gcc/ada/exp_intr.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             E X P _ I N T R                              --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2005 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 2,  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 COPYING.  If not, write --
  19 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  20 -- MA 02111-1307, USA.                                                      --
  21 --                                                                          --
  22 -- GNAT was originally developed  by the GNAT team at  New York University. --
  23 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  24 --                                                                          --
  25 ------------------------------------------------------------------------------
  26
  27 with Atree;    use Atree;
  28 with Einfo;    use Einfo;
  29 with Elists;   use Elists;
  30 with Errout;   use Errout;
  31 with Exp_Ch4;  use Exp_Ch4;
  32 with Exp_Ch7;  use Exp_Ch7;
  33 with Exp_Ch11; use Exp_Ch11;
  34 with Exp_Code; use Exp_Code;
  35 with Exp_Disp; use Exp_Disp;
  36 with Exp_Fixd; use Exp_Fixd;
  37 with Exp_Util; use Exp_Util;
  38 with Itypes;   use Itypes;
  39 with Namet;    use Namet;
  40 with Nmake;    use Nmake;
  41 with Nlists;   use Nlists;
  42 with Restrict; use Restrict;
  43 with Rtsfind;  use Rtsfind;
  44 with Sem;      use Sem;
  45 with Sem_Eval; use Sem_Eval;
  46 with Sem_Res;  use Sem_Res;
  47 with Sem_Util; use Sem_Util;
  48 with Sinfo;    use Sinfo;
  49 with Sinput;   use Sinput;
  50 with Snames;   use Snames;
  51 with Stand;    use Stand;
  52 with Stringt;  use Stringt;
  53 with Tbuild;   use Tbuild;
  54 with Uintp;    use Uintp;
  55 with Urealp;   use Urealp;
  56
  57 package body Exp_Intr is
  58
  59    -----------------------
  60    -- Local Subprograms --
  61    -----------------------
  62
  63    procedure Expand_Is_Negative (N : Node_Id);
  64    --  Expand a call to the intrinsic Is_Negative function
  65
  66    procedure Expand_Dispatching_Constructor_Call (N : Node_Id);
  67    --  Expand a call to an instantiation of Generic_Dispatching_Constructor
  68    --  into a dispatching call to the actual subprogram associated with the
  69    --  Constructor formal subprogram, passing it the Parameters actual of
  70    --  the call to the instantiation and dispatching based on call's Tag
  71    --  parameter.
  72
  73    procedure Expand_Exception_Call (N : Node_Id; Ent : RE_Id);
  74    --  Expand a call to Exception_Information/Message/Name. The first
  75    --  parameter, N, is the node for the function call, and Ent is the
  76    --  entity for the corresponding routine in the Ada.Exceptions package.
  77
  78    procedure Expand_Import_Call (N : Node_Id);
  79    --  Expand a call to Import_Address/Longest_Integer/Value. The parameter
  80    --  N is the node for the function call.
  81
  82    procedure Expand_Shift (N : Node_Id; E : Entity_Id; K : Node_Kind);
  83    --  Expand an intrinsic shift operation, N and E are from the call to
  84    --  Expand_Intrinsic_Call (call node and subprogram spec entity) and
  85    --  K is the kind for the shift node
  86
  87    procedure Expand_Unc_Conversion (N : Node_Id; E : Entity_Id);
  88    --  Expand a call to an instantiation of Unchecked_Convertion into a node
  89    --  N_Unchecked_Type_Conversion.
  90
  91    procedure Expand_Unc_Deallocation (N : Node_Id);
  92    --  Expand a call to an instantiation of Unchecked_Deallocation into a node
  93    --  N_Free_Statement and appropriate context.
  94
  95    procedure Expand_To_Address (N : Node_Id);
  96    procedure Expand_To_Pointer (N : Node_Id);
  97    --  Expand a call to corresponding function, declared in an instance of
  98    --  System.Addess_To_Access_Conversions.
  99
 100    procedure Expand_Source_Info (N : Node_Id; Nam : Name_Id);
 101    --  Rewrite the node by the appropriate string or positive constant.
 102    --  Nam can be one of the following:
 103    --    Name_File             - expand string that is the name of source file
 104    --    Name_Line             - expand integer line number
 105    --    Name_Source_Location  - expand string of form file:line
 106    --    Name_Enclosing_Entity - expand string  with name of enclosing entity
 107
 108    -----------------------------------------
 109    -- Expand_Dispatching_Constructor_Call --
 110    -----------------------------------------
 111
 112    --  Transform a call to an instantiation of Generic_Dispatching_Constructor
 113    --  of the form:
 114
 115    --     GDC_Instance (The_Tag, Parameters'Access)
 116
 117    --  to a class-wide conversion of a dispatching call to the actual
 118    --  associated with the formal subprogram Construct, designating
 119    --  The_Tag as the controlling tag of the call:
 120
 121    --     T'Class (Construct'Actual (Params)) -- Controlling tag is The_Tag
 122
 123    --  which will eventually be expanded to the following:
 124
 125    --     T'Class (The_Tag.all (Construct'Actual'Index).all (Params))
 126
 127    --  A class-wide membership test is also generated, preceding the call,
 128    --  to ensure that the controlling tag denotes a type in T'Class.
 129
 130    procedure Expand_Dispatching_Constructor_Call (N : Node_Id) is
 131       Loc        : constant Source_Ptr := Sloc (N);
 132       Tag_Arg    : constant Node_Id    := First_Actual (N);
 133       Param_Arg  : constant Node_Id    := Next_Actual (Tag_Arg);
 134       Subp_Decl  : constant Node_Id    := Parent (Parent (Entity (Name (N))));
 135       Inst_Pkg   : constant Node_Id    := Parent (Subp_Decl);
 136       Act_Rename : constant Node_Id    :=
 137                      Next (Next (First (Visible_Declarations (Inst_Pkg))));
 138       Act_Constr : constant Entity_Id  := Entity (Name (Act_Rename));
 139       Result_Typ : constant Entity_Id  := Class_Wide_Type (Etype (Act_Constr));
 140       Cnstr_Call : Node_Id;
 141
 142    begin
 143       --  Create the call to the actual Constructor function
 144
 145       Cnstr_Call :=
 146         Make_Function_Call (Loc,
 147           Name                   => New_Occurrence_Of (Act_Constr, Loc),
 148           Parameter_Associations => New_List (Relocate_Node (Param_Arg)));
 149
 150       --  Establish its controlling tag from the tag passed to the instance
 151
 152       Set_Controlling_Argument (Cnstr_Call, Relocate_Node (Tag_Arg));
 153
 154       --  Rewrite and analyze the call to the instance as a class-wide
 155       --  conversion of the call to the actual constructor.
 156
 157       Rewrite (N, Convert_To (Result_Typ, Cnstr_Call));
 158       Analyze_And_Resolve (N, Etype (Act_Constr));
 159
 160       --  Generate a class-wide membership test to ensure that the call's tag
 161       --  argument denotes a type within the class.
 162
 163       Insert_Action (N,
 164         Make_Implicit_If_Statement (N,
 165           Condition =>
 166             Make_Op_Not (Loc,
 167               Make_DT_Access_Action (Result_Typ,
 168                  Action => CW_Membership,
 169                  Args   => New_List (
 170                    Duplicate_Subexpr (Tag_Arg),
 171                    New_Reference_To (
 172                      Node (First_Elmt (Access_Disp_Table (
 173                                          Root_Type (Result_Typ)))), Loc)))),
 174           Then_Statements =>
 175             New_List (Make_Raise_Statement (Loc,
 176                         New_Occurrence_Of (RTE (RE_Tag_Error), Loc)))));
 177    end Expand_Dispatching_Constructor_Call;
 178
 179    ---------------------------
 180    -- Expand_Exception_Call --
 181    ---------------------------
 182
 183    --  If the function call is not within an exception handler, then the
 184    --  call is replaced by a null string. Otherwise the appropriate routine
 185    --  in Ada.Exceptions is called passing the choice parameter specification
 186    --  from the enclosing handler. If the enclosing handler lacks a choice
 187    --  parameter, then one is supplied.
 188
 189    procedure Expand_Exception_Call (N : Node_Id; Ent : RE_Id) is
 190       Loc : constant Source_Ptr := Sloc (N);
 191       P   : Node_Id;
 192       E   : Entity_Id;
 193
 194    begin
 195       --  Climb up parents to see if we are in exception handler
 196
 197       P := Parent (N);
 198       loop
 199          --  Case of not in exception handler, replace by null string
 200
 201          if No (P) then
 202             Rewrite (N,
 203               Make_String_Literal (Loc,
 204                 Strval => ""));
 205             exit;
 206
 207          --  Case of in exception handler
 208
 209          elsif Nkind (P) = N_Exception_Handler then
 210             if No (Choice_Parameter (P)) then
 211
 212                --  If no choice parameter present, then put one there. Note
 213                --  that we do not need to put it on the entity chain, since
 214                --  no one will be referencing it by normal visibility methods.
 215
 216                E := Make_Defining_Identifier (Loc, New_Internal_Name ('E'));
 217                Set_Choice_Parameter (P, E);
 218                Set_Ekind (E, E_Variable);
 219                Set_Etype (E, RTE (RE_Exception_Occurrence));
 220                Set_Scope (E, Current_Scope);
 221             end if;
 222
 223             Rewrite (N,
 224               Make_Function_Call (Loc,
 225                 Name => New_Occurrence_Of (RTE (Ent), Loc),
 226                 Parameter_Associations => New_List (
 227                   New_Occurrence_Of (Choice_Parameter (P), Loc))));
 228             exit;
 229
 230          --  Keep climbing!
 231
 232          else
 233             P := Parent (P);
 234          end if;
 235       end loop;
 236
 237       Analyze_And_Resolve (N, Standard_String);
 238    end Expand_Exception_Call;
 239
 240    ------------------------
 241    -- Expand_Import_Call --
 242    ------------------------
 243
 244    --  The function call must have a static string as its argument. We create
 245    --  a dummy variable which uses this string as the external name in an
 246    --  Import pragma. The result is then obtained as the address of this
 247    --  dummy variable, converted to the appropriate target type.
 248
 249    procedure Expand_Import_Call (N : Node_Id) is
 250       Loc : constant Source_Ptr := Sloc (N);
 251       Ent : constant Entity_Id  := Entity (Name (N));
 252       Str : constant Node_Id    := First_Actual (N);
 253       Dum : Entity_Id;
 254
 255    begin
 256       Dum := Make_Defining_Identifier (Loc, New_Internal_Name ('D'));
 257
 258       Insert_Actions (N, New_List (
 259         Make_Object_Declaration (Loc,
 260           Defining_Identifier => Dum,
 261           Object_Definition   =>
 262             New_Occurrence_Of (Standard_Character, Loc)),
 263
 264         Make_Pragma (Loc,
 265           Chars => Name_Import,
 266           Pragma_Argument_Associations => New_List (
 267             Make_Pragma_Argument_Association (Loc,
 268               Expression => Make_Identifier (Loc, Name_Ada)),
 269
 270             Make_Pragma_Argument_Association (Loc,
 271               Expression => Make_Identifier (Loc, Chars (Dum))),
 272
 273             Make_Pragma_Argument_Association (Loc,
 274               Chars => Name_Link_Name,
 275               Expression => Relocate_Node (Str))))));
 276
 277       Rewrite (N,
 278         Unchecked_Convert_To (Etype (Ent),
 279           Make_Attribute_Reference (Loc,
 280             Attribute_Name => Name_Address,
 281             Prefix => Make_Identifier (Loc, Chars (Dum)))));
 282
 283       Analyze_And_Resolve (N, Etype (Ent));
 284    end Expand_Import_Call;
 285
 286    ---------------------------
 287    -- Expand_Intrinsic_Call --
 288    ---------------------------
 289
 290    procedure Expand_Intrinsic_Call (N : Node_Id; E : Entity_Id) is
 291       Nam : Name_Id;
 292
 293    begin
 294       --  If the intrinsic subprogram is generic, gets its original name
 295
 296       if Present (Parent (E))
 297         and then Present (Generic_Parent (Parent (E)))
 298       then
 299          Nam := Chars (Generic_Parent (Parent (E)));
 300       else
 301          Nam := Chars (E);
 302       end if;
 303
 304       if Nam = Name_Asm then
 305          Expand_Asm_Call (N);
 306
 307       elsif Nam = Name_Divide then
 308          Expand_Decimal_Divide_Call (N);
 309
 310       elsif Nam = Name_Exception_Information then
 311          Expand_Exception_Call (N, RE_Exception_Information);
 312
 313       elsif Nam = Name_Exception_Message then
 314          Expand_Exception_Call (N, RE_Exception_Message);
 315
 316       elsif Nam = Name_Exception_Name then
 317          Expand_Exception_Call (N, RE_Exception_Name_Simple);
 318
 319       elsif Nam = Name_Generic_Dispatching_Constructor then
 320          Expand_Dispatching_Constructor_Call (N);
 321
 322       elsif Nam = Name_Import_Address
 323               or else
 324             Nam = Name_Import_Largest_Value
 325               or else
 326             Nam = Name_Import_Value
 327       then
 328          Expand_Import_Call (N);
 329
 330       elsif Nam = Name_Is_Negative then
 331          Expand_Is_Negative (N);
 332
 333       elsif Nam = Name_Rotate_Left then
 334          Expand_Shift (N, E, N_Op_Rotate_Left);
 335
 336       elsif Nam = Name_Rotate_Right then
 337          Expand_Shift (N, E, N_Op_Rotate_Right);
 338
 339       elsif Nam = Name_Shift_Left then
 340          Expand_Shift (N, E, N_Op_Shift_Left);
 341
 342       elsif Nam = Name_Shift_Right then
 343          Expand_Shift (N, E, N_Op_Shift_Right);
 344
 345       elsif Nam = Name_Shift_Right_Arithmetic then
 346          Expand_Shift (N, E, N_Op_Shift_Right_Arithmetic);
 347
 348       elsif Nam = Name_Unchecked_Conversion then
 349          Expand_Unc_Conversion (N, E);
 350
 351       elsif Nam = Name_Unchecked_Deallocation then
 352          Expand_Unc_Deallocation (N);
 353
 354       elsif Nam = Name_To_Address then
 355          Expand_To_Address (N);
 356
 357       elsif Nam = Name_To_Pointer then
 358          Expand_To_Pointer (N);
 359
 360       elsif Nam = Name_File
 361         or else Nam = Name_Line
 362         or else Nam = Name_Source_Location
 363         or else Nam = Name_Enclosing_Entity
 364       then
 365          Expand_Source_Info (N, Nam);
 366
 367          --  If we have a renaming, expand the call to the original operation,
 368          --  which must itself be intrinsic, since renaming requires matching
 369          --  conventions and this has already been checked.
 370
 371       elsif Present (Alias (E)) then
 372          Expand_Intrinsic_Call (N,  Alias (E));
 373
 374          --  The only other case is where an external name was specified,
 375          --  since this is the only way that an otherwise unrecognized
 376          --  name could escape the checking in Sem_Prag. Nothing needs
 377          --  to be done in such a case, since we pass such a call to the
 378          --  back end unchanged.
 379
 380       else
 381          null;
 382       end if;
 383    end Expand_Intrinsic_Call;
 384
 385    ------------------------
 386    -- Expand_Is_Negative --
 387    ------------------------
 388
 389    procedure Expand_Is_Negative (N : Node_Id) is
 390       Loc   : constant Source_Ptr := Sloc (N);
 391       Opnd  : constant Node_Id    := Relocate_Node (First_Actual (N));
 392
 393    begin
 394
 395       --  We replace the function call by the following expression
 396
 397       --    if Opnd < 0.0 then
 398       --       True
 399       --    else
 400       --       if Opnd > 0.0 then
 401       --          False;
 402       --       else
 403       --          Float_Unsigned!(Float (Opnd)) /= 0
 404       --       end if;
 405       --    end if;
 406
 407       Rewrite (N,
 408         Make_Conditional_Expression (Loc,
 409           Expressions => New_List (
 410             Make_Op_Lt (Loc,
 411               Left_Opnd  => Duplicate_Subexpr (Opnd),
 412               Right_Opnd => Make_Real_Literal (Loc, Ureal_0)),
 413
 414             New_Occurrence_Of (Standard_True, Loc),
 415
 416             Make_Conditional_Expression (Loc,
 417              Expressions => New_List (
 418                Make_Op_Gt (Loc,
 419                  Left_Opnd  => Duplicate_Subexpr_No_Checks (Opnd),
 420                  Right_Opnd => Make_Real_Literal (Loc, Ureal_0)),
 421
 422                New_Occurrence_Of (Standard_False, Loc),
 423
 424                 Make_Op_Ne (Loc,
 425                   Left_Opnd =>
 426                     Unchecked_Convert_To
 427                       (RTE (RE_Float_Unsigned),
 428                        Convert_To
 429                          (Standard_Float,
 430                           Duplicate_Subexpr_No_Checks (Opnd))),
 431                   Right_Opnd =>
 432                     Make_Integer_Literal (Loc, 0)))))));
 433
 434       Analyze_And_Resolve (N, Standard_Boolean);
 435    end Expand_Is_Negative;
 436
 437    ------------------
 438    -- Expand_Shift --
 439    ------------------
 440
 441    --  This procedure is used to convert a call to a shift function to the
 442    --  corresponding operator node. This conversion is not done by the usual
 443    --  circuit for converting calls to operator functions (e.g. "+"(1,2)) to
 444    --  operator nodes, because shifts are not predefined operators.
 445
 446    --  As a result, whenever a shift is used in the source program, it will
 447    --  remain as a call until converted by this routine to the operator node
 448    --  form which Gigi is expecting to see.
 449
 450    --  Note: it is possible for the expander to generate shift operator nodes
 451    --  directly, which will be analyzed in the normal manner by calling Analyze
 452    --  and Resolve. Such shift operator nodes will not be seen by Expand_Shift.
 453
 454    procedure Expand_Shift (N : Node_Id; E : Entity_Id; K : Node_Kind) is
 455       Loc   : constant Source_Ptr := Sloc (N);
 456       Typ   : constant Entity_Id  := Etype (N);
 457       Left  : constant Node_Id    := First_Actual (N);
 458       Right : constant Node_Id    := Next_Actual (Left);
 459       Ltyp  : constant Node_Id    := Etype (Left);
 460       Rtyp  : constant Node_Id    := Etype (Right);
 461       Snode : Node_Id;
 462
 463    begin
 464       Snode := New_Node (K, Loc);
 465       Set_Left_Opnd  (Snode, Relocate_Node (Left));
 466       Set_Right_Opnd (Snode, Relocate_Node (Right));
 467       Set_Chars      (Snode, Chars (E));
 468       Set_Etype      (Snode, Base_Type (Typ));
 469       Set_Entity     (Snode, E);
 470
 471       if Compile_Time_Known_Value (Type_High_Bound (Rtyp))
 472         and then Expr_Value (Type_High_Bound (Rtyp)) < Esize (Ltyp)
 473       then
 474          Set_Shift_Count_OK (Snode, True);
 475       end if;
 476
 477       --  Do the rewrite. Note that we don't call Analyze and Resolve on
 478       --  this node, because it already got analyzed and resolved when
 479       --  it was a function call!
 480
 481       Rewrite (N, Snode);
 482       Set_Analyzed (N);
 483    end Expand_Shift;
 484
 485    ------------------------
 486    -- Expand_Source_Info --
 487    ------------------------
 488
 489    procedure Expand_Source_Info (N : Node_Id; Nam : Name_Id) is
 490       Loc : constant Source_Ptr := Sloc (N);
 491       Ent : Entity_Id;
 492
 493    begin
 494       --  Integer cases
 495
 496       if Nam = Name_Line then
 497          Rewrite (N,
 498            Make_Integer_Literal (Loc,
 499              Intval => UI_From_Int (Int (Get_Logical_Line_Number (Loc)))));
 500          Analyze_And_Resolve (N, Standard_Positive);
 501
 502       --  String cases
 503
 504       else
 505          case Nam is
 506             when Name_File =>
 507                Get_Decoded_Name_String
 508                  (Reference_Name (Get_Source_File_Index (Loc)));
 509
 510             when Name_Source_Location =>
 511                Build_Location_String (Loc);
 512
 513             when Name_Enclosing_Entity =>
 514                Name_Len := 0;
 515
 516                Ent := Current_Scope;
 517
 518                --  Skip enclosing blocks to reach enclosing unit.
 519
 520                while Present (Ent) loop
 521                   exit when Ekind (Ent) /= E_Block
 522                     and then Ekind (Ent) /= E_Loop;
 523                   Ent := Scope (Ent);
 524                end loop;
 525
 526                --  Ent now points to the relevant defining entity
 527
 528                declare
 529                   SDef : Source_Ptr := Sloc (Ent);
 530                   TDef : Source_Buffer_Ptr;
 531
 532                begin
 533                   TDef := Source_Text (Get_Source_File_Index (SDef));
 534                   Name_Len := 0;
 535
 536                   while TDef (SDef) in '0' .. '9'
 537                     or else TDef (SDef) >= 'A'
 538                     or else TDef (SDef) = ASCII.ESC
 539                   loop
 540                      Add_Char_To_Name_Buffer (TDef (SDef));
 541                      SDef := SDef + 1;
 542                   end loop;
 543                end;
 544
 545             when others =>
 546                raise Program_Error;
 547          end case;
 548
 549          Rewrite (N,
 550            Make_String_Literal (Loc, Strval => String_From_Name_Buffer));
 551          Analyze_And_Resolve (N, Standard_String);
 552       end if;
 553
 554       Set_Is_Static_Expression (N);
 555    end Expand_Source_Info;
 556
 557    ---------------------------
 558    -- Expand_Unc_Conversion --
 559    ---------------------------
 560
 561    procedure Expand_Unc_Conversion (N : Node_Id; E : Entity_Id) is
 562       Func : constant Entity_Id  := Entity (Name (N));
 563       Conv : Node_Id;
 564       Ftyp : Entity_Id;
 565       Ttyp : Entity_Id;
 566
 567    begin
 568       --  Rewrite as unchecked conversion node. Note that we must convert
 569       --  the operand to the formal type of the input parameter of the
 570       --  function, so that the resulting N_Unchecked_Type_Conversion
 571       --  call indicates the correct types for Gigi.
 572
 573       --  Right now, we only do this if a scalar type is involved. It is
 574       --  not clear if it is needed in other cases. If we do attempt to
 575       --  do the conversion unconditionally, it crashes 3411-018. To be
 576       --  investigated further ???
 577
 578       Conv := Relocate_Node (First_Actual (N));
 579       Ftyp := Etype (First_Formal (Func));
 580
 581       if Is_Scalar_Type (Ftyp) then
 582          Conv := Convert_To (Ftyp, Conv);
 583          Set_Parent (Conv, N);
 584          Analyze_And_Resolve (Conv);
 585       end if;
 586
 587       --  The instantiation of Unchecked_Conversion creates a wrapper package,
 588       --  and the target type is declared as a subtype of the actual. Recover
 589       --  the actual, which is the subtype indic. in the subtype declaration
 590       --  for the target type. This is semantically correct, and avoids
 591       --  anomalies with access subtypes. For entities, leave type as is.
 592
 593       --  We do the analysis here, because we do not want the compiler
 594       --  to try to optimize or otherwise reorganize the unchecked
 595       --  conversion node.
 596
 597       Ttyp := Etype (E);
 598
 599       if Is_Entity_Name (Conv) then
 600          null;
 601
 602       elsif Nkind (Parent (Ttyp)) = N_Subtype_Declaration then
 603          Ttyp := Entity (Subtype_Indication (Parent (Etype (E))));
 604
 605       elsif Is_Itype (Ttyp) then
 606          Ttyp :=
 607            Entity (Subtype_Indication (Associated_Node_For_Itype (Ttyp)));
 608       else
 609          raise Program_Error;
 610       end if;
 611
 612       Rewrite (N, Unchecked_Convert_To (Ttyp, Conv));
 613       Set_Etype (N, Ttyp);
 614       Set_Analyzed (N);
 615
 616       if Nkind (N) = N_Unchecked_Type_Conversion then
 617          Expand_N_Unchecked_Type_Conversion (N);
 618       end if;
 619    end Expand_Unc_Conversion;
 620
 621    -----------------------------
 622    -- Expand_Unc_Deallocation --
 623    -----------------------------
 624
 625    --  Generate the following Code :
 626
 627    --    if Arg /= null then
 628    --     <Finalize_Call> (.., T'Class(Arg.all), ..);  -- for controlled types
 629    --       Free (Arg);
 630    --       Arg := Null;
 631    --    end if;
 632
 633    --  For a task, we also generate a call to Free_Task to ensure that the
 634    --  task itself is freed if it is terminated, ditto for a simple protected
 635    --  object, with a call to Finalize_Protection. For composite types that
 636    --  have tasks or simple protected objects as components, we traverse the
 637    --  structures to find and terminate those components.
 638
 639    procedure Expand_Unc_Deallocation (N : Node_Id) is
 640       Loc   : constant Source_Ptr := Sloc (N);
 641       Arg   : constant Node_Id    := First_Actual (N);
 642       Typ   : constant Entity_Id  := Etype (Arg);
 643       Stmts : constant List_Id    := New_List;
 644       Rtyp  : constant Entity_Id  := Underlying_Type (Root_Type (Typ));
 645       Pool  : constant Entity_Id  := Associated_Storage_Pool (Rtyp);
 646
 647       Desig_T   : constant Entity_Id  := Designated_Type (Typ);
 648       Gen_Code  : Node_Id;
 649       Free_Node : Node_Id;
 650       Deref     : Node_Id;
 651       Free_Arg  : Node_Id;
 652       Free_Cod  : List_Id;
 653       Blk       : Node_Id;
 654
 655    begin
 656       if No_Pool_Assigned (Rtyp) then
 657          Error_Msg_N ("?deallocation from empty storage pool", N);
 658       end if;
 659
 660       if Controlled_Type (Desig_T) then
 661          Deref :=
 662            Make_Explicit_Dereference (Loc,
 663              Prefix => Duplicate_Subexpr_No_Checks (Arg));
 664
 665          --  If the type is tagged, then we must force dispatching on the
 666          --  finalization call because the designated type may not be the
 667          --  actual type of the object
 668
 669          if Is_Tagged_Type (Desig_T)
 670            and then not Is_Class_Wide_Type (Desig_T)
 671          then
 672             Deref := Unchecked_Convert_To (Class_Wide_Type (Desig_T), Deref);
 673          end if;
 674
 675          Free_Cod :=
 676            Make_Final_Call
 677             (Ref         => Deref,
 678              Typ         => Desig_T,
 679              With_Detach => New_Reference_To (Standard_True, Loc));
 680
 681          if Abort_Allowed then
 682             Prepend_To (Free_Cod,
 683               Build_Runtime_Call (Loc, RE_Abort_Defer));
 684
 685             Blk :=
 686               Make_Block_Statement (Loc, Handled_Statement_Sequence =>
 687                 Make_Handled_Sequence_Of_Statements (Loc,
 688                   Statements  => Free_Cod,
 689                   At_End_Proc =>
 690                     New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc)));
 691
 692             --  We now expand the exception (at end) handler. We set a
 693             --  temporary parent pointer since we have not attached Blk
 694             --  to the tree yet.
 695
 696             Set_Parent (Blk, N);
 697             Analyze (Blk);
 698             Expand_At_End_Handler
 699               (Handled_Statement_Sequence (Blk), Entity (Identifier (Blk)));
 700             Append (Blk, Stmts);
 701
 702          else
 703             Append_List_To (Stmts, Free_Cod);
 704          end if;
 705       end if;
 706
 707       --  For a task type, call Free_Task before freeing the ATCB
 708
 709       if Is_Task_Type (Desig_T) then
 710          declare
 711             Stat : Node_Id := Prev (N);
 712             Nam1 : Node_Id;
 713             Nam2 : Node_Id;
 714
 715          begin
 716             --  An Abort followed by a Free will not do what the user
 717             --  expects, because the abort is not immediate. This is
 718             --  worth a friendly warning.
 719
 720             while Present (Stat)
 721               and then not Comes_From_Source (Original_Node (Stat))
 722             loop
 723                Prev (Stat);
 724             end loop;
 725
 726             if Present (Stat)
 727               and then Nkind (Original_Node (Stat)) = N_Abort_Statement
 728             then
 729                Stat := Original_Node (Stat);
 730                Nam1 := First (Names (Stat));
 731                Nam2 := Original_Node (First (Parameter_Associations (N)));
 732
 733                if Nkind (Nam1) = N_Explicit_Dereference
 734                  and then Is_Entity_Name (Prefix (Nam1))
 735                  and then Is_Entity_Name (Nam2)
 736                  and then Entity (Prefix (Nam1)) = Entity (Nam2)
 737                then
 738                   Error_Msg_N ("Abort may take time to complete?", N);
 739                   Error_Msg_N ("\deallocation might have no effect?", N);
 740                   Error_Msg_N ("\safer to wait for termination.?", N);
 741                end if;
 742             end if;
 743          end;
 744
 745          Append_To
 746            (Stmts, Cleanup_Task (N, Duplicate_Subexpr_No_Checks (Arg)));
 747
 748       --  For composite types that contain tasks, recurse over the structure
 749       --  to build the selectors for the task subcomponents.
 750
 751       elsif Has_Task (Desig_T) then
 752          if Is_Record_Type (Desig_T) then
 753             Append_List_To (Stmts, Cleanup_Record (N, Arg, Desig_T));
 754
 755          elsif Is_Array_Type (Desig_T) then
 756             Append_List_To (Stmts, Cleanup_Array (N, Arg, Desig_T));
 757          end if;
 758       end if;
 759
 760       --  Same for simple protected types. Eventually call Finalize_Protection
 761       --  before freeing the PO for each protected component.
 762
 763       if Is_Simple_Protected_Type (Desig_T) then
 764          Append_To (Stmts,
 765            Cleanup_Protected_Object (N, Duplicate_Subexpr_No_Checks (Arg)));
 766
 767       elsif Has_Simple_Protected_Object (Desig_T) then
 768          if Is_Record_Type (Desig_T) then
 769             Append_List_To (Stmts, Cleanup_Record (N, Arg, Desig_T));
 770          elsif Is_Array_Type (Desig_T) then
 771             Append_List_To (Stmts, Cleanup_Array (N, Arg, Desig_T));
 772          end if;
 773       end if;
 774
 775       --  Normal processing for non-controlled types
 776
 777       Free_Arg := Duplicate_Subexpr_No_Checks (Arg);
 778       Free_Node := Make_Free_Statement (Loc, Empty);
 779       Append_To (Stmts, Free_Node);
 780       Set_Storage_Pool (Free_Node, Pool);
 781
 782       --  Make implicit if statement. We omit this if we are the then part
 783       --  of a test of the form:
 784
 785       --    if not (Arg = null) then
 786
 787       --  i.e. if the test is explicit in the source. Arg must be a simple
 788       --  identifier for the purposes of this special test. Note that the
 789       --  use of /= in the source is always transformed into the above form.
 790
 791       declare
 792          Test_Needed : Boolean := True;
 793          P           : constant Node_Id := Parent (N);
 794          C           : Node_Id;
 795
 796       begin
 797          if Nkind (Arg) = N_Identifier
 798            and then Nkind (P) =  N_If_Statement
 799            and then First (Then_Statements (P)) = N
 800          then
 801             if Nkind (Condition (P)) = N_Op_Not then
 802                C := Right_Opnd (Condition (P));
 803
 804                if Nkind (C) = N_Op_Eq
 805                  and then Nkind (Left_Opnd (C)) = N_Identifier
 806                  and then Chars (Arg) = Chars (Left_Opnd (C))
 807                  and then Nkind (Right_Opnd (C)) = N_Null
 808                then
 809                   Test_Needed := False;
 810                end if;
 811             end if;
 812          end if;
 813
 814          --  Generate If_Statement if needed
 815
 816          if Test_Needed then
 817             Gen_Code :=
 818               Make_Implicit_If_Statement (N,
 819                 Condition =>
 820                   Make_Op_Ne (Loc,
 821                     Left_Opnd  => Duplicate_Subexpr (Arg),
 822                     Right_Opnd => Make_Null (Loc)),
 823                 Then_Statements => Stmts);
 824
 825          else
 826             Gen_Code :=
 827               Make_Block_Statement (Loc,
 828                 Handled_Statement_Sequence =>
 829                   Make_Handled_Sequence_Of_Statements (Loc,
 830                     Statements => Stmts));
 831          end if;
 832       end;
 833
 834       --  Deal with storage pool
 835
 836       if Present (Pool) then
 837
 838          --  Freeing the secondary stack is meaningless
 839
 840          if Is_RTE (Pool, RE_SS_Pool) then
 841             null;
 842
 843          elsif Is_Class_Wide_Type (Etype (Pool)) then
 844             Set_Procedure_To_Call (Free_Node,
 845               RTE (RE_Deallocate_Any));
 846          else
 847             Set_Procedure_To_Call (Free_Node,
 848               Find_Prim_Op (Etype (Pool), Name_Deallocate));
 849
 850             --  If the type is class wide, we generate an implicit type
 851             --  with the right dynamic size, so that the deallocate call
 852             --  gets the right size parameter computed by gigi
 853
 854             if Is_Class_Wide_Type (Desig_T) then
 855                declare
 856                   Acc_Type : constant Entity_Id :=
 857                                Create_Itype (E_Access_Type, N);
 858                   Deref    : constant Node_Id :=
 859                                Make_Explicit_Dereference (Loc,
 860                                  Duplicate_Subexpr_No_Checks (Arg));
 861
 862                begin
 863                   Set_Etype  (Deref, Typ);
 864                   Set_Parent (Deref, Free_Node);
 865
 866                   Set_Etype     (Acc_Type, Acc_Type);
 867                   Set_Size_Info (Acc_Type, Typ);
 868                   Set_Directly_Designated_Type
 869                                 (Acc_Type, Entity (Make_Subtype_From_Expr
 870                                                     (Deref, Desig_T)));
 871
 872                   Free_Arg := Unchecked_Convert_To (Acc_Type, Free_Arg);
 873                end;
 874             end if;
 875          end if;
 876       end if;
 877
 878       Set_Expression (Free_Node, Free_Arg);
 879
 880       declare
 881          Lhs : constant Node_Id := Duplicate_Subexpr_No_Checks (Arg);
 882
 883       begin
 884          Set_Assignment_OK (Lhs);
 885          Append_To (Stmts,
 886            Make_Assignment_Statement (Loc,
 887              Name       => Lhs,
 888              Expression => Make_Null (Loc)));
 889       end;
 890
 891       Rewrite (N, Gen_Code);
 892       Analyze (N);
 893    end Expand_Unc_Deallocation;
 894
 895    -----------------------
 896    -- Expand_To_Address --
 897    -----------------------
 898
 899    procedure Expand_To_Address (N : Node_Id) is
 900       Loc : constant Source_Ptr := Sloc (N);
 901       Arg : constant Node_Id := First_Actual (N);
 902       Obj : Node_Id;
 903
 904    begin
 905       Remove_Side_Effects (Arg);
 906
 907       Obj := Make_Explicit_Dereference (Loc, Relocate_Node (Arg));
 908
 909       Rewrite (N,
 910         Make_Conditional_Expression (Loc,
 911           Expressions => New_List (
 912             Make_Op_Eq (Loc,
 913               Left_Opnd => New_Copy_Tree (Arg),
 914               Right_Opnd => Make_Null (Loc)),
 915             New_Occurrence_Of (RTE (RE_Null_Address), Loc),
 916             Make_Attribute_Reference (Loc,
 917               Attribute_Name => Name_Address,
 918               Prefix => Obj))));
 919
 920       Analyze_And_Resolve (N, RTE (RE_Address));
 921    end Expand_To_Address;
 922
 923    -----------------------
 924    -- Expand_To_Pointer --
 925    -----------------------
 926
 927    procedure Expand_To_Pointer (N : Node_Id) is
 928       Arg : constant Node_Id := First_Actual (N);
 929
 930    begin
 931       Rewrite (N, Unchecked_Convert_To (Etype (N), Arg));
 932       Analyze (N);
 933    end Expand_To_Pointer;
 934
 935 end Exp_Intr;