File : 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) 1992-2015, 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; use Debug;
28 with Debug_A; use Debug_A;
29 with Exp_Aggr; use Exp_Aggr;
30 with Exp_SPARK; use Exp_SPARK;
31 with Exp_Attr; use Exp_Attr;
32 with Exp_Ch2; use Exp_Ch2;
33 with Exp_Ch3; use Exp_Ch3;
34 with Exp_Ch4; use Exp_Ch4;
35 with Exp_Ch5; use Exp_Ch5;
36 with Exp_Ch6; use Exp_Ch6;
37 with Exp_Ch7; use Exp_Ch7;
38 with Exp_Ch8; use Exp_Ch8;
39 with Exp_Ch9; use Exp_Ch9;
40 with Exp_Ch11; use Exp_Ch11;
41 with Exp_Ch12; use Exp_Ch12;
42 with Exp_Ch13; use Exp_Ch13;
43 with Exp_Prag; use Exp_Prag;
44 with Opt; use Opt;
45 with Rtsfind; use Rtsfind;
46 with Sem; use Sem;
47 with Sem_Ch8; use Sem_Ch8;
48 with Sem_Util; use Sem_Util;
49 with Sinfo; use Sinfo;
50 with Table;
51
52 package body Expander is
53
54 ----------------
55 -- Local Data --
56 ----------------
57
58 -- The following table is used to save values of the Expander_Active flag
59 -- when they are saved by Expander_Mode_Save_And_Set. We use an extendible
60 -- table (which is a bit of overkill) because it is easier than figuring
61 -- out a maximum value or bothering with range checks.
62
63 package Expander_Flags is new Table.Table (
64 Table_Component_Type => Boolean,
65 Table_Index_Type => Int,
66 Table_Low_Bound => 0,
67 Table_Initial => 32,
68 Table_Increment => 200,
69 Table_Name => "Expander_Flags");
70
71 Abort_Bug_Box_Error : exception;
72 -- Arbitrary exception to raise for implementation of -gnatd.B. See "when
73 -- N_Abort_Statement" below. See also debug.adb.
74
75 ------------
76 -- Expand --
77 ------------
78
79 procedure Expand (N : Node_Id) is
80 begin
81 -- If we were analyzing a default expression (or other spec expression)
82 -- the Full_Analysis flag must be off. If we are in expansion mode then
83 -- we must be performing a full analysis. If we are analyzing a generic
84 -- then Expansion must be off.
85
86 pragma Assert
87 (not (Full_Analysis and then In_Spec_Expression)
88 and then (Full_Analysis or else not Expander_Active)
89 and then not (Inside_A_Generic and then Expander_Active));
90
91 -- The GNATprove_Mode flag indicates that a light expansion for formal
92 -- verification should be used. This expansion is never done inside
93 -- generics, because otherwise, this breaks the name resolution
94 -- mechanism for generic instances.
95
96 if GNATprove_Mode then
97 if not Inside_A_Generic then
98 Expand_SPARK (N);
99 end if;
100
101 Set_Analyzed (N, Full_Analysis);
102
103 -- Regular expansion is normally followed by special handling for
104 -- transient scopes for unconstrained results, etc. but this is not
105 -- needed, and in general cannot be done correctly, in this mode, so
106 -- we are all done.
107
108 return;
109
110 -- There are three reasons for the Expander_Active flag to be false
111
112 -- The first is when are not generating code. In this mode the
113 -- Full_Analysis flag indicates whether we are performing a complete
114 -- analysis, in which case Full_Analysis = True or a pre-analysis in
115 -- which case Full_Analysis = False. See the spec of Sem for more info
116 -- on this.
117
118 -- The second reason for the Expander_Active flag to be False is that
119 -- we are performing a pre-analysis. During pre-analysis all expansion
120 -- activity is turned off to make sure nodes are semantically decorated
121 -- but no extra nodes are generated. This is for instance needed for
122 -- the first pass of aggregate semantic processing. Note that in this
123 -- case the Full_Analysis flag is set to False because the node will
124 -- subsequently be re-analyzed with expansion on (see the spec of sem).
125
126 -- Finally, expansion is turned off in a regular compilation if there
127 -- are serious errors. In that case there will be no further expansion,
128 -- but one cleanup action may be required: if a transient scope was
129 -- created (e.g. for a function that returns an unconstrained type) the
130 -- scope may still be on the stack, and must be removed explicitly,
131 -- given that the expansion actions that would normally process it will
132 -- not take place. This prevents cascaded errors due to stack mismatch.
133
134 elsif not Expander_Active then
135 Set_Analyzed (N, Full_Analysis);
136
137 if Serious_Errors_Detected > 0 and then Scope_Is_Transient then
138 Scope_Stack.Table
139 (Scope_Stack.Last).Actions_To_Be_Wrapped := (others => No_List);
140 Pop_Scope;
141 end if;
142
143 return;
144
145 else
146 begin
147 Debug_A_Entry ("expanding ", N);
148
149 -- Processing depends on node kind. For full details on the
150 -- expansion activity required in each case, see bodies of
151 -- corresponding expand routines.
152
153 case Nkind (N) is
154
155 when N_Abort_Statement =>
156 Expand_N_Abort_Statement (N);
157
158 -- If -gnatd.B switch was given, crash the compiler. See
159 -- debug.adb for explanation.
160
161 if Debug_Flag_Dot_BB then
162 raise Abort_Bug_Box_Error;
163 end if;
164
165 when N_Accept_Statement =>
166 Expand_N_Accept_Statement (N);
167
168 when N_Aggregate =>
169 Expand_N_Aggregate (N);
170
171 when N_Allocator =>
172 Expand_N_Allocator (N);
173
174 when N_And_Then =>
175 Expand_N_And_Then (N);
176
177 when N_Assignment_Statement =>
178 Expand_N_Assignment_Statement (N);
179
180 when N_Asynchronous_Select =>
181 Expand_N_Asynchronous_Select (N);
182
183 when N_Attribute_Definition_Clause =>
184 Expand_N_Attribute_Definition_Clause (N);
185
186 when N_Attribute_Reference =>
187 Expand_N_Attribute_Reference (N);
188
189 when N_Block_Statement =>
190 Expand_N_Block_Statement (N);
191
192 when N_Case_Expression =>
193 Expand_N_Case_Expression (N);
194
195 when N_Case_Statement =>
196 Expand_N_Case_Statement (N);
197
198 when N_Conditional_Entry_Call =>
199 Expand_N_Conditional_Entry_Call (N);
200
201 when N_Delay_Relative_Statement =>
202 Expand_N_Delay_Relative_Statement (N);
203
204 when N_Delay_Until_Statement =>
205 Expand_N_Delay_Until_Statement (N);
206
207 when N_Entry_Body =>
208 Expand_N_Entry_Body (N);
209
210 when N_Entry_Call_Statement =>
211 Expand_N_Entry_Call_Statement (N);
212
213 when N_Entry_Declaration =>
214 Expand_N_Entry_Declaration (N);
215
216 when N_Exception_Declaration =>
217 Expand_N_Exception_Declaration (N);
218
219 when N_Exception_Renaming_Declaration =>
220 Expand_N_Exception_Renaming_Declaration (N);
221
222 when N_Exit_Statement =>
223 Expand_N_Exit_Statement (N);
224
225 when N_Expanded_Name =>
226 Expand_N_Expanded_Name (N);
227
228 when N_Explicit_Dereference =>
229 Expand_N_Explicit_Dereference (N);
230
231 when N_Expression_With_Actions =>
232 Expand_N_Expression_With_Actions (N);
233
234 when N_Extended_Return_Statement =>
235 Expand_N_Extended_Return_Statement (N);
236
237 when N_Extension_Aggregate =>
238 Expand_N_Extension_Aggregate (N);
239
240 when N_Free_Statement =>
241 Expand_N_Free_Statement (N);
242
243 when N_Freeze_Entity =>
244 Expand_N_Freeze_Entity (N);
245
246 when N_Full_Type_Declaration =>
247 Expand_N_Full_Type_Declaration (N);
248
249 when N_Function_Call =>
250 Expand_N_Function_Call (N);
251
252 when N_Generic_Instantiation =>
253 Expand_N_Generic_Instantiation (N);
254
255 when N_Goto_Statement =>
256 Expand_N_Goto_Statement (N);
257
258 when N_Handled_Sequence_Of_Statements =>
259 Expand_N_Handled_Sequence_Of_Statements (N);
260
261 when N_Identifier =>
262 Expand_N_Identifier (N);
263
264 when N_If_Expression =>
265 Expand_N_If_Expression (N);
266
267 when N_Indexed_Component =>
268 Expand_N_Indexed_Component (N);
269
270 when N_If_Statement =>
271 Expand_N_If_Statement (N);
272
273 when N_In =>
274 Expand_N_In (N);
275
276 when N_Loop_Statement =>
277 Expand_N_Loop_Statement (N);
278
279 when N_Not_In =>
280 Expand_N_Not_In (N);
281
282 when N_Null =>
283 Expand_N_Null (N);
284
285 when N_Object_Declaration =>
286 Expand_N_Object_Declaration (N);
287
288 when N_Object_Renaming_Declaration =>
289 Expand_N_Object_Renaming_Declaration (N);
290
291 when N_Op_Add =>
292 Expand_N_Op_Add (N);
293
294 when N_Op_Abs =>
295 Expand_N_Op_Abs (N);
296
297 when N_Op_And =>
298 Expand_N_Op_And (N);
299
300 when N_Op_Concat =>
301 Expand_N_Op_Concat (N);
302
303 when N_Op_Divide =>
304 Expand_N_Op_Divide (N);
305
306 when N_Op_Eq =>
307 Expand_N_Op_Eq (N);
308
309 when N_Op_Expon =>
310 Expand_N_Op_Expon (N);
311
312 when N_Op_Ge =>
313 Expand_N_Op_Ge (N);
314
315 when N_Op_Gt =>
316 Expand_N_Op_Gt (N);
317
318 when N_Op_Le =>
319 Expand_N_Op_Le (N);
320
321 when N_Op_Lt =>
322 Expand_N_Op_Lt (N);
323
324 when N_Op_Minus =>
325 Expand_N_Op_Minus (N);
326
327 when N_Op_Mod =>
328 Expand_N_Op_Mod (N);
329
330 when N_Op_Multiply =>
331 Expand_N_Op_Multiply (N);
332
333 when N_Op_Ne =>
334 Expand_N_Op_Ne (N);
335
336 when N_Op_Not =>
337 Expand_N_Op_Not (N);
338
339 when N_Op_Or =>
340 Expand_N_Op_Or (N);
341
342 when N_Op_Plus =>
343 Expand_N_Op_Plus (N);
344
345 when N_Op_Rem =>
346 Expand_N_Op_Rem (N);
347
348 when N_Op_Rotate_Left =>
349 Expand_N_Op_Rotate_Left (N);
350
351 when N_Op_Rotate_Right =>
352 Expand_N_Op_Rotate_Right (N);
353
354 when N_Op_Shift_Left =>
355 Expand_N_Op_Shift_Left (N);
356
357 when N_Op_Shift_Right =>
358 Expand_N_Op_Shift_Right (N);
359
360 when N_Op_Shift_Right_Arithmetic =>
361 Expand_N_Op_Shift_Right_Arithmetic (N);
362
363 when N_Op_Subtract =>
364 Expand_N_Op_Subtract (N);
365
366 when N_Op_Xor =>
367 Expand_N_Op_Xor (N);
368
369 when N_Or_Else =>
370 Expand_N_Or_Else (N);
371
372 when N_Package_Body =>
373 Expand_N_Package_Body (N);
374
375 when N_Package_Declaration =>
376 Expand_N_Package_Declaration (N);
377
378 when N_Package_Renaming_Declaration =>
379 Expand_N_Package_Renaming_Declaration (N);
380
381 when N_Subprogram_Renaming_Declaration =>
382 Expand_N_Subprogram_Renaming_Declaration (N);
383
384 when N_Pragma =>
385 Expand_N_Pragma (N);
386
387 when N_Procedure_Call_Statement =>
388 Expand_N_Procedure_Call_Statement (N);
389
390 when N_Protected_Type_Declaration =>
391 Expand_N_Protected_Type_Declaration (N);
392
393 when N_Protected_Body =>
394 Expand_N_Protected_Body (N);
395
396 when N_Qualified_Expression =>
397 Expand_N_Qualified_Expression (N);
398
399 when N_Quantified_Expression =>
400 Expand_N_Quantified_Expression (N);
401
402 when N_Raise_Statement =>
403 Expand_N_Raise_Statement (N);
404
405 when N_Raise_Constraint_Error =>
406 Expand_N_Raise_Constraint_Error (N);
407
408 when N_Raise_Expression =>
409 Expand_N_Raise_Expression (N);
410
411 when N_Raise_Program_Error =>
412 Expand_N_Raise_Program_Error (N);
413
414 when N_Raise_Storage_Error =>
415 Expand_N_Raise_Storage_Error (N);
416
417 when N_Real_Literal =>
418 Expand_N_Real_Literal (N);
419
420 when N_Record_Representation_Clause =>
421 Expand_N_Record_Representation_Clause (N);
422
423 when N_Requeue_Statement =>
424 Expand_N_Requeue_Statement (N);
425
426 when N_Simple_Return_Statement =>
427 Expand_N_Simple_Return_Statement (N);
428
429 when N_Selected_Component =>
430 Expand_N_Selected_Component (N);
431
432 when N_Selective_Accept =>
433 Expand_N_Selective_Accept (N);
434
435 when N_Single_Protected_Declaration =>
436 Expand_N_Single_Protected_Declaration (N);
437
438 when N_Single_Task_Declaration =>
439 Expand_N_Single_Task_Declaration (N);
440
441 when N_Slice =>
442 Expand_N_Slice (N);
443
444 when N_Subtype_Indication =>
445 Expand_N_Subtype_Indication (N);
446
447 when N_Subprogram_Body =>
448 Expand_N_Subprogram_Body (N);
449
450 when N_Subprogram_Body_Stub =>
451 Expand_N_Subprogram_Body_Stub (N);
452
453 when N_Subprogram_Declaration =>
454 Expand_N_Subprogram_Declaration (N);
455
456 when N_Task_Body =>
457 Expand_N_Task_Body (N);
458
459 when N_Task_Type_Declaration =>
460 Expand_N_Task_Type_Declaration (N);
461
462 when N_Timed_Entry_Call =>
463 Expand_N_Timed_Entry_Call (N);
464
465 when N_Type_Conversion =>
466 Expand_N_Type_Conversion (N);
467
468 when N_Unchecked_Expression =>
469 Expand_N_Unchecked_Expression (N);
470
471 when N_Unchecked_Type_Conversion =>
472 Expand_N_Unchecked_Type_Conversion (N);
473
474 when N_Variant_Part =>
475 Expand_N_Variant_Part (N);
476
477 -- For all other node kinds, no expansion activity required
478
479 when others =>
480 null;
481
482 end case;
483
484 exception
485 when RE_Not_Available =>
486 return;
487 end;
488
489 -- Set result as analyzed and then do a possible transient wrap. The
490 -- transient wrap must be done after the Analyzed flag is set on, so
491 -- that we do not get a recursive attempt to expand the node N.
492
493 Set_Analyzed (N);
494
495 -- Deal with transient scopes
496
497 if Scope_Is_Transient and then N = Node_To_Be_Wrapped then
498 case Nkind (N) is
499 when N_Statement_Other_Than_Procedure_Call |
500 N_Procedure_Call_Statement =>
501 Wrap_Transient_Statement (N);
502
503 when N_Object_Declaration |
504 N_Object_Renaming_Declaration |
505 N_Subtype_Declaration =>
506 Wrap_Transient_Declaration (N);
507
508 when others => Wrap_Transient_Expression (N);
509 end case;
510 end if;
511
512 Debug_A_Exit ("expanding ", N, " (done)");
513 end if;
514 end Expand;
515
516 ---------------------------
517 -- Expander_Mode_Restore --
518 ---------------------------
519
520 procedure Expander_Mode_Restore is
521 begin
522 -- Not active (has no effect) in ASIS and GNATprove modes (see comments
523 -- in spec of Expander_Mode_Save_And_Set).
524
525 if ASIS_Mode or GNATprove_Mode then
526 return;
527 end if;
528
529 -- Otherwise restore the flag
530
531 Expander_Active := Expander_Flags.Table (Expander_Flags.Last);
532 Expander_Flags.Decrement_Last;
533
534 -- Keep expander off if serious errors detected. In this case we do not
535 -- need expansion, and continued expansion may cause cascaded errors or
536 -- compiler bombs.
537
538 if Serious_Errors_Detected /= 0 then
539 Expander_Active := False;
540 end if;
541 end Expander_Mode_Restore;
542
543 --------------------------------
544 -- Expander_Mode_Save_And_Set --
545 --------------------------------
546
547 procedure Expander_Mode_Save_And_Set (Status : Boolean) is
548 begin
549 -- Not active (has no effect) in ASIS and GNATprove modes (see comments
550 -- in spec of Expander_Mode_Save_And_Set).
551
552 if ASIS_Mode or GNATprove_Mode then
553 return;
554 end if;
555
556 -- Otherwise save and set the flag
557
558 Expander_Flags.Increment_Last;
559 Expander_Flags.Table (Expander_Flags.Last) := Expander_Active;
560 Expander_Active := Status;
561 end Expander_Mode_Save_And_Set;
562
563 end Expander;