gcc/ada/exp_ch13.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             E X P _ C H 1 3                              --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2009, 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 Atree;    use Atree;
  27 with Checks;   use Checks;
  28 with Einfo;    use Einfo;
  29 with Exp_Ch3;  use Exp_Ch3;
  30 with Exp_Ch6;  use Exp_Ch6;
  31 with Exp_Imgv; use Exp_Imgv;
  32 with Exp_Tss;  use Exp_Tss;
  33 with Exp_Util; use Exp_Util;
  34 with Namet;    use Namet;
  35 with Nlists;   use Nlists;
  36 with Nmake;    use Nmake;
  37 with Opt;      use Opt;
  38 with Rtsfind;  use Rtsfind;
  39 with Sem;      use Sem;
  40 with Sem_Ch7;  use Sem_Ch7;
  41 with Sem_Ch8;  use Sem_Ch8;
  42 with Sem_Eval; use Sem_Eval;
  43 with Sem_Util; use Sem_Util;
  44 with Sinfo;    use Sinfo;
  45 with Snames;   use Snames;
  46 with Stand;    use Stand;
  47 with Tbuild;   use Tbuild;
  48 with Uintp;    use Uintp;
  49
  50 package body Exp_Ch13 is
  51
  52    ------------------------------------------
  53    -- Expand_N_Attribute_Definition_Clause --
  54    ------------------------------------------
  55
  56    --  Expansion action depends on attribute involved
  57
  58    procedure Expand_N_Attribute_Definition_Clause (N : Node_Id) is
  59       Loc : constant Source_Ptr := Sloc (N);
  60       Exp : constant Node_Id    := Expression (N);
  61       Ent : Entity_Id;
  62       V   : Node_Id;
  63
  64    begin
  65       Ent := Entity (Name (N));
  66
  67       if Is_Type (Ent) then
  68          Ent := Underlying_Type (Ent);
  69       end if;
  70
  71       case Get_Attribute_Id (Chars (N)) is
  72
  73          -------------
  74          -- Address --
  75          -------------
  76
  77          when Attribute_Address =>
  78
  79             --  If there is an initialization which did not come from the
  80             --  source program, then it is an artifact of our expansion, and we
  81             --  suppress it. The case we are most concerned about here is the
  82             --  initialization of a packed array to all false, which seems
  83             --  inappropriate for variable to which an address clause is
  84             --  applied. The expression may itself have been rewritten if the
  85             --  type is packed array, so we need to examine whether the
  86             --  original node is in the source. An exception though is the case
  87             --  of an access variable which is default initialized to null, and
  88             --  such initialization is retained.
  89
  90             --  Furthermore, if the initialization is the equivalent aggregate
  91             --  of the type initialization procedure, it replaces an implicit
  92             --  call to the init proc, and must be respected. Note that for
  93             --  packed types we do not build equivalent aggregates.
  94
  95             --  Also, if Init_Or_Norm_Scalars applies, then we need to retain
  96             --  any default initialization for objects of scalar types and
  97             --  types with scalar components. Normally a composite type will
  98             --  have an init_proc in the presence of Init_Or_Norm_Scalars,
  99             --  so when that flag is set we have just have to do a test for
 100             --  scalar and string types (the predefined string types such as
 101             --  String and Wide_String don't have an init_proc).
 102
 103             declare
 104                Decl : constant Node_Id := Declaration_Node (Ent);
 105                Typ  : constant Entity_Id := Etype (Ent);
 106
 107             begin
 108                if Nkind (Decl) = N_Object_Declaration
 109                   and then Present (Expression (Decl))
 110                   and then Nkind (Expression (Decl)) /= N_Null
 111                   and then
 112                    not Comes_From_Source (Original_Node (Expression (Decl)))
 113                then
 114                   if Present (Base_Init_Proc (Typ))
 115                     and then
 116                       Present (Static_Initialization (Base_Init_Proc (Typ)))
 117                   then
 118                      null;
 119
 120                   elsif Init_Or_Norm_Scalars
 121                     and then
 122                       (Is_Scalar_Type (Typ) or else Is_String_Type (Typ))
 123                   then
 124                      null;
 125
 126                   else
 127                      Set_Expression (Decl, Empty);
 128                   end if;
 129                end if;
 130             end;
 131
 132          ---------------
 133          -- Alignment --
 134          ---------------
 135
 136          when Attribute_Alignment =>
 137
 138             --  As required by Gigi, we guarantee that the operand is an
 139             --  integer literal (this simplifies things in Gigi).
 140
 141             if Nkind (Exp) /= N_Integer_Literal then
 142                Rewrite
 143                  (Exp, Make_Integer_Literal (Loc, Expr_Value (Exp)));
 144             end if;
 145
 146          ------------------
 147          -- Storage_Size --
 148          ------------------
 149
 150          when Attribute_Storage_Size =>
 151
 152             --  If the type is a task type, then assign the value of the
 153             --  storage size to the Size variable associated with the task.
 154             --    task_typeZ := expression
 155
 156             if Ekind (Ent) = E_Task_Type then
 157                Insert_Action (N,
 158                  Make_Assignment_Statement (Loc,
 159                    Name => New_Reference_To (Storage_Size_Variable (Ent), Loc),
 160                    Expression =>
 161                      Convert_To (RTE (RE_Size_Type), Expression (N))));
 162
 163             --  For Storage_Size for an access type, create a variable to hold
 164             --  the value of the specified size with name typeV and expand an
 165             --  assignment statement to initialize this value.
 166
 167             elsif Is_Access_Type (Ent) then
 168
 169                --  We don't need the variable for a storage size of zero
 170
 171                if not No_Pool_Assigned (Ent) then
 172                   V :=
 173                     Make_Defining_Identifier (Loc,
 174                       Chars => New_External_Name (Chars (Ent), 'V'));
 175
 176                   --  Insert the declaration of the object
 177
 178                   Insert_Action (N,
 179                     Make_Object_Declaration (Loc,
 180                       Defining_Identifier => V,
 181                       Object_Definition  =>
 182                         New_Reference_To (RTE (RE_Storage_Offset), Loc),
 183                       Expression =>
 184                         Convert_To (RTE (RE_Storage_Offset), Expression (N))));
 185
 186                   Set_Storage_Size_Variable (Ent, Entity_Id (V));
 187                end if;
 188             end if;
 189
 190          --  Other attributes require no expansion
 191
 192          when others =>
 193             null;
 194
 195       end case;
 196    end Expand_N_Attribute_Definition_Clause;
 197
 198    ----------------------------
 199    -- Expand_N_Freeze_Entity --
 200    ----------------------------
 201
 202    procedure Expand_N_Freeze_Entity (N : Node_Id) is
 203       E              : constant Entity_Id := Entity (N);
 204       E_Scope        : Entity_Id;
 205       S              : Entity_Id;
 206       In_Other_Scope : Boolean;
 207       In_Outer_Scope : Boolean;
 208       Decl           : Node_Id;
 209       Delete         : Boolean := False;
 210
 211    begin
 212       --  Processing for objects with address clauses
 213
 214       if Is_Object (E) and then Present (Address_Clause (E)) then
 215          Apply_Address_Clause_Check (E, N);
 216          return;
 217
 218       --  Only other items requiring any front end action are types and
 219       --  subprograms.
 220
 221       elsif not Is_Type (E) and then not Is_Subprogram (E) then
 222          return;
 223       end if;
 224
 225       --  Here E is a type or a subprogram
 226
 227       E_Scope := Scope (E);
 228
 229       --  This is an error protection against previous errors
 230
 231       if No (E_Scope) then
 232          return;
 233       end if;
 234
 235       --  Remember that we are processing a freezing entity and its freezing
 236       --  nodes. This flag (non-zero = set) is used to avoid the need of
 237       --  climbing through the tree while processing the freezing actions (ie.
 238       --  to avoid generating spurious warnings or to avoid killing constant
 239       --  indications while processing the code associated with freezing
 240       --  actions). We use a counter to deal with nesting.
 241
 242       Inside_Freezing_Actions := Inside_Freezing_Actions + 1;
 243
 244       --  If we are freezing entities defined in protected types, they belong
 245       --  in the enclosing scope, given that the original type has been
 246       --  expanded away. The same is true for entities in task types, in
 247       --  particular the parameter records of entries (Entities in bodies are
 248       --  all frozen within the body). If we are in the task body, this is a
 249       --  proper scope. If we are within a subprogram body, the proper scope
 250       --  is the corresponding spec. This may happen for itypes generated in
 251       --  the bodies of protected operations.
 252
 253       if Ekind (E_Scope) = E_Protected_Type
 254         or else (Ekind (E_Scope) = E_Task_Type
 255                    and then not Has_Completion (E_Scope))
 256       then
 257          E_Scope := Scope (E_Scope);
 258
 259       elsif Ekind (E_Scope) = E_Subprogram_Body then
 260          E_Scope := Corresponding_Spec (Unit_Declaration_Node (E_Scope));
 261       end if;
 262
 263       S := Current_Scope;
 264       while S /= Standard_Standard and then S /= E_Scope loop
 265          S := Scope (S);
 266       end loop;
 267
 268       In_Other_Scope := not (S = E_Scope);
 269       In_Outer_Scope := (not In_Other_Scope) and then (S /= Current_Scope);
 270
 271       --  If the entity being frozen is defined in a scope that is not
 272       --  currently on the scope stack, we must establish the proper
 273       --  visibility before freezing the entity and related subprograms.
 274
 275       if In_Other_Scope then
 276          Push_Scope (E_Scope);
 277          Install_Visible_Declarations (E_Scope);
 278
 279          if Is_Package_Or_Generic_Package (E_Scope) or else
 280             Is_Protected_Type (E_Scope)             or else
 281             Is_Task_Type (E_Scope)
 282          then
 283             Install_Private_Declarations (E_Scope);
 284          end if;
 285
 286       --  If the entity is in an outer scope, then that scope needs to
 287       --  temporarily become the current scope so that operations created
 288       --  during type freezing will be declared in the right scope and
 289       --  can properly override any corresponding inherited operations.
 290
 291       elsif In_Outer_Scope then
 292          Push_Scope (E_Scope);
 293       end if;
 294
 295       --  If type, freeze the type
 296
 297       if Is_Type (E) then
 298          Delete := Freeze_Type (N);
 299
 300          --  And for enumeration type, build the enumeration tables
 301
 302          if Is_Enumeration_Type (E) then
 303             Build_Enumeration_Image_Tables (E, N);
 304          end if;
 305
 306       --  If subprogram, freeze the subprogram
 307
 308       elsif Is_Subprogram (E) then
 309          Freeze_Subprogram (N);
 310
 311          --  Ada 2005 (AI-251): Remove the freezing node associated with the
 312          --  entities internally used by the frontend to register primitives
 313          --  covering abstract interfaces. The call to Freeze_Subprogram has
 314          --  already expanded the code that fills the corresponding entry in
 315          --  its secondary dispatch table and therefore the code generator
 316          --  has nothing else to do with this freezing node.
 317
 318          Delete := Present (Interface_Alias (E));
 319       end if;
 320
 321       --  Analyze actions generated by freezing. The init_proc contains source
 322       --  expressions that may raise Constraint_Error, and the assignment
 323       --  procedure for complex types needs checks on individual component
 324       --  assignments, but all other freezing actions should be compiled with
 325       --  all checks off.
 326
 327       if Present (Actions (N)) then
 328          Decl := First (Actions (N));
 329          while Present (Decl) loop
 330             if Nkind (Decl) = N_Subprogram_Body
 331               and then (Is_Init_Proc (Defining_Entity (Decl))
 332                           or else
 333                             Chars (Defining_Entity (Decl)) = Name_uAssign)
 334             then
 335                Analyze (Decl);
 336
 337             --  A subprogram body created for a renaming_as_body completes
 338             --  a previous declaration, which may be in a different scope.
 339             --  Establish the proper scope before analysis.
 340
 341             elsif Nkind (Decl) = N_Subprogram_Body
 342               and then Present (Corresponding_Spec (Decl))
 343               and then Scope (Corresponding_Spec (Decl)) /= Current_Scope
 344             then
 345                Push_Scope (Scope (Corresponding_Spec (Decl)));
 346                Analyze (Decl, Suppress => All_Checks);
 347                Pop_Scope;
 348
 349             else
 350                Analyze (Decl, Suppress => All_Checks);
 351             end if;
 352
 353             Next (Decl);
 354          end loop;
 355       end if;
 356
 357       --  If we are to delete this N_Freeze_Entity, do so by rewriting so that
 358       --  a loop on all nodes being inserted will work propertly.
 359
 360       if Delete then
 361          Rewrite (N, Make_Null_Statement (Sloc (N)));
 362       end if;
 363
 364       if In_Other_Scope then
 365          if Ekind (Current_Scope) = E_Package then
 366             End_Package_Scope (E_Scope);
 367          else
 368             End_Scope;
 369          end if;
 370
 371       elsif In_Outer_Scope then
 372          Pop_Scope;
 373       end if;
 374
 375       --  Restore previous value of the nesting-level counter that records
 376       --  whether we are inside a (possibly nested) call to this procedure.
 377
 378       Inside_Freezing_Actions := Inside_Freezing_Actions - 1;
 379    end Expand_N_Freeze_Entity;
 380
 381    -------------------------------------------
 382    -- Expand_N_Record_Representation_Clause --
 383    -------------------------------------------
 384
 385    --  The only expansion required is for the case of a mod clause present,
 386    --  which is removed, and translated into an alignment representation
 387    --  clause inserted immediately after the record rep clause with any
 388    --  initial pragmas inserted at the start of the component clause list.
 389
 390    procedure Expand_N_Record_Representation_Clause (N : Node_Id) is
 391       Loc     : constant Source_Ptr := Sloc (N);
 392       Rectype : constant Entity_Id  := Entity (Identifier (N));
 393       Mod_Val : Uint;
 394       Citems  : List_Id;
 395       Repitem : Node_Id;
 396       AtM_Nod : Node_Id;
 397
 398    begin
 399       if Present (Mod_Clause (N)) and then not Ignore_Rep_Clauses then
 400          Mod_Val := Expr_Value (Expression (Mod_Clause (N)));
 401          Citems  := Pragmas_Before (Mod_Clause (N));
 402
 403          if Present (Citems) then
 404             Append_List_To (Citems, Component_Clauses (N));
 405             Set_Component_Clauses (N, Citems);
 406          end if;
 407
 408          AtM_Nod :=
 409            Make_Attribute_Definition_Clause (Loc,
 410              Name       => New_Reference_To (Base_Type (Rectype), Loc),
 411              Chars      => Name_Alignment,
 412              Expression => Make_Integer_Literal (Loc, Mod_Val));
 413
 414          Set_From_At_Mod (AtM_Nod);
 415          Insert_After (N, AtM_Nod);
 416          Set_Mod_Clause (N, Empty);
 417       end if;
 418
 419       --  If the record representation clause has no components, then
 420       --  completely remove it.  Note that we also have to remove
 421       --  ourself from the Rep Item list.
 422
 423       if Is_Empty_List (Component_Clauses (N)) then
 424          if First_Rep_Item (Rectype) = N then
 425             Set_First_Rep_Item (Rectype, Next_Rep_Item (N));
 426          else
 427             Repitem := First_Rep_Item (Rectype);
 428             while Present (Next_Rep_Item (Repitem)) loop
 429                if Next_Rep_Item (Repitem) = N then
 430                   Set_Next_Rep_Item (Repitem, Next_Rep_Item (N));
 431                   exit;
 432                end if;
 433
 434                Next_Rep_Item (Repitem);
 435             end loop;
 436          end if;
 437
 438          Rewrite (N,
 439            Make_Null_Statement (Loc));
 440       end if;
 441    end Expand_N_Record_Representation_Clause;
 442
 443 end Exp_Ch13;