* corelow.c (core_close): Don't hardcode the core's pid.
[deliverable/binutils-gdb.git] / gdb / value.c
1 /* Low level packing and unpacking of values for GDB, the GNU Debugger.
2
3 Copyright (C) 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
4 1996, 1997, 1998, 1999, 2000, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
5 2009 Free Software Foundation, Inc.
6
7 This file is part of GDB.
8
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or
12 (at your option) any later version.
13
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
18
19 You should have received a copy of the GNU General Public License
20 along with this program. If not, see <http://www.gnu.org/licenses/>. */
21
22 #include "defs.h"
23 #include "gdb_string.h"
24 #include "symtab.h"
25 #include "gdbtypes.h"
26 #include "value.h"
27 #include "gdbcore.h"
28 #include "command.h"
29 #include "gdbcmd.h"
30 #include "target.h"
31 #include "language.h"
32 #include "demangle.h"
33 #include "doublest.h"
34 #include "gdb_assert.h"
35 #include "regcache.h"
36 #include "block.h"
37 #include "dfp.h"
38 #include "objfiles.h"
39 #include "valprint.h"
40
41 #include "python/python.h"
42
43 /* Prototypes for exported functions. */
44
45 void _initialize_values (void);
46
47 struct value
48 {
49 /* Type of value; either not an lval, or one of the various
50 different possible kinds of lval. */
51 enum lval_type lval;
52
53 /* Is it modifiable? Only relevant if lval != not_lval. */
54 int modifiable;
55
56 /* Location of value (if lval). */
57 union
58 {
59 /* If lval == lval_memory, this is the address in the inferior.
60 If lval == lval_register, this is the byte offset into the
61 registers structure. */
62 CORE_ADDR address;
63
64 /* Pointer to internal variable. */
65 struct internalvar *internalvar;
66
67 /* If lval == lval_computed, this is a set of function pointers
68 to use to access and describe the value, and a closure pointer
69 for them to use. */
70 struct
71 {
72 struct lval_funcs *funcs; /* Functions to call. */
73 void *closure; /* Closure for those functions to use. */
74 } computed;
75 } location;
76
77 /* Describes offset of a value within lval of a structure in bytes.
78 If lval == lval_memory, this is an offset to the address. If
79 lval == lval_register, this is a further offset from
80 location.address within the registers structure. Note also the
81 member embedded_offset below. */
82 int offset;
83
84 /* Only used for bitfields; number of bits contained in them. */
85 int bitsize;
86
87 /* Only used for bitfields; position of start of field. For
88 gdbarch_bits_big_endian=0 targets, it is the position of the LSB. For
89 gdbarch_bits_big_endian=1 targets, it is the position of the MSB. */
90 int bitpos;
91
92 /* Frame register value is relative to. This will be described in
93 the lval enum above as "lval_register". */
94 struct frame_id frame_id;
95
96 /* Type of the value. */
97 struct type *type;
98
99 /* If a value represents a C++ object, then the `type' field gives
100 the object's compile-time type. If the object actually belongs
101 to some class derived from `type', perhaps with other base
102 classes and additional members, then `type' is just a subobject
103 of the real thing, and the full object is probably larger than
104 `type' would suggest.
105
106 If `type' is a dynamic class (i.e. one with a vtable), then GDB
107 can actually determine the object's run-time type by looking at
108 the run-time type information in the vtable. When this
109 information is available, we may elect to read in the entire
110 object, for several reasons:
111
112 - When printing the value, the user would probably rather see the
113 full object, not just the limited portion apparent from the
114 compile-time type.
115
116 - If `type' has virtual base classes, then even printing `type'
117 alone may require reaching outside the `type' portion of the
118 object to wherever the virtual base class has been stored.
119
120 When we store the entire object, `enclosing_type' is the run-time
121 type -- the complete object -- and `embedded_offset' is the
122 offset of `type' within that larger type, in bytes. The
123 value_contents() macro takes `embedded_offset' into account, so
124 most GDB code continues to see the `type' portion of the value,
125 just as the inferior would.
126
127 If `type' is a pointer to an object, then `enclosing_type' is a
128 pointer to the object's run-time type, and `pointed_to_offset' is
129 the offset in bytes from the full object to the pointed-to object
130 -- that is, the value `embedded_offset' would have if we followed
131 the pointer and fetched the complete object. (I don't really see
132 the point. Why not just determine the run-time type when you
133 indirect, and avoid the special case? The contents don't matter
134 until you indirect anyway.)
135
136 If we're not doing anything fancy, `enclosing_type' is equal to
137 `type', and `embedded_offset' is zero, so everything works
138 normally. */
139 struct type *enclosing_type;
140 int embedded_offset;
141 int pointed_to_offset;
142
143 /* Values are stored in a chain, so that they can be deleted easily
144 over calls to the inferior. Values assigned to internal
145 variables, put into the value history or exposed to Python are
146 taken off this list. */
147 struct value *next;
148
149 /* Register number if the value is from a register. */
150 short regnum;
151
152 /* If zero, contents of this value are in the contents field. If
153 nonzero, contents are in inferior. If the lval field is lval_memory,
154 the contents are in inferior memory at location.address plus offset.
155 The lval field may also be lval_register.
156
157 WARNING: This field is used by the code which handles watchpoints
158 (see breakpoint.c) to decide whether a particular value can be
159 watched by hardware watchpoints. If the lazy flag is set for
160 some member of a value chain, it is assumed that this member of
161 the chain doesn't need to be watched as part of watching the
162 value itself. This is how GDB avoids watching the entire struct
163 or array when the user wants to watch a single struct member or
164 array element. If you ever change the way lazy flag is set and
165 reset, be sure to consider this use as well! */
166 char lazy;
167
168 /* If nonzero, this is the value of a variable which does not
169 actually exist in the program. */
170 char optimized_out;
171
172 /* If value is a variable, is it initialized or not. */
173 int initialized;
174
175 /* Actual contents of the value. Target byte-order. NULL or not
176 valid if lazy is nonzero. */
177 gdb_byte *contents;
178 };
179
180 /* Prototypes for local functions. */
181
182 static void show_values (char *, int);
183
184 static void show_convenience (char *, int);
185
186
187 /* The value-history records all the values printed
188 by print commands during this session. Each chunk
189 records 60 consecutive values. The first chunk on
190 the chain records the most recent values.
191 The total number of values is in value_history_count. */
192
193 #define VALUE_HISTORY_CHUNK 60
194
195 struct value_history_chunk
196 {
197 struct value_history_chunk *next;
198 struct value *values[VALUE_HISTORY_CHUNK];
199 };
200
201 /* Chain of chunks now in use. */
202
203 static struct value_history_chunk *value_history_chain;
204
205 static int value_history_count; /* Abs number of last entry stored */
206 \f
207 /* List of all value objects currently allocated
208 (except for those released by calls to release_value)
209 This is so they can be freed after each command. */
210
211 static struct value *all_values;
212
213 /* Allocate a lazy value for type TYPE. Its actual content is
214 "lazily" allocated too: the content field of the return value is
215 NULL; it will be allocated when it is fetched from the target. */
216
217 struct value *
218 allocate_value_lazy (struct type *type)
219 {
220 struct value *val;
221 struct type *atype = check_typedef (type);
222
223 val = (struct value *) xzalloc (sizeof (struct value));
224 val->contents = NULL;
225 val->next = all_values;
226 all_values = val;
227 val->type = type;
228 val->enclosing_type = type;
229 VALUE_LVAL (val) = not_lval;
230 VALUE_ADDRESS (val) = 0;
231 VALUE_FRAME_ID (val) = null_frame_id;
232 val->offset = 0;
233 val->bitpos = 0;
234 val->bitsize = 0;
235 VALUE_REGNUM (val) = -1;
236 val->lazy = 1;
237 val->optimized_out = 0;
238 val->embedded_offset = 0;
239 val->pointed_to_offset = 0;
240 val->modifiable = 1;
241 val->initialized = 1; /* Default to initialized. */
242 return val;
243 }
244
245 /* Allocate the contents of VAL if it has not been allocated yet. */
246
247 void
248 allocate_value_contents (struct value *val)
249 {
250 if (!val->contents)
251 val->contents = (gdb_byte *) xzalloc (TYPE_LENGTH (val->enclosing_type));
252 }
253
254 /* Allocate a value and its contents for type TYPE. */
255
256 struct value *
257 allocate_value (struct type *type)
258 {
259 struct value *val = allocate_value_lazy (type);
260 allocate_value_contents (val);
261 val->lazy = 0;
262 return val;
263 }
264
265 /* Allocate a value that has the correct length
266 for COUNT repetitions of type TYPE. */
267
268 struct value *
269 allocate_repeat_value (struct type *type, int count)
270 {
271 int low_bound = current_language->string_lower_bound; /* ??? */
272 /* FIXME-type-allocation: need a way to free this type when we are
273 done with it. */
274 struct type *range_type
275 = create_range_type ((struct type *) NULL, builtin_type_int32,
276 low_bound, count + low_bound - 1);
277 /* FIXME-type-allocation: need a way to free this type when we are
278 done with it. */
279 return allocate_value (create_array_type ((struct type *) NULL,
280 type, range_type));
281 }
282
283 /* Needed if another module needs to maintain its on list of values. */
284 void
285 value_prepend_to_list (struct value **head, struct value *val)
286 {
287 val->next = *head;
288 *head = val;
289 }
290
291 /* Needed if another module needs to maintain its on list of values. */
292 void
293 value_remove_from_list (struct value **head, struct value *val)
294 {
295 struct value *prev;
296
297 if (*head == val)
298 *head = (*head)->next;
299 else
300 for (prev = *head; prev->next; prev = prev->next)
301 if (prev->next == val)
302 {
303 prev->next = val->next;
304 break;
305 }
306 }
307
308 struct value *
309 allocate_computed_value (struct type *type,
310 struct lval_funcs *funcs,
311 void *closure)
312 {
313 struct value *v = allocate_value (type);
314 VALUE_LVAL (v) = lval_computed;
315 v->location.computed.funcs = funcs;
316 v->location.computed.closure = closure;
317 set_value_lazy (v, 1);
318
319 return v;
320 }
321
322 /* Accessor methods. */
323
324 struct value *
325 value_next (struct value *value)
326 {
327 return value->next;
328 }
329
330 struct type *
331 value_type (struct value *value)
332 {
333 return value->type;
334 }
335 void
336 deprecated_set_value_type (struct value *value, struct type *type)
337 {
338 value->type = type;
339 }
340
341 int
342 value_offset (struct value *value)
343 {
344 return value->offset;
345 }
346 void
347 set_value_offset (struct value *value, int offset)
348 {
349 value->offset = offset;
350 }
351
352 int
353 value_bitpos (struct value *value)
354 {
355 return value->bitpos;
356 }
357 void
358 set_value_bitpos (struct value *value, int bit)
359 {
360 value->bitpos = bit;
361 }
362
363 int
364 value_bitsize (struct value *value)
365 {
366 return value->bitsize;
367 }
368 void
369 set_value_bitsize (struct value *value, int bit)
370 {
371 value->bitsize = bit;
372 }
373
374 gdb_byte *
375 value_contents_raw (struct value *value)
376 {
377 allocate_value_contents (value);
378 return value->contents + value->embedded_offset;
379 }
380
381 gdb_byte *
382 value_contents_all_raw (struct value *value)
383 {
384 allocate_value_contents (value);
385 return value->contents;
386 }
387
388 struct type *
389 value_enclosing_type (struct value *value)
390 {
391 return value->enclosing_type;
392 }
393
394 const gdb_byte *
395 value_contents_all (struct value *value)
396 {
397 if (value->lazy)
398 value_fetch_lazy (value);
399 return value->contents;
400 }
401
402 int
403 value_lazy (struct value *value)
404 {
405 return value->lazy;
406 }
407
408 void
409 set_value_lazy (struct value *value, int val)
410 {
411 value->lazy = val;
412 }
413
414 const gdb_byte *
415 value_contents (struct value *value)
416 {
417 return value_contents_writeable (value);
418 }
419
420 gdb_byte *
421 value_contents_writeable (struct value *value)
422 {
423 if (value->lazy)
424 value_fetch_lazy (value);
425 return value_contents_raw (value);
426 }
427
428 /* Return non-zero if VAL1 and VAL2 have the same contents. Note that
429 this function is different from value_equal; in C the operator ==
430 can return 0 even if the two values being compared are equal. */
431
432 int
433 value_contents_equal (struct value *val1, struct value *val2)
434 {
435 struct type *type1;
436 struct type *type2;
437 int len;
438
439 type1 = check_typedef (value_type (val1));
440 type2 = check_typedef (value_type (val2));
441 len = TYPE_LENGTH (type1);
442 if (len != TYPE_LENGTH (type2))
443 return 0;
444
445 return (memcmp (value_contents (val1), value_contents (val2), len) == 0);
446 }
447
448 int
449 value_optimized_out (struct value *value)
450 {
451 return value->optimized_out;
452 }
453
454 void
455 set_value_optimized_out (struct value *value, int val)
456 {
457 value->optimized_out = val;
458 }
459
460 int
461 value_embedded_offset (struct value *value)
462 {
463 return value->embedded_offset;
464 }
465
466 void
467 set_value_embedded_offset (struct value *value, int val)
468 {
469 value->embedded_offset = val;
470 }
471
472 int
473 value_pointed_to_offset (struct value *value)
474 {
475 return value->pointed_to_offset;
476 }
477
478 void
479 set_value_pointed_to_offset (struct value *value, int val)
480 {
481 value->pointed_to_offset = val;
482 }
483
484 struct lval_funcs *
485 value_computed_funcs (struct value *v)
486 {
487 gdb_assert (VALUE_LVAL (v) == lval_computed);
488
489 return v->location.computed.funcs;
490 }
491
492 void *
493 value_computed_closure (struct value *v)
494 {
495 gdb_assert (VALUE_LVAL (v) == lval_computed);
496
497 return v->location.computed.closure;
498 }
499
500 enum lval_type *
501 deprecated_value_lval_hack (struct value *value)
502 {
503 return &value->lval;
504 }
505
506 CORE_ADDR *
507 deprecated_value_address_hack (struct value *value)
508 {
509 return &value->location.address;
510 }
511
512 struct internalvar **
513 deprecated_value_internalvar_hack (struct value *value)
514 {
515 return &value->location.internalvar;
516 }
517
518 struct frame_id *
519 deprecated_value_frame_id_hack (struct value *value)
520 {
521 return &value->frame_id;
522 }
523
524 short *
525 deprecated_value_regnum_hack (struct value *value)
526 {
527 return &value->regnum;
528 }
529
530 int
531 deprecated_value_modifiable (struct value *value)
532 {
533 return value->modifiable;
534 }
535 void
536 deprecated_set_value_modifiable (struct value *value, int modifiable)
537 {
538 value->modifiable = modifiable;
539 }
540 \f
541 /* Return a mark in the value chain. All values allocated after the
542 mark is obtained (except for those released) are subject to being freed
543 if a subsequent value_free_to_mark is passed the mark. */
544 struct value *
545 value_mark (void)
546 {
547 return all_values;
548 }
549
550 void
551 value_free (struct value *val)
552 {
553 if (val)
554 {
555 if (VALUE_LVAL (val) == lval_computed)
556 {
557 struct lval_funcs *funcs = val->location.computed.funcs;
558
559 if (funcs->free_closure)
560 funcs->free_closure (val);
561 }
562
563 xfree (val->contents);
564 }
565 xfree (val);
566 }
567
568 /* Free all values allocated since MARK was obtained by value_mark
569 (except for those released). */
570 void
571 value_free_to_mark (struct value *mark)
572 {
573 struct value *val;
574 struct value *next;
575
576 for (val = all_values; val && val != mark; val = next)
577 {
578 next = val->next;
579 value_free (val);
580 }
581 all_values = val;
582 }
583
584 /* Free all the values that have been allocated (except for those released).
585 Called after each command, successful or not. */
586
587 void
588 free_all_values (void)
589 {
590 struct value *val;
591 struct value *next;
592
593 for (val = all_values; val; val = next)
594 {
595 next = val->next;
596 value_free (val);
597 }
598
599 all_values = 0;
600 }
601
602 /* Remove VAL from the chain all_values
603 so it will not be freed automatically. */
604
605 void
606 release_value (struct value *val)
607 {
608 struct value *v;
609
610 if (all_values == val)
611 {
612 all_values = val->next;
613 return;
614 }
615
616 for (v = all_values; v; v = v->next)
617 {
618 if (v->next == val)
619 {
620 v->next = val->next;
621 break;
622 }
623 }
624 }
625
626 /* Release all values up to mark */
627 struct value *
628 value_release_to_mark (struct value *mark)
629 {
630 struct value *val;
631 struct value *next;
632
633 for (val = next = all_values; next; next = next->next)
634 if (next->next == mark)
635 {
636 all_values = next->next;
637 next->next = NULL;
638 return val;
639 }
640 all_values = 0;
641 return val;
642 }
643
644 /* Return a copy of the value ARG.
645 It contains the same contents, for same memory address,
646 but it's a different block of storage. */
647
648 struct value *
649 value_copy (struct value *arg)
650 {
651 struct type *encl_type = value_enclosing_type (arg);
652 struct value *val;
653
654 if (value_lazy (arg))
655 val = allocate_value_lazy (encl_type);
656 else
657 val = allocate_value (encl_type);
658 val->type = arg->type;
659 VALUE_LVAL (val) = VALUE_LVAL (arg);
660 val->location = arg->location;
661 val->offset = arg->offset;
662 val->bitpos = arg->bitpos;
663 val->bitsize = arg->bitsize;
664 VALUE_FRAME_ID (val) = VALUE_FRAME_ID (arg);
665 VALUE_REGNUM (val) = VALUE_REGNUM (arg);
666 val->lazy = arg->lazy;
667 val->optimized_out = arg->optimized_out;
668 val->embedded_offset = value_embedded_offset (arg);
669 val->pointed_to_offset = arg->pointed_to_offset;
670 val->modifiable = arg->modifiable;
671 if (!value_lazy (val))
672 {
673 memcpy (value_contents_all_raw (val), value_contents_all_raw (arg),
674 TYPE_LENGTH (value_enclosing_type (arg)));
675
676 }
677 if (VALUE_LVAL (val) == lval_computed)
678 {
679 struct lval_funcs *funcs = val->location.computed.funcs;
680
681 if (funcs->copy_closure)
682 val->location.computed.closure = funcs->copy_closure (val);
683 }
684 return val;
685 }
686
687 void
688 set_value_component_location (struct value *component, struct value *whole)
689 {
690 if (VALUE_LVAL (whole) == lval_internalvar)
691 VALUE_LVAL (component) = lval_internalvar_component;
692 else
693 VALUE_LVAL (component) = VALUE_LVAL (whole);
694
695 component->location = whole->location;
696 if (VALUE_LVAL (whole) == lval_computed)
697 {
698 struct lval_funcs *funcs = whole->location.computed.funcs;
699
700 if (funcs->copy_closure)
701 component->location.computed.closure = funcs->copy_closure (whole);
702 }
703 }
704
705 \f
706 /* Access to the value history. */
707
708 /* Record a new value in the value history.
709 Returns the absolute history index of the entry.
710 Result of -1 indicates the value was not saved; otherwise it is the
711 value history index of this new item. */
712
713 int
714 record_latest_value (struct value *val)
715 {
716 int i;
717
718 /* We don't want this value to have anything to do with the inferior anymore.
719 In particular, "set $1 = 50" should not affect the variable from which
720 the value was taken, and fast watchpoints should be able to assume that
721 a value on the value history never changes. */
722 if (value_lazy (val))
723 value_fetch_lazy (val);
724 /* We preserve VALUE_LVAL so that the user can find out where it was fetched
725 from. This is a bit dubious, because then *&$1 does not just return $1
726 but the current contents of that location. c'est la vie... */
727 val->modifiable = 0;
728 release_value (val);
729
730 /* Here we treat value_history_count as origin-zero
731 and applying to the value being stored now. */
732
733 i = value_history_count % VALUE_HISTORY_CHUNK;
734 if (i == 0)
735 {
736 struct value_history_chunk *new
737 = (struct value_history_chunk *)
738 xmalloc (sizeof (struct value_history_chunk));
739 memset (new->values, 0, sizeof new->values);
740 new->next = value_history_chain;
741 value_history_chain = new;
742 }
743
744 value_history_chain->values[i] = val;
745
746 /* Now we regard value_history_count as origin-one
747 and applying to the value just stored. */
748
749 return ++value_history_count;
750 }
751
752 /* Return a copy of the value in the history with sequence number NUM. */
753
754 struct value *
755 access_value_history (int num)
756 {
757 struct value_history_chunk *chunk;
758 int i;
759 int absnum = num;
760
761 if (absnum <= 0)
762 absnum += value_history_count;
763
764 if (absnum <= 0)
765 {
766 if (num == 0)
767 error (_("The history is empty."));
768 else if (num == 1)
769 error (_("There is only one value in the history."));
770 else
771 error (_("History does not go back to $$%d."), -num);
772 }
773 if (absnum > value_history_count)
774 error (_("History has not yet reached $%d."), absnum);
775
776 absnum--;
777
778 /* Now absnum is always absolute and origin zero. */
779
780 chunk = value_history_chain;
781 for (i = (value_history_count - 1) / VALUE_HISTORY_CHUNK - absnum / VALUE_HISTORY_CHUNK;
782 i > 0; i--)
783 chunk = chunk->next;
784
785 return value_copy (chunk->values[absnum % VALUE_HISTORY_CHUNK]);
786 }
787
788 static void
789 show_values (char *num_exp, int from_tty)
790 {
791 int i;
792 struct value *val;
793 static int num = 1;
794
795 if (num_exp)
796 {
797 /* "show values +" should print from the stored position.
798 "show values <exp>" should print around value number <exp>. */
799 if (num_exp[0] != '+' || num_exp[1] != '\0')
800 num = parse_and_eval_long (num_exp) - 5;
801 }
802 else
803 {
804 /* "show values" means print the last 10 values. */
805 num = value_history_count - 9;
806 }
807
808 if (num <= 0)
809 num = 1;
810
811 for (i = num; i < num + 10 && i <= value_history_count; i++)
812 {
813 struct value_print_options opts;
814 val = access_value_history (i);
815 printf_filtered (("$%d = "), i);
816 get_user_print_options (&opts);
817 value_print (val, gdb_stdout, &opts);
818 printf_filtered (("\n"));
819 }
820
821 /* The next "show values +" should start after what we just printed. */
822 num += 10;
823
824 /* Hitting just return after this command should do the same thing as
825 "show values +". If num_exp is null, this is unnecessary, since
826 "show values +" is not useful after "show values". */
827 if (from_tty && num_exp)
828 {
829 num_exp[0] = '+';
830 num_exp[1] = '\0';
831 }
832 }
833 \f
834 /* Internal variables. These are variables within the debugger
835 that hold values assigned by debugger commands.
836 The user refers to them with a '$' prefix
837 that does not appear in the variable names stored internally. */
838
839 static struct internalvar *internalvars;
840
841 /* If the variable does not already exist create it and give it the value given.
842 If no value is given then the default is zero. */
843 static void
844 init_if_undefined_command (char* args, int from_tty)
845 {
846 struct internalvar* intvar;
847
848 /* Parse the expression - this is taken from set_command(). */
849 struct expression *expr = parse_expression (args);
850 register struct cleanup *old_chain =
851 make_cleanup (free_current_contents, &expr);
852
853 /* Validate the expression.
854 Was the expression an assignment?
855 Or even an expression at all? */
856 if (expr->nelts == 0 || expr->elts[0].opcode != BINOP_ASSIGN)
857 error (_("Init-if-undefined requires an assignment expression."));
858
859 /* Extract the variable from the parsed expression.
860 In the case of an assign the lvalue will be in elts[1] and elts[2]. */
861 if (expr->elts[1].opcode != OP_INTERNALVAR)
862 error (_("The first parameter to init-if-undefined should be a GDB variable."));
863 intvar = expr->elts[2].internalvar;
864
865 /* Only evaluate the expression if the lvalue is void.
866 This may still fail if the expresssion is invalid. */
867 if (TYPE_CODE (value_type (intvar->value)) == TYPE_CODE_VOID)
868 evaluate_expression (expr);
869
870 do_cleanups (old_chain);
871 }
872
873
874 /* Look up an internal variable with name NAME. NAME should not
875 normally include a dollar sign.
876
877 If the specified internal variable does not exist,
878 the return value is NULL. */
879
880 struct internalvar *
881 lookup_only_internalvar (char *name)
882 {
883 struct internalvar *var;
884
885 for (var = internalvars; var; var = var->next)
886 if (strcmp (var->name, name) == 0)
887 return var;
888
889 return NULL;
890 }
891
892
893 /* Create an internal variable with name NAME and with a void value.
894 NAME should not normally include a dollar sign. */
895
896 struct internalvar *
897 create_internalvar (char *name)
898 {
899 struct internalvar *var;
900 var = (struct internalvar *) xmalloc (sizeof (struct internalvar));
901 var->name = concat (name, (char *)NULL);
902 var->value = allocate_value (builtin_type_void);
903 var->endian = gdbarch_byte_order (current_gdbarch);
904 var->make_value = NULL;
905 release_value (var->value);
906 var->next = internalvars;
907 internalvars = var;
908 return var;
909 }
910
911 /* Create an internal variable with name NAME and register FUN as the
912 function that value_of_internalvar uses to create a value whenever
913 this variable is referenced. NAME should not normally include a
914 dollar sign. */
915
916 struct internalvar *
917 create_internalvar_type_lazy (char *name, internalvar_make_value fun)
918 {
919 struct internalvar *var;
920 var = (struct internalvar *) xmalloc (sizeof (struct internalvar));
921 var->name = concat (name, (char *)NULL);
922 var->value = NULL;
923 var->make_value = fun;
924 var->endian = gdbarch_byte_order (current_gdbarch);
925 var->next = internalvars;
926 internalvars = var;
927 return var;
928 }
929
930 /* Look up an internal variable with name NAME. NAME should not
931 normally include a dollar sign.
932
933 If the specified internal variable does not exist,
934 one is created, with a void value. */
935
936 struct internalvar *
937 lookup_internalvar (char *name)
938 {
939 struct internalvar *var;
940
941 var = lookup_only_internalvar (name);
942 if (var)
943 return var;
944
945 return create_internalvar (name);
946 }
947
948 struct value *
949 value_of_internalvar (struct internalvar *var)
950 {
951 struct value *val;
952 int i, j;
953 gdb_byte temp;
954
955 if (var->make_value != NULL)
956 val = (*var->make_value) (var);
957 else
958 {
959 val = value_copy (var->value);
960 if (value_lazy (val))
961 value_fetch_lazy (val);
962
963 /* If the variable's value is a computed lvalue, we want
964 references to it to produce another computed lvalue, where
965 referencces and assignments actually operate through the
966 computed value's functions.
967
968 This means that internal variables with computed values
969 behave a little differently from other internal variables:
970 assignments to them don't just replace the previous value
971 altogether. At the moment, this seems like the behavior we
972 want. */
973 if (var->value->lval == lval_computed)
974 VALUE_LVAL (val) = lval_computed;
975 else
976 {
977 VALUE_LVAL (val) = lval_internalvar;
978 VALUE_INTERNALVAR (val) = var;
979 }
980 }
981
982 /* Values are always stored in the target's byte order. When connected to a
983 target this will most likely always be correct, so there's normally no
984 need to worry about it.
985
986 However, internal variables can be set up before the target endian is
987 known and so may become out of date. Fix it up before anybody sees.
988
989 Internal variables usually hold simple scalar values, and we can
990 correct those. More complex values (e.g. structures and floating
991 point types) are left alone, because they would be too complicated
992 to correct. */
993
994 if (var->endian != gdbarch_byte_order (current_gdbarch))
995 {
996 gdb_byte *array = value_contents_raw (val);
997 struct type *type = check_typedef (value_enclosing_type (val));
998 switch (TYPE_CODE (type))
999 {
1000 case TYPE_CODE_INT:
1001 case TYPE_CODE_PTR:
1002 /* Reverse the bytes. */
1003 for (i = 0, j = TYPE_LENGTH (type) - 1; i < j; i++, j--)
1004 {
1005 temp = array[j];
1006 array[j] = array[i];
1007 array[i] = temp;
1008 }
1009 break;
1010 }
1011 }
1012
1013 return val;
1014 }
1015
1016 void
1017 set_internalvar_component (struct internalvar *var, int offset, int bitpos,
1018 int bitsize, struct value *newval)
1019 {
1020 gdb_byte *addr = value_contents_writeable (var->value) + offset;
1021
1022 if (bitsize)
1023 modify_field (addr, value_as_long (newval),
1024 bitpos, bitsize);
1025 else
1026 memcpy (addr, value_contents (newval), TYPE_LENGTH (value_type (newval)));
1027 }
1028
1029 void
1030 set_internalvar (struct internalvar *var, struct value *val)
1031 {
1032 struct value *newval;
1033
1034 newval = value_copy (val);
1035 newval->modifiable = 1;
1036
1037 /* Force the value to be fetched from the target now, to avoid problems
1038 later when this internalvar is referenced and the target is gone or
1039 has changed. */
1040 if (value_lazy (newval))
1041 value_fetch_lazy (newval);
1042
1043 /* Begin code which must not call error(). If var->value points to
1044 something free'd, an error() obviously leaves a dangling pointer.
1045 But we also get a danling pointer if var->value points to
1046 something in the value chain (i.e., before release_value is
1047 called), because after the error free_all_values will get called before
1048 long. */
1049 value_free (var->value);
1050 var->value = newval;
1051 var->endian = gdbarch_byte_order (current_gdbarch);
1052 release_value (newval);
1053 /* End code which must not call error(). */
1054 }
1055
1056 char *
1057 internalvar_name (struct internalvar *var)
1058 {
1059 return var->name;
1060 }
1061
1062 /* Update VALUE before discarding OBJFILE. COPIED_TYPES is used to
1063 prevent cycles / duplicates. */
1064
1065 static void
1066 preserve_one_value (struct value *value, struct objfile *objfile,
1067 htab_t copied_types)
1068 {
1069 if (TYPE_OBJFILE (value->type) == objfile)
1070 value->type = copy_type_recursive (objfile, value->type, copied_types);
1071
1072 if (TYPE_OBJFILE (value->enclosing_type) == objfile)
1073 value->enclosing_type = copy_type_recursive (objfile,
1074 value->enclosing_type,
1075 copied_types);
1076 }
1077
1078 /* Update the internal variables and value history when OBJFILE is
1079 discarded; we must copy the types out of the objfile. New global types
1080 will be created for every convenience variable which currently points to
1081 this objfile's types, and the convenience variables will be adjusted to
1082 use the new global types. */
1083
1084 void
1085 preserve_values (struct objfile *objfile)
1086 {
1087 htab_t copied_types;
1088 struct value_history_chunk *cur;
1089 struct internalvar *var;
1090 struct value *val;
1091 int i;
1092
1093 /* Create the hash table. We allocate on the objfile's obstack, since
1094 it is soon to be deleted. */
1095 copied_types = create_copied_types_hash (objfile);
1096
1097 for (cur = value_history_chain; cur; cur = cur->next)
1098 for (i = 0; i < VALUE_HISTORY_CHUNK; i++)
1099 if (cur->values[i])
1100 preserve_one_value (cur->values[i], objfile, copied_types);
1101
1102 for (var = internalvars; var; var = var->next)
1103 if (var->value)
1104 preserve_one_value (var->value, objfile, copied_types);
1105
1106 for (val = values_in_python; val; val = val->next)
1107 preserve_one_value (val, objfile, copied_types);
1108
1109 htab_delete (copied_types);
1110 }
1111
1112 static void
1113 show_convenience (char *ignore, int from_tty)
1114 {
1115 struct internalvar *var;
1116 int varseen = 0;
1117 struct value_print_options opts;
1118
1119 get_user_print_options (&opts);
1120 for (var = internalvars; var; var = var->next)
1121 {
1122 if (!varseen)
1123 {
1124 varseen = 1;
1125 }
1126 printf_filtered (("$%s = "), var->name);
1127 value_print (value_of_internalvar (var), gdb_stdout,
1128 &opts);
1129 printf_filtered (("\n"));
1130 }
1131 if (!varseen)
1132 printf_unfiltered (_("\
1133 No debugger convenience variables now defined.\n\
1134 Convenience variables have names starting with \"$\";\n\
1135 use \"set\" as in \"set $foo = 5\" to define them.\n"));
1136 }
1137 \f
1138 /* Extract a value as a C number (either long or double).
1139 Knows how to convert fixed values to double, or
1140 floating values to long.
1141 Does not deallocate the value. */
1142
1143 LONGEST
1144 value_as_long (struct value *val)
1145 {
1146 /* This coerces arrays and functions, which is necessary (e.g.
1147 in disassemble_command). It also dereferences references, which
1148 I suspect is the most logical thing to do. */
1149 val = coerce_array (val);
1150 return unpack_long (value_type (val), value_contents (val));
1151 }
1152
1153 DOUBLEST
1154 value_as_double (struct value *val)
1155 {
1156 DOUBLEST foo;
1157 int inv;
1158
1159 foo = unpack_double (value_type (val), value_contents (val), &inv);
1160 if (inv)
1161 error (_("Invalid floating value found in program."));
1162 return foo;
1163 }
1164
1165 /* Extract a value as a C pointer. Does not deallocate the value.
1166 Note that val's type may not actually be a pointer; value_as_long
1167 handles all the cases. */
1168 CORE_ADDR
1169 value_as_address (struct value *val)
1170 {
1171 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
1172 whether we want this to be true eventually. */
1173 #if 0
1174 /* gdbarch_addr_bits_remove is wrong if we are being called for a
1175 non-address (e.g. argument to "signal", "info break", etc.), or
1176 for pointers to char, in which the low bits *are* significant. */
1177 return gdbarch_addr_bits_remove (current_gdbarch, value_as_long (val));
1178 #else
1179
1180 /* There are several targets (IA-64, PowerPC, and others) which
1181 don't represent pointers to functions as simply the address of
1182 the function's entry point. For example, on the IA-64, a
1183 function pointer points to a two-word descriptor, generated by
1184 the linker, which contains the function's entry point, and the
1185 value the IA-64 "global pointer" register should have --- to
1186 support position-independent code. The linker generates
1187 descriptors only for those functions whose addresses are taken.
1188
1189 On such targets, it's difficult for GDB to convert an arbitrary
1190 function address into a function pointer; it has to either find
1191 an existing descriptor for that function, or call malloc and
1192 build its own. On some targets, it is impossible for GDB to
1193 build a descriptor at all: the descriptor must contain a jump
1194 instruction; data memory cannot be executed; and code memory
1195 cannot be modified.
1196
1197 Upon entry to this function, if VAL is a value of type `function'
1198 (that is, TYPE_CODE (VALUE_TYPE (val)) == TYPE_CODE_FUNC), then
1199 VALUE_ADDRESS (val) is the address of the function. This is what
1200 you'll get if you evaluate an expression like `main'. The call
1201 to COERCE_ARRAY below actually does all the usual unary
1202 conversions, which includes converting values of type `function'
1203 to `pointer to function'. This is the challenging conversion
1204 discussed above. Then, `unpack_long' will convert that pointer
1205 back into an address.
1206
1207 So, suppose the user types `disassemble foo' on an architecture
1208 with a strange function pointer representation, on which GDB
1209 cannot build its own descriptors, and suppose further that `foo'
1210 has no linker-built descriptor. The address->pointer conversion
1211 will signal an error and prevent the command from running, even
1212 though the next step would have been to convert the pointer
1213 directly back into the same address.
1214
1215 The following shortcut avoids this whole mess. If VAL is a
1216 function, just return its address directly. */
1217 if (TYPE_CODE (value_type (val)) == TYPE_CODE_FUNC
1218 || TYPE_CODE (value_type (val)) == TYPE_CODE_METHOD)
1219 return VALUE_ADDRESS (val);
1220
1221 val = coerce_array (val);
1222
1223 /* Some architectures (e.g. Harvard), map instruction and data
1224 addresses onto a single large unified address space. For
1225 instance: An architecture may consider a large integer in the
1226 range 0x10000000 .. 0x1000ffff to already represent a data
1227 addresses (hence not need a pointer to address conversion) while
1228 a small integer would still need to be converted integer to
1229 pointer to address. Just assume such architectures handle all
1230 integer conversions in a single function. */
1231
1232 /* JimB writes:
1233
1234 I think INTEGER_TO_ADDRESS is a good idea as proposed --- but we
1235 must admonish GDB hackers to make sure its behavior matches the
1236 compiler's, whenever possible.
1237
1238 In general, I think GDB should evaluate expressions the same way
1239 the compiler does. When the user copies an expression out of
1240 their source code and hands it to a `print' command, they should
1241 get the same value the compiler would have computed. Any
1242 deviation from this rule can cause major confusion and annoyance,
1243 and needs to be justified carefully. In other words, GDB doesn't
1244 really have the freedom to do these conversions in clever and
1245 useful ways.
1246
1247 AndrewC pointed out that users aren't complaining about how GDB
1248 casts integers to pointers; they are complaining that they can't
1249 take an address from a disassembly listing and give it to `x/i'.
1250 This is certainly important.
1251
1252 Adding an architecture method like integer_to_address() certainly
1253 makes it possible for GDB to "get it right" in all circumstances
1254 --- the target has complete control over how things get done, so
1255 people can Do The Right Thing for their target without breaking
1256 anyone else. The standard doesn't specify how integers get
1257 converted to pointers; usually, the ABI doesn't either, but
1258 ABI-specific code is a more reasonable place to handle it. */
1259
1260 if (TYPE_CODE (value_type (val)) != TYPE_CODE_PTR
1261 && TYPE_CODE (value_type (val)) != TYPE_CODE_REF
1262 && gdbarch_integer_to_address_p (current_gdbarch))
1263 return gdbarch_integer_to_address (current_gdbarch, value_type (val),
1264 value_contents (val));
1265
1266 return unpack_long (value_type (val), value_contents (val));
1267 #endif
1268 }
1269 \f
1270 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
1271 as a long, or as a double, assuming the raw data is described
1272 by type TYPE. Knows how to convert different sizes of values
1273 and can convert between fixed and floating point. We don't assume
1274 any alignment for the raw data. Return value is in host byte order.
1275
1276 If you want functions and arrays to be coerced to pointers, and
1277 references to be dereferenced, call value_as_long() instead.
1278
1279 C++: It is assumed that the front-end has taken care of
1280 all matters concerning pointers to members. A pointer
1281 to member which reaches here is considered to be equivalent
1282 to an INT (or some size). After all, it is only an offset. */
1283
1284 LONGEST
1285 unpack_long (struct type *type, const gdb_byte *valaddr)
1286 {
1287 enum type_code code = TYPE_CODE (type);
1288 int len = TYPE_LENGTH (type);
1289 int nosign = TYPE_UNSIGNED (type);
1290
1291 switch (code)
1292 {
1293 case TYPE_CODE_TYPEDEF:
1294 return unpack_long (check_typedef (type), valaddr);
1295 case TYPE_CODE_ENUM:
1296 case TYPE_CODE_FLAGS:
1297 case TYPE_CODE_BOOL:
1298 case TYPE_CODE_INT:
1299 case TYPE_CODE_CHAR:
1300 case TYPE_CODE_RANGE:
1301 case TYPE_CODE_MEMBERPTR:
1302 if (nosign)
1303 return extract_unsigned_integer (valaddr, len);
1304 else
1305 return extract_signed_integer (valaddr, len);
1306
1307 case TYPE_CODE_FLT:
1308 return extract_typed_floating (valaddr, type);
1309
1310 case TYPE_CODE_DECFLOAT:
1311 /* libdecnumber has a function to convert from decimal to integer, but
1312 it doesn't work when the decimal number has a fractional part. */
1313 return decimal_to_doublest (valaddr, len);
1314
1315 case TYPE_CODE_PTR:
1316 case TYPE_CODE_REF:
1317 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
1318 whether we want this to be true eventually. */
1319 return extract_typed_address (valaddr, type);
1320
1321 default:
1322 error (_("Value can't be converted to integer."));
1323 }
1324 return 0; /* Placate lint. */
1325 }
1326
1327 /* Return a double value from the specified type and address.
1328 INVP points to an int which is set to 0 for valid value,
1329 1 for invalid value (bad float format). In either case,
1330 the returned double is OK to use. Argument is in target
1331 format, result is in host format. */
1332
1333 DOUBLEST
1334 unpack_double (struct type *type, const gdb_byte *valaddr, int *invp)
1335 {
1336 enum type_code code;
1337 int len;
1338 int nosign;
1339
1340 *invp = 0; /* Assume valid. */
1341 CHECK_TYPEDEF (type);
1342 code = TYPE_CODE (type);
1343 len = TYPE_LENGTH (type);
1344 nosign = TYPE_UNSIGNED (type);
1345 if (code == TYPE_CODE_FLT)
1346 {
1347 /* NOTE: cagney/2002-02-19: There was a test here to see if the
1348 floating-point value was valid (using the macro
1349 INVALID_FLOAT). That test/macro have been removed.
1350
1351 It turns out that only the VAX defined this macro and then
1352 only in a non-portable way. Fixing the portability problem
1353 wouldn't help since the VAX floating-point code is also badly
1354 bit-rotten. The target needs to add definitions for the
1355 methods gdbarch_float_format and gdbarch_double_format - these
1356 exactly describe the target floating-point format. The
1357 problem here is that the corresponding floatformat_vax_f and
1358 floatformat_vax_d values these methods should be set to are
1359 also not defined either. Oops!
1360
1361 Hopefully someone will add both the missing floatformat
1362 definitions and the new cases for floatformat_is_valid (). */
1363
1364 if (!floatformat_is_valid (floatformat_from_type (type), valaddr))
1365 {
1366 *invp = 1;
1367 return 0.0;
1368 }
1369
1370 return extract_typed_floating (valaddr, type);
1371 }
1372 else if (code == TYPE_CODE_DECFLOAT)
1373 return decimal_to_doublest (valaddr, len);
1374 else if (nosign)
1375 {
1376 /* Unsigned -- be sure we compensate for signed LONGEST. */
1377 return (ULONGEST) unpack_long (type, valaddr);
1378 }
1379 else
1380 {
1381 /* Signed -- we are OK with unpack_long. */
1382 return unpack_long (type, valaddr);
1383 }
1384 }
1385
1386 /* Unpack raw data (copied from debugee, target byte order) at VALADDR
1387 as a CORE_ADDR, assuming the raw data is described by type TYPE.
1388 We don't assume any alignment for the raw data. Return value is in
1389 host byte order.
1390
1391 If you want functions and arrays to be coerced to pointers, and
1392 references to be dereferenced, call value_as_address() instead.
1393
1394 C++: It is assumed that the front-end has taken care of
1395 all matters concerning pointers to members. A pointer
1396 to member which reaches here is considered to be equivalent
1397 to an INT (or some size). After all, it is only an offset. */
1398
1399 CORE_ADDR
1400 unpack_pointer (struct type *type, const gdb_byte *valaddr)
1401 {
1402 /* Assume a CORE_ADDR can fit in a LONGEST (for now). Not sure
1403 whether we want this to be true eventually. */
1404 return unpack_long (type, valaddr);
1405 }
1406
1407 \f
1408 /* Get the value of the FIELDN'th field (which must be static) of
1409 TYPE. Return NULL if the field doesn't exist or has been
1410 optimized out. */
1411
1412 struct value *
1413 value_static_field (struct type *type, int fieldno)
1414 {
1415 struct value *retval;
1416
1417 if (TYPE_FIELD_LOC_KIND (type, fieldno) == FIELD_LOC_KIND_PHYSADDR)
1418 {
1419 retval = value_at (TYPE_FIELD_TYPE (type, fieldno),
1420 TYPE_FIELD_STATIC_PHYSADDR (type, fieldno));
1421 }
1422 else
1423 {
1424 char *phys_name = TYPE_FIELD_STATIC_PHYSNAME (type, fieldno);
1425 struct symbol *sym = lookup_symbol (phys_name, 0, VAR_DOMAIN, 0);
1426 if (sym == NULL)
1427 {
1428 /* With some compilers, e.g. HP aCC, static data members are reported
1429 as non-debuggable symbols */
1430 struct minimal_symbol *msym = lookup_minimal_symbol (phys_name, NULL, NULL);
1431 if (!msym)
1432 return NULL;
1433 else
1434 {
1435 retval = value_at (TYPE_FIELD_TYPE (type, fieldno),
1436 SYMBOL_VALUE_ADDRESS (msym));
1437 }
1438 }
1439 else
1440 {
1441 /* SYM should never have a SYMBOL_CLASS which will require
1442 read_var_value to use the FRAME parameter. */
1443 if (symbol_read_needs_frame (sym))
1444 warning (_("static field's value depends on the current "
1445 "frame - bad debug info?"));
1446 retval = read_var_value (sym, NULL);
1447 }
1448 if (retval && VALUE_LVAL (retval) == lval_memory)
1449 SET_FIELD_PHYSADDR (TYPE_FIELD (type, fieldno),
1450 VALUE_ADDRESS (retval));
1451 }
1452 return retval;
1453 }
1454
1455 /* Change the enclosing type of a value object VAL to NEW_ENCL_TYPE.
1456 You have to be careful here, since the size of the data area for the value
1457 is set by the length of the enclosing type. So if NEW_ENCL_TYPE is bigger
1458 than the old enclosing type, you have to allocate more space for the data.
1459 The return value is a pointer to the new version of this value structure. */
1460
1461 struct value *
1462 value_change_enclosing_type (struct value *val, struct type *new_encl_type)
1463 {
1464 if (TYPE_LENGTH (new_encl_type) > TYPE_LENGTH (value_enclosing_type (val)))
1465 val->contents =
1466 (gdb_byte *) xrealloc (val->contents, TYPE_LENGTH (new_encl_type));
1467
1468 val->enclosing_type = new_encl_type;
1469 return val;
1470 }
1471
1472 /* Given a value ARG1 (offset by OFFSET bytes)
1473 of a struct or union type ARG_TYPE,
1474 extract and return the value of one of its (non-static) fields.
1475 FIELDNO says which field. */
1476
1477 struct value *
1478 value_primitive_field (struct value *arg1, int offset,
1479 int fieldno, struct type *arg_type)
1480 {
1481 struct value *v;
1482 struct type *type;
1483
1484 CHECK_TYPEDEF (arg_type);
1485 type = TYPE_FIELD_TYPE (arg_type, fieldno);
1486
1487 /* Handle packed fields */
1488
1489 if (TYPE_FIELD_BITSIZE (arg_type, fieldno))
1490 {
1491 v = value_from_longest (type,
1492 unpack_field_as_long (arg_type,
1493 value_contents (arg1)
1494 + offset,
1495 fieldno));
1496 v->bitpos = TYPE_FIELD_BITPOS (arg_type, fieldno) % 8;
1497 v->bitsize = TYPE_FIELD_BITSIZE (arg_type, fieldno);
1498 v->offset = value_offset (arg1) + offset
1499 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8;
1500 }
1501 else if (fieldno < TYPE_N_BASECLASSES (arg_type))
1502 {
1503 /* This field is actually a base subobject, so preserve the
1504 entire object's contents for later references to virtual
1505 bases, etc. */
1506
1507 /* Lazy register values with offsets are not supported. */
1508 if (VALUE_LVAL (arg1) == lval_register && value_lazy (arg1))
1509 value_fetch_lazy (arg1);
1510
1511 if (value_lazy (arg1))
1512 v = allocate_value_lazy (value_enclosing_type (arg1));
1513 else
1514 {
1515 v = allocate_value (value_enclosing_type (arg1));
1516 memcpy (value_contents_all_raw (v), value_contents_all_raw (arg1),
1517 TYPE_LENGTH (value_enclosing_type (arg1)));
1518 }
1519 v->type = type;
1520 v->offset = value_offset (arg1);
1521 v->embedded_offset = (offset + value_embedded_offset (arg1)
1522 + TYPE_FIELD_BITPOS (arg_type, fieldno) / 8);
1523 }
1524 else
1525 {
1526 /* Plain old data member */
1527 offset += TYPE_FIELD_BITPOS (arg_type, fieldno) / 8;
1528
1529 /* Lazy register values with offsets are not supported. */
1530 if (VALUE_LVAL (arg1) == lval_register && value_lazy (arg1))
1531 value_fetch_lazy (arg1);
1532
1533 if (value_lazy (arg1))
1534 v = allocate_value_lazy (type);
1535 else
1536 {
1537 v = allocate_value (type);
1538 memcpy (value_contents_raw (v),
1539 value_contents_raw (arg1) + offset,
1540 TYPE_LENGTH (type));
1541 }
1542 v->offset = (value_offset (arg1) + offset
1543 + value_embedded_offset (arg1));
1544 }
1545 set_value_component_location (v, arg1);
1546 VALUE_REGNUM (v) = VALUE_REGNUM (arg1);
1547 VALUE_FRAME_ID (v) = VALUE_FRAME_ID (arg1);
1548 return v;
1549 }
1550
1551 /* Given a value ARG1 of a struct or union type,
1552 extract and return the value of one of its (non-static) fields.
1553 FIELDNO says which field. */
1554
1555 struct value *
1556 value_field (struct value *arg1, int fieldno)
1557 {
1558 return value_primitive_field (arg1, 0, fieldno, value_type (arg1));
1559 }
1560
1561 /* Return a non-virtual function as a value.
1562 F is the list of member functions which contains the desired method.
1563 J is an index into F which provides the desired method.
1564
1565 We only use the symbol for its address, so be happy with either a
1566 full symbol or a minimal symbol.
1567 */
1568
1569 struct value *
1570 value_fn_field (struct value **arg1p, struct fn_field *f, int j, struct type *type,
1571 int offset)
1572 {
1573 struct value *v;
1574 struct type *ftype = TYPE_FN_FIELD_TYPE (f, j);
1575 char *physname = TYPE_FN_FIELD_PHYSNAME (f, j);
1576 struct symbol *sym;
1577 struct minimal_symbol *msym;
1578
1579 sym = lookup_symbol (physname, 0, VAR_DOMAIN, 0);
1580 if (sym != NULL)
1581 {
1582 msym = NULL;
1583 }
1584 else
1585 {
1586 gdb_assert (sym == NULL);
1587 msym = lookup_minimal_symbol (physname, NULL, NULL);
1588 if (msym == NULL)
1589 return NULL;
1590 }
1591
1592 v = allocate_value (ftype);
1593 if (sym)
1594 {
1595 VALUE_ADDRESS (v) = BLOCK_START (SYMBOL_BLOCK_VALUE (sym));
1596 }
1597 else
1598 {
1599 /* The minimal symbol might point to a function descriptor;
1600 resolve it to the actual code address instead. */
1601 struct objfile *objfile = msymbol_objfile (msym);
1602 struct gdbarch *gdbarch = get_objfile_arch (objfile);
1603
1604 VALUE_ADDRESS (v)
1605 = gdbarch_convert_from_func_ptr_addr
1606 (gdbarch, SYMBOL_VALUE_ADDRESS (msym), &current_target);
1607 }
1608
1609 if (arg1p)
1610 {
1611 if (type != value_type (*arg1p))
1612 *arg1p = value_ind (value_cast (lookup_pointer_type (type),
1613 value_addr (*arg1p)));
1614
1615 /* Move the `this' pointer according to the offset.
1616 VALUE_OFFSET (*arg1p) += offset;
1617 */
1618 }
1619
1620 return v;
1621 }
1622
1623 \f
1624 /* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at
1625 VALADDR.
1626
1627 Extracting bits depends on endianness of the machine. Compute the
1628 number of least significant bits to discard. For big endian machines,
1629 we compute the total number of bits in the anonymous object, subtract
1630 off the bit count from the MSB of the object to the MSB of the
1631 bitfield, then the size of the bitfield, which leaves the LSB discard
1632 count. For little endian machines, the discard count is simply the
1633 number of bits from the LSB of the anonymous object to the LSB of the
1634 bitfield.
1635
1636 If the field is signed, we also do sign extension. */
1637
1638 LONGEST
1639 unpack_field_as_long (struct type *type, const gdb_byte *valaddr, int fieldno)
1640 {
1641 ULONGEST val;
1642 ULONGEST valmask;
1643 int bitpos = TYPE_FIELD_BITPOS (type, fieldno);
1644 int bitsize = TYPE_FIELD_BITSIZE (type, fieldno);
1645 int lsbcount;
1646 struct type *field_type;
1647
1648 val = extract_unsigned_integer (valaddr + bitpos / 8, sizeof (val));
1649 field_type = TYPE_FIELD_TYPE (type, fieldno);
1650 CHECK_TYPEDEF (field_type);
1651
1652 /* Extract bits. See comment above. */
1653
1654 if (gdbarch_bits_big_endian (current_gdbarch))
1655 lsbcount = (sizeof val * 8 - bitpos % 8 - bitsize);
1656 else
1657 lsbcount = (bitpos % 8);
1658 val >>= lsbcount;
1659
1660 /* If the field does not entirely fill a LONGEST, then zero the sign bits.
1661 If the field is signed, and is negative, then sign extend. */
1662
1663 if ((bitsize > 0) && (bitsize < 8 * (int) sizeof (val)))
1664 {
1665 valmask = (((ULONGEST) 1) << bitsize) - 1;
1666 val &= valmask;
1667 if (!TYPE_UNSIGNED (field_type))
1668 {
1669 if (val & (valmask ^ (valmask >> 1)))
1670 {
1671 val |= ~valmask;
1672 }
1673 }
1674 }
1675 return (val);
1676 }
1677
1678 /* Modify the value of a bitfield. ADDR points to a block of memory in
1679 target byte order; the bitfield starts in the byte pointed to. FIELDVAL
1680 is the desired value of the field, in host byte order. BITPOS and BITSIZE
1681 indicate which bits (in target bit order) comprise the bitfield.
1682 Requires 0 < BITSIZE <= lbits, 0 <= BITPOS+BITSIZE <= lbits, and
1683 0 <= BITPOS, where lbits is the size of a LONGEST in bits. */
1684
1685 void
1686 modify_field (gdb_byte *addr, LONGEST fieldval, int bitpos, int bitsize)
1687 {
1688 ULONGEST oword;
1689 ULONGEST mask = (ULONGEST) -1 >> (8 * sizeof (ULONGEST) - bitsize);
1690
1691 /* If a negative fieldval fits in the field in question, chop
1692 off the sign extension bits. */
1693 if ((~fieldval & ~(mask >> 1)) == 0)
1694 fieldval &= mask;
1695
1696 /* Warn if value is too big to fit in the field in question. */
1697 if (0 != (fieldval & ~mask))
1698 {
1699 /* FIXME: would like to include fieldval in the message, but
1700 we don't have a sprintf_longest. */
1701 warning (_("Value does not fit in %d bits."), bitsize);
1702
1703 /* Truncate it, otherwise adjoining fields may be corrupted. */
1704 fieldval &= mask;
1705 }
1706
1707 oword = extract_unsigned_integer (addr, sizeof oword);
1708
1709 /* Shifting for bit field depends on endianness of the target machine. */
1710 if (gdbarch_bits_big_endian (current_gdbarch))
1711 bitpos = sizeof (oword) * 8 - bitpos - bitsize;
1712
1713 oword &= ~(mask << bitpos);
1714 oword |= fieldval << bitpos;
1715
1716 store_unsigned_integer (addr, sizeof oword, oword);
1717 }
1718 \f
1719 /* Pack NUM into BUF using a target format of TYPE. */
1720
1721 void
1722 pack_long (gdb_byte *buf, struct type *type, LONGEST num)
1723 {
1724 int len;
1725
1726 type = check_typedef (type);
1727 len = TYPE_LENGTH (type);
1728
1729 switch (TYPE_CODE (type))
1730 {
1731 case TYPE_CODE_INT:
1732 case TYPE_CODE_CHAR:
1733 case TYPE_CODE_ENUM:
1734 case TYPE_CODE_FLAGS:
1735 case TYPE_CODE_BOOL:
1736 case TYPE_CODE_RANGE:
1737 case TYPE_CODE_MEMBERPTR:
1738 store_signed_integer (buf, len, num);
1739 break;
1740
1741 case TYPE_CODE_REF:
1742 case TYPE_CODE_PTR:
1743 store_typed_address (buf, type, (CORE_ADDR) num);
1744 break;
1745
1746 default:
1747 error (_("Unexpected type (%d) encountered for integer constant."),
1748 TYPE_CODE (type));
1749 }
1750 }
1751
1752
1753 /* Convert C numbers into newly allocated values. */
1754
1755 struct value *
1756 value_from_longest (struct type *type, LONGEST num)
1757 {
1758 struct value *val = allocate_value (type);
1759
1760 pack_long (value_contents_raw (val), type, num);
1761
1762 return val;
1763 }
1764
1765
1766 /* Create a value representing a pointer of type TYPE to the address
1767 ADDR. */
1768 struct value *
1769 value_from_pointer (struct type *type, CORE_ADDR addr)
1770 {
1771 struct value *val = allocate_value (type);
1772 store_typed_address (value_contents_raw (val), type, addr);
1773 return val;
1774 }
1775
1776
1777 /* Create a value for a string constant to be stored locally
1778 (not in the inferior's memory space, but in GDB memory).
1779 This is analogous to value_from_longest, which also does not
1780 use inferior memory. String shall NOT contain embedded nulls. */
1781
1782 struct value *
1783 value_from_string (char *ptr)
1784 {
1785 struct value *val;
1786 int len = strlen (ptr);
1787 int lowbound = current_language->string_lower_bound;
1788 struct type *string_char_type;
1789 struct type *rangetype;
1790 struct type *stringtype;
1791
1792 rangetype = create_range_type ((struct type *) NULL,
1793 builtin_type_int32,
1794 lowbound, len + lowbound - 1);
1795 string_char_type = language_string_char_type (current_language,
1796 current_gdbarch);
1797 stringtype = create_array_type ((struct type *) NULL,
1798 string_char_type,
1799 rangetype);
1800 val = allocate_value (stringtype);
1801 memcpy (value_contents_raw (val), ptr, len);
1802 return val;
1803 }
1804
1805 /* Create a value of type TYPE whose contents come from VALADDR, if it
1806 is non-null, and whose memory address (in the inferior) is
1807 ADDRESS. */
1808
1809 struct value *
1810 value_from_contents_and_address (struct type *type,
1811 const gdb_byte *valaddr,
1812 CORE_ADDR address)
1813 {
1814 struct value *v = allocate_value (type);
1815 if (valaddr == NULL)
1816 set_value_lazy (v, 1);
1817 else
1818 memcpy (value_contents_raw (v), valaddr, TYPE_LENGTH (type));
1819 VALUE_ADDRESS (v) = address;
1820 VALUE_LVAL (v) = lval_memory;
1821 return v;
1822 }
1823
1824 struct value *
1825 value_from_double (struct type *type, DOUBLEST num)
1826 {
1827 struct value *val = allocate_value (type);
1828 struct type *base_type = check_typedef (type);
1829 enum type_code code = TYPE_CODE (base_type);
1830 int len = TYPE_LENGTH (base_type);
1831
1832 if (code == TYPE_CODE_FLT)
1833 {
1834 store_typed_floating (value_contents_raw (val), base_type, num);
1835 }
1836 else
1837 error (_("Unexpected type encountered for floating constant."));
1838
1839 return val;
1840 }
1841
1842 struct value *
1843 value_from_decfloat (struct type *type, const gdb_byte *dec)
1844 {
1845 struct value *val = allocate_value (type);
1846
1847 memcpy (value_contents_raw (val), dec, TYPE_LENGTH (type));
1848
1849 return val;
1850 }
1851
1852 struct value *
1853 coerce_ref (struct value *arg)
1854 {
1855 struct type *value_type_arg_tmp = check_typedef (value_type (arg));
1856 if (TYPE_CODE (value_type_arg_tmp) == TYPE_CODE_REF)
1857 arg = value_at_lazy (TYPE_TARGET_TYPE (value_type_arg_tmp),
1858 unpack_pointer (value_type (arg),
1859 value_contents (arg)));
1860 return arg;
1861 }
1862
1863 struct value *
1864 coerce_array (struct value *arg)
1865 {
1866 struct type *type;
1867
1868 arg = coerce_ref (arg);
1869 type = check_typedef (value_type (arg));
1870
1871 switch (TYPE_CODE (type))
1872 {
1873 case TYPE_CODE_ARRAY:
1874 if (current_language->c_style_arrays)
1875 arg = value_coerce_array (arg);
1876 break;
1877 case TYPE_CODE_FUNC:
1878 arg = value_coerce_function (arg);
1879 break;
1880 }
1881 return arg;
1882 }
1883 \f
1884
1885 /* Return true if the function returning the specified type is using
1886 the convention of returning structures in memory (passing in the
1887 address as a hidden first parameter). */
1888
1889 int
1890 using_struct_return (struct type *func_type, struct type *value_type)
1891 {
1892 enum type_code code = TYPE_CODE (value_type);
1893
1894 if (code == TYPE_CODE_ERROR)
1895 error (_("Function return type unknown."));
1896
1897 if (code == TYPE_CODE_VOID)
1898 /* A void return value is never in memory. See also corresponding
1899 code in "print_return_value". */
1900 return 0;
1901
1902 /* Probe the architecture for the return-value convention. */
1903 return (gdbarch_return_value (current_gdbarch, func_type, value_type,
1904 NULL, NULL, NULL)
1905 != RETURN_VALUE_REGISTER_CONVENTION);
1906 }
1907
1908 /* Set the initialized field in a value struct. */
1909
1910 void
1911 set_value_initialized (struct value *val, int status)
1912 {
1913 val->initialized = status;
1914 }
1915
1916 /* Return the initialized field in a value struct. */
1917
1918 int
1919 value_initialized (struct value *val)
1920 {
1921 return val->initialized;
1922 }
1923
1924 void
1925 _initialize_values (void)
1926 {
1927 add_cmd ("convenience", no_class, show_convenience, _("\
1928 Debugger convenience (\"$foo\") variables.\n\
1929 These variables are created when you assign them values;\n\
1930 thus, \"print $foo=1\" gives \"$foo\" the value 1. Values may be any type.\n\
1931 \n\
1932 A few convenience variables are given values automatically:\n\
1933 \"$_\"holds the last address examined with \"x\" or \"info lines\",\n\
1934 \"$__\" holds the contents of the last address examined with \"x\"."),
1935 &showlist);
1936
1937 add_cmd ("values", no_class, show_values,
1938 _("Elements of value history around item number IDX (or last ten)."),
1939 &showlist);
1940
1941 add_com ("init-if-undefined", class_vars, init_if_undefined_command, _("\
1942 Initialize a convenience variable if necessary.\n\
1943 init-if-undefined VARIABLE = EXPRESSION\n\
1944 Set an internal VARIABLE to the result of the EXPRESSION if it does not\n\
1945 exist or does not contain a value. The EXPRESSION is not evaluated if the\n\
1946 VARIABLE is already initialized."));
1947 }
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