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) 1992-2012, 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 Exp_Aggr; use Exp_Aggr;
  29 with Exp_Alfa; use Exp_Alfa;
  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 (or other spec expression)
  77       --  the Full_Analysis flag must be off. If we are in expansion mode then
  78       --  we must be performing a full analysis. If we are analyzing a generic
  79       --  then Expansion must be off.
  80
  81       pragma Assert
  82         (not (Full_Analysis and then In_Spec_Expression)
  83           and then (Full_Analysis or else not Expander_Active)
  84           and then not (Inside_A_Generic and then Expander_Active));
  85
  86       --  There are three reasons for the Expander_Active flag to be false
  87       --
  88       --  The first is when are not generating code. In this mode the
  89       --  Full_Analysis flag indicates whether we are performing a complete
  90       --  analysis, in which case Full_Analysis = True or a pre-analysis in
  91       --  which case Full_Analysis = False. See the spec of Sem for more
  92       --  info on this.
  93       --
  94       --  The second reason for the Expander_Active flag to be False is that
  95       --  we are performing a pre-analysis. During pre-analysis all expansion
  96       --  activity is turned off to make sure nodes are semantically decorated
  97       --  but no extra nodes are generated. This is for instance needed for
  98       --  the first pass of aggregate semantic processing. Note that in this
  99       --  case the Full_Analysis flag is set to False because the node will
 100       --  subsequently be re-analyzed with expansion on (see the spec of sem).
 101
 102       --  Finally, expansion is turned off in a regular compilation if there
 103       --  are serious errors. In that case there will be no further expansion,
 104       --  but one cleanup action may be required: if a transient scope was
 105       --  created (e.g. for a function that returns an unconstrained type) the
 106       --  scope may still be on the stack, and must be removed explicitly,
 107       --  given that the expansion actions that would normally process it will
 108       --  not take place. This prevents cascaded errors due to stack mismatch.
 109
 110       if not Expander_Active then
 111          Set_Analyzed (N, Full_Analysis);
 112
 113          if Serious_Errors_Detected > 0
 114            and then Scope_Is_Transient
 115          then
 116             Scope_Stack.Table
 117              (Scope_Stack.Last).Actions_To_Be_Wrapped_Before := No_List;
 118             Scope_Stack.Table
 119              (Scope_Stack.Last).Actions_To_Be_Wrapped_After  := No_List;
 120
 121             Pop_Scope;
 122          end if;
 123
 124          return;
 125
 126       else
 127          Debug_A_Entry ("expanding  ", N);
 128
 129          begin
 130             --  In Alfa mode we only need a very limited subset of the usual
 131             --  expansions. This limited subset is implemented in Expand_Alfa.
 132
 133             if Alfa_Mode then
 134                Expand_Alfa (N);
 135
 136             --  Here for normal non-Alfa mode
 137
 138             else
 139                --  Processing depends on node kind. For full details on the
 140                --  expansion activity required in each case, see bodies of
 141                --  corresponding expand routines.
 142
 143                case Nkind (N) is
 144
 145                   when N_Abort_Statement =>
 146                      Expand_N_Abort_Statement (N);
 147
 148                   when N_Accept_Statement =>
 149                      Expand_N_Accept_Statement (N);
 150
 151                   when N_Aggregate =>
 152                      Expand_N_Aggregate (N);
 153
 154                   when N_Allocator =>
 155                      Expand_N_Allocator (N);
 156
 157                   when N_And_Then =>
 158                      Expand_N_And_Then (N);
 159
 160                   when N_Assignment_Statement =>
 161                      Expand_N_Assignment_Statement (N);
 162
 163                   when N_Asynchronous_Select =>
 164                      Expand_N_Asynchronous_Select (N);
 165
 166                   when N_Attribute_Definition_Clause =>
 167                      Expand_N_Attribute_Definition_Clause (N);
 168
 169                   when N_Attribute_Reference =>
 170                      Expand_N_Attribute_Reference (N);
 171
 172                   when N_Block_Statement =>
 173                      Expand_N_Block_Statement (N);
 174
 175                   when N_Case_Expression =>
 176                      Expand_N_Case_Expression (N);
 177
 178                   when N_Case_Statement =>
 179                      Expand_N_Case_Statement (N);
 180
 181                   when N_Conditional_Entry_Call =>
 182                      Expand_N_Conditional_Entry_Call (N);
 183
 184                   when N_Delay_Relative_Statement =>
 185                      Expand_N_Delay_Relative_Statement (N);
 186
 187                   when N_Delay_Until_Statement =>
 188                      Expand_N_Delay_Until_Statement (N);
 189
 190                   when N_Entry_Body =>
 191                      Expand_N_Entry_Body (N);
 192
 193                   when N_Entry_Call_Statement =>
 194                      Expand_N_Entry_Call_Statement (N);
 195
 196                   when N_Entry_Declaration =>
 197                      Expand_N_Entry_Declaration (N);
 198
 199                   when N_Exception_Declaration =>
 200                      Expand_N_Exception_Declaration (N);
 201
 202                   when N_Exception_Renaming_Declaration =>
 203                      Expand_N_Exception_Renaming_Declaration (N);
 204
 205                   when N_Exit_Statement =>
 206                      Expand_N_Exit_Statement (N);
 207
 208                   when N_Expanded_Name =>
 209                      Expand_N_Expanded_Name (N);
 210
 211                   when N_Explicit_Dereference =>
 212                      Expand_N_Explicit_Dereference (N);
 213
 214                   when N_Expression_With_Actions =>
 215                      Expand_N_Expression_With_Actions (N);
 216
 217                   when N_Extended_Return_Statement =>
 218                      Expand_N_Extended_Return_Statement (N);
 219
 220                   when N_Extension_Aggregate =>
 221                      Expand_N_Extension_Aggregate (N);
 222
 223                   when N_Free_Statement =>
 224                      Expand_N_Free_Statement (N);
 225
 226                   when N_Freeze_Entity =>
 227                      Expand_N_Freeze_Entity (N);
 228
 229                   when N_Full_Type_Declaration =>
 230                      Expand_N_Full_Type_Declaration (N);
 231
 232                   when N_Function_Call =>
 233                      Expand_N_Function_Call (N);
 234
 235                   when N_Generic_Instantiation =>
 236                      Expand_N_Generic_Instantiation (N);
 237
 238                   when N_Goto_Statement =>
 239                      Expand_N_Goto_Statement (N);
 240
 241                   when N_Handled_Sequence_Of_Statements =>
 242                      Expand_N_Handled_Sequence_Of_Statements (N);
 243
 244                   when N_Identifier =>
 245                      Expand_N_Identifier (N);
 246
 247                   when N_If_Expression =>
 248                      Expand_N_If_Expression (N);
 249
 250                   when N_Indexed_Component =>
 251                      Expand_N_Indexed_Component (N);
 252
 253                   when N_If_Statement =>
 254                      Expand_N_If_Statement (N);
 255
 256                   when N_In =>
 257                      Expand_N_In (N);
 258
 259                   when N_Loop_Statement =>
 260                      Expand_N_Loop_Statement (N);
 261
 262                   when N_Not_In =>
 263                      Expand_N_Not_In (N);
 264
 265                   when N_Null =>
 266                      Expand_N_Null (N);
 267
 268                   when N_Object_Declaration =>
 269                      Expand_N_Object_Declaration (N);
 270
 271                   when N_Object_Renaming_Declaration =>
 272                      Expand_N_Object_Renaming_Declaration (N);
 273
 274                   when N_Op_Add =>
 275                      Expand_N_Op_Add (N);
 276
 277                   when N_Op_Abs =>
 278                      Expand_N_Op_Abs (N);
 279
 280                   when N_Op_And =>
 281                      Expand_N_Op_And (N);
 282
 283                   when N_Op_Concat =>
 284                      Expand_N_Op_Concat (N);
 285
 286                   when N_Op_Divide =>
 287                      Expand_N_Op_Divide (N);
 288
 289                   when N_Op_Eq =>
 290                      Expand_N_Op_Eq (N);
 291
 292                   when N_Op_Expon =>
 293                      Expand_N_Op_Expon (N);
 294
 295                   when N_Op_Ge =>
 296                      Expand_N_Op_Ge (N);
 297
 298                   when N_Op_Gt =>
 299                      Expand_N_Op_Gt (N);
 300
 301                   when N_Op_Le =>
 302                      Expand_N_Op_Le (N);
 303
 304                   when N_Op_Lt =>
 305                      Expand_N_Op_Lt (N);
 306
 307                   when N_Op_Minus =>
 308                      Expand_N_Op_Minus (N);
 309
 310                   when N_Op_Mod =>
 311                      Expand_N_Op_Mod (N);
 312
 313                   when N_Op_Multiply =>
 314                      Expand_N_Op_Multiply (N);
 315
 316                   when N_Op_Ne =>
 317                      Expand_N_Op_Ne (N);
 318
 319                   when N_Op_Not =>
 320                      Expand_N_Op_Not (N);
 321
 322                   when N_Op_Or =>
 323                      Expand_N_Op_Or (N);
 324
 325                   when N_Op_Plus =>
 326                      Expand_N_Op_Plus (N);
 327
 328                   when N_Op_Rem =>
 329                      Expand_N_Op_Rem (N);
 330
 331                   when N_Op_Rotate_Left =>
 332                      Expand_N_Op_Rotate_Left (N);
 333
 334                   when N_Op_Rotate_Right =>
 335                      Expand_N_Op_Rotate_Right (N);
 336
 337                   when N_Op_Shift_Left =>
 338                      Expand_N_Op_Shift_Left (N);
 339
 340                   when N_Op_Shift_Right =>
 341                      Expand_N_Op_Shift_Right (N);
 342
 343                   when N_Op_Shift_Right_Arithmetic =>
 344                      Expand_N_Op_Shift_Right_Arithmetic (N);
 345
 346                   when N_Op_Subtract =>
 347                      Expand_N_Op_Subtract (N);
 348
 349                   when N_Op_Xor =>
 350                      Expand_N_Op_Xor (N);
 351
 352                   when N_Or_Else =>
 353                      Expand_N_Or_Else (N);
 354
 355                   when N_Package_Body =>
 356                      Expand_N_Package_Body (N);
 357
 358                   when N_Package_Declaration =>
 359                      Expand_N_Package_Declaration (N);
 360
 361                   when N_Package_Renaming_Declaration =>
 362                      Expand_N_Package_Renaming_Declaration (N);
 363
 364                   when N_Subprogram_Renaming_Declaration =>
 365                      Expand_N_Subprogram_Renaming_Declaration (N);
 366
 367                   when N_Pragma =>
 368                      Expand_N_Pragma (N);
 369
 370                   when N_Procedure_Call_Statement =>
 371                      Expand_N_Procedure_Call_Statement (N);
 372
 373                   when N_Protected_Type_Declaration =>
 374                      Expand_N_Protected_Type_Declaration (N);
 375
 376                   when N_Protected_Body =>
 377                      Expand_N_Protected_Body (N);
 378
 379                   when N_Qualified_Expression =>
 380                      Expand_N_Qualified_Expression (N);
 381
 382                   when N_Quantified_Expression  =>
 383                      Expand_N_Quantified_Expression (N);
 384
 385                   when N_Raise_Statement =>
 386                      Expand_N_Raise_Statement (N);
 387
 388                   when N_Raise_Constraint_Error =>
 389                      Expand_N_Raise_Constraint_Error (N);
 390
 391                   when N_Raise_Program_Error =>
 392                      Expand_N_Raise_Program_Error (N);
 393
 394                   when N_Raise_Storage_Error =>
 395                      Expand_N_Raise_Storage_Error (N);
 396
 397                   when N_Real_Literal =>
 398                      Expand_N_Real_Literal (N);
 399
 400                   when N_Record_Representation_Clause =>
 401                      Expand_N_Record_Representation_Clause (N);
 402
 403                   when N_Requeue_Statement =>
 404                      Expand_N_Requeue_Statement (N);
 405
 406                   when N_Simple_Return_Statement =>
 407                      Expand_N_Simple_Return_Statement (N);
 408
 409                   when N_Selected_Component =>
 410                      Expand_N_Selected_Component (N);
 411
 412                   when N_Selective_Accept =>
 413                      Expand_N_Selective_Accept (N);
 414
 415                   when N_Single_Task_Declaration =>
 416                      Expand_N_Single_Task_Declaration (N);
 417
 418                   when N_Slice =>
 419                      Expand_N_Slice (N);
 420
 421                   when N_Subtype_Indication =>
 422                      Expand_N_Subtype_Indication (N);
 423
 424                   when N_Subprogram_Body =>
 425                      Expand_N_Subprogram_Body (N);
 426
 427                   when N_Subprogram_Body_Stub =>
 428                      Expand_N_Subprogram_Body_Stub (N);
 429
 430                   when N_Subprogram_Declaration =>
 431                      Expand_N_Subprogram_Declaration (N);
 432
 433                   when N_Subprogram_Info =>
 434                      Expand_N_Subprogram_Info (N);
 435
 436                   when N_Task_Body =>
 437                      Expand_N_Task_Body (N);
 438
 439                   when N_Task_Type_Declaration =>
 440                      Expand_N_Task_Type_Declaration (N);
 441
 442                   when N_Timed_Entry_Call =>
 443                      Expand_N_Timed_Entry_Call (N);
 444
 445                   when N_Type_Conversion =>
 446                      Expand_N_Type_Conversion (N);
 447
 448                   when N_Unchecked_Expression =>
 449                      Expand_N_Unchecked_Expression (N);
 450
 451                   when N_Unchecked_Type_Conversion =>
 452                      Expand_N_Unchecked_Type_Conversion (N);
 453
 454                   when N_Variant_Part =>
 455                      Expand_N_Variant_Part (N);
 456
 457                   --  For all other node kinds, no expansion activity required
 458
 459                   when others =>
 460                      null;
 461
 462                end case;
 463             end if;
 464
 465          exception
 466             when RE_Not_Available =>
 467                return;
 468          end;
 469
 470          --  Set result as analyzed and then do a possible transient wrap. The
 471          --  transient wrap must be done after the Analyzed flag is set on, so
 472          --  that we do not get a recursive attempt to expand the node N.
 473
 474          Set_Analyzed (N);
 475
 476          --  Deal with transient scopes
 477
 478          if Scope_Is_Transient and then N = Node_To_Be_Wrapped then
 479             case Nkind (N) is
 480                when N_Statement_Other_Than_Procedure_Call |
 481                     N_Procedure_Call_Statement            =>
 482                   Wrap_Transient_Statement (N);
 483
 484                when N_Object_Declaration          |
 485                     N_Object_Renaming_Declaration |
 486                     N_Subtype_Declaration         =>
 487                   Wrap_Transient_Declaration (N);
 488
 489                when others => Wrap_Transient_Expression (N);
 490             end case;
 491          end if;
 492
 493          Debug_A_Exit ("expanding  ", N, "  (done)");
 494       end if;
 495    end Expand;
 496
 497    ---------------------------
 498    -- Expander_Mode_Restore --
 499    ---------------------------
 500
 501    procedure Expander_Mode_Restore is
 502    begin
 503       --  Not active (has no effect) in ASIS mode (see comments in spec of
 504       --  Expander_Mode_Save_And_Set).
 505
 506       if ASIS_Mode then
 507          return;
 508       end if;
 509
 510       --  Otherwise restore the flag
 511
 512       Expander_Active := Expander_Flags.Table (Expander_Flags.Last);
 513       Expander_Flags.Decrement_Last;
 514
 515       --  Keep expander off if serious errors detected. In this case we do not
 516       --  need expansion, and continued expansion may cause cascaded errors or
 517       --  compiler bombs.
 518
 519       if Serious_Errors_Detected /= 0 then
 520          Expander_Active := False;
 521       end if;
 522    end Expander_Mode_Restore;
 523
 524    --------------------------------
 525    -- Expander_Mode_Save_And_Set --
 526    --------------------------------
 527
 528    procedure Expander_Mode_Save_And_Set (Status : Boolean) is
 529    begin
 530       --  Not active (has no effect) in ASIS mode (see comments in spec of
 531       --  Expander_Mode_Save_And_Set).
 532
 533       if ASIS_Mode then
 534          return;
 535       end if;
 536
 537       --  Otherwise save and set the flag
 538
 539       Expander_Flags.Increment_Last;
 540       Expander_Flags.Table (Expander_Flags.Last) := Expander_Active;
 541       Expander_Active := Status;
 542    end Expander_Mode_Save_And_Set;
 543
 544 end Expander;