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) 1992-2008, 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    function In_Finalization_Root (E : Entity_Id) return Boolean;
  39    --  True if current scope is in package System.Finalization_Root. Used
  40    --  to avoid certain expansions that would involve circularity in the
  41    --  Rtsfind mechanism.
  42
  43    procedure Build_Final_List (N : Node_Id; Typ : Entity_Id);
  44    --  Build finalization list for anonymous access types, and for access
  45    --  types that are frozen before their designated types are known to
  46    --  be controlled.
  47
  48    procedure Build_Controlling_Procs (Typ : Entity_Id);
  49    --  Typ is a record, and array type having controlled components.
  50    --  Create the procedures Deep_Initialize, Deep_Adjust and Deep_Finalize
  51    --  that take care of finalization management at run-time.
  52
  53    procedure Build_Late_Proc (Typ : Entity_Id; Nam : Name_Id);
  54    --  Build one controlling procedure when a late body overrides one of
  55    --  the controlling operations.
  56
  57    function Controller_Component (Typ : Entity_Id) return Entity_Id;
  58    --  Returns the entity of the component whose name is 'Name_uController'
  59
  60    function Needs_Finalization (T : Entity_Id) return Boolean;
  61    --  True if T potentially needs finalization actions. True if T is
  62    --  controlled, or has subcomponents. Also True if T is a class-wide type,
  63    --  because some type extension might add controlled subcomponents, except
  64    --  that if pragma Restrictions (No_Finalization) applies, this is False for
  65    --  class-wide types.
  66
  67    function CW_Or_Has_Controlled_Part (T : Entity_Id) return Boolean;
  68    --  True if T is a class-wide type, or if it has controlled parts ("part"
  69    --  means T or any of its subcomponents). This is the same as
  70    --  Needs_Finalization, except when pragma Restrictions (No_Finalization)
  71    --  applies, in which case we know that class-wide objects do not contain
  72    --  controlled parts.
  73
  74    function Find_Final_List
  75      (E   : Entity_Id;
  76       Ref : Node_Id := Empty) return Node_Id;
  77    --  E is an entity representing a controlled object, a controlled type or a
  78    --  scope. If Ref is not empty, it is a reference to a controlled record,
  79    --  the closest Final list is in the controller component of the record
  80    --  containing Ref otherwise this function returns a reference to the final
  81    --  list attached to the closest dynamic scope (that can be E itself)
  82    --  creating this final list if necessary.
  83
  84    function Has_New_Controlled_Component (E : Entity_Id) return Boolean;
  85    --  E is a type entity. Give the same result as Has_Controlled_Component
  86    --  except for tagged extensions where the result is True only if the
  87    --  latest extension contains a controlled component.
  88
  89    function Make_Attach_Call
  90      (Obj_Ref     : Node_Id;
  91       Flist_Ref   : Node_Id;
  92       With_Attach : Node_Id) return Node_Id;
  93    --  Attach the referenced object to the referenced Final Chain 'Flist_Ref'
  94    --  With_Attach is an expression of type Short_Short_Integer which can be
  95    --  either '0' to signify no attachment, '1' for attachment to a simply
  96    --  linked list or '2' for attachment to a doubly linked list.
  97
  98    function Make_Init_Call
  99      (Ref         : Node_Id;
 100       Typ         : Entity_Id;
 101       Flist_Ref   : Node_Id;
 102       With_Attach : Node_Id) return List_Id;
 103    --  Ref is an expression (with no-side effect and is not required to have
 104    --  been previously analyzed) that references the object to be initialized.
 105    --  Typ is the expected type of Ref, which is either a controlled type
 106    --  (Is_Controlled) or a type with controlled components (Has_Controlled).
 107    --  With_Attach is an integer expression which is the attachment level,
 108    --  see System.Finalization_Implementation.Attach_To_Final_List for the
 109    --  documentation of Nb_Link.
 110    --
 111    --  This function will generate the appropriate calls to make sure that the
 112    --  objects referenced by Ref are initialized. The generated code is quite
 113    --  different for an IS_Controlled type or a HAS_Controlled type, but this
 114    --  is not the problem for the caller, the details are in the body.
 115
 116    function Make_Adjust_Call
 117      (Ref         : Node_Id;
 118       Typ         : Entity_Id;
 119       Flist_Ref   : Node_Id;
 120       With_Attach : Node_Id;
 121       Allocator   : Boolean := False) return List_Id;
 122    --  Ref is an expression (with no-side effect and is not required to have
 123    --  been previously analyzed) that references the object to be adjusted. Typ
 124    --  is the expected type of Ref, which is a controlled type (Is_Controlled)
 125    --  or a type with controlled components (Has_Controlled). With_Attach is an
 126    --  integer expression giving the attachment level (see documentation of
 127    --  Attach_To_Final_List.Nb_Link param documentation in s-finimp.ads.
 128    --  Note: if Typ is Finalize_Storage_Only and the object is at library
 129    --  level, then With_Attach will be ignored, and a zero link level will be
 130    --  passed to Attach_To_Final_List.
 131    --
 132    --  This function will generate the appropriate calls to make sure that the
 133    --  objects referenced by Ref are adjusted. The generated code is quite
 134    --  different depending on the fact the type IS_Controlled or HAS_Controlled
 135    --  but this is not the problem of the caller, the details are in the body.
 136    --  The objects must be attached when the adjust takes place after an
 137    --  initialization expression but not when it takes place after a regular
 138    --  assignment.
 139    --
 140    --  If Allocator is True, we are adjusting a newly-created object. The
 141    --  existing chaining pointers should not be left unchanged, because they
 142    --  may come from a bit-for-bit copy of those from an initializing object.
 143    --  So, when this flag is True, if the chaining pointers should otherwise
 144    --  be left unset, instead they are reset to null.
 145
 146    function Make_Final_Call
 147      (Ref         : Node_Id;
 148       Typ         : Entity_Id;
 149       With_Detach : Node_Id) return List_Id;
 150    --  Ref is an expression (with no-side effect and is not required to have
 151    --  been previously analyzed) that references the object to be Finalized.
 152    --  Typ is the expected type of Ref, which is a controlled type
 153    --  (Is_Controlled) or a type with controlled components (Has_Controlled).
 154    --  With_Detach is a boolean expression indicating whether to detach the
 155    --  controlled object from whatever finalization list it is currently
 156    --  attached to.
 157    --
 158    --  This function will generate the appropriate calls to make sure that the
 159    --  objects referenced by Ref are finalized. The generated code is quite
 160    --  different depending on the fact the type IS_Controlled or HAS_Controlled
 161    --  but this is not the problem of the caller, the details are in the body.
 162    --  The objects must be detached when finalizing an unchecked deallocated
 163    --  object but not when finalizing the target of an assignment, it is not
 164    --  necessary either on scope exit.
 165
 166    procedure Expand_Ctrl_Function_Call (N : Node_Id);
 167    --  Expand a call to a function returning a controlled value. That is to
 168    --  say attach the result of the call to the current finalization list,
 169    --  which is the one of the transient scope created for such constructs.
 170
 171    function Make_Handler_For_Ctrl_Operation (Loc : Source_Ptr) return Node_Id;
 172    --  Generate an implicit exception handler with an 'others' choice,
 173    --  converting any occurrence to a raise of Program_Error.
 174
 175    --------------------------------------------
 176    -- Task and Protected Object finalization --
 177    --------------------------------------------
 178
 179    function Cleanup_Array
 180      (N   : Node_Id;
 181       Obj : Node_Id;
 182       Typ : Entity_Id) return List_Id;
 183    --  Generate loops to finalize any tasks or simple protected objects that
 184    --  are subcomponents of an array.
 185
 186    function Cleanup_Protected_Object
 187      (N   : Node_Id;
 188       Ref : Node_Id) return Node_Id;
 189    --  Generate code to finalize a protected object without entries
 190
 191    function Cleanup_Record
 192      (N   : Node_Id;
 193       Obj : Node_Id;
 194       Typ : Entity_Id) return List_Id;
 195    --  For each subcomponent of a record that contains tasks or simple
 196    --  protected objects, generate the appropriate finalization call.
 197
 198    function Cleanup_Task
 199      (N   : Node_Id;
 200       Ref : Node_Id) return Node_Id;
 201    --  Generate code to finalize a task
 202
 203    function Has_Simple_Protected_Object (T : Entity_Id) return Boolean;
 204    --  Check whether composite type contains a simple protected component
 205
 206    function Is_Simple_Protected_Type (T : Entity_Id) return Boolean;
 207    --  Check whether argument is a protected type without entries. Protected
 208    --  types with entries are controlled, and their cleanup is handled by the
 209    --  standard finalization machinery. For simple protected types we generate
 210    --  inline code to release their locks.
 211
 212    --------------------------------
 213    -- Transient Scope Management --
 214    --------------------------------
 215
 216    procedure Expand_Cleanup_Actions (N : Node_Id);
 217    --  Expand the necessary stuff into a scope to enable finalization of local
 218    --  objects and deallocation of transient data when exiting the scope. N is
 219    --  a "scope node" that is to say one of the following: N_Block_Statement,
 220    --  N_Subprogram_Body, N_Task_Body, N_Entry_Body.
 221
 222    procedure Establish_Transient_Scope (N : Node_Id; Sec_Stack : Boolean);
 223    --  Push a new transient scope on the scope stack. N is the node responsible
 224    --  for the need of a transient scope. If Sec_Stack is True then the
 225    --  secondary stack is brought in, otherwise it isn't.
 226
 227    function Node_To_Be_Wrapped return Node_Id;
 228    --  return the node to be wrapped if the current scope is transient
 229
 230    procedure Store_Before_Actions_In_Scope (L : List_Id);
 231    --  Append the list L of actions to the end of the before-actions store in
 232    --  the top of the scope stack
 233
 234    procedure Store_After_Actions_In_Scope (L : List_Id);
 235    --  Append the list L of actions to the beginning of the after-actions store
 236    --  in the top of the scope stack
 237
 238    procedure Wrap_Transient_Declaration (N : Node_Id);
 239    --  N is an object declaration. Expand the finalization calls after the
 240    --  declaration and make the outer scope being the transient one.
 241
 242    procedure Wrap_Transient_Expression (N : Node_Id);
 243    --  N is a sub-expression. Expand a transient block around an expression
 244
 245    procedure Wrap_Transient_Statement (N : Node_Id);
 246    --  N is a statement. Expand a transient block around an instruction
 247
 248 end Exp_Ch7;