gcc/ada/exp_ch7.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                              E X P _ C H 7                               --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2015, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT; see file COPYING3.  If not, go to --
  19 -- http://www.gnu.org/licenses for a complete copy of the license.          --
  20 --                                                                          --
  21 -- GNAT was originally developed  by the GNAT team at  New York University. --
  22 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  23 --                                                                          --
  24 ------------------------------------------------------------------------------
  25
  26 with Namet; use Namet;
  27 with Types; use Types;
  28
  29 package Exp_Ch7 is
  30
  31    procedure Expand_N_Package_Body        (N : Node_Id);
  32    procedure Expand_N_Package_Declaration (N : Node_Id);
  33
  34    -----------------------------
  35    -- Finalization Management --
  36    -----------------------------
  37
  38    procedure Build_Controlling_Procs (Typ : Entity_Id);
  39    --  Typ is a record, and array type having controlled components.
  40    --  Create the procedures Deep_Initialize, Deep_Adjust and Deep_Finalize
  41    --  that take care of finalization management at run-time.
  42
  43    --  Support of exceptions from user finalization procedures
  44
  45    --  There is a specific mechanism to handle these exceptions, continue
  46    --  finalization and then raise PE. This mechanism is used by this package
  47    --  but also by exp_intr for Ada.Unchecked_Deallocation.
  48
  49    --  There are 3 subprograms to use this mechanism, and the type
  50    --  Finalization_Exception_Data carries internal data between these
  51    --  subprograms:
  52    --
  53    --    1. Build_Object_Declaration: create the variables for the next two
  54    --       subprograms.
  55    --    2. Build_Exception_Handler: create the exception handler for a call
  56    --       to a user finalization procedure.
  57    --    3. Build_Raise_Stmt: create code to potentially raise a PE exception
  58    --       if an exception was raise in a user finalization procedure.
  59
  60    type Finalization_Exception_Data is record
  61       Loc : Source_Ptr;
  62       --  Sloc for the added nodes
  63
  64       Abort_Id : Entity_Id;
  65       --  Boolean variable set to true if the finalization was triggered by
  66       --  an abort.
  67
  68       E_Id : Entity_Id;
  69       --  Variable containing the exception occurrence raised by user code
  70
  71       Raised_Id : Entity_Id;
  72       --  Boolean variable set to true if an exception was raised in user code
  73    end record;
  74
  75    function Build_Exception_Handler
  76      (Data        : Finalization_Exception_Data;
  77       For_Library : Boolean := False) return Node_Id;
  78    --  Subsidiary to Build_Finalizer, Make_Deep_Array_Body and Make_Deep_Record
  79    --  _Body. Create an exception handler of the following form:
  80    --
  81    --    when others =>
  82    --       if not Raised_Id then
  83    --          Raised_Id := True;
  84    --          Save_Occurrence (E_Id, Get_Current_Excep.all.all);
  85    --       end if;
  86    --
  87    --  If flag For_Library is set (and not in restricted profile):
  88    --
  89    --    when others =>
  90    --       if not Raised_Id then
  91    --          Raised_Id := True;
  92    --          Save_Library_Occurrence (Get_Current_Excep.all);
  93    --       end if;
  94    --
  95    --  E_Id denotes the defining identifier of a local exception occurrence.
  96    --  Raised_Id is the entity of a local boolean flag. Flag For_Library is
  97    --  used when operating at the library level, when enabled the current
  98    --  exception will be saved to a global location.
  99
 100    procedure Build_Finalization_Master
 101      (Typ            : Entity_Id;
 102       For_Anonymous  : Boolean   := False;
 103       For_Private    : Boolean   := False;
 104       Context_Scope  : Entity_Id := Empty;
 105       Insertion_Node : Node_Id   := Empty);
 106    --  Build a finalization master for an access type. The designated type may
 107    --  not necessarely be controlled or need finalization actions depending on
 108    --  the context. Flag For_Anonymous must be set when creating a master for
 109    --  an anonymous access type. Flag For_Private must be set when the
 110    --  designated type contains a private component. Parameters Context_Scope
 111    --  and Insertion_Node must be used in conjunction with flags For_Anonymous
 112    --  and For_Private. Context_Scope is the scope of the context where the
 113    --  finalization master must be analyzed. Insertion_Node is the insertion
 114    --  point before which the master is inserted.
 115
 116    procedure Build_Late_Proc (Typ : Entity_Id; Nam : Name_Id);
 117    --  Build one controlling procedure when a late body overrides one of
 118    --  the controlling operations.
 119
 120    procedure Build_Object_Declarations
 121      (Data        : out Finalization_Exception_Data;
 122       Decls       : List_Id;
 123       Loc         : Source_Ptr;
 124       For_Package : Boolean := False);
 125    --  Subsidiary to Make_Deep_Array_Body and Make_Deep_Record_Body. Create the
 126    --  list List containing the object declarations of boolean flag Abort_Id,
 127    --  the exception occurrence E_Id and boolean flag Raised_Id.
 128    --
 129    --    Abort_Id  : constant Boolean :=
 130    --                  Exception_Identity (Get_Current_Excep.all) =
 131    --                    Standard'Abort_Signal'Identity;
 132    --      <or>
 133    --    Abort_Id  : constant Boolean := False;  --  no abort or For_Package
 134    --
 135    --    E_Id      : Exception_Occurrence;
 136    --    Raised_Id : Boolean := False;
 137
 138    function Build_Raise_Statement
 139      (Data : Finalization_Exception_Data) return Node_Id;
 140    --  Subsidiary to routines Build_Finalizer, Make_Deep_Array_Body and Make_
 141    --  Deep_Record_Body. Generate the following conditional raise statement:
 142    --
 143    --    if Raised_Id and then not Abort_Id then
 144    --       Raise_From_Controlled_Operation (E_Id);
 145    --    end if;
 146    --
 147    --  Abort_Id is a local boolean flag which is set when the finalization was
 148    --  triggered by an abort, E_Id denotes the defining identifier of a local
 149    --  exception occurrence, Raised_Id is the entity of a local boolean flag.
 150
 151    function CW_Or_Has_Controlled_Part (T : Entity_Id) return Boolean;
 152    --  True if T is a class-wide type, or if it has controlled parts ("part"
 153    --  means T or any of its subcomponents). Same as Needs_Finalization, except
 154    --  when pragma Restrictions (No_Finalization) applies, in which case we
 155    --  know that class-wide objects do not contain controlled parts.
 156
 157    function Has_New_Controlled_Component (E : Entity_Id) return Boolean;
 158    --  E is a type entity. Give the same result as Has_Controlled_Component
 159    --  except for tagged extensions where the result is True only if the
 160    --  latest extension contains a controlled component.
 161
 162    function Make_Adjust_Call
 163      (Obj_Ref   : Node_Id;
 164       Typ       : Entity_Id;
 165       Skip_Self : Boolean := False) return Node_Id;
 166    --  Create a call to either Adjust or Deep_Adjust depending on the structure
 167    --  of type Typ. Obj_Ref is an expression with no-side effect (not required
 168    --  to have been previously analyzed) that references the object to be
 169    --  adjusted. Typ is the expected type of Obj_Ref. When Skip_Self is set,
 170    --  only the components (if any) are adjusted.
 171
 172    function Make_Attach_Call
 173      (Obj_Ref : Node_Id;
 174       Ptr_Typ : Entity_Id) return Node_Id;
 175    --  Create a call to prepend an object to a finalization collection. Obj_Ref
 176    --  is the object, Ptr_Typ is the access type that owns the collection. This
 177    --  is used only for .NET/JVM, that is, when VM_Target /= No_VM.
 178    --  Generate the following:
 179    --
 180    --    Ada.Finalization.Heap_Management.Attach
 181    --      (<Ptr_Typ>FC,
 182    --       System.Finalization_Root.Root_Controlled_Ptr (Obj_Ref));
 183
 184    function Make_Detach_Call (Obj_Ref : Node_Id) return Node_Id;
 185    --  Create a call to unhook an object from an arbitrary list. Obj_Ref is the
 186    --  object. Generate the following:
 187    --
 188    --    Ada.Finalization.Heap_Management.Detach
 189    --      (System.Finalization_Root.Root_Controlled_Ptr (Obj_Ref));
 190
 191    function Make_Final_Call
 192      (Obj_Ref   : Node_Id;
 193       Typ       : Entity_Id;
 194       Skip_Self : Boolean := False) return Node_Id;
 195    --  Create a call to either Finalize or Deep_Finalize depending on the
 196    --  structure of type Typ. Obj_Ref is an expression (with no-side effect
 197    --  and is not required to have been previously analyzed) that references
 198    --  the object to be finalized. Typ is the expected type of Obj_Ref. When
 199    --  Skip_Self is set, only the components (if any) are finalized.
 200
 201    procedure Make_Finalize_Address_Body (Typ : Entity_Id);
 202    --  Create the body of TSS routine Finalize_Address if Typ is controlled and
 203    --  does not have a TSS entry for Finalize_Address. The procedure converts
 204    --  an address into a pointer and subsequently calls Deep_Finalize on the
 205    --  dereference.
 206
 207    function Make_Init_Call
 208      (Obj_Ref : Node_Id;
 209       Typ     : Entity_Id) return Node_Id;
 210    --  Obj_Ref is an expression with no-side effect (not required to have been
 211    --  previously analyzed) that references the object to be initialized. Typ
 212    --  is the expected type of Obj_Ref, which is either a controlled type
 213    --  (Is_Controlled) or a type with controlled components (Has_Controlled_
 214    --  Components).
 215
 216    function Make_Handler_For_Ctrl_Operation (Loc : Source_Ptr) return Node_Id;
 217    --  Generate an implicit exception handler with an 'others' choice,
 218    --  converting any occurrence to a raise of Program_Error.
 219
 220    function Make_Local_Deep_Finalize
 221      (Typ : Entity_Id;
 222       Nam : Entity_Id) return Node_Id;
 223    --  Create a special version of Deep_Finalize with identifier Nam. The
 224    --  routine has state information and can parform partial finalization.
 225
 226    function Make_Set_Finalize_Address_Call
 227      (Loc     : Source_Ptr;
 228       Ptr_Typ : Entity_Id) return Node_Id;
 229    --  Associate the Finalize_Address primitive of the designated type with the
 230    --  finalization master of access type Ptr_Typ. The returned call is:
 231    --  Generate the following call:
 232    --
 233    --    Set_Finalize_Address
 234    --      (<Ptr_Typ>FM, <Desig_Typ>FD'Unrestricted_Access);
 235
 236    --------------------------------------------
 237    -- Task and Protected Object finalization --
 238    --------------------------------------------
 239
 240    function Cleanup_Array
 241      (N   : Node_Id;
 242       Obj : Node_Id;
 243       Typ : Entity_Id) return List_Id;
 244    --  Generate loops to finalize any tasks or simple protected objects that
 245    --  are subcomponents of an array.
 246
 247    function Cleanup_Protected_Object
 248      (N   : Node_Id;
 249       Ref : Node_Id) return Node_Id;
 250    --  Generate code to finalize a protected object without entries
 251
 252    function Cleanup_Record
 253      (N   : Node_Id;
 254       Obj : Node_Id;
 255       Typ : Entity_Id) return List_Id;
 256    --  For each subcomponent of a record that contains tasks or simple
 257    --  protected objects, generate the appropriate finalization call.
 258
 259    function Cleanup_Task
 260      (N   : Node_Id;
 261       Ref : Node_Id) return Node_Id;
 262    --  Generate code to finalize a task
 263
 264    function Has_Simple_Protected_Object (T : Entity_Id) return Boolean;
 265    --  Check whether composite type contains a simple protected component
 266
 267    function Is_Simple_Protected_Type (T : Entity_Id) return Boolean;
 268    --  Determine whether T denotes a protected type without entires whose
 269    --  _object field is of type System.Tasking.Protected_Objects.Protection.
 270    --  Something wrong here, implementation was changed to test Lock_Free
 271    --  but this spec does not mention that ???
 272
 273    --------------------------------
 274    -- Transient Scope Management --
 275    --------------------------------
 276
 277    procedure Expand_Cleanup_Actions (N : Node_Id);
 278    --  Expand the necessary stuff into a scope to enable finalization of local
 279    --  objects and deallocation of transient data when exiting the scope. N is
 280    --  a "scope node" that is to say one of the following: N_Block_Statement,
 281    --  N_Subprogram_Body, N_Task_Body, N_Entry_Body.
 282
 283    procedure Establish_Transient_Scope (N : Node_Id; Sec_Stack : Boolean);
 284    --  Push a new transient scope on the scope stack. N is the node responsible
 285    --  for the need of a transient scope. If Sec_Stack is True then the
 286    --  secondary stack is brought in, otherwise it isn't.
 287
 288    function Node_To_Be_Wrapped return Node_Id;
 289    --  Return the node to be wrapped if the current scope is transient
 290
 291    procedure Store_Before_Actions_In_Scope (L : List_Id);
 292    --  Append the list L of actions to the end of the before-actions store in
 293    --  the top of the scope stack (also analyzes these actions).
 294
 295    procedure Store_After_Actions_In_Scope (L : List_Id);
 296    --  Prepend the list L of actions to the beginning of the after-actions
 297    --  stored in the top of the scope stack (also analyzes these actions).
 298    --
 299    --  Note that we are prepending here rather than appending. This means that
 300    --  if several calls are made to this procedure for the same scope, the
 301    --  actions will be executed in reverse order of the calls (actions for the
 302    --  last call executed first). Within the list L for a single call, the
 303    --  actions are executed in the order in which they appear in this list.
 304
 305    procedure Store_Cleanup_Actions_In_Scope (L : List_Id);
 306    --  Prepend the list L of actions to the beginning of the cleanup-actions
 307    --  store in the top of the scope stack.
 308
 309    procedure Wrap_Transient_Declaration (N : Node_Id);
 310    --  N is an object declaration. Expand the finalization calls after the
 311    --  declaration and make the outer scope being the transient one.
 312
 313    procedure Wrap_Transient_Expression (N : Node_Id);
 314    --  N is a sub-expression. Expand a transient block around an expression
 315
 316    procedure Wrap_Transient_Statement (N : Node_Id);
 317    --  N is a statement. Expand a transient block around an instruction
 318
 319 end Exp_Ch7;