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[/] [openrisc/] [trunk/] [gnu-old/] [gdb-6.8/] [gdb/] [gnu-v3-abi.c] - Blame information for rev 866

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1 24 jeremybenn
/* Abstraction of GNU v3 abi.
2
   Contributed by Jim Blandy <jimb@redhat.com>
3
 
4
   Copyright (C) 2001, 2002, 2003, 2005, 2006, 2007, 2008
5
   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 "value.h"
24
#include "cp-abi.h"
25
#include "cp-support.h"
26
#include "demangle.h"
27
#include "objfiles.h"
28
#include "valprint.h"
29
 
30
#include "gdb_assert.h"
31
#include "gdb_string.h"
32
 
33
static struct cp_abi_ops gnu_v3_abi_ops;
34
 
35
static int
36
gnuv3_is_vtable_name (const char *name)
37
{
38
  return strncmp (name, "_ZTV", 4) == 0;
39
}
40
 
41
static int
42
gnuv3_is_operator_name (const char *name)
43
{
44
  return strncmp (name, "operator", 8) == 0;
45
}
46
 
47
 
48
/* To help us find the components of a vtable, we build ourselves a
49
   GDB type object representing the vtable structure.  Following the
50
   V3 ABI, it goes something like this:
51
 
52
   struct gdb_gnu_v3_abi_vtable {
53
 
54
     / * An array of virtual call and virtual base offsets.  The real
55
         length of this array depends on the class hierarchy; we use
56
         negative subscripts to access the elements.  Yucky, but
57
         better than the alternatives.  * /
58
     ptrdiff_t vcall_and_vbase_offsets[0];
59
 
60
     / * The offset from a virtual pointer referring to this table
61
         to the top of the complete object.  * /
62
     ptrdiff_t offset_to_top;
63
 
64
     / * The type_info pointer for this class.  This is really a
65
         std::type_info *, but GDB doesn't really look at the
66
         type_info object itself, so we don't bother to get the type
67
         exactly right.  * /
68
     void *type_info;
69
 
70
     / * Virtual table pointers in objects point here.  * /
71
 
72
     / * Virtual function pointers.  Like the vcall/vbase array, the
73
         real length of this table depends on the class hierarchy.  * /
74
     void (*virtual_functions[0]) ();
75
 
76
   };
77
 
78
   The catch, of course, is that the exact layout of this table
79
   depends on the ABI --- word size, endianness, alignment, etc.  So
80
   the GDB type object is actually a per-architecture kind of thing.
81
 
82
   vtable_type_gdbarch_data is a gdbarch per-architecture data pointer
83
   which refers to the struct type * for this structure, laid out
84
   appropriately for the architecture.  */
85
static struct gdbarch_data *vtable_type_gdbarch_data;
86
 
87
 
88
/* Human-readable names for the numbers of the fields above.  */
89
enum {
90
  vtable_field_vcall_and_vbase_offsets,
91
  vtable_field_offset_to_top,
92
  vtable_field_type_info,
93
  vtable_field_virtual_functions
94
};
95
 
96
 
97
/* Return a GDB type representing `struct gdb_gnu_v3_abi_vtable',
98
   described above, laid out appropriately for ARCH.
99
 
100
   We use this function as the gdbarch per-architecture data
101
   initialization function.  */
102
static void *
103
build_gdb_vtable_type (struct gdbarch *arch)
104
{
105
  struct type *t;
106
  struct field *field_list, *field;
107
  int offset;
108
 
109
  struct type *void_ptr_type
110
    = lookup_pointer_type (builtin_type_void);
111
  struct type *ptr_to_void_fn_type
112
    = lookup_pointer_type (lookup_function_type (builtin_type_void));
113
 
114
  /* ARCH can't give us the true ptrdiff_t type, so we guess.  */
115
  struct type *ptrdiff_type
116
    = init_type (TYPE_CODE_INT,
117
                 gdbarch_ptr_bit (arch) / TARGET_CHAR_BIT, 0,
118
                 "ptrdiff_t", 0);
119
 
120
  /* We assume no padding is necessary, since GDB doesn't know
121
     anything about alignment at the moment.  If this assumption bites
122
     us, we should add a gdbarch method which, given a type, returns
123
     the alignment that type requires, and then use that here.  */
124
 
125
  /* Build the field list.  */
126
  field_list = xmalloc (sizeof (struct field [4]));
127
  memset (field_list, 0, sizeof (struct field [4]));
128
  field = &field_list[0];
129
  offset = 0;
130
 
131
  /* ptrdiff_t vcall_and_vbase_offsets[0]; */
132
  FIELD_NAME (*field) = "vcall_and_vbase_offsets";
133
  FIELD_TYPE (*field)
134
    = create_array_type (0, ptrdiff_type,
135
                         create_range_type (0, builtin_type_int, 0, -1));
136
  FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
137
  offset += TYPE_LENGTH (FIELD_TYPE (*field));
138
  field++;
139
 
140
  /* ptrdiff_t offset_to_top; */
141
  FIELD_NAME (*field) = "offset_to_top";
142
  FIELD_TYPE (*field) = ptrdiff_type;
143
  FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
144
  offset += TYPE_LENGTH (FIELD_TYPE (*field));
145
  field++;
146
 
147
  /* void *type_info; */
148
  FIELD_NAME (*field) = "type_info";
149
  FIELD_TYPE (*field) = void_ptr_type;
150
  FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
151
  offset += TYPE_LENGTH (FIELD_TYPE (*field));
152
  field++;
153
 
154
  /* void (*virtual_functions[0]) (); */
155
  FIELD_NAME (*field) = "virtual_functions";
156
  FIELD_TYPE (*field)
157
    = create_array_type (0, ptr_to_void_fn_type,
158
                         create_range_type (0, builtin_type_int, 0, -1));
159
  FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
160
  offset += TYPE_LENGTH (FIELD_TYPE (*field));
161
  field++;
162
 
163
  /* We assumed in the allocation above that there were four fields.  */
164
  gdb_assert (field == (field_list + 4));
165
 
166
  t = init_type (TYPE_CODE_STRUCT, offset, 0, 0, 0);
167
  TYPE_NFIELDS (t) = field - field_list;
168
  TYPE_FIELDS (t) = field_list;
169
  TYPE_TAG_NAME (t) = "gdb_gnu_v3_abi_vtable";
170
 
171
  return t;
172
}
173
 
174
 
175
/* Return the offset from the start of the imaginary `struct
176
   gdb_gnu_v3_abi_vtable' object to the vtable's "address point"
177
   (i.e., where objects' virtual table pointers point).  */
178
static int
179
vtable_address_point_offset (void)
180
{
181
  struct type *vtable_type = gdbarch_data (current_gdbarch,
182
                                           vtable_type_gdbarch_data);
183
 
184
  return (TYPE_FIELD_BITPOS (vtable_type, vtable_field_virtual_functions)
185
          / TARGET_CHAR_BIT);
186
}
187
 
188
 
189
static struct type *
190
gnuv3_rtti_type (struct value *value,
191
                 int *full_p, int *top_p, int *using_enc_p)
192
{
193
  struct type *vtable_type = gdbarch_data (current_gdbarch,
194
                                           vtable_type_gdbarch_data);
195
  struct type *values_type = check_typedef (value_type (value));
196
  CORE_ADDR vtable_address;
197
  struct value *vtable;
198
  struct minimal_symbol *vtable_symbol;
199
  const char *vtable_symbol_name;
200
  const char *class_name;
201
  struct type *run_time_type;
202
  struct type *base_type;
203
  LONGEST offset_to_top;
204
  struct type *values_type_vptr_basetype;
205
  int values_type_vptr_fieldno;
206
 
207
  /* We only have RTTI for class objects.  */
208
  if (TYPE_CODE (values_type) != TYPE_CODE_CLASS)
209
    return NULL;
210
 
211
  /* If we can't find the virtual table pointer for values_type, we
212
     can't find the RTTI.  */
213
  values_type_vptr_fieldno = get_vptr_fieldno (values_type,
214
                                               &values_type_vptr_basetype);
215
  if (values_type_vptr_fieldno == -1)
216
    return NULL;
217
 
218
  if (using_enc_p)
219
    *using_enc_p = 0;
220
 
221
  /* Fetch VALUE's virtual table pointer, and tweak it to point at
222
     an instance of our imaginary gdb_gnu_v3_abi_vtable structure.  */
223
  base_type = check_typedef (values_type_vptr_basetype);
224
  if (values_type != base_type)
225
    {
226
      value = value_cast (base_type, value);
227
      if (using_enc_p)
228
        *using_enc_p = 1;
229
    }
230
  vtable_address
231
    = value_as_address (value_field (value, values_type_vptr_fieldno));
232
  vtable = value_at_lazy (vtable_type,
233
                          vtable_address - vtable_address_point_offset ());
234
 
235
  /* Find the linker symbol for this vtable.  */
236
  vtable_symbol
237
    = lookup_minimal_symbol_by_pc (VALUE_ADDRESS (vtable)
238
                                   + value_offset (vtable)
239
                                   + value_embedded_offset (vtable));
240
  if (! vtable_symbol)
241
    return NULL;
242
 
243
  /* The symbol's demangled name should be something like "vtable for
244
     CLASS", where CLASS is the name of the run-time type of VALUE.
245
     If we didn't like this approach, we could instead look in the
246
     type_info object itself to get the class name.  But this way
247
     should work just as well, and doesn't read target memory.  */
248
  vtable_symbol_name = SYMBOL_DEMANGLED_NAME (vtable_symbol);
249
  if (vtable_symbol_name == NULL
250
      || strncmp (vtable_symbol_name, "vtable for ", 11))
251
    {
252
      warning (_("can't find linker symbol for virtual table for `%s' value"),
253
               TYPE_NAME (values_type));
254
      if (vtable_symbol_name)
255
        warning (_("  found `%s' instead"), vtable_symbol_name);
256
      return NULL;
257
    }
258
  class_name = vtable_symbol_name + 11;
259
 
260
  /* Try to look up the class name as a type name.  */
261
  /* FIXME: chastain/2003-11-26: block=NULL is bogus.  See pr gdb/1465. */
262
  run_time_type = cp_lookup_rtti_type (class_name, NULL);
263
  if (run_time_type == NULL)
264
    return NULL;
265
 
266
  /* Get the offset from VALUE to the top of the complete object.
267
     NOTE: this is the reverse of the meaning of *TOP_P.  */
268
  offset_to_top
269
    = value_as_long (value_field (vtable, vtable_field_offset_to_top));
270
 
271
  if (full_p)
272
    *full_p = (- offset_to_top == value_embedded_offset (value)
273
               && (TYPE_LENGTH (value_enclosing_type (value))
274
                   >= TYPE_LENGTH (run_time_type)));
275
  if (top_p)
276
    *top_p = - offset_to_top;
277
 
278
  return run_time_type;
279
}
280
 
281
/* Find the vtable for CONTAINER and return a value of the correct
282
   vtable type for this architecture.  */
283
 
284
static struct value *
285
gnuv3_get_vtable (struct value *container)
286
{
287
  struct type *vtable_type = gdbarch_data (current_gdbarch,
288
                                           vtable_type_gdbarch_data);
289
  struct type *vtable_pointer_type;
290
  struct value *vtable_pointer;
291
  CORE_ADDR vtable_pointer_address, vtable_address;
292
 
293
  /* We do not consult the debug information to find the virtual table.
294
     The ABI specifies that it is always at offset zero in any class,
295
     and debug information may not represent it.  We won't issue an
296
     error if there's a class with virtual functions but no virtual table
297
     pointer, but something's already gone seriously wrong if that
298
     happens.
299
 
300
     We avoid using value_contents on principle, because the object might
301
     be large.  */
302
 
303
  /* Find the type "pointer to virtual table".  */
304
  vtable_pointer_type = lookup_pointer_type (vtable_type);
305
 
306
  /* Load it from the start of the class.  */
307
  vtable_pointer_address = value_as_address (value_addr (container));
308
  vtable_pointer = value_at (vtable_pointer_type, vtable_pointer_address);
309
  vtable_address = value_as_address (vtable_pointer);
310
 
311
  /* Correct it to point at the start of the virtual table, rather
312
     than the address point.  */
313
  return value_at_lazy (vtable_type,
314
                        vtable_address - vtable_address_point_offset ());
315
}
316
 
317
/* Return a function pointer for CONTAINER's VTABLE_INDEX'th virtual
318
   function, of type FNTYPE.  */
319
 
320
static struct value *
321
gnuv3_get_virtual_fn (struct value *container, struct type *fntype,
322
                      int vtable_index)
323
{
324
  struct value *vtable = gnuv3_get_vtable (container);
325
  struct value *vfn;
326
 
327
  /* Fetch the appropriate function pointer from the vtable.  */
328
  vfn = value_subscript (value_field (vtable, vtable_field_virtual_functions),
329
                         value_from_longest (builtin_type_int, vtable_index));
330
 
331
  /* If this architecture uses function descriptors directly in the vtable,
332
     then the address of the vtable entry is actually a "function pointer"
333
     (i.e. points to the descriptor).  We don't need to scale the index
334
     by the size of a function descriptor; GCC does that before outputing
335
     debug information.  */
336
  if (gdbarch_vtable_function_descriptors (current_gdbarch))
337
    vfn = value_addr (vfn);
338
 
339
  /* Cast the function pointer to the appropriate type.  */
340
  vfn = value_cast (lookup_pointer_type (fntype), vfn);
341
 
342
  return vfn;
343
}
344
 
345
/* GNU v3 implementation of value_virtual_fn_field.  See cp-abi.h
346
   for a description of the arguments.  */
347
 
348
static struct value *
349
gnuv3_virtual_fn_field (struct value **value_p,
350
                        struct fn_field *f, int j,
351
                        struct type *vfn_base, int offset)
352
{
353
  struct type *values_type = check_typedef (value_type (*value_p));
354
 
355
  /* Some simple sanity checks.  */
356
  if (TYPE_CODE (values_type) != TYPE_CODE_CLASS)
357
    error (_("Only classes can have virtual functions."));
358
 
359
  /* Cast our value to the base class which defines this virtual
360
     function.  This takes care of any necessary `this'
361
     adjustments.  */
362
  if (vfn_base != values_type)
363
    *value_p = value_cast (vfn_base, *value_p);
364
 
365
  return gnuv3_get_virtual_fn (*value_p, TYPE_FN_FIELD_TYPE (f, j),
366
                               TYPE_FN_FIELD_VOFFSET (f, j));
367
}
368
 
369
/* Compute the offset of the baseclass which is
370
   the INDEXth baseclass of class TYPE,
371
   for value at VALADDR (in host) at ADDRESS (in target).
372
   The result is the offset of the baseclass value relative
373
   to (the address of)(ARG) + OFFSET.
374
 
375
   -1 is returned on error. */
376
static int
377
gnuv3_baseclass_offset (struct type *type, int index, const bfd_byte *valaddr,
378
                        CORE_ADDR address)
379
{
380
  struct type *vtable_type = gdbarch_data (current_gdbarch,
381
                                           vtable_type_gdbarch_data);
382
  struct value *vtable;
383
  struct type *vbasetype;
384
  struct value *offset_val, *vbase_array;
385
  CORE_ADDR vtable_address;
386
  long int cur_base_offset, base_offset;
387
  int vbasetype_vptr_fieldno;
388
 
389
  /* If it isn't a virtual base, this is easy.  The offset is in the
390
     type definition.  */
391
  if (!BASETYPE_VIA_VIRTUAL (type, index))
392
    return TYPE_BASECLASS_BITPOS (type, index) / 8;
393
 
394
  /* To access a virtual base, we need to use the vbase offset stored in
395
     our vtable.  Recent GCC versions provide this information.  If it isn't
396
     available, we could get what we needed from RTTI, or from drawing the
397
     complete inheritance graph based on the debug info.  Neither is
398
     worthwhile.  */
399
  cur_base_offset = TYPE_BASECLASS_BITPOS (type, index) / 8;
400
  if (cur_base_offset >= - vtable_address_point_offset ())
401
    error (_("Expected a negative vbase offset (old compiler?)"));
402
 
403
  cur_base_offset = cur_base_offset + vtable_address_point_offset ();
404
  if ((- cur_base_offset) % TYPE_LENGTH (builtin_type_void_data_ptr) != 0)
405
    error (_("Misaligned vbase offset."));
406
  cur_base_offset = cur_base_offset
407
    / ((int) TYPE_LENGTH (builtin_type_void_data_ptr));
408
 
409
  /* We're now looking for the cur_base_offset'th entry (negative index)
410
     in the vcall_and_vbase_offsets array.  We used to cast the object to
411
     its TYPE_VPTR_BASETYPE, and reference the vtable as TYPE_VPTR_FIELDNO;
412
     however, that cast can not be done without calling baseclass_offset again
413
     if the TYPE_VPTR_BASETYPE is a virtual base class, as described in the
414
     v3 C++ ABI Section 2.4.I.2.b.  Fortunately the ABI guarantees that the
415
     vtable pointer will be located at the beginning of the object, so we can
416
     bypass the casting.  Verify that the TYPE_VPTR_FIELDNO is in fact at the
417
     start of whichever baseclass it resides in, as a sanity measure - iff
418
     we have debugging information for that baseclass.  */
419
 
420
  vbasetype = TYPE_VPTR_BASETYPE (type);
421
  vbasetype_vptr_fieldno = get_vptr_fieldno (vbasetype, NULL);
422
 
423
  if (vbasetype_vptr_fieldno >= 0
424
      && TYPE_FIELD_BITPOS (vbasetype, vbasetype_vptr_fieldno) != 0)
425
    error (_("Illegal vptr offset in class %s"),
426
           TYPE_NAME (vbasetype) ? TYPE_NAME (vbasetype) : "<unknown>");
427
 
428
  vtable_address = value_as_address (value_at_lazy (builtin_type_void_data_ptr,
429
                                                    address));
430
  vtable = value_at_lazy (vtable_type,
431
                          vtable_address - vtable_address_point_offset ());
432
  offset_val = value_from_longest(builtin_type_int, cur_base_offset);
433
  vbase_array = value_field (vtable, vtable_field_vcall_and_vbase_offsets);
434
  base_offset = value_as_long (value_subscript (vbase_array, offset_val));
435
  return base_offset;
436
}
437
 
438
/* Locate a virtual method in DOMAIN or its non-virtual base classes
439
   which has virtual table index VOFFSET.  The method has an associated
440
   "this" adjustment of ADJUSTMENT bytes.  */
441
 
442
const char *
443
gnuv3_find_method_in (struct type *domain, CORE_ADDR voffset,
444
                      LONGEST adjustment)
445
{
446
  int i;
447
  const char *physname;
448
 
449
  /* Search this class first.  */
450
  physname = NULL;
451
  if (adjustment == 0)
452
    {
453
      int len;
454
 
455
      len = TYPE_NFN_FIELDS (domain);
456
      for (i = 0; i < len; i++)
457
        {
458
          int len2, j;
459
          struct fn_field *f;
460
 
461
          f = TYPE_FN_FIELDLIST1 (domain, i);
462
          len2 = TYPE_FN_FIELDLIST_LENGTH (domain, i);
463
 
464
          check_stub_method_group (domain, i);
465
          for (j = 0; j < len2; j++)
466
            if (TYPE_FN_FIELD_VOFFSET (f, j) == voffset)
467
              return TYPE_FN_FIELD_PHYSNAME (f, j);
468
        }
469
    }
470
 
471
  /* Next search non-virtual bases.  If it's in a virtual base,
472
     we're out of luck.  */
473
  for (i = 0; i < TYPE_N_BASECLASSES (domain); i++)
474
    {
475
      int pos;
476
      struct type *basetype;
477
 
478
      if (BASETYPE_VIA_VIRTUAL (domain, i))
479
        continue;
480
 
481
      pos = TYPE_BASECLASS_BITPOS (domain, i) / 8;
482
      basetype = TYPE_FIELD_TYPE (domain, i);
483
      /* Recurse with a modified adjustment.  We don't need to adjust
484
         voffset.  */
485
      if (adjustment >= pos && adjustment < pos + TYPE_LENGTH (basetype))
486
        return gnuv3_find_method_in (basetype, voffset, adjustment - pos);
487
    }
488
 
489
  return NULL;
490
}
491
 
492
/* GNU v3 implementation of cplus_print_method_ptr.  */
493
 
494
static void
495
gnuv3_print_method_ptr (const gdb_byte *contents,
496
                        struct type *type,
497
                        struct ui_file *stream)
498
{
499
  CORE_ADDR ptr_value;
500
  LONGEST adjustment;
501
  struct type *domain;
502
  int vbit;
503
 
504
  domain = TYPE_DOMAIN_TYPE (type);
505
 
506
  /* Extract the pointer to member.  */
507
  ptr_value = extract_typed_address (contents, builtin_type_void_func_ptr);
508
  contents += TYPE_LENGTH (builtin_type_void_func_ptr);
509
  adjustment = extract_signed_integer (contents,
510
                                       TYPE_LENGTH (builtin_type_long));
511
 
512
  if (!gdbarch_vbit_in_delta (current_gdbarch))
513
    {
514
      vbit = ptr_value & 1;
515
      ptr_value = ptr_value ^ vbit;
516
    }
517
  else
518
    {
519
      vbit = adjustment & 1;
520
      adjustment = adjustment >> 1;
521
    }
522
 
523
  /* Check for NULL.  */
524
  if (ptr_value == 0 && vbit == 0)
525
    {
526
      fprintf_filtered (stream, "NULL");
527
      return;
528
    }
529
 
530
  /* Search for a virtual method.  */
531
  if (vbit)
532
    {
533
      CORE_ADDR voffset;
534
      const char *physname;
535
 
536
      /* It's a virtual table offset, maybe in this class.  Search
537
         for a field with the correct vtable offset.  First convert it
538
         to an index, as used in TYPE_FN_FIELD_VOFFSET.  */
539
      voffset = ptr_value / TYPE_LENGTH (builtin_type_long);
540
 
541
      physname = gnuv3_find_method_in (domain, voffset, adjustment);
542
 
543
      /* If we found a method, print that.  We don't bother to disambiguate
544
         possible paths to the method based on the adjustment.  */
545
      if (physname)
546
        {
547
          char *demangled_name = cplus_demangle (physname,
548
                                                 DMGL_ANSI | DMGL_PARAMS);
549
          if (demangled_name != NULL)
550
            {
551
              fprintf_filtered (stream, "&virtual ");
552
              fputs_filtered (demangled_name, stream);
553
              xfree (demangled_name);
554
              return;
555
            }
556
        }
557
    }
558
 
559
  /* We didn't find it; print the raw data.  */
560
  if (vbit)
561
    {
562
      fprintf_filtered (stream, "&virtual table offset ");
563
      print_longest (stream, 'd', 1, ptr_value);
564
    }
565
  else
566
    print_address_demangle (ptr_value, stream, demangle);
567
 
568
  if (adjustment)
569
    {
570
      fprintf_filtered (stream, ", this adjustment ");
571
      print_longest (stream, 'd', 1, adjustment);
572
    }
573
}
574
 
575
/* GNU v3 implementation of cplus_method_ptr_size.  */
576
 
577
static int
578
gnuv3_method_ptr_size (void)
579
{
580
  return 2 * TYPE_LENGTH (builtin_type_void_data_ptr);
581
}
582
 
583
/* GNU v3 implementation of cplus_make_method_ptr.  */
584
 
585
static void
586
gnuv3_make_method_ptr (gdb_byte *contents, CORE_ADDR value, int is_virtual)
587
{
588
  int size = TYPE_LENGTH (builtin_type_void_data_ptr);
589
 
590
  /* FIXME drow/2006-12-24: The adjustment of "this" is currently
591
     always zero, since the method pointer is of the correct type.
592
     But if the method pointer came from a base class, this is
593
     incorrect - it should be the offset to the base.  The best
594
     fix might be to create the pointer to member pointing at the
595
     base class and cast it to the derived class, but that requires
596
     support for adjusting pointers to members when casting them -
597
     not currently supported by GDB.  */
598
 
599
  if (!gdbarch_vbit_in_delta (current_gdbarch))
600
    {
601
      store_unsigned_integer (contents, size, value | is_virtual);
602
      store_unsigned_integer (contents + size, size, 0);
603
    }
604
  else
605
    {
606
      store_unsigned_integer (contents, size, value);
607
      store_unsigned_integer (contents + size, size, is_virtual);
608
    }
609
}
610
 
611
/* GNU v3 implementation of cplus_method_ptr_to_value.  */
612
 
613
static struct value *
614
gnuv3_method_ptr_to_value (struct value **this_p, struct value *method_ptr)
615
{
616
  const gdb_byte *contents = value_contents (method_ptr);
617
  CORE_ADDR ptr_value;
618
  struct type *final_type, *method_type;
619
  LONGEST adjustment;
620
  struct value *adjval;
621
  int vbit;
622
 
623
  final_type = TYPE_DOMAIN_TYPE (check_typedef (value_type (method_ptr)));
624
  final_type = lookup_pointer_type (final_type);
625
 
626
  method_type = TYPE_TARGET_TYPE (check_typedef (value_type (method_ptr)));
627
 
628
  ptr_value = extract_typed_address (contents, builtin_type_void_func_ptr);
629
  contents += TYPE_LENGTH (builtin_type_void_func_ptr);
630
  adjustment = extract_signed_integer (contents,
631
                                       TYPE_LENGTH (builtin_type_long));
632
 
633
  if (!gdbarch_vbit_in_delta (current_gdbarch))
634
    {
635
      vbit = ptr_value & 1;
636
      ptr_value = ptr_value ^ vbit;
637
    }
638
  else
639
    {
640
      vbit = adjustment & 1;
641
      adjustment = adjustment >> 1;
642
    }
643
 
644
  /* First convert THIS to match the containing type of the pointer to
645
     member.  This cast may adjust the value of THIS.  */
646
  *this_p = value_cast (final_type, *this_p);
647
 
648
  /* Then apply whatever adjustment is necessary.  This creates a somewhat
649
     strange pointer: it claims to have type FINAL_TYPE, but in fact it
650
     might not be a valid FINAL_TYPE.  For instance, it might be a
651
     base class of FINAL_TYPE.  And if it's not the primary base class,
652
     then printing it out as a FINAL_TYPE object would produce some pretty
653
     garbage.
654
 
655
     But we don't really know the type of the first argument in
656
     METHOD_TYPE either, which is why this happens.  We can't
657
     dereference this later as a FINAL_TYPE, but once we arrive in the
658
     called method we'll have debugging information for the type of
659
     "this" - and that'll match the value we produce here.
660
 
661
     You can provoke this case by casting a Base::* to a Derived::*, for
662
     instance.  */
663
  *this_p = value_cast (builtin_type_void_data_ptr, *this_p);
664
  adjval = value_from_longest (builtin_type_long, adjustment);
665
  *this_p = value_add (*this_p, adjval);
666
  *this_p = value_cast (final_type, *this_p);
667
 
668
  if (vbit)
669
    {
670
      LONGEST voffset = ptr_value / TYPE_LENGTH (builtin_type_long);
671
      return gnuv3_get_virtual_fn (value_ind (*this_p), method_type, voffset);
672
    }
673
  else
674
    return value_from_pointer (lookup_pointer_type (method_type), ptr_value);
675
}
676
 
677
/* Determine if we are currently in a C++ thunk.  If so, get the address
678
   of the routine we are thunking to and continue to there instead.  */
679
 
680
static CORE_ADDR
681
gnuv3_skip_trampoline (struct frame_info *frame, CORE_ADDR stop_pc)
682
{
683
  CORE_ADDR real_stop_pc, method_stop_pc;
684
  struct gdbarch *gdbarch = get_frame_arch (frame);
685
  struct minimal_symbol *thunk_sym, *fn_sym;
686
  struct obj_section *section;
687
  char *thunk_name, *fn_name;
688
 
689
  real_stop_pc = gdbarch_skip_trampoline_code (gdbarch, frame, stop_pc);
690
  if (real_stop_pc == 0)
691
    real_stop_pc = stop_pc;
692
 
693
  /* Find the linker symbol for this potential thunk.  */
694
  thunk_sym = lookup_minimal_symbol_by_pc (real_stop_pc);
695
  section = find_pc_section (real_stop_pc);
696
  if (thunk_sym == NULL || section == NULL)
697
    return 0;
698
 
699
  /* The symbol's demangled name should be something like "virtual
700
     thunk to FUNCTION", where FUNCTION is the name of the function
701
     being thunked to.  */
702
  thunk_name = SYMBOL_DEMANGLED_NAME (thunk_sym);
703
  if (thunk_name == NULL || strstr (thunk_name, " thunk to ") == NULL)
704
    return 0;
705
 
706
  fn_name = strstr (thunk_name, " thunk to ") + strlen (" thunk to ");
707
  fn_sym = lookup_minimal_symbol (fn_name, NULL, section->objfile);
708
  if (fn_sym == NULL)
709
    return 0;
710
 
711
  method_stop_pc = SYMBOL_VALUE_ADDRESS (fn_sym);
712
  real_stop_pc = gdbarch_skip_trampoline_code
713
                   (gdbarch, frame, method_stop_pc);
714
  if (real_stop_pc == 0)
715
    real_stop_pc = method_stop_pc;
716
 
717
  return real_stop_pc;
718
}
719
 
720
/* Return nonzero if a type should be passed by reference.
721
 
722
   The rule in the v3 ABI document comes from section 3.1.1.  If the
723
   type has a non-trivial copy constructor or destructor, then the
724
   caller must make a copy (by calling the copy constructor if there
725
   is one or perform the copy itself otherwise), pass the address of
726
   the copy, and then destroy the temporary (if necessary).
727
 
728
   For return values with non-trivial copy constructors or
729
   destructors, space will be allocated in the caller, and a pointer
730
   will be passed as the first argument (preceding "this").
731
 
732
   We don't have a bulletproof mechanism for determining whether a
733
   constructor or destructor is trivial.  For GCC and DWARF2 debug
734
   information, we can check the artificial flag.
735
 
736
   We don't do anything with the constructors or destructors,
737
   but we have to get the argument passing right anyway.  */
738
static int
739
gnuv3_pass_by_reference (struct type *type)
740
{
741
  int fieldnum, fieldelem;
742
 
743
  CHECK_TYPEDEF (type);
744
 
745
  /* We're only interested in things that can have methods.  */
746
  if (TYPE_CODE (type) != TYPE_CODE_STRUCT
747
      && TYPE_CODE (type) != TYPE_CODE_CLASS
748
      && TYPE_CODE (type) != TYPE_CODE_UNION)
749
    return 0;
750
 
751
  for (fieldnum = 0; fieldnum < TYPE_NFN_FIELDS (type); fieldnum++)
752
    for (fieldelem = 0; fieldelem < TYPE_FN_FIELDLIST_LENGTH (type, fieldnum);
753
         fieldelem++)
754
      {
755
        struct fn_field *fn = TYPE_FN_FIELDLIST1 (type, fieldnum);
756
        char *name = TYPE_FN_FIELDLIST_NAME (type, fieldnum);
757
        struct type *fieldtype = TYPE_FN_FIELD_TYPE (fn, fieldelem);
758
 
759
        /* If this function is marked as artificial, it is compiler-generated,
760
           and we assume it is trivial.  */
761
        if (TYPE_FN_FIELD_ARTIFICIAL (fn, fieldelem))
762
          continue;
763
 
764
        /* If we've found a destructor, we must pass this by reference.  */
765
        if (name[0] == '~')
766
          return 1;
767
 
768
        /* If the mangled name of this method doesn't indicate that it
769
           is a constructor, we're not interested.
770
 
771
           FIXME drow/2007-09-23: We could do this using the name of
772
           the method and the name of the class instead of dealing
773
           with the mangled name.  We don't have a convenient function
774
           to strip off both leading scope qualifiers and trailing
775
           template arguments yet.  */
776
        if (!is_constructor_name (TYPE_FN_FIELD_PHYSNAME (fn, fieldelem)))
777
          continue;
778
 
779
        /* If this method takes two arguments, and the second argument is
780
           a reference to this class, then it is a copy constructor.  */
781
        if (TYPE_NFIELDS (fieldtype) == 2
782
            && TYPE_CODE (TYPE_FIELD_TYPE (fieldtype, 1)) == TYPE_CODE_REF
783
            && check_typedef (TYPE_TARGET_TYPE (TYPE_FIELD_TYPE (fieldtype, 1))) == type)
784
          return 1;
785
      }
786
 
787
  /* Even if all the constructors and destructors were artificial, one
788
     of them may have invoked a non-artificial constructor or
789
     destructor in a base class.  If any base class needs to be passed
790
     by reference, so does this class.  Similarly for members, which
791
     are constructed whenever this class is.  We do not need to worry
792
     about recursive loops here, since we are only looking at members
793
     of complete class type.  */
794
  for (fieldnum = 0; fieldnum < TYPE_NFIELDS (type); fieldnum++)
795
    if (gnuv3_pass_by_reference (TYPE_FIELD_TYPE (type, fieldnum)))
796
      return 1;
797
 
798
  return 0;
799
}
800
 
801
static void
802
init_gnuv3_ops (void)
803
{
804
  vtable_type_gdbarch_data = gdbarch_data_register_post_init (build_gdb_vtable_type);
805
 
806
  gnu_v3_abi_ops.shortname = "gnu-v3";
807
  gnu_v3_abi_ops.longname = "GNU G++ Version 3 ABI";
808
  gnu_v3_abi_ops.doc = "G++ Version 3 ABI";
809
  gnu_v3_abi_ops.is_destructor_name =
810
    (enum dtor_kinds (*) (const char *))is_gnu_v3_mangled_dtor;
811
  gnu_v3_abi_ops.is_constructor_name =
812
    (enum ctor_kinds (*) (const char *))is_gnu_v3_mangled_ctor;
813
  gnu_v3_abi_ops.is_vtable_name = gnuv3_is_vtable_name;
814
  gnu_v3_abi_ops.is_operator_name = gnuv3_is_operator_name;
815
  gnu_v3_abi_ops.rtti_type = gnuv3_rtti_type;
816
  gnu_v3_abi_ops.virtual_fn_field = gnuv3_virtual_fn_field;
817
  gnu_v3_abi_ops.baseclass_offset = gnuv3_baseclass_offset;
818
  gnu_v3_abi_ops.print_method_ptr = gnuv3_print_method_ptr;
819
  gnu_v3_abi_ops.method_ptr_size = gnuv3_method_ptr_size;
820
  gnu_v3_abi_ops.make_method_ptr = gnuv3_make_method_ptr;
821
  gnu_v3_abi_ops.method_ptr_to_value = gnuv3_method_ptr_to_value;
822
  gnu_v3_abi_ops.skip_trampoline = gnuv3_skip_trampoline;
823
  gnu_v3_abi_ops.pass_by_reference = gnuv3_pass_by_reference;
824
}
825
 
826
extern initialize_file_ftype _initialize_gnu_v3_abi; /* -Wmissing-prototypes */
827
 
828
void
829
_initialize_gnu_v3_abi (void)
830
{
831
  init_gnuv3_ops ();
832
 
833
  register_cp_abi (&gnu_v3_abi_ops);
834
}

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