gcc/ada/expander.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             E X P A N D E R                              --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2007, 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 Debug_A;   use Debug_A;
  28 with Errout;    use Errout;
  29 with Exp_Aggr;  use Exp_Aggr;
  30 with Exp_Attr;  use Exp_Attr;
  31 with Exp_Ch2;   use Exp_Ch2;
  32 with Exp_Ch3;   use Exp_Ch3;
  33 with Exp_Ch4;   use Exp_Ch4;
  34 with Exp_Ch5;   use Exp_Ch5;
  35 with Exp_Ch6;   use Exp_Ch6;
  36 with Exp_Ch7;   use Exp_Ch7;
  37 with Exp_Ch8;   use Exp_Ch8;
  38 with Exp_Ch9;   use Exp_Ch9;
  39 with Exp_Ch11;  use Exp_Ch11;
  40 with Exp_Ch12;  use Exp_Ch12;
  41 with Exp_Ch13;  use Exp_Ch13;
  42 with Exp_Prag;  use Exp_Prag;
  43 with Opt;       use Opt;
  44 with Rtsfind;   use Rtsfind;
  45 with Sem;       use Sem;
  46 with Sem_Ch8;   use Sem_Ch8;
  47 with Sem_Util;  use Sem_Util;
  48 with Sinfo;     use Sinfo;
  49 with Table;
  50
  51 package body Expander is
  52
  53    ----------------
  54    -- Local Data --
  55    ----------------
  56
  57    --  The following table is used to save values of the Expander_Active flag
  58    --  when they are saved by Expander_Mode_Save_And_Set. We use an extendible
  59    --  table (which is a bit of overkill) because it is easier than figuring
  60    --  out a maximum value or bothering with range checks!
  61
  62    package Expander_Flags is new Table.Table (
  63      Table_Component_Type => Boolean,
  64      Table_Index_Type     => Int,
  65      Table_Low_Bound      => 0,
  66      Table_Initial        => 32,
  67      Table_Increment      => 200,
  68      Table_Name           => "Expander_Flags");
  69
  70    ------------
  71    -- Expand --
  72    ------------
  73
  74    procedure Expand (N : Node_Id) is
  75    begin
  76       --  If we were analyzing a default expression the Full_Analysis flag must
  77       --  be off. If we are in expansion mode then we must be performing a full
  78       --  analysis. If we are analyzing a generic then Expansion must be off.
  79
  80       pragma Assert
  81         (not (Full_Analysis and then In_Default_Expression)
  82           and then (Full_Analysis or else not Expander_Active)
  83           and then not (Inside_A_Generic and then Expander_Active));
  84
  85       --  There are three reasons for the Expander_Active flag to be false
  86       --
  87       --  The first is when are not generating code. In this mode the
  88       --  Full_Analysis flag indicates whether we are performing a complete
  89       --  analysis, in which case Full_Analysis = True or a pre-analysis in
  90       --  which case Full_Analysis = False. See the spec of Sem for more
  91       --  info on this.
  92       --
  93       --  The second reason for the Expander_Active flag to be False is that
  94       --  we are performing a pre-analysis. During pre-analysis all expansion
  95       --  activity is turned off to make sure nodes are semantically decorated
  96       --  but no extra nodes are generated. This is for instance needed for
  97       --  the first pass of aggregate semantic processing. Note that in this
  98       --  case the Full_Analysis flag is set to False because the node will
  99       --  subsequently be re-analyzed with expansion on (see the spec of sem).
 100
 101       --  Finally, expansion is turned off in a regular compilation if there
 102       --  are serious errors. In that case there will be no further expansion,
 103       --  but one cleanup action may be required: if a transient scope was
 104       --  created (e.g. for a function that returns an unconstrained type) the
 105       --  scope may still be on the stack, and must be removed explicitly,
 106       --  given that the expansion actions that would normally process it will
 107       --  not take place. This prevents cascaded errors due to stack mismatch.
 108
 109       if not Expander_Active then
 110          Set_Analyzed (N, Full_Analysis);
 111
 112          if Serious_Errors_Detected > 0
 113            and then Scope_Is_Transient
 114          then
 115             Scope_Stack.Table
 116              (Scope_Stack.Last).Actions_To_Be_Wrapped_Before := No_List;
 117             Scope_Stack.Table
 118              (Scope_Stack.Last).Actions_To_Be_Wrapped_After  := No_List;
 119
 120             Pop_Scope;
 121          end if;
 122
 123          return;
 124
 125       else
 126          Debug_A_Entry ("expanding  ", N);
 127
 128          --  Processing depends on node kind. For full details on the expansion
 129          --  activity required in each case, see bodies of corresponding expand
 130          --  routines.
 131
 132          begin
 133             case Nkind (N) is
 134
 135                when N_Abort_Statement =>
 136                   Expand_N_Abort_Statement (N);
 137
 138                when N_Accept_Statement =>
 139                   Expand_N_Accept_Statement (N);
 140
 141                when N_Aggregate =>
 142                   Expand_N_Aggregate (N);
 143
 144                when N_Allocator =>
 145                   Expand_N_Allocator (N);
 146
 147                when N_And_Then =>
 148                   Expand_N_And_Then (N);
 149
 150                when N_Assignment_Statement =>
 151                   Expand_N_Assignment_Statement (N);
 152
 153                when N_Asynchronous_Select =>
 154                   Expand_N_Asynchronous_Select (N);
 155
 156                when N_Attribute_Definition_Clause =>
 157                   Expand_N_Attribute_Definition_Clause (N);
 158
 159                when N_Attribute_Reference =>
 160                   Expand_N_Attribute_Reference (N);
 161
 162                when N_Block_Statement =>
 163                   Expand_N_Block_Statement (N);
 164
 165                when N_Case_Statement =>
 166                   Expand_N_Case_Statement (N);
 167
 168                when N_Conditional_Entry_Call =>
 169                   Expand_N_Conditional_Entry_Call (N);
 170
 171                when N_Conditional_Expression =>
 172                   Expand_N_Conditional_Expression (N);
 173
 174                when N_Delay_Relative_Statement =>
 175                   Expand_N_Delay_Relative_Statement (N);
 176
 177                when N_Delay_Until_Statement =>
 178                   Expand_N_Delay_Until_Statement (N);
 179
 180                when N_Entry_Body =>
 181                   Expand_N_Entry_Body (N);
 182
 183                when N_Entry_Call_Statement =>
 184                   Expand_N_Entry_Call_Statement (N);
 185
 186                when N_Entry_Declaration =>
 187                   Expand_N_Entry_Declaration (N);
 188
 189                when N_Exception_Declaration =>
 190                   Expand_N_Exception_Declaration (N);
 191
 192                when N_Exception_Renaming_Declaration =>
 193                   Expand_N_Exception_Renaming_Declaration (N);
 194
 195                when N_Exit_Statement =>
 196                   Expand_N_Exit_Statement (N);
 197
 198                when N_Expanded_Name =>
 199                   Expand_N_Expanded_Name (N);
 200
 201                when N_Explicit_Dereference =>
 202                   Expand_N_Explicit_Dereference (N);
 203
 204                when N_Extended_Return_Statement =>
 205                   Expand_N_Extended_Return_Statement (N);
 206
 207                when N_Extension_Aggregate =>
 208                   Expand_N_Extension_Aggregate (N);
 209
 210                when N_Freeze_Entity =>
 211                   Expand_N_Freeze_Entity (N);
 212
 213                when N_Full_Type_Declaration =>
 214                   Expand_N_Full_Type_Declaration (N);
 215
 216                when N_Function_Call =>
 217                   Expand_N_Function_Call (N);
 218
 219                when N_Generic_Instantiation =>
 220                   Expand_N_Generic_Instantiation (N);
 221
 222                when N_Goto_Statement =>
 223                   Expand_N_Goto_Statement (N);
 224
 225                when N_Handled_Sequence_Of_Statements =>
 226                   Expand_N_Handled_Sequence_Of_Statements (N);
 227
 228                when N_Identifier =>
 229                   Expand_N_Identifier (N);
 230
 231                when N_Indexed_Component =>
 232                   Expand_N_Indexed_Component (N);
 233
 234                when N_If_Statement =>
 235                   Expand_N_If_Statement (N);
 236
 237                when N_In =>
 238                   Expand_N_In (N);
 239
 240                when N_Loop_Statement =>
 241                   Expand_N_Loop_Statement (N);
 242
 243                when N_Not_In =>
 244                   Expand_N_Not_In (N);
 245
 246                when N_Null =>
 247                   Expand_N_Null (N);
 248
 249                when N_Object_Declaration =>
 250                   Expand_N_Object_Declaration (N);
 251
 252                when N_Object_Renaming_Declaration =>
 253                   Expand_N_Object_Renaming_Declaration (N);
 254
 255                when N_Op_Add =>
 256                   Expand_N_Op_Add (N);
 257
 258                when N_Op_Abs =>
 259                   Expand_N_Op_Abs (N);
 260
 261                when N_Op_And =>
 262                   Expand_N_Op_And (N);
 263
 264                when N_Op_Concat =>
 265                   Expand_N_Op_Concat (N);
 266
 267                when N_Op_Divide =>
 268                   Expand_N_Op_Divide (N);
 269
 270                when N_Op_Eq =>
 271                   Expand_N_Op_Eq (N);
 272
 273                when N_Op_Expon =>
 274                   Expand_N_Op_Expon (N);
 275
 276                when N_Op_Ge =>
 277                   Expand_N_Op_Ge (N);
 278
 279                when N_Op_Gt =>
 280                   Expand_N_Op_Gt (N);
 281
 282                when N_Op_Le =>
 283                   Expand_N_Op_Le (N);
 284
 285                when N_Op_Lt =>
 286                   Expand_N_Op_Lt (N);
 287
 288                when N_Op_Minus =>
 289                   Expand_N_Op_Minus (N);
 290
 291                when N_Op_Mod =>
 292                   Expand_N_Op_Mod (N);
 293
 294                when N_Op_Multiply =>
 295                   Expand_N_Op_Multiply (N);
 296
 297                when N_Op_Ne =>
 298                   Expand_N_Op_Ne (N);
 299
 300                when N_Op_Not =>
 301                   Expand_N_Op_Not (N);
 302
 303                when N_Op_Or =>
 304                   Expand_N_Op_Or (N);
 305
 306                when N_Op_Plus =>
 307                   Expand_N_Op_Plus (N);
 308
 309                when N_Op_Rem =>
 310                   Expand_N_Op_Rem (N);
 311
 312                when N_Op_Rotate_Left =>
 313                   Expand_N_Op_Rotate_Left (N);
 314
 315                when N_Op_Rotate_Right =>
 316                   Expand_N_Op_Rotate_Right (N);
 317
 318                when N_Op_Shift_Left =>
 319                   Expand_N_Op_Shift_Left (N);
 320
 321                when N_Op_Shift_Right =>
 322                   Expand_N_Op_Shift_Right (N);
 323
 324                when N_Op_Shift_Right_Arithmetic =>
 325                   Expand_N_Op_Shift_Right_Arithmetic (N);
 326
 327                when N_Op_Subtract =>
 328                   Expand_N_Op_Subtract (N);
 329
 330                when N_Op_Xor =>
 331                   Expand_N_Op_Xor (N);
 332
 333                when N_Or_Else =>
 334                   Expand_N_Or_Else (N);
 335
 336                when N_Package_Body =>
 337                   Expand_N_Package_Body (N);
 338
 339                when N_Package_Declaration =>
 340                   Expand_N_Package_Declaration (N);
 341
 342                when N_Package_Renaming_Declaration =>
 343                   Expand_N_Package_Renaming_Declaration (N);
 344
 345                when N_Subprogram_Renaming_Declaration =>
 346                   Expand_N_Subprogram_Renaming_Declaration (N);
 347
 348                when N_Pragma =>
 349                   Expand_N_Pragma (N);
 350
 351                when N_Procedure_Call_Statement =>
 352                   Expand_N_Procedure_Call_Statement (N);
 353
 354                when N_Protected_Type_Declaration =>
 355                   Expand_N_Protected_Type_Declaration (N);
 356
 357                when N_Protected_Body =>
 358                   Expand_N_Protected_Body (N);
 359
 360                when N_Qualified_Expression =>
 361                   Expand_N_Qualified_Expression (N);
 362
 363                when N_Raise_Statement =>
 364                   Expand_N_Raise_Statement (N);
 365
 366                when N_Raise_Constraint_Error =>
 367                   Expand_N_Raise_Constraint_Error (N);
 368
 369                when N_Raise_Program_Error =>
 370                   Expand_N_Raise_Program_Error (N);
 371
 372                when N_Raise_Storage_Error =>
 373                   Expand_N_Raise_Storage_Error (N);
 374
 375                when N_Real_Literal =>
 376                   Expand_N_Real_Literal (N);
 377
 378                when N_Record_Representation_Clause =>
 379                   Expand_N_Record_Representation_Clause (N);
 380
 381                when N_Requeue_Statement =>
 382                   Expand_N_Requeue_Statement (N);
 383
 384                when N_Simple_Return_Statement =>
 385                   Expand_N_Simple_Return_Statement (N);
 386
 387                when N_Selected_Component =>
 388                   Expand_N_Selected_Component (N);
 389
 390                when N_Selective_Accept =>
 391                   Expand_N_Selective_Accept (N);
 392
 393                when N_Single_Task_Declaration =>
 394                   Expand_N_Single_Task_Declaration (N);
 395
 396                when N_Slice =>
 397                   Expand_N_Slice (N);
 398
 399                when N_Subtype_Indication =>
 400                   Expand_N_Subtype_Indication (N);
 401
 402                when N_Subprogram_Body =>
 403                   Expand_N_Subprogram_Body (N);
 404
 405                when N_Subprogram_Body_Stub =>
 406                   Expand_N_Subprogram_Body_Stub (N);
 407
 408                when N_Subprogram_Declaration =>
 409                   Expand_N_Subprogram_Declaration (N);
 410
 411                when N_Subprogram_Info =>
 412                   Expand_N_Subprogram_Info (N);
 413
 414                when N_Task_Body =>
 415                   Expand_N_Task_Body (N);
 416
 417                when N_Task_Type_Declaration =>
 418                   Expand_N_Task_Type_Declaration (N);
 419
 420                when N_Timed_Entry_Call =>
 421                   Expand_N_Timed_Entry_Call (N);
 422
 423                when N_Type_Conversion =>
 424                   Expand_N_Type_Conversion (N);
 425
 426                when N_Unchecked_Expression =>
 427                   Expand_N_Unchecked_Expression (N);
 428
 429                when N_Unchecked_Type_Conversion =>
 430                   Expand_N_Unchecked_Type_Conversion (N);
 431
 432                when N_Variant_Part =>
 433                   Expand_N_Variant_Part (N);
 434
 435                --  For all other node kinds, no expansion activity is required
 436
 437                when others => null;
 438
 439             end case;
 440
 441          exception
 442             when RE_Not_Available =>
 443                return;
 444          end;
 445
 446          --  Set result as analyzed and then do a possible transient wrap. The
 447          --  transient wrap must be done after the Analyzed flag is set on, so
 448          --  that we do not get a recursive attempt to expand the node N.
 449
 450          Set_Analyzed (N);
 451
 452          --  Deal with transient scopes
 453
 454          if Scope_Is_Transient and then N = Node_To_Be_Wrapped then
 455
 456             case Nkind (N) is
 457                when N_Statement_Other_Than_Procedure_Call |
 458                     N_Procedure_Call_Statement            =>
 459                   Wrap_Transient_Statement (N);
 460
 461                when N_Object_Declaration          |
 462                     N_Object_Renaming_Declaration |
 463                     N_Subtype_Declaration         =>
 464                   Wrap_Transient_Declaration (N);
 465
 466                when others => Wrap_Transient_Expression (N);
 467             end case;
 468          end if;
 469
 470          Debug_A_Exit ("expanding  ", N, "  (done)");
 471       end if;
 472
 473    end Expand;
 474
 475    ---------------------------
 476    -- Expander_Mode_Restore --
 477    ---------------------------
 478
 479    procedure Expander_Mode_Restore is
 480    begin
 481       --  Not active (has no effect) in ASIS mode (see comments in spec of
 482       --  Expander_Mode_Save_And_Set).
 483
 484       if ASIS_Mode then
 485          return;
 486       end if;
 487
 488       --  Otherwise restore the flag
 489
 490       Expander_Active := Expander_Flags.Table (Expander_Flags.Last);
 491       Expander_Flags.Decrement_Last;
 492
 493       --  Keep expander off if serious errors detected. In this case we do not
 494       --  need expansion, and continued expansion may cause cascaded errors or
 495       --  compiler bombs.
 496
 497       if Serious_Errors_Detected /= 0 then
 498          Expander_Active := False;
 499       end if;
 500    end Expander_Mode_Restore;
 501
 502    --------------------------------
 503    -- Expander_Mode_Save_And_Set --
 504    --------------------------------
 505
 506    procedure Expander_Mode_Save_And_Set (Status : Boolean) is
 507    begin
 508       --  Not active (has no effect) in ASIS mode (see comments in spec of
 509       --  Expander_Mode_Save_And_Set).
 510
 511       if ASIS_Mode then
 512          return;
 513       end if;
 514
 515       --  Otherwise save and set the flag
 516
 517       Expander_Flags.Increment_Last;
 518       Expander_Flags.Table (Expander_Flags.Last) := Expander_Active;
 519       Expander_Active := Status;
 520    end Expander_Mode_Save_And_Set;
 521
 522 end Expander;