(** ** Coercing a global environment into a symbol environment *)

Definition to_senv (ge: t) : Senv.t :=
 @Senv.mksenv
    (find_symbol ge)
    (public_symbol ge)
    (invert_symbol ge)
    (block_is_volatile ge)
    ge.(genv_next)
    ge.(genv_vars_inj)
    (invert_find_symbol ge)
    (find_invert_symbol ge)
    (public_symbol_exists ge)
    ge.(genv_symb_range)
    (block_is_volatile_below ge).Definition store_init_data (m: mem) (b: block) (p: Z) (id: init_data) : option mem :=
  match id with
  | Init_int8 n => Mem.store Mint8unsigned m b p (Vint n)
  | Init_int16 n => Mem.store Mint16unsigned m b p (Vint n)
  | Init_int32 n => Mem.store Mint32 m b p (Vint n)
  | Init_int64 n => Mem.store Mint64 m b p (Vlong n)
  | Init_float32 n => Mem.store Mfloat32 m b p (Vsingle n)
  | Init_float64 n => Mem.store Mfloat64 m b p (Vfloat n)
  | Init_addrof symb ofs =>
      match find_symbol ge symb with
      | None => None
      | Some b' => Mem.store Mptr m b p (Vptr b' ofs)
      end
  | Init_space n => Some m
  end.Fixpoint store_init_data_list (m: mem) (b: block) (p: Z) (idl: list init_data)
                              {struct idl}: option mem :=
  match idl with
  | nil => Some m
  | id :: idl' =>
      match store_init_data m b p id with
      | None => None
      | Some m' => store_init_data_list m' b (p + init_data_size id) idl'
      end
  end.Definition perm_globvar (gv: globvar V) : permission :=
  if gv.(gvar_volatile) then Nonempty
  else if gv.(gvar_readonly) then Readable
  else Writable.Definition alloc_global (m: mem) (idg: ident * globdef F V): option mem :=
  match idg with
  | (id, Gfun f) =>
      let (m1, b) := Mem.alloc m 0 1 in
      Mem.drop_perm m1 b 0 1 Nonempty
  | (id, Gvar v) =>
      let init := v.(gvar_init) in
      let sz := init_data_list_size init in
      let (m1, b) := Mem.alloc m 0 sz in
      match store_zeros m1 b 0 sz with
      | None => None
      | Some m2 =>
          match store_init_data_list m2 b 0 init with
          | None => None
          | Some m3 => Mem.drop_perm m3 b 0 sz (perm_globvar v)
          end
      end
  end.Fixpoint alloc_globals (m: mem) (gl: list (ident * globdef F V))
                       {struct gl} : option mem :=
  match gl with
  | nil => Some m
  | g :: gl' =>
      match alloc_global m g with
      | None => None
      | Some m' => alloc_globals m' gl'
      end
  end.

Lemma alloc_globals_app : forall gl1 gl2 m m1, alloc_globals m gl1 = Some m1 -> alloc_globals m1 gl2 = alloc_globals m (gl1 ++ gl2).