invariant on call stacks.

Lemma sound_stack_ext:
  forall m' bc stk m bound,
  sound_stack bc stk m bound ->
  (forall b ofs n bytes,
       Plt b bound -> bc b = BCinvalid -> n >= 0 ->
       Mem.loadbytes m' b ofs n = Some bytes ->
       Mem.loadbytes m b ofs n = Some bytes) ->
  sound_stack bc stk m' bound.
Proof.
  induction 1; intros INV.
- constructor.
- assert (Plt sp bound') by eauto with va.
  eapply sound_stack_public_call; eauto. apply IHsound_stack; intros.
  apply INV. xomega. rewrite SAME; auto. xomega. auto. auto.
- assert (Plt sp bound') by eauto with va.
  eapply sound_stack_private_call; eauto. apply IHsound_stack; intros.
  apply INV. xomega. rewrite SAME; auto. xomega. auto. auto.
  apply bmatch_ext with m; auto. intros. apply INV. xomega. auto. auto. auto.
Qed.

Lemma sound_stack_inv:
  forall m' bc stk m bound,
  sound_stack bc stk m bound ->
  (forall b ofs n, Plt b bound -> bc b = BCinvalid -> n >= 0 -> Mem.loadbytes m' b ofs n = Mem.loadbytes m b ofs n) ->
  sound_stack bc stk m' bound.
Proof.
  intros. eapply sound_stack_ext; eauto. intros. rewrite <- H0; auto.
Qed.

Lemma sound_stack_storev:
  forall chunk m addr v m' bc aaddr stk bound,
  Mem.storev chunk m addr v = Some m' ->
  vmatch bc addr aaddr ->
  sound_stack bc stk m bound ->
  sound_stack bc stk m' bound.
Proof.
  intros. apply sound_stack_inv with m; auto.
  destruct addr; simpl in H; try discriminate.
  assert (A: pmatch bc b i Ptop).
  { inv H0; eapply pmatch_top'; eauto. }
  inv A.
  intros. eapply Mem.loadbytes_store_other; eauto. left; congruence.
Qed.

Lemma sound_stack_storebytes:
  forall m b ofs bytes m' bc aaddr stk bound,
  Mem.storebytes m b (Ptrofs.unsigned ofs) bytes = Some m' ->
  vmatch bc (Vptr b ofs) aaddr ->
  sound_stack bc stk m bound ->
  sound_stack bc stk m' bound.
Proof.
  intros. apply sound_stack_inv with m; auto.
  assert (A: pmatch bc b ofs Ptop).
  { inv H0; eapply pmatch_top'; eauto. }
  inv A.
  intros. eapply Mem.loadbytes_storebytes_other; eauto. left; congruence.
Qed.

Lemma sound_stack_free:
  forall m b lo hi m' bc stk bound,
  Mem.free m b lo hi = Some m' ->
  sound_stack bc stk m bound ->
  sound_stack bc stk m' bound.
Proof.
  intros. eapply sound_stack_ext; eauto. intros.
  eapply Mem.loadbytes_free_2; eauto.
Qed.

Lemma sound_stack_new_bound:
  forall bc stk m bound bound',
  sound_stack bc stk m bound ->
  Ple bound bound' ->
  sound_stack bc stk m bound'.
Proof.
  intros. inv H.
- constructor.
- eapply sound_stack_public_call with (bound' := bound'0); eauto. xomega.
- eapply sound_stack_private_call with (bound' := bound'0); eauto. xomega.
Qed.

Lemma sound_stack_exten:
  forall bc stk m bound (bc1: block_classification),
  sound_stack bc stk m bound ->
  (forall b, Plt b bound -> bc1 b = bc b) ->
  sound_stack bc1 stk m bound.
Proof.
  intros. inv H.
- constructor.
- assert (Plt sp bound') by eauto with va.
  eapply sound_stack_public_call; eauto.
  rewrite H0; auto. xomega.
  intros. rewrite H0; auto. xomega.
- assert (Plt sp bound') by eauto with va.
  eapply sound_stack_private_call; eauto.
  rewrite H0; auto. xomega.
  intros. rewrite H0; auto. xomega.
Qed.

Preservation of the semantic invariant by one step of execution


Lemma sound_succ_state:
  forall bc pc ae am instr ae' am' s f sp pc' e' m',
  (analyze rm f)!!pc = VA.State ae am ->
  f.(fn_code)!pc = Some instr ->
  In pc' (successors_instr instr) ->
  transfer f rm pc ae am = VA.State ae' am' ->
  ematch bc e' ae' ->
  mmatch bc m' am' ->
  romatch bc m' rm ->
  genv_match bc ge ->
  bc sp = BCstack ->
  sound_stack bc s m' sp ->
  sound_state_base (State s f (Vptr sp Ptrofs.zero) pc' e' m').
Proof.
  intros. exploit analyze_succ; eauto. intros (ae'' & am'' & AN & EM & MM).
  econstructor; eauto.
Qed.

Theorem sound_step_base:
  forall st t st', RTL.step ge st t st' -> sound_state_base st -> sound_state_base st'.
Proof.
  induction 1; intros SOUND; inv SOUND.

- (* nop *)
  eapply sound_succ_state; eauto. simpl; auto.
  unfold transfer; rewrite H. auto.

- (* op *)
  eapply sound_succ_state; eauto. simpl; auto.
  unfold transfer; rewrite H. eauto.
  apply ematch_update; auto. eapply eval_static_operation_sound; eauto with va.

- (* load *)
  eapply sound_succ_state; eauto. simpl; auto.
  unfold transfer; rewrite H. eauto.
  apply ematch_update; auto. eapply loadv_sound; eauto with va.
  eapply eval_static_addressing_sound; eauto with va.

- (* store *)
  exploit eval_static_addressing_sound; eauto with va. intros VMADDR.
  eapply sound_succ_state; eauto. simpl; auto.
  unfold transfer; rewrite H. eauto.
  eapply storev_sound; eauto.
  destruct a; simpl in H1; try discriminate. eapply romatch_store; eauto.
  eapply sound_stack_storev; eauto.

- (* call *)
  assert (TR: transfer f rm pc ae am = transfer_call ae am args res).
  { unfold transfer; rewrite H; auto. }
  unfold transfer_call, analyze_call in TR.
  destruct (pincl (am_nonstack am) Nonstack &&
            forallb (fun av => vpincl av Nonstack) (aregs ae args)) eqn:NOLEAK.
+ (* private call *)
  InvBooleans.
  exploit analyze_successor; eauto. simpl; eauto. rewrite TR. intros SUCC.
  exploit hide_stack; eauto. apply pincl_ge; auto.
  intros (bc' & A & B & C & D & E & F & G).
  apply sound_call_state with bc'; auto.
  * eapply sound_stack_private_call with (bound' := Mem.nextblock m) (bc' := bc); eauto.
    apply Ple_refl.
    eapply mmatch_below; eauto.
    eapply mmatch_stack; eauto.
  * intros. exploit list_in_map_inv; eauto. intros (r & P & Q). subst v.
    apply D with (areg ae r).
    rewrite forallb_forall in H2. apply vpincl_ge.
    apply H2. apply in_map; auto.
    auto with va.
+ (* public call *)
  exploit analyze_successor; eauto. simpl; eauto. rewrite TR. intros SUCC.
  exploit anonymize_stack; eauto. intros (bc' & A & B & C & D & E & F & G).
  apply sound_call_state with bc'; auto.
  * eapply sound_stack_public_call with (bound' := Mem.nextblock m) (bc' := bc); eauto.
    apply Ple_refl.
    eapply mmatch_below; eauto.
  * intros. exploit list_in_map_inv; eauto. intros (r & P & Q). subst v.
    apply D with (areg ae r). auto with va.

- (* tailcall *)
  exploit anonymize_stack; eauto. intros (bc' & A & B & C & D & E & F & G).
  apply sound_call_state with bc'; auto.
  erewrite Mem.nextblock_free by eauto.
  apply sound_stack_new_bound with stk.
  apply sound_stack_exten with bc.
  eapply sound_stack_free; eauto.
  intros. apply C. apply Plt_ne; auto.
  apply Plt_Ple. eapply mmatch_below; eauto. congruence.
  intros. exploit list_in_map_inv; eauto. intros (r & P & Q). subst v.
  apply D with (areg ae r). auto with va.
  eapply romatch_free; eauto.
  eapply mmatch_free; eauto.

- (* builtin *)
  assert (SPVALID: Plt sp0 (Mem.nextblock m)) by (eapply mmatch_below; eauto with va).
  assert (TR: transfer f rm pc ae am = transfer_builtin ae am rm ef args res).
  { unfold transfer; rewrite H; auto. }
 The default case *)  assert (DEFAULT:
            transfer f rm pc ae am = transfer_builtin_default ae am rm args res ->
            sound_state_base
               (State s f (Vptr sp0 Ptrofs.zero) pc' (regmap_setres res vres rs) m')).
  { unfold transfer_builtin_default, analyze_call; intros TR'.
  set (aargs := map (abuiltin_arg ae am rm) args) in *.
  assert (ARGS: list_forall2 (vmatch bc) vargs aargs) by (eapply abuiltin_args_sound; eauto).
  destruct (pincl (am_nonstack am) Nonstack &&
            forallb (fun av => vpincl av Nonstack) aargs)
        eqn: NOLEAK.
* (* private builtin call *)
  InvBooleans. rewrite forallb_forall in H3.
  exploit hide_stack; eauto. apply pincl_ge; auto.
  intros (bc1 & A & B & C & D & E & F & G).
  exploit external_call_match; eauto.
  intros. exploit list_forall2_in_l; eauto. intros (av & U & V).
  eapply D; eauto with va. apply vpincl_ge. apply H3; auto.
  intros (bc2 & J & K & L & M & N & O & P & Q).
  exploit (return_from_private_call bc bc2); eauto.
  eapply mmatch_below; eauto.
  rewrite K; auto.
  intros. rewrite K; auto. rewrite C; auto.
  apply bmatch_inv with m. eapply mmatch_stack; eauto.
  intros. apply Q; auto.
  eapply external_call_nextblock; eauto.
  intros (bc3 & U & V & W & X & Y & Z & AA).
  eapply sound_succ_state with (bc := bc3); eauto. simpl; auto.
  apply set_builtin_res_sound; auto.
  apply sound_stack_exten with bc.
  apply sound_stack_inv with m. auto.
  intros. apply Q. red. eapply Plt_trans; eauto.
  rewrite C; auto.
  exact AA.
* (* public builtin call *)
  exploit anonymize_stack; eauto.
  intros (bc1 & A & B & C & D & E & F & G).
  exploit external_call_match; eauto.
  intros. exploit list_forall2_in_l; eauto. intros (av & U & V). eapply D; eauto with va.
  intros (bc2 & J & K & L & M & N & O & P & Q).
  exploit (return_from_public_call bc bc2); eauto.
  eapply mmatch_below; eauto.
  rewrite K; auto.
  intros. rewrite K; auto. rewrite C; auto.
  eapply external_call_nextblock; eauto.
  intros (bc3 & U & V & W & X & Y & Z & AA).
  eapply sound_succ_state with (bc := bc3); eauto. simpl; auto.
  apply set_builtin_res_sound; auto.
  apply sound_stack_exten with bc.
  apply sound_stack_inv with m. auto.
  intros. apply Q. red. eapply Plt_trans; eauto.
  rewrite C; auto.
  exact AA.
  }
  unfold transfer_builtin in TR.
  destruct ef; auto.
+ (* volatile load *)
  inv H0; auto. inv H3; auto. inv H1.
  exploit abuiltin_arg_sound; eauto. intros VM1.
  eapply sound_succ_state; eauto. simpl; auto.
  apply set_builtin_res_sound; auto.
  inv H3.
  * (* true volatile access *)
    assert (V: vmatch bc v (Ifptr Glob)).
    { inv H4; simpl in *; constructor. econstructor. eapply GE; eauto. }
    destruct (va_strict tt). apply vmatch_lub_r. apply vnormalize_sound. auto.
    apply vnormalize_sound. eapply vmatch_ge; eauto. constructor. constructor.
  * (* normal memory access *)
    exploit loadv_sound; eauto. simpl; eauto. intros V.
    destruct (va_strict tt).
    apply vmatch_lub_l. auto.
    eapply vnormalize_cast; eauto. eapply vmatch_top; eauto.
+ (* volatile store *)
  inv H0; auto. inv H3; auto. inv H4; auto. inv H1.
  exploit abuiltin_arg_sound. eauto. eauto. eauto. eauto. eauto. eexact H0. intros VM1.
  exploit abuiltin_arg_sound. eauto. eauto. eauto. eauto. eauto. eexact H2. intros VM2.
  inv H9.
  * (* true volatile access *)
    eapply sound_succ_state; eauto. simpl; auto.
    apply set_builtin_res_sound; auto. constructor.
    apply mmatch_lub_l; auto.
  * (* normal memory access *)
    eapply sound_succ_state; eauto. simpl; auto.
    apply set_builtin_res_sound; auto. constructor.
    apply mmatch_lub_r. eapply storev_sound; eauto. auto.
    eapply romatch_store; eauto.
    eapply sound_stack_storev; eauto. simpl; eauto.
+ (* memcpy *)
  inv H0; auto. inv H3; auto. inv H4; auto. inv H1.
  exploit abuiltin_arg_sound. eauto. eauto. eauto. eauto. eauto. eexact H0. intros VM1.
  exploit abuiltin_arg_sound. eauto. eauto. eauto. eauto. eauto. eexact H2. intros VM2.
  eapply sound_succ_state; eauto. simpl; auto.
  apply set_builtin_res_sound; auto. constructor.
  eapply storebytes_sound; eauto.
  apply match_aptr_of_aval; auto.
  eapply Mem.loadbytes_length; eauto.
  intros. eapply loadbytes_sound; eauto. apply match_aptr_of_aval; auto.
  eapply romatch_storebytes; eauto.
  eapply sound_stack_storebytes; eauto.
+ (* annot *)
  inv H1. eapply sound_succ_state; eauto. simpl; auto. apply set_builtin_res_sound; auto. constructor.
+ (* annot val *)
  inv H0; auto. inv H3; auto. inv H1.
  eapply sound_succ_state; eauto. simpl; auto.
  apply set_builtin_res_sound; auto. eapply abuiltin_arg_sound; eauto.
+ (* debug *)
  inv H1. eapply sound_succ_state; eauto. simpl; auto. apply set_builtin_res_sound; auto. constructor.

- (* cond *)
  eapply sound_succ_state; eauto.
  simpl. destruct b; auto.
  unfold transfer; rewrite H; auto.

- (* jumptable *)
  eapply sound_succ_state; eauto.
  simpl. eapply list_nth_z_in; eauto.
  unfold transfer; rewrite H; auto.

- (* return *)
  exploit anonymize_stack; eauto. intros (bc' & A & B & C & D & E & F & G).
  apply sound_return_state with bc'; auto.
  erewrite Mem.nextblock_free by eauto.
  apply sound_stack_new_bound with stk.
  apply sound_stack_exten with bc.
  eapply sound_stack_free; eauto.
  intros. apply C. apply Plt_ne; auto.
  apply Plt_Ple. eapply mmatch_below; eauto with va.
  destruct or; simpl. eapply D; eauto. constructor.
  eapply romatch_free; eauto.
  eapply mmatch_free; eauto.

- (* internal function *)
  exploit allocate_stack; eauto.
  intros (bc' & A & B & C & D & E & F & G).
  exploit (analyze_entrypoint rm f args m' bc'); eauto.
  intros (ae & am & AN & EM & MM').
  econstructor; eauto.
  erewrite Mem.alloc_result by eauto.
  apply sound_stack_exten with bc; auto.
  apply sound_stack_inv with m; auto.
  intros. eapply Mem.loadbytes_alloc_unchanged; eauto.
  intros. apply F. erewrite Mem.alloc_result by eauto. auto.

- (* external function *)
  exploit external_call_match; eauto with va.
  intros (bc' & A & B & C & D & E & F & G & K).
  econstructor; eauto.
  apply sound_stack_new_bound with (Mem.nextblock m).
  apply sound_stack_exten with bc; auto.
  apply sound_stack_inv with m; auto.
  eapply external_call_nextblock; eauto.

- (* return *)
  inv STK.
  + (* from public call *)
   exploit return_from_public_call; eauto.
   intros; rewrite SAME; auto.
   intros (bc1 & A & B & C & D & E & F & G).
   destruct (analyze rm f)#pc as [ |ae' am'] eqn:EQ; simpl in AN; try contradiction. destruct AN as [A1 A2].
   eapply sound_regular_state with (bc := bc1); eauto.
   apply sound_stack_exten with bc'; auto.
   eapply ematch_ge; eauto. apply ematch_update. auto. auto.
  + (* from private call *)
   exploit return_from_private_call; eauto.
   intros; rewrite SAME; auto.
   intros (bc1 & A & B & C & D & E & F & G).
   destruct (analyze rm f)#pc as [ |ae' am'] eqn:EQ; simpl in AN; try contradiction. destruct AN as [A1 A2].
   eapply sound_regular_state with (bc := bc1); eauto.
   apply sound_stack_exten with bc'; auto.
   eapply ematch_ge; eauto. apply ematch_update. auto. auto.
Qed.

End SOUNDNESS.

Extension to separate compilation


Following Kang et al, POPL 2016, we now extend the results above to the case where only one compilation unit is analyzed, and not the whole program.

Section LINKING.

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

Inductive sound_state: state -> Prop :=
  | sound_state_intro: forall st,
      (forall cunit, linkorder cunit prog -> sound_state_base cunit ge st) ->
      sound_state st.

Theorem sound_step:
  forall st t st', RTL.step ge st t st' -> sound_state st -> sound_state st'.
Proof.
  intros. inv H0. constructor; intros. eapply sound_step_base; eauto.
Qed.

Remark sound_state_inv:
  forall st cunit,
  sound_state st -> linkorder cunit prog -> sound_state_base cunit ge st.
Proof.
  intros. inv H. eauto.
Qed.

End LINKING.

Soundness of the initial memory abstraction


Section INITIAL.

Variable prog: program.

Let ge := Genv.globalenv prog.

Lemma initial_block_classification:
  forall m,
  Genv.init_mem prog = Some m ->
  exists bc,
     genv_match bc ge
  /\ bc_below bc (Mem.nextblock m)
  /\ bc_nostack bc
  /\ (forall b id, bc b = BCglob id -> Genv.find_symbol ge id = Some b)
  /\ (forall b, Mem.valid_block m b -> bc b <> BCinvalid).
Proof.
  intros.
  set (f := fun b =>
              if plt b (Genv.genv_next ge) then
                match Genv.invert_symbol ge b with None => BCother | Some id => BCglob id end
              else
                BCinvalid).
  assert (F_glob: forall b1 b2 id, f b1 = BCglob id -> f b2 = BCglob id -> b1 = b2).
  {
    unfold f; intros.
    destruct (plt b1 (Genv.genv_next ge)); try discriminate.
    destruct (Genv.invert_symbol ge b1) as [id1|] eqn:I1; inv H0.
    destruct (plt b2 (Genv.genv_next ge)); try discriminate.
    destruct (Genv.invert_symbol ge b2) as [id2|] eqn:I2; inv H1.
    exploit Genv.invert_find_symbol. eexact I1.
    exploit Genv.invert_find_symbol. eexact I2.
    congruence.
  }
  assert (F_stack: forall b1 b2, f b1 = BCstack -> f b2 = BCstack -> b1 = b2).
  {
    unfold f; intros.
    destruct (plt b1 (Genv.genv_next ge)); try discriminate.
    destruct (Genv.invert_symbol ge b1); discriminate.
  }
  set (bc := BC f F_stack F_glob). unfold f in bc.
  exists bc; splitall.
- split; simpl; intros.
  + split; intros.
    * rewrite pred_dec_true by (eapply Genv.genv_symb_range; eauto).
      erewrite Genv.find_invert_symbol; eauto.
    * apply Genv.invert_find_symbol.
      destruct (plt b (Genv.genv_next ge)); try discriminate.
      destruct (Genv.invert_symbol ge b); congruence.
  + rewrite ! pred_dec_true by assumption.
    destruct (Genv.invert_symbol); split; congruence.
- red; simpl; intros. destruct (plt b (Genv.genv_next ge)); try congruence.
  erewrite <- Genv.init_mem_genv_next by eauto. auto.
- red; simpl; intros.
  destruct (plt b (Genv.genv_next ge)).
  destruct (Genv.invert_symbol ge b); congruence.
  congruence.
- simpl; intros. destruct (plt b (Genv.genv_next ge)); try discriminate.
  destruct (Genv.invert_symbol ge b) as [id' | ] eqn:IS; inv H0.
  apply Genv.invert_find_symbol; auto.
- intros; simpl. unfold ge; erewrite Genv.init_mem_genv_next by eauto.
  rewrite pred_dec_true by assumption.
  destruct (Genv.invert_symbol (Genv.globalenv prog) b); congruence.
Qed.

Section INIT.

Variable bc: block_classification.
Hypothesis GMATCH: genv_match bc ge.

Lemma store_init_data_summary:
  forall ab p id,
  pge Glob (ab_summary ab) ->
  pge Glob (ab_summary (store_init_data ab p id)).
Proof.
  intros.
  assert (DFL: forall chunk av,
               vge (Ifptr Glob) av ->
               pge Glob (ab_summary (ablock_store chunk ab p av))).
  {
    intros. simpl. unfold vplub; destruct av; auto.
    inv H0. apply plub_least; auto.
    inv H0. apply plub_least; auto.
  }
  destruct id; auto.
  simpl. destruct (propagate_float_constants tt); auto.
  simpl. destruct (propagate_float_constants tt); auto.
  apply DFL. constructor. constructor.
Qed.

Lemma store_init_data_list_summary:
  forall idl ab p,
  pge Glob (ab_summary ab) ->
  pge Glob (ab_summary (store_init_data_list ab p idl)).
Proof.
  induction idl; simpl; intros. auto. apply IHidl. apply store_init_data_summary; auto.
Qed.

Lemma store_init_data_sound:
  forall m b p id m' ab,
  Genv.store_init_data ge m b p id = Some m' ->
  bmatch bc m b ab ->
  bmatch bc m' b (store_init_data ab p id).
Proof.
  intros. destruct id; try (eapply ablock_store_sound; eauto; constructor).
- (* float32 *)
  simpl. destruct (propagate_float_constants tt); eapply ablock_store_sound; eauto; constructor.
- (* float64 *)
  simpl. destruct (propagate_float_constants tt); eapply ablock_store_sound; eauto; constructor.
- (* space *)
  simpl in H. inv H. auto.
- (* addrof *)
  simpl in H. destruct (Genv.find_symbol ge i) as [b'|] eqn:FS; try discriminate.
  eapply ablock_store_sound; eauto. constructor. constructor. apply GMATCH; auto.
Qed.

Lemma store_init_data_list_sound:
  forall idl m b p m' ab,
  Genv.store_init_data_list ge m b p idl = Some m' ->
  bmatch bc m b ab ->
  bmatch bc m' b (store_init_data_list ab p idl).
Proof.
  induction idl; simpl; intros.
- inv H; auto.
- destruct (Genv.store_init_data ge m b p a) as [m1|] eqn:SI; try discriminate.
  eapply IHidl; eauto. eapply store_init_data_sound; eauto.
Qed.

Lemma store_init_data_other:
  forall m b p id m' ab b',
  Genv.store_init_data ge m b p id = Some m' ->
  b' <> b ->
  bmatch bc m b' ab ->
  bmatch bc m' b' ab.
Proof.
  intros. eapply bmatch_inv; eauto.
  intros. destruct id; try (eapply Mem.loadbytes_store_other; eauto; fail); simpl in H.
  inv H; auto.
  destruct (Genv.find_symbol ge i); try discriminate.
  eapply Mem.loadbytes_store_other; eauto.
Qed.

Lemma store_init_data_list_other:
  forall b b' ab idl m p m',
  Genv.store_init_data_list ge m b p idl = Some m' ->
  b' <> b ->
  bmatch bc m b' ab ->
  bmatch bc m' b' ab.
Proof.
  induction idl; simpl; intros.
  inv H; auto.
  destruct (Genv.store_init_data ge m b p a) as [m1|] eqn:SI; try discriminate.
  eapply IHidl; eauto. eapply store_init_data_other; eauto.
Qed.

Lemma store_zeros_same:
  forall p m b pos n m',
  store_zeros m b pos n = Some m' ->
  smatch bc m b p ->
  smatch bc m' b p.
Proof.
  intros until n. functional induction (store_zeros m b pos n); intros.
- inv H. auto.
- eapply IHo; eauto. change p with (vplub (I Int.zero) p).
  eapply smatch_store; eauto. constructor.
- discriminate.
Qed.

Lemma store_zeros_other:
  forall b' ab m b p n m',
  store_zeros m b p n = Some m' ->
  b' <> b ->
  bmatch bc m b' ab ->
  bmatch bc m' b' ab.
Proof.
  intros until n. functional induction (store_zeros m b p n); intros.
- inv H. auto.
- eapply IHo; eauto. eapply bmatch_inv; eauto.
  intros. eapply Mem.loadbytes_store_other; eauto.
- discriminate.
Qed.

Definition initial_mem_match (bc: block_classification) (m: mem) (g: genv) :=
  forall id b v,
  Genv.find_symbol g id = Some b -> Genv.find_var_info g b = Some v ->
  v.(gvar_volatile) = false -> v.(gvar_readonly) = true ->
  bmatch bc m b (store_init_data_list (ablock_init Pbot) 0 v.(gvar_init)).

Lemma alloc_global_match:
  forall m g idg m',
  Genv.genv_next g = Mem.nextblock m ->
  initial_mem_match bc m g ->
  Genv.alloc_global ge m idg = Some m' ->
  initial_mem_match bc m' (Genv.add_global g idg).
Proof.
  intros; red; intros. destruct idg as [id1 [fd | gv]]; simpl in *.
- destruct (Mem.alloc m 0 1) as [m1 b1] eqn:ALLOC.
  unfold Genv.find_symbol in H2; simpl in H2.
  unfold Genv.find_var_info, Genv.find_def in H3; simpl in H3.
  rewrite PTree.gsspec in H2. destruct (peq id id1).
  inv H2. rewrite PTree.gss in H3. discriminate.
  assert (Plt b (Genv.genv_next g)) by (eapply Genv.genv_symb_range; eauto).
  rewrite PTree.gso in H3 by (apply Plt_ne; auto).
  assert (Mem.valid_block m b) by (red; rewrite <- H; auto).
  assert (b <> b1) by (apply Mem.valid_not_valid_diff with m; eauto with mem).
  apply bmatch_inv with m.
  eapply H0; eauto.
  intros. transitivity (Mem.loadbytes m1 b ofs n0).
  eapply Mem.loadbytes_drop; eauto.
  eapply Mem.loadbytes_alloc_unchanged; eauto.
- set (sz := init_data_list_size (gvar_init gv)) in *.
  destruct (Mem.alloc m 0 sz) as [m1 b1] eqn:ALLOC.
  destruct (store_zeros m1 b1 0 sz) as [m2 | ] eqn:STZ; try discriminate.
  destruct (Genv.store_init_data_list ge m2 b1 0 (gvar_init gv)) as [m3 | ] eqn:SIDL; try discriminate.
  unfold Genv.find_symbol in H2; simpl in H2.
  unfold Genv.find_var_info, Genv.find_def in H3; simpl in H3.
  rewrite PTree.gsspec in H2. destruct (peq id id1).
+ injection H2; clear H2; intro EQ.
  rewrite EQ, PTree.gss in H3. injection H3; clear H3; intros EQ'; subst v.
  assert (b = b1). { erewrite Mem.alloc_result by eauto. congruence. }
  clear EQ. subst b.
  apply bmatch_inv with m3.
  eapply store_init_data_list_sound; eauto.
  apply ablock_init_sound.
  eapply store_zeros_same; eauto.
  split; intros.
  exploit Mem.load_alloc_same; eauto. intros EQ; subst v; constructor.
  exploit Mem.loadbytes_alloc_same; eauto with coqlib. congruence.
  intros. eapply Mem.loadbytes_drop; eauto.
  right; right; right. unfold Genv.perm_globvar. rewrite H4, H5. constructor.
+ assert (Plt b (Genv.genv_next g)) by (eapply Genv.genv_symb_range; eauto).
  rewrite PTree.gso in H3 by (apply Plt_ne; auto).
  assert (Mem.valid_block m b) by (red; rewrite <- H; auto).
  assert (b <> b1) by (apply Mem.valid_not_valid_diff with m; eauto with mem).
  apply bmatch_inv with m3.
  eapply store_init_data_list_other; eauto.
  eapply store_zeros_other; eauto.
  apply bmatch_inv with m.
  eapply H0; eauto.
  intros. eapply Mem.loadbytes_alloc_unchanged; eauto.
  intros. eapply Mem.loadbytes_drop; eauto.
Qed.

Lemma alloc_globals_match:
  forall gl m g m',
  Genv.genv_next g = Mem.nextblock m ->
  initial_mem_match bc m g ->
  Genv.alloc_globals ge m gl = Some m' ->
  initial_mem_match bc m' (Genv.add_globals g gl).
Proof.
  induction gl; simpl; intros.
- inv H1; auto.
- destruct (Genv.alloc_global ge m a) as [m1|] eqn:AG; try discriminate.
  eapply IHgl; eauto.
  erewrite Genv.alloc_global_nextblock; eauto. simpl. congruence.
  eapply alloc_global_match; eauto.
Qed.

Definition romem_consistent (defmap: PTree.t (globdef fundef unit)) (rm: romem) :=
  forall id ab,
  rm!id = Some ab ->
  exists v,
     defmap!id = Some (Gvar v)
  /\ v.(gvar_readonly) = true
  /\ v.(gvar_volatile) = false
  /\ definitive_initializer v.(gvar_init) = true
  /\ ab = store_init_data_list (ablock_init Pbot) 0 v.(gvar_init).

Lemma alloc_global_consistent:
  forall dm rm idg,
  romem_consistent dm rm ->
  romem_consistent (PTree.set (fst idg) (snd idg) dm) (alloc_global rm idg).
Proof.
  intros; red; intros. destruct idg as [id1 [f1 | v1]]; simpl in *.
- rewrite PTree.grspec in H0. destruct (PTree.elt_eq id id1); try discriminate.
  rewrite PTree.gso by auto. apply H; auto.
- destruct (gvar_readonly v1 && negb (gvar_volatile v1) && definitive_initializer (gvar_init v1)) eqn:RO.
+ InvBooleans. rewrite negb_true_iff in H4.
  rewrite PTree.gsspec in *. destruct (peq id id1).
* inv H0. exists v1; auto.
* apply H; auto.
+ rewrite PTree.grspec in H0. destruct (PTree.elt_eq id id1); try discriminate.
  rewrite PTree.gso by auto. apply H; auto.
Qed.

Lemma romem_for_consistent:
  forall cunit, romem_consistent (prog_defmap cunit) (romem_for cunit).
Proof.
  assert (REC: forall l dm rm,
            romem_consistent dm rm ->
            romem_consistent (fold_left (fun m idg => PTree.set (fst idg) (snd idg) m) l dm)
                             (fold_left alloc_global l rm)).
  { induction l; intros; simpl; auto. apply IHl. apply alloc_global_consistent; auto. }
  intros. apply REC.
  red; intros. rewrite PTree.gempty in H; discriminate.
Qed.

Lemma romem_for_consistent_2:
  forall cunit, linkorder cunit prog -> romem_consistent (prog_defmap prog) (romem_for cunit).
Proof.
  intros; red; intros.
  exploit (romem_for_consistent cunit); eauto. intros (v & DM & RO & VO & DEFN & AB).
  destruct (prog_defmap_linkorder _ _ _ _ H DM) as (gd & P & Q).
  assert (gd = Gvar v).
  { inv Q. inv H2. simpl in *. f_equal. f_equal.
    destruct info1, info2; auto.
    inv H3; auto; discriminate. }
  subst gd. exists v; auto.
Qed.

End INIT.

Theorem initial_mem_matches:
  forall m,
  Genv.init_mem prog = Some m ->
  exists bc,
     genv_match bc ge
  /\ bc_below bc (Mem.nextblock m)
  /\ bc_nostack bc
  /\ (forall cunit, linkorder cunit prog -> romatch bc m (romem_for cunit))
  /\ (forall b, Mem.valid_block m b -> bc b <> BCinvalid).
Proof.
  intros.
  exploit initial_block_classification; eauto. intros (bc & GE & BELOW & NOSTACK & INV & VALID).
  exists bc; splitall; auto.
  intros.
  assert (A: initial_mem_match bc m ge).
  {
    apply alloc_globals_match with (m := Mem.empty); auto.
    red. unfold Genv.find_symbol; simpl; intros. rewrite PTree.gempty in H1; discriminate.
  }
  assert (B: romem_consistent (prog_defmap prog) (romem_for cunit)) by (apply romem_for_consistent_2; auto).
  red; intros.
  exploit B; eauto. intros (v & DM & RO & NVOL & DEFN & EQ).
  rewrite Genv.find_def_symbol in DM. destruct DM as (b1 & FS & FD).
  rewrite <- Genv.find_var_info_iff in FD.
  assert (b1 = b). { apply INV in H1. unfold ge in H1; congruence. }
  subst b1.
  split. subst ab. apply store_init_data_list_summary. constructor.
  split. subst ab. eapply A; eauto.
  exploit Genv.init_mem_characterization; eauto.
  intros (P & Q & R).
  intros; red; intros. exploit Q; eauto. intros [U V].
  unfold Genv.perm_globvar in V; rewrite RO, NVOL in V. inv V.
Qed.

End INITIAL.

Require Import Axioms.

Theorem sound_initial:
  forall prog st, initial_state prog st -> sound_state prog st.
Proof.
  destruct 1.
  exploit initial_mem_matches; eauto. intros (bc & GE & BELOW & NOSTACK & RM & VALID).
  constructor; intros. apply sound_call_state with bc.
- constructor.
- simpl; tauto.
- apply RM; auto.
- apply mmatch_inj_top with m0.
  replace (inj_of_bc bc) with (Mem.flat_inj (Mem.nextblock m0)).
  eapply Genv.initmem_inject; eauto.
  symmetry; apply extensionality; unfold Mem.flat_inj; intros x.
  destruct (plt x (Mem.nextblock m0)).
  apply inj_of_bc_valid; auto.
  unfold inj_of_bc. erewrite bc_below_invalid; eauto.
- exact GE.
- exact NOSTACK.
Qed.

Hint Resolve areg_sound aregs_sound: va.

Interface with other optimizations


Ltac InvSoundState :=
  match goal with
  | H1: sound_state ?prog ?st, H2: linkorder ?cunit ?prog |- _ =>
      let S := fresh "S" in generalize (sound_state_inv _ _ _ H1 H2); intros S; inv S
  end.

Definition avalue (a: VA.t) (r: reg) : aval :=
  match a with
  | VA.Bot => Vbot
  | VA.State ae am => AE.get r ae
  end.

Lemma avalue_sound:
  forall cunit prog s f sp pc e m r,
  sound_state prog (State s f (Vptr sp Ptrofs.zero) pc e m) ->
  linkorder cunit prog ->
  exists bc,
     vmatch bc e#r (avalue (analyze (romem_for cunit) f)!!pc r)
  /\ genv_match bc (Genv.globalenv prog)
  /\ bc sp = BCstack.
Proof.
  intros. InvSoundState. exists bc; split; auto. rewrite AN. apply EM.
Qed.

Definition aaddr (a: VA.t) (r: reg) : aptr :=
  match a with
  | VA.Bot => Pbot
  | VA.State ae am => aptr_of_aval (AE.get r ae)
  end.

Lemma aaddr_sound:
  forall cunit prog s f sp pc e m r b ofs,
  sound_state prog (State s f (Vptr sp Ptrofs.zero) pc e m) ->
  linkorder cunit prog ->
  e#r = Vptr b ofs ->
  exists bc,
     pmatch bc b ofs (aaddr (analyze (romem_for cunit) f)!!pc r)
  /\ genv_match bc (Genv.globalenv prog)
  /\ bc sp = BCstack.
Proof.
  intros. InvSoundState. exists bc; split; auto.
  unfold aaddr; rewrite AN. apply match_aptr_of_aval. rewrite <- H1. apply EM.
Qed.

Definition aaddressing (a: VA.t) (addr: addressing) (args: list reg) : aptr :=
  match a with
  | VA.Bot => Pbot
  | VA.State ae am => aptr_of_aval (eval_static_addressing addr (aregs ae args))
  end.

Lemma aaddressing_sound:
  forall cunit prog s f sp pc e m addr args b ofs,
  sound_state prog (State s f (Vptr sp Ptrofs.zero) pc e m) ->
  linkorder cunit prog ->
  eval_addressing (Genv.globalenv prog) (Vptr sp Ptrofs.zero) addr e##args = Some (Vptr b ofs) ->
  exists bc,
     pmatch bc b ofs (aaddressing (analyze (romem_for cunit) f)!!pc addr args)
  /\ genv_match bc (Genv.globalenv prog)
  /\ bc sp = BCstack.
Proof.
  intros. InvSoundState. exists bc; split; auto.
  unfold aaddressing. rewrite AN. apply match_aptr_of_aval.
  eapply eval_static_addressing_sound; eauto with va.
Qed.

This is a less precise version of abuiltin_arg, where memory contents are not taken into account.

Definition aaddr_arg (a: VA.t) (ba: builtin_arg reg) : aptr :=
  match a with
  | VA.Bot => Pbot
  | VA.State ae am =>
      match ba with
      | BA r => aptr_of_aval (AE.get r ae)
      | BA_addrstack ofs => Stk ofs
      | BA_addrglobal id ofs => Gl id ofs
      | _ => Ptop
      end
  end.

Lemma aaddr_arg_sound_1:
  forall bc rs ae m rm am ge sp a b ofs,
  ematch bc rs ae ->
  romatch bc m rm ->
  mmatch bc m am ->
  genv_match bc ge ->
  bc sp = BCstack ->
  eval_builtin_arg ge (fun r : positive => rs # r) (Vptr sp Ptrofs.zero) m a (Vptr b ofs) ->
  pmatch bc b ofs (aaddr_arg (VA.State ae am) a).
Proof.
  intros.
  apply pmatch_ge with (aptr_of_aval (abuiltin_arg ae am rm a)).
  simpl. destruct a; try (apply pge_top); simpl; apply pge_refl.
  apply match_aptr_of_aval. eapply abuiltin_arg_sound; eauto.
Qed.

Lemma aaddr_arg_sound:
  forall cunit prog s f sp pc e m a b ofs,
  sound_state prog (State s f (Vptr sp Ptrofs.zero) pc e m) ->
  linkorder cunit prog ->
  eval_builtin_arg (Genv.globalenv prog) (fun r => e#r) (Vptr sp Ptrofs.zero) m a (Vptr b ofs) ->
  exists bc,
     pmatch bc b ofs (aaddr_arg (analyze (romem_for cunit) f)!!pc a)
  /\ genv_match bc (Genv.globalenv prog)
  /\ bc sp = BCstack.
Proof.
  intros. InvSoundState. rewrite AN. exists bc; split; auto.
  eapply aaddr_arg_sound_1; eauto.
Qed.