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 --                            $Revision: 1.76 $
  10 --                                                                          --
  11 --          Copyright (C) 1992-2001 Free Software Foundation, Inc.          --
  12 --                                                                          --
  13 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  14 -- terms of the  GNU General Public License as published  by the Free Soft- --
  15 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  16 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  17 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  18 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  19 -- for  more details.  You should have  received  a copy of the GNU General --
  20 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  21 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  22 -- MA 02111-1307, USA.                                                      --
  23 --                                                                          --
  24 -- GNAT was originally developed  by the GNAT team at  New York University. --
  25 -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
  26 --                                                                          --
  27 ------------------------------------------------------------------------------
  28
  29 with Atree;    use Atree;
  30 with Einfo;    use Einfo;
  31 with Errout;   use Errout;
  32 with Exp_Ch4;  use Exp_Ch4;
  33 with Exp_Ch7;  use Exp_Ch7;
  34 with Exp_Ch9;  use Exp_Ch9;
  35 with Exp_Ch11; use Exp_Ch11;
  36 with Exp_Code; use Exp_Code;
  37 with Exp_Fixd; use Exp_Fixd;
  38 with Exp_Util; use Exp_Util;
  39 with Itypes;   use Itypes;
  40 with Namet;    use Namet;
  41 with Nmake;    use Nmake;
  42 with Nlists;   use Nlists;
  43 with Restrict; use Restrict;
  44 with Rtsfind;  use Rtsfind;
  45 with Sem;      use Sem;
  46 with Sem_Eval; use Sem_Eval;
  47 with Sem_Res;  use Sem_Res;
  48 with Sem_Util; use Sem_Util;
  49 with Sinfo;    use Sinfo;
  50 with Sinput;   use Sinput;
  51 with Snames;   use Snames;
  52 with Stand;    use Stand;
  53 with Stringt;  use Stringt;
  54 with Tbuild;   use Tbuild;
  55 with Uintp;    use Uintp;
  56 with Urealp;   use Urealp;
  57
  58 package body Exp_Intr is
  59
  60    -----------------------
  61    -- Local Subprograms --
  62    -----------------------
  63
  64    procedure Expand_Is_Negative (N : Node_Id);
  65    --  Expand a call to the intrinsic Is_Negative function
  66
  67    procedure Expand_Exception_Call (N : Node_Id; Ent : RE_Id);
  68    --  Expand a call to Exception_Information/Message/Name. The first
  69    --  parameter, N, is the node for the function call, and Ent is the
  70    --  entity for the corresponding routine in the Ada.Exceptions package.
  71
  72    procedure Expand_Import_Call (N : Node_Id);
  73    --  Expand a call to Import_Address/Longest_Integer/Value. The parameter
  74    --  N is the node for the function call.
  75
  76    procedure Expand_Shift (N : Node_Id; E : Entity_Id; K : Node_Kind);
  77    --  Expand an intrinsic shift operation, N and E are from the call to
  78    --  Expand_Instrinsic_Call (call node and subprogram spec entity) and
  79    --  K is the kind for the shift node
  80
  81    procedure Expand_Unc_Conversion (N : Node_Id; E : Entity_Id);
  82    --  Expand a call to an instantiation of Unchecked_Convertion into a node
  83    --  N_Unchecked_Type_Conversion.
  84
  85    procedure Expand_Unc_Deallocation (N : Node_Id; E : Entity_Id);
  86    --  Expand a call to an instantiation of Unchecked_Deallocation into a node
  87    --  N_Free_Statement and appropriate context.
  88
  89    procedure Expand_Source_Info (N : Node_Id; E : Entity_Id; Nam : Name_Id);
  90    --  Rewrite the node by the appropriate string or positive constant.
  91    --  Nam can be one of the following:
  92    --    Name_File             - expand string that is the name of source file
  93    --    Name_Line             - expand integer line number
  94    --    Name_Source_Location  - expand string of form file:line
  95    --    Name_Enclosing_Entity - expand string  with name of enclosing entity
  96
  97    ---------------------------
  98    -- Expand_Exception_Call --
  99    ---------------------------
 100
 101    --  If the function call is not within an exception handler, then the
 102    --  call is replaced by a null string. Otherwise the appropriate routine
 103    --  in Ada.Exceptions is called passing the choice parameter specification
 104    --  from the enclosing handler. If the enclosing handler lacks a choice
 105    --  parameter, then one is supplied.
 106
 107    procedure Expand_Exception_Call (N : Node_Id; Ent : RE_Id) is
 108       Loc : constant Source_Ptr := Sloc (N);
 109       P   : Node_Id;
 110       E   : Entity_Id;
 111       S   : String_Id;
 112
 113    begin
 114       --  Climb up parents to see if we are in exception handler
 115
 116       P := Parent (N);
 117       loop
 118          --  Case of not in exception handler
 119
 120          if No (P) then
 121             Start_String;
 122             S := End_String;
 123             Rewrite (N,
 124               Make_String_Literal (Loc,
 125                 Strval => S));
 126             exit;
 127
 128          --  Case of in exception handler
 129
 130          elsif Nkind (P) = N_Exception_Handler then
 131             if No (Choice_Parameter (P)) then
 132
 133                --  If no choice parameter present, then put one there. Note
 134                --  that we do not need to put it on the entity chain, since
 135                --  no one will be referencing it by normal visibility methods.
 136
 137                E := Make_Defining_Identifier (Loc, New_Internal_Name ('E'));
 138                Set_Choice_Parameter (P, E);
 139                Set_Ekind (E, E_Variable);
 140                Set_Etype (E, RTE (RE_Exception_Occurrence));
 141                Set_Scope (E, Current_Scope);
 142             end if;
 143
 144             Rewrite (N,
 145               Make_Function_Call (Loc,
 146                 Name => New_Occurrence_Of (RTE (Ent), Loc),
 147                 Parameter_Associations => New_List (
 148                   New_Occurrence_Of (Choice_Parameter (P), Loc))));
 149             exit;
 150
 151          --  Keep climbing!
 152
 153          else
 154             P := Parent (P);
 155          end if;
 156       end loop;
 157
 158       Analyze_And_Resolve (N, Standard_String);
 159    end Expand_Exception_Call;
 160
 161    ------------------------
 162    -- Expand_Import_Call --
 163    ------------------------
 164
 165    --  The function call must have a static string as its argument. We create
 166    --  a dummy variable which uses this string as the external name in an
 167    --  Import pragma. The result is then obtained as the address of this
 168    --  dummy variable, converted to the appropriate target type.
 169
 170    procedure Expand_Import_Call (N : Node_Id) is
 171       Loc : constant Source_Ptr := Sloc (N);
 172       Ent : constant Entity_Id  := Entity (Name (N));
 173       Str : constant Node_Id    := First_Actual (N);
 174       Dum : Entity_Id;
 175
 176    begin
 177       Dum := Make_Defining_Identifier (Loc, New_Internal_Name ('D'));
 178
 179       Insert_Actions (N, New_List (
 180         Make_Object_Declaration (Loc,
 181           Defining_Identifier => Dum,
 182           Object_Definition   =>
 183             New_Occurrence_Of (Standard_Character, Loc)),
 184
 185         Make_Pragma (Loc,
 186           Chars => Name_Import,
 187           Pragma_Argument_Associations => New_List (
 188             Make_Pragma_Argument_Association (Loc,
 189               Expression => Make_Identifier (Loc, Name_Ada)),
 190
 191             Make_Pragma_Argument_Association (Loc,
 192               Expression => Make_Identifier (Loc, Chars (Dum))),
 193
 194             Make_Pragma_Argument_Association (Loc,
 195               Chars => Name_Link_Name,
 196               Expression => Relocate_Node (Str))))));
 197
 198       Rewrite (N,
 199         Unchecked_Convert_To (Etype (Ent),
 200           Make_Attribute_Reference (Loc,
 201             Attribute_Name => Name_Address,
 202             Prefix => Make_Identifier (Loc, Chars (Dum)))));
 203
 204       Analyze_And_Resolve (N, Etype (Ent));
 205    end Expand_Import_Call;
 206
 207    ---------------------------
 208    -- Expand_Intrinsic_Call --
 209    ---------------------------
 210
 211    procedure Expand_Intrinsic_Call (N : Node_Id; E : Entity_Id) is
 212       Nam : Name_Id;
 213
 214    begin
 215       --  If the intrinsic subprogram is generic, gets its original name.
 216
 217       if Present (Parent (E))
 218         and then Present (Generic_Parent (Parent (E)))
 219       then
 220          Nam := Chars (Generic_Parent (Parent (E)));
 221       else
 222          Nam := Chars (E);
 223       end if;
 224
 225       if Nam = Name_Asm then
 226          Expand_Asm_Call (N);
 227
 228       elsif Nam = Name_Divide then
 229          Expand_Decimal_Divide_Call (N);
 230
 231       elsif Nam = Name_Exception_Information then
 232          Expand_Exception_Call (N, RE_Exception_Information);
 233
 234       elsif Nam = Name_Exception_Message then
 235          Expand_Exception_Call (N, RE_Exception_Message);
 236
 237       elsif Nam = Name_Exception_Name then
 238          Expand_Exception_Call (N, RE_Exception_Name_Simple);
 239
 240       elsif Nam = Name_Import_Address
 241               or else
 242             Nam = Name_Import_Largest_Value
 243               or else
 244             Nam = Name_Import_Value
 245       then
 246          Expand_Import_Call (N);
 247
 248       elsif Nam = Name_Is_Negative then
 249          Expand_Is_Negative (N);
 250
 251       elsif Nam = Name_Rotate_Left then
 252          Expand_Shift (N, E, N_Op_Rotate_Left);
 253
 254       elsif Nam = Name_Rotate_Right then
 255          Expand_Shift (N, E, N_Op_Rotate_Right);
 256
 257       elsif Nam = Name_Shift_Left then
 258          Expand_Shift (N, E, N_Op_Shift_Left);
 259
 260       elsif Nam = Name_Shift_Right then
 261          Expand_Shift (N, E, N_Op_Shift_Right);
 262
 263       elsif Nam = Name_Shift_Right_Arithmetic then
 264          Expand_Shift (N, E, N_Op_Shift_Right_Arithmetic);
 265
 266       elsif Nam = Name_Unchecked_Conversion then
 267          Expand_Unc_Conversion (N, E);
 268
 269       elsif Nam = Name_Unchecked_Deallocation then
 270          Expand_Unc_Deallocation (N, E);
 271
 272       elsif Nam = Name_File
 273         or else Nam = Name_Line
 274         or else Nam = Name_Source_Location
 275         or else Nam = Name_Enclosing_Entity
 276       then
 277          Expand_Source_Info (N, E, Nam);
 278
 279       else
 280          --  Only other possibility is a renaming, in which case we expand
 281          --  the call to the original operation (which must be intrinsic).
 282
 283          pragma Assert (Present (Alias (E)));
 284          Expand_Intrinsic_Call (N,  Alias (E));
 285       end if;
 286
 287    end Expand_Intrinsic_Call;
 288
 289    ------------------------
 290    -- Expand_Is_Negative --
 291    ------------------------
 292
 293    procedure Expand_Is_Negative (N : Node_Id) is
 294       Loc   : constant Source_Ptr := Sloc (N);
 295       Opnd  : constant Node_Id    := Relocate_Node (First_Actual (N));
 296
 297    begin
 298
 299       --  We replace the function call by the following expression
 300
 301       --    if Opnd < 0.0 then
 302       --       True
 303       --    else
 304       --       if Opnd > 0.0 then
 305       --          False;
 306       --       else
 307       --          Float_Unsigned!(Float (Opnd)) /= 0
 308       --       end if;
 309       --    end if;
 310
 311       Rewrite (N,
 312         Make_Conditional_Expression (Loc,
 313           Expressions => New_List (
 314             Make_Op_Lt (Loc,
 315               Left_Opnd  => Duplicate_Subexpr (Opnd),
 316               Right_Opnd => Make_Real_Literal (Loc, Ureal_0)),
 317
 318             New_Occurrence_Of (Standard_True, Loc),
 319
 320             Make_Conditional_Expression (Loc,
 321              Expressions => New_List (
 322                Make_Op_Gt (Loc,
 323                  Left_Opnd  => Duplicate_Subexpr (Opnd),
 324                  Right_Opnd => Make_Real_Literal (Loc, Ureal_0)),
 325
 326                New_Occurrence_Of (Standard_False, Loc),
 327
 328                 Make_Op_Ne (Loc,
 329                   Left_Opnd =>
 330                     Unchecked_Convert_To (RTE (RE_Float_Unsigned),
 331                                           Convert_To (Standard_Float,
 332                                             Duplicate_Subexpr (Opnd))),
 333                   Right_Opnd =>
 334                     Make_Integer_Literal (Loc, 0)))))));
 335
 336       Analyze_And_Resolve (N, Standard_Boolean);
 337    end Expand_Is_Negative;
 338
 339    ------------------
 340    -- Expand_Shift --
 341    ------------------
 342
 343    --  This procedure is used to convert a call to a shift function to the
 344    --  corresponding operator node. This conversion is not done by the usual
 345    --  circuit for converting calls to operator functions (e.g. "+"(1,2)) to
 346    --  operator nodes, because shifts are not predefined operators.
 347
 348    --  As a result, whenever a shift is used in the source program, it will
 349    --  remain as a call until converted by this routine to the operator node
 350    --  form which Gigi is expecting to see.
 351
 352    --  Note: it is possible for the expander to generate shift operator nodes
 353    --  directly, which will be analyzed in the normal manner by calling Analyze
 354    --  and Resolve. Such shift operator nodes will not be seen by Expand_Shift.
 355
 356    procedure Expand_Shift (N : Node_Id; E : Entity_Id; K : Node_Kind) is
 357       Loc   : constant Source_Ptr := Sloc (N);
 358       Typ   : constant Entity_Id  := Etype (N);
 359       Left  : constant Node_Id    := First_Actual (N);
 360       Right : constant Node_Id    := Next_Actual (Left);
 361       Ltyp  : constant Node_Id    := Etype (Left);
 362       Rtyp  : constant Node_Id    := Etype (Right);
 363       Snode : Node_Id;
 364
 365    begin
 366       Snode := New_Node (K, Loc);
 367       Set_Left_Opnd  (Snode, Relocate_Node (Left));
 368       Set_Right_Opnd (Snode, Relocate_Node (Right));
 369       Set_Chars      (Snode, Chars (E));
 370       Set_Etype      (Snode, Base_Type (Typ));
 371       Set_Entity     (Snode, E);
 372
 373       if Compile_Time_Known_Value (Type_High_Bound (Rtyp))
 374         and then Expr_Value (Type_High_Bound (Rtyp)) < Esize (Ltyp)
 375       then
 376          Set_Shift_Count_OK (Snode, True);
 377       end if;
 378
 379       --  Do the rewrite. Note that we don't call Analyze and Resolve on
 380       --  this node, because it already got analyzed and resolved when
 381       --  it was a function call!
 382
 383       Rewrite (N, Snode);
 384       Set_Analyzed (N);
 385
 386    end Expand_Shift;
 387
 388    ------------------------
 389    -- Expand_Source_Info --
 390    ------------------------
 391
 392    procedure Expand_Source_Info (N : Node_Id; E : Entity_Id; Nam : Name_Id) is
 393       Loc : constant Source_Ptr := Sloc (N);
 394       Ent : Entity_Id;
 395
 396    begin
 397       --  Integer cases
 398
 399       if Nam = Name_Line then
 400          Rewrite (N,
 401            Make_Integer_Literal (Loc,
 402              Intval => UI_From_Int (Int (Get_Logical_Line_Number (Loc)))));
 403          Analyze_And_Resolve (N, Standard_Positive);
 404
 405       --  String cases
 406
 407       else
 408          case Nam is
 409             when Name_File =>
 410                Get_Decoded_Name_String
 411                  (Reference_Name (Get_Source_File_Index (Loc)));
 412
 413             when Name_Source_Location =>
 414                Build_Location_String (Loc);
 415
 416             when Name_Enclosing_Entity =>
 417                Name_Len := 0;
 418
 419                Ent := Current_Scope;
 420
 421                --  Skip enclosing blocks to reach enclosing unit.
 422
 423                while Present (Ent) loop
 424                   exit when Ekind (Ent) /= E_Block
 425                     and then Ekind (Ent) /= E_Loop;
 426                   Ent := Scope (Ent);
 427                end loop;
 428
 429                --  Ent now points to the relevant defining entity
 430
 431                declare
 432                   SDef : Source_Ptr := Sloc (Ent);
 433                   TDef : Source_Buffer_Ptr;
 434
 435                begin
 436                   TDef := Source_Text (Get_Source_File_Index (SDef));
 437                   Name_Len := 0;
 438
 439                   while TDef (SDef) in '0' .. '9'
 440                     or else TDef (SDef) >= 'A'
 441                     or else TDef (SDef) = ASCII.ESC
 442                   loop
 443                      Add_Char_To_Name_Buffer (TDef (SDef));
 444                      SDef := SDef + 1;
 445                   end loop;
 446                end;
 447
 448             when others =>
 449                raise Program_Error;
 450          end case;
 451
 452          Rewrite (N,
 453            Make_String_Literal (Loc, Strval => String_From_Name_Buffer));
 454          Analyze_And_Resolve (N, Standard_String);
 455       end if;
 456
 457       Set_Is_Static_Expression (N);
 458    end Expand_Source_Info;
 459
 460    ---------------------------
 461    -- Expand_Unc_Conversion --
 462    ---------------------------
 463
 464    procedure Expand_Unc_Conversion (N : Node_Id; E : Entity_Id) is
 465       Func : constant Entity_Id  := Entity (Name (N));
 466       Conv : Node_Id;
 467       Ftyp : Entity_Id;
 468
 469    begin
 470       --  Rewrite as unchecked conversion node. Note that we must convert
 471       --  the operand to the formal type of the input parameter of the
 472       --  function, so that the resulting N_Unchecked_Type_Conversion
 473       --  call indicates the correct types for Gigi.
 474
 475       --  Right now, we only do this if a scalar type is involved. It is
 476       --  not clear if it is needed in other cases. If we do attempt to
 477       --  do the conversion unconditionally, it crashes 3411-018. To be
 478       --  investigated further ???
 479
 480       Conv := Relocate_Node (First_Actual (N));
 481       Ftyp := Etype (First_Formal (Func));
 482
 483       if Is_Scalar_Type (Ftyp) then
 484          Conv := Convert_To (Ftyp, Conv);
 485          Set_Parent (Conv, N);
 486          Analyze_And_Resolve (Conv);
 487       end if;
 488
 489       --  We do the analysis here, because we do not want the compiler
 490       --  to try to optimize or otherwise reorganize the unchecked
 491       --  conversion node.
 492
 493       Rewrite (N, Unchecked_Convert_To (Etype (E), Conv));
 494       Set_Etype (N, Etype (E));
 495       Set_Analyzed (N);
 496
 497       if Nkind (N) = N_Unchecked_Type_Conversion then
 498          Expand_N_Unchecked_Type_Conversion (N);
 499       end if;
 500    end Expand_Unc_Conversion;
 501
 502    -----------------------------
 503    -- Expand_Unc_Deallocation --
 504    -----------------------------
 505
 506    --  Generate the following Code :
 507
 508    --    if Arg /= null then
 509    --     <Finalize_Call> (.., T'Class(Arg.all), ..);  -- for controlled types
 510    --       Free (Arg);
 511    --       Arg := Null;
 512    --    end if;
 513
 514    --  For a task, we also generate a call to Free_Task to ensure that the
 515    --  task itself is freed if it is terminated, ditto for a simple protected
 516    --  object, with a call to Finalize_Protection
 517
 518    procedure Expand_Unc_Deallocation (N : Node_Id; E : Entity_Id) is
 519       Loc   : constant Source_Ptr := Sloc (N);
 520       Arg   : constant Node_Id    := First_Actual (N);
 521       Typ   : constant Entity_Id  := Etype (Arg);
 522       Stmts : constant List_Id    := New_List;
 523       Pool  : constant Entity_Id  :=
 524                 Associated_Storage_Pool (Underlying_Type (Root_Type (Typ)));
 525
 526       Desig_T   : Entity_Id  := Designated_Type (Typ);
 527       Gen_Code  : Node_Id;
 528       Free_Node : Node_Id;
 529       Deref     : Node_Id;
 530       Free_Arg  : Node_Id;
 531       Free_Cod  : List_Id;
 532       Blk       : Node_Id;
 533
 534    begin
 535       if Controlled_Type (Desig_T) then
 536
 537          Deref := Make_Explicit_Dereference (Loc, Duplicate_Subexpr (Arg));
 538
 539          --  If the type is tagged, then we must force dispatching on the
 540          --  finalization call because the designated type may not be the
 541          --  actual type of the object
 542
 543          if Is_Tagged_Type (Desig_T)
 544            and then not Is_Class_Wide_Type (Desig_T)
 545          then
 546             Deref := Unchecked_Convert_To (Class_Wide_Type (Desig_T), Deref);
 547          end if;
 548
 549          Free_Cod :=
 550            Make_Final_Call
 551             (Ref         => Deref,
 552              Typ         => Desig_T,
 553              With_Detach => New_Reference_To (Standard_True, Loc));
 554
 555          if Abort_Allowed then
 556             Prepend_To (Free_Cod,
 557               Build_Runtime_Call (Loc, RE_Abort_Defer));
 558
 559             Blk :=
 560               Make_Block_Statement (Loc, Handled_Statement_Sequence =>
 561                 Make_Handled_Sequence_Of_Statements (Loc,
 562                   Statements  => Free_Cod,
 563                   At_End_Proc =>
 564                     New_Occurrence_Of (RTE (RE_Abort_Undefer_Direct), Loc)));
 565
 566             --  We now expand the exception (at end) handler. We set a
 567             --  temporary parent pointer since we have not attached Blk
 568             --  to the tree yet.
 569
 570             Set_Parent (Blk, N);
 571             Analyze (Blk);
 572             Expand_At_End_Handler
 573               (Handled_Statement_Sequence (Blk), Entity (Identifier (Blk)));
 574             Append (Blk, Stmts);
 575
 576          else
 577             Append_List_To (Stmts, Free_Cod);
 578          end if;
 579       end if;
 580
 581       --  For a task type, call Free_Task before freeing the ATCB.
 582
 583       if Is_Task_Type (Desig_T) then
 584
 585          declare
 586             Stat : Node_Id := Prev (N);
 587             Nam1 : Node_Id;
 588             Nam2 : Node_Id;
 589
 590          begin
 591             --  An Abort followed by a Free will not do what the user
 592             --  expects, because the abort is not immediate. This is worth
 593             --  a friendly warning.
 594
 595             while Present (Stat)
 596               and then not Comes_From_Source (Original_Node (Stat))
 597             loop
 598                Prev (Stat);
 599             end loop;
 600
 601             if Present (Stat)
 602               and then Nkind (Original_Node (Stat)) = N_Abort_Statement
 603             then
 604                Stat := Original_Node (Stat);
 605                Nam1 := First (Names (Stat));
 606                Nam2 := Original_Node (First (Parameter_Associations (N)));
 607
 608                if Nkind (Nam1) = N_Explicit_Dereference
 609                  and then Is_Entity_Name (Prefix (Nam1))
 610                  and then Is_Entity_Name (Nam2)
 611                  and then Entity (Prefix (Nam1)) = Entity (Nam2)
 612                then
 613                   Error_Msg_N ("Abort may take time to complete?", N);
 614                   Error_Msg_N ("\deallocation might have no effect?", N);
 615                   Error_Msg_N ("\safer to wait for termination.?", N);
 616                end if;
 617             end if;
 618          end;
 619
 620          Append_To (Stmts,
 621            Make_Procedure_Call_Statement (Loc,
 622              Name => New_Reference_To (RTE (RE_Free_Task), Loc),
 623              Parameter_Associations => New_List (
 624                Concurrent_Ref (Duplicate_Subexpr (Arg)))));
 625       end if;
 626
 627       --  For a protected type with no entries, call Finalize_Protection
 628       --  before freeing the PO.
 629
 630       if Is_Protected_Type (Desig_T) and then not Has_Entries (Desig_T) then
 631          Append_To (Stmts,
 632            Make_Procedure_Call_Statement (Loc,
 633              Name => New_Reference_To (RTE (RE_Finalize_Protection), Loc),
 634              Parameter_Associations => New_List (
 635                Concurrent_Ref (Duplicate_Subexpr (Arg)))));
 636       end if;
 637
 638       --  Normal processing for non-controlled types
 639
 640       Free_Arg := Duplicate_Subexpr (Arg);
 641       Free_Node := Make_Free_Statement (Loc, Empty);
 642       Append_To (Stmts, Free_Node);
 643       Set_Storage_Pool (Free_Node, Pool);
 644
 645       --  Make implicit if statement. We omit this if we are the then part
 646       --  of a test of the form:
 647
 648       --    if not (Arg = null) then
 649
 650       --  i.e. if the test is explicit in the source. Arg must be a simple
 651       --  identifier for the purposes of this special test. Note that the
 652       --  use of /= in the source is always transformed into the above form.
 653
 654       declare
 655          Test_Needed : Boolean := True;
 656          P           : constant Node_Id := Parent (N);
 657          C           : Node_Id;
 658
 659       begin
 660          if Nkind (Arg) = N_Identifier
 661            and then Nkind (P) =  N_If_Statement
 662            and then First (Then_Statements (P)) = N
 663          then
 664             if Nkind (Condition (P)) = N_Op_Not then
 665                C := Right_Opnd (Condition (P));
 666
 667                if Nkind (C) = N_Op_Eq
 668                  and then Nkind (Left_Opnd (C)) = N_Identifier
 669                  and then Chars (Arg) = Chars (Left_Opnd (C))
 670                  and then Nkind (Right_Opnd (C)) = N_Null
 671                then
 672                   Test_Needed := False;
 673                end if;
 674             end if;
 675          end if;
 676
 677          --  Generate If_Statement if needed
 678
 679          if Test_Needed then
 680             Gen_Code :=
 681               Make_Implicit_If_Statement (N,
 682                 Condition =>
 683                   Make_Op_Ne (Loc,
 684                     Left_Opnd  => Duplicate_Subexpr (Arg),
 685                     Right_Opnd => Make_Null (Loc)),
 686                 Then_Statements => Stmts);
 687
 688          else
 689             Gen_Code :=
 690               Make_Block_Statement (Loc,
 691                 Handled_Statement_Sequence =>
 692                   Make_Handled_Sequence_Of_Statements (Loc,
 693                     Statements => Stmts));
 694          end if;
 695       end;
 696
 697       --  Deal with storage pool
 698
 699       if Present (Pool) then
 700
 701          --  Freeing the secondary stack is meaningless
 702
 703          if Is_RTE (Pool, RE_SS_Pool) then
 704             null;
 705
 706          else
 707             Set_Procedure_To_Call (Free_Node,
 708               Find_Prim_Op (Etype (Pool), Name_Deallocate));
 709
 710             --  If the type is class wide, we generate an implicit type
 711             --  with the right dynamic size, so that the deallocate call
 712             --  gets the right size parameter computed by gigi
 713
 714             if Is_Class_Wide_Type (Desig_T) then
 715                declare
 716                   Acc_Type : constant Entity_Id :=
 717                                Create_Itype (E_Access_Type, N);
 718                   Deref    : constant Node_Id :=
 719                                Make_Explicit_Dereference (Loc,
 720                                  Duplicate_Subexpr (Arg));
 721
 722                begin
 723                   Set_Etype  (Deref, Typ);
 724                   Set_Parent (Deref, Free_Node);
 725
 726                   Set_Etype     (Acc_Type, Acc_Type);
 727                   Set_Size_Info (Acc_Type, Typ);
 728                   Set_Directly_Designated_Type
 729                                 (Acc_Type, Entity (Make_Subtype_From_Expr
 730                                                     (Deref, Desig_T)));
 731
 732                   Free_Arg := Unchecked_Convert_To (Acc_Type, Free_Arg);
 733                end;
 734             end if;
 735          end if;
 736       end if;
 737
 738       Set_Expression (Free_Node, Free_Arg);
 739
 740       declare
 741          Lhs : Node_Id := Duplicate_Subexpr (Arg);
 742
 743       begin
 744          Set_Assignment_OK (Lhs);
 745          Append_To (Stmts,
 746            Make_Assignment_Statement (Loc,
 747              Name       => Lhs,
 748              Expression => Make_Null (Loc)));
 749       end;
 750
 751       Rewrite (N, Gen_Code);
 752       Analyze (N);
 753    end Expand_Unc_Deallocation;
 754
 755 end Exp_Intr;