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1 /* Abstraction of GNU v3 abi.
2 Contributed by Jim Blandy <jimb@redhat.com>
3
4 Copyright (C) 2001, 2002, 2003, 2005, 2006, 2007
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
10 modify it under the terms of the GNU General Public License as
11 published by the Free Software Foundation; either version 2 of the
12 License, or (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, write to the Free Software
21 Foundation, Inc., 51 Franklin Street, Fifth Floor,
22 Boston, MA 02110-1301, USA. */
23
24 #include "defs.h"
25 #include "value.h"
26 #include "cp-abi.h"
27 #include "cp-support.h"
28 #include "demangle.h"
29 #include "valprint.h"
30
31 #include "gdb_assert.h"
32 #include "gdb_string.h"
33
34 static struct cp_abi_ops gnu_v3_abi_ops;
35
36 static int
37 gnuv3_is_vtable_name (const char *name)
38 {
39 return strncmp (name, "_ZTV", 4) == 0;
40 }
41
42 static int
43 gnuv3_is_operator_name (const char *name)
44 {
45 return strncmp (name, "operator", 8) == 0;
46 }
47
48
49 /* To help us find the components of a vtable, we build ourselves a
50 GDB type object representing the vtable structure. Following the
51 V3 ABI, it goes something like this:
52
53 struct gdb_gnu_v3_abi_vtable {
54
55 / * An array of virtual call and virtual base offsets. The real
56 length of this array depends on the class hierarchy; we use
57 negative subscripts to access the elements. Yucky, but
58 better than the alternatives. * /
59 ptrdiff_t vcall_and_vbase_offsets[0];
60
61 / * The offset from a virtual pointer referring to this table
62 to the top of the complete object. * /
63 ptrdiff_t offset_to_top;
64
65 / * The type_info pointer for this class. This is really a
66 std::type_info *, but GDB doesn't really look at the
67 type_info object itself, so we don't bother to get the type
68 exactly right. * /
69 void *type_info;
70
71 / * Virtual table pointers in objects point here. * /
72
73 / * Virtual function pointers. Like the vcall/vbase array, the
74 real length of this table depends on the class hierarchy. * /
75 void (*virtual_functions[0]) ();
76
77 };
78
79 The catch, of course, is that the exact layout of this table
80 depends on the ABI --- word size, endianness, alignment, etc. So
81 the GDB type object is actually a per-architecture kind of thing.
82
83 vtable_type_gdbarch_data is a gdbarch per-architecture data pointer
84 which refers to the struct type * for this structure, laid out
85 appropriately for the architecture. */
86 static struct gdbarch_data *vtable_type_gdbarch_data;
87
88
89 /* Human-readable names for the numbers of the fields above. */
90 enum {
91 vtable_field_vcall_and_vbase_offsets,
92 vtable_field_offset_to_top,
93 vtable_field_type_info,
94 vtable_field_virtual_functions
95 };
96
97
98 /* Return a GDB type representing `struct gdb_gnu_v3_abi_vtable',
99 described above, laid out appropriately for ARCH.
100
101 We use this function as the gdbarch per-architecture data
102 initialization function. We assume that the gdbarch framework
103 calls the per-architecture data initialization functions after it
104 sets current_gdbarch to the new architecture. */
105 static void *
106 build_gdb_vtable_type (struct gdbarch *arch)
107 {
108 struct type *t;
109 struct field *field_list, *field;
110 int offset;
111
112 struct type *void_ptr_type
113 = lookup_pointer_type (builtin_type_void);
114 struct type *ptr_to_void_fn_type
115 = lookup_pointer_type (lookup_function_type (builtin_type_void));
116
117 /* ARCH can't give us the true ptrdiff_t type, so we guess. */
118 struct type *ptrdiff_type
119 = init_type (TYPE_CODE_INT, TARGET_PTR_BIT / TARGET_CHAR_BIT, 0,
120 "ptrdiff_t", 0);
121
122 /* We assume no padding is necessary, since GDB doesn't know
123 anything about alignment at the moment. If this assumption bites
124 us, we should add a gdbarch method which, given a type, returns
125 the alignment that type requires, and then use that here. */
126
127 /* Build the field list. */
128 field_list = xmalloc (sizeof (struct field [4]));
129 memset (field_list, 0, sizeof (struct field [4]));
130 field = &field_list[0];
131 offset = 0;
132
133 /* ptrdiff_t vcall_and_vbase_offsets[0]; */
134 FIELD_NAME (*field) = "vcall_and_vbase_offsets";
135 FIELD_TYPE (*field)
136 = create_array_type (0, ptrdiff_type,
137 create_range_type (0, builtin_type_int, 0, -1));
138 FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
139 offset += TYPE_LENGTH (FIELD_TYPE (*field));
140 field++;
141
142 /* ptrdiff_t offset_to_top; */
143 FIELD_NAME (*field) = "offset_to_top";
144 FIELD_TYPE (*field) = ptrdiff_type;
145 FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
146 offset += TYPE_LENGTH (FIELD_TYPE (*field));
147 field++;
148
149 /* void *type_info; */
150 FIELD_NAME (*field) = "type_info";
151 FIELD_TYPE (*field) = void_ptr_type;
152 FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
153 offset += TYPE_LENGTH (FIELD_TYPE (*field));
154 field++;
155
156 /* void (*virtual_functions[0]) (); */
157 FIELD_NAME (*field) = "virtual_functions";
158 FIELD_TYPE (*field)
159 = create_array_type (0, ptr_to_void_fn_type,
160 create_range_type (0, builtin_type_int, 0, -1));
161 FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
162 offset += TYPE_LENGTH (FIELD_TYPE (*field));
163 field++;
164
165 /* We assumed in the allocation above that there were four fields. */
166 gdb_assert (field == (field_list + 4));
167
168 t = init_type (TYPE_CODE_STRUCT, offset, 0, 0, 0);
169 TYPE_NFIELDS (t) = field - field_list;
170 TYPE_FIELDS (t) = field_list;
171 TYPE_TAG_NAME (t) = "gdb_gnu_v3_abi_vtable";
172
173 return t;
174 }
175
176
177 /* Return the offset from the start of the imaginary `struct
178 gdb_gnu_v3_abi_vtable' object to the vtable's "address point"
179 (i.e., where objects' virtual table pointers point). */
180 static int
181 vtable_address_point_offset (void)
182 {
183 struct type *vtable_type = gdbarch_data (current_gdbarch,
184 vtable_type_gdbarch_data);
185
186 return (TYPE_FIELD_BITPOS (vtable_type, vtable_field_virtual_functions)
187 / TARGET_CHAR_BIT);
188 }
189
190
191 static struct type *
192 gnuv3_rtti_type (struct value *value,
193 int *full_p, int *top_p, int *using_enc_p)
194 {
195 struct type *vtable_type = gdbarch_data (current_gdbarch,
196 vtable_type_gdbarch_data);
197 struct type *values_type = check_typedef (value_type (value));
198 CORE_ADDR vtable_address;
199 struct value *vtable;
200 struct minimal_symbol *vtable_symbol;
201 const char *vtable_symbol_name;
202 const char *class_name;
203 struct type *run_time_type;
204 struct type *base_type;
205 LONGEST offset_to_top;
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 fill_in_vptr_fieldno (values_type);
214 if (TYPE_VPTR_FIELDNO (values_type) == -1)
215 return NULL;
216
217 if (using_enc_p)
218 *using_enc_p = 0;
219
220 /* Fetch VALUE's virtual table pointer, and tweak it to point at
221 an instance of our imaginary gdb_gnu_v3_abi_vtable structure. */
222 base_type = check_typedef (TYPE_VPTR_BASETYPE (values_type));
223 if (values_type != base_type)
224 {
225 value = value_cast (base_type, value);
226 if (using_enc_p)
227 *using_enc_p = 1;
228 }
229 vtable_address
230 = value_as_address (value_field (value, TYPE_VPTR_FIELDNO (values_type)));
231 vtable = value_at_lazy (vtable_type,
232 vtable_address - vtable_address_point_offset ());
233
234 /* Find the linker symbol for this vtable. */
235 vtable_symbol
236 = lookup_minimal_symbol_by_pc (VALUE_ADDRESS (vtable)
237 + value_offset (vtable)
238 + value_embedded_offset (vtable));
239 if (! vtable_symbol)
240 return NULL;
241
242 /* The symbol's demangled name should be something like "vtable for
243 CLASS", where CLASS is the name of the run-time type of VALUE.
244 If we didn't like this approach, we could instead look in the
245 type_info object itself to get the class name. But this way
246 should work just as well, and doesn't read target memory. */
247 vtable_symbol_name = SYMBOL_DEMANGLED_NAME (vtable_symbol);
248 if (vtable_symbol_name == NULL
249 || strncmp (vtable_symbol_name, "vtable for ", 11))
250 {
251 warning (_("can't find linker symbol for virtual table for `%s' value"),
252 TYPE_NAME (values_type));
253 if (vtable_symbol_name)
254 warning (_(" found `%s' instead"), vtable_symbol_name);
255 return NULL;
256 }
257 class_name = vtable_symbol_name + 11;
258
259 /* Try to look up the class name as a type name. */
260 /* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */
261 run_time_type = cp_lookup_rtti_type (class_name, NULL);
262 if (run_time_type == NULL)
263 return NULL;
264
265 /* Get the offset from VALUE to the top of the complete object.
266 NOTE: this is the reverse of the meaning of *TOP_P. */
267 offset_to_top
268 = value_as_long (value_field (vtable, vtable_field_offset_to_top));
269
270 if (full_p)
271 *full_p = (- offset_to_top == value_embedded_offset (value)
272 && (TYPE_LENGTH (value_enclosing_type (value))
273 >= TYPE_LENGTH (run_time_type)));
274 if (top_p)
275 *top_p = - offset_to_top;
276
277 return run_time_type;
278 }
279
280 /* Find the vtable for CONTAINER and return a value of the correct
281 vtable type for this architecture. */
282
283 static struct value *
284 gnuv3_get_vtable (struct value *container)
285 {
286 struct type *vtable_type = gdbarch_data (current_gdbarch,
287 vtable_type_gdbarch_data);
288 struct type *vtable_pointer_type;
289 struct value *vtable_pointer;
290 CORE_ADDR vtable_pointer_address, vtable_address;
291
292 /* We do not consult the debug information to find the virtual table.
293 The ABI specifies that it is always at offset zero in any class,
294 and debug information may not represent it. We won't issue an
295 error if there's a class with virtual functions but no virtual table
296 pointer, but something's already gone seriously wrong if that
297 happens.
298
299 We avoid using value_contents on principle, because the object might
300 be large. */
301
302 /* Find the type "pointer to virtual table". */
303 vtable_pointer_type = lookup_pointer_type (vtable_type);
304
305 /* Load it from the start of the class. */
306 vtable_pointer_address = value_as_address (value_addr (container));
307 vtable_pointer = value_at (vtable_pointer_type, vtable_pointer_address);
308 vtable_address = value_as_address (vtable_pointer);
309
310 /* Correct it to point at the start of the virtual table, rather
311 than the address point. */
312 return value_at_lazy (vtable_type,
313 vtable_address - vtable_address_point_offset ());
314 }
315
316 /* Return a function pointer for CONTAINER's VTABLE_INDEX'th virtual
317 function, of type FNTYPE. */
318
319 static struct value *
320 gnuv3_get_virtual_fn (struct value *container, struct type *fntype,
321 int vtable_index)
322 {
323 struct value *vtable = gnuv3_get_vtable (container);
324 struct value *vfn;
325
326 /* Fetch the appropriate function pointer from the vtable. */
327 vfn = value_subscript (value_field (vtable, vtable_field_virtual_functions),
328 value_from_longest (builtin_type_int, vtable_index));
329
330 /* If this architecture uses function descriptors directly in the vtable,
331 then the address of the vtable entry is actually a "function pointer"
332 (i.e. points to the descriptor). We don't need to scale the index
333 by the size of a function descriptor; GCC does that before outputing
334 debug information. */
335 if (gdbarch_vtable_function_descriptors (current_gdbarch))
336 vfn = value_addr (vfn);
337
338 /* Cast the function pointer to the appropriate type. */
339 vfn = value_cast (lookup_pointer_type (fntype), vfn);
340
341 return vfn;
342 }
343
344 /* GNU v3 implementation of value_virtual_fn_field. See cp-abi.h
345 for a description of the arguments. */
346
347 static struct value *
348 gnuv3_virtual_fn_field (struct value **value_p,
349 struct fn_field *f, int j,
350 struct type *vfn_base, int offset)
351 {
352 struct type *values_type = check_typedef (value_type (*value_p));
353
354 /* Some simple sanity checks. */
355 if (TYPE_CODE (values_type) != TYPE_CODE_CLASS)
356 error (_("Only classes can have virtual functions."));
357
358 /* Cast our value to the base class which defines this virtual
359 function. This takes care of any necessary `this'
360 adjustments. */
361 if (vfn_base != values_type)
362 *value_p = value_cast (vfn_base, *value_p);
363
364 return gnuv3_get_virtual_fn (*value_p, TYPE_FN_FIELD_TYPE (f, j),
365 TYPE_FN_FIELD_VOFFSET (f, j));
366 }
367
368 /* Compute the offset of the baseclass which is
369 the INDEXth baseclass of class TYPE,
370 for value at VALADDR (in host) at ADDRESS (in target).
371 The result is the offset of the baseclass value relative
372 to (the address of)(ARG) + OFFSET.
373
374 -1 is returned on error. */
375 static int
376 gnuv3_baseclass_offset (struct type *type, int index, const bfd_byte *valaddr,
377 CORE_ADDR address)
378 {
379 struct type *vtable_type = gdbarch_data (current_gdbarch,
380 vtable_type_gdbarch_data);
381 struct value *vtable;
382 struct type *vbasetype;
383 struct value *offset_val, *vbase_array;
384 CORE_ADDR vtable_address;
385 long int cur_base_offset, base_offset;
386
387 /* If it isn't a virtual base, this is easy. The offset is in the
388 type definition. */
389 if (!BASETYPE_VIA_VIRTUAL (type, index))
390 return TYPE_BASECLASS_BITPOS (type, index) / 8;
391
392 /* To access a virtual base, we need to use the vbase offset stored in
393 our vtable. Recent GCC versions provide this information. If it isn't
394 available, we could get what we needed from RTTI, or from drawing the
395 complete inheritance graph based on the debug info. Neither is
396 worthwhile. */
397 cur_base_offset = TYPE_BASECLASS_BITPOS (type, index) / 8;
398 if (cur_base_offset >= - vtable_address_point_offset ())
399 error (_("Expected a negative vbase offset (old compiler?)"));
400
401 cur_base_offset = cur_base_offset + vtable_address_point_offset ();
402 if ((- cur_base_offset) % TYPE_LENGTH (builtin_type_void_data_ptr) != 0)
403 error (_("Misaligned vbase offset."));
404 cur_base_offset = cur_base_offset
405 / ((int) TYPE_LENGTH (builtin_type_void_data_ptr));
406
407 /* We're now looking for the cur_base_offset'th entry (negative index)
408 in the vcall_and_vbase_offsets array. We used to cast the object to
409 its TYPE_VPTR_BASETYPE, and reference the vtable as TYPE_VPTR_FIELDNO;
410 however, that cast can not be done without calling baseclass_offset again
411 if the TYPE_VPTR_BASETYPE is a virtual base class, as described in the
412 v3 C++ ABI Section 2.4.I.2.b. Fortunately the ABI guarantees that the
413 vtable pointer will be located at the beginning of the object, so we can
414 bypass the casting. Verify that the TYPE_VPTR_FIELDNO is in fact at the
415 start of whichever baseclass it resides in, as a sanity measure - iff
416 we have debugging information for that baseclass. */
417
418 vbasetype = TYPE_VPTR_BASETYPE (type);
419 if (TYPE_VPTR_FIELDNO (vbasetype) < 0)
420 fill_in_vptr_fieldno (vbasetype);
421
422 if (TYPE_VPTR_FIELDNO (vbasetype) >= 0
423 && TYPE_FIELD_BITPOS (vbasetype, TYPE_VPTR_FIELDNO (vbasetype)) != 0)
424 error (_("Illegal vptr offset in class %s"),
425 TYPE_NAME (vbasetype) ? TYPE_NAME (vbasetype) : "<unknown>");
426
427 vtable_address = value_as_address (value_at_lazy (builtin_type_void_data_ptr,
428 address));
429 vtable = value_at_lazy (vtable_type,
430 vtable_address - vtable_address_point_offset ());
431 offset_val = value_from_longest(builtin_type_int, cur_base_offset);
432 vbase_array = value_field (vtable, vtable_field_vcall_and_vbase_offsets);
433 base_offset = value_as_long (value_subscript (vbase_array, offset_val));
434 return base_offset;
435 }
436
437 /* Locate a virtual method in DOMAIN or its non-virtual base classes
438 which has virtual table index VOFFSET. The method has an associated
439 "this" adjustment of ADJUSTMENT bytes. */
440
441 const char *
442 gnuv3_find_method_in (struct type *domain, CORE_ADDR voffset,
443 LONGEST adjustment)
444 {
445 int i;
446 const char *physname;
447
448 /* Search this class first. */
449 physname = NULL;
450 if (adjustment == 0)
451 {
452 int len;
453
454 len = TYPE_NFN_FIELDS (domain);
455 for (i = 0; i < len; i++)
456 {
457 int len2, j;
458 struct fn_field *f;
459
460 f = TYPE_FN_FIELDLIST1 (domain, i);
461 len2 = TYPE_FN_FIELDLIST_LENGTH (domain, i);
462
463 check_stub_method_group (domain, i);
464 for (j = 0; j < len2; j++)
465 if (TYPE_FN_FIELD_VOFFSET (f, j) == voffset)
466 return TYPE_FN_FIELD_PHYSNAME (f, j);
467 }
468 }
469
470 /* Next search non-virtual bases. If it's in a virtual base,
471 we're out of luck. */
472 for (i = 0; i < TYPE_N_BASECLASSES (domain); i++)
473 {
474 int pos;
475 struct type *basetype;
476
477 if (BASETYPE_VIA_VIRTUAL (domain, i))
478 continue;
479
480 pos = TYPE_BASECLASS_BITPOS (domain, i) / 8;
481 basetype = TYPE_FIELD_TYPE (domain, i);
482 /* Recurse with a modified adjustment. We don't need to adjust
483 voffset. */
484 if (adjustment >= pos && adjustment < pos + TYPE_LENGTH (basetype))
485 return gnuv3_find_method_in (basetype, voffset, adjustment - pos);
486 }
487
488 return NULL;
489 }
490
491 /* GNU v3 implementation of cplus_print_method_ptr. */
492
493 static void
494 gnuv3_print_method_ptr (const gdb_byte *contents,
495 struct type *type,
496 struct ui_file *stream)
497 {
498 CORE_ADDR ptr_value;
499 LONGEST adjustment;
500 struct type *domain;
501 int vbit;
502
503 domain = TYPE_DOMAIN_TYPE (type);
504
505 /* Extract the pointer to member. */
506 ptr_value = extract_typed_address (contents, builtin_type_void_func_ptr);
507 contents += TYPE_LENGTH (builtin_type_void_func_ptr);
508 adjustment = extract_signed_integer (contents,
509 TYPE_LENGTH (builtin_type_long));
510
511 if (!gdbarch_vbit_in_delta (current_gdbarch))
512 {
513 vbit = ptr_value & 1;
514 ptr_value = ptr_value ^ vbit;
515 }
516 else
517 {
518 vbit = adjustment & 1;
519 adjustment = adjustment >> 1;
520 }
521
522 /* Check for NULL. */
523 if (ptr_value == 0 && vbit == 0)
524 {
525 fprintf_filtered (stream, "NULL");
526 return;
527 }
528
529 /* Search for a virtual method. */
530 if (vbit)
531 {
532 CORE_ADDR voffset;
533 const char *physname;
534
535 /* It's a virtual table offset, maybe in this class. Search
536 for a field with the correct vtable offset. First convert it
537 to an index, as used in TYPE_FN_FIELD_VOFFSET. */
538 voffset = ptr_value / TYPE_LENGTH (builtin_type_long);
539
540 physname = gnuv3_find_method_in (domain, voffset, adjustment);
541
542 /* If we found a method, print that. We don't bother to disambiguate
543 possible paths to the method based on the adjustment. */
544 if (physname)
545 {
546 char *demangled_name = cplus_demangle (physname,
547 DMGL_ANSI | DMGL_PARAMS);
548 if (demangled_name != NULL)
549 {
550 fprintf_filtered (stream, "&virtual ");
551 fputs_filtered (demangled_name, stream);
552 xfree (demangled_name);
553 return;
554 }
555 }
556 }
557
558 /* We didn't find it; print the raw data. */
559 if (vbit)
560 {
561 fprintf_filtered (stream, "&virtual table offset ");
562 print_longest (stream, 'd', 1, ptr_value);
563 }
564 else
565 print_address_demangle (ptr_value, stream, demangle);
566
567 if (adjustment)
568 {
569 fprintf_filtered (stream, ", this adjustment ");
570 print_longest (stream, 'd', 1, adjustment);
571 }
572 }
573
574 /* GNU v3 implementation of cplus_method_ptr_size. */
575
576 static int
577 gnuv3_method_ptr_size (void)
578 {
579 return 2 * TYPE_LENGTH (builtin_type_void_data_ptr);
580 }
581
582 /* GNU v3 implementation of cplus_make_method_ptr. */
583
584 static void
585 gnuv3_make_method_ptr (gdb_byte *contents, CORE_ADDR value, int is_virtual)
586 {
587 int size = TYPE_LENGTH (builtin_type_void_data_ptr);
588
589 /* FIXME drow/2006-12-24: The adjustment of "this" is currently
590 always zero, since the method pointer is of the correct type.
591 But if the method pointer came from a base class, this is
592 incorrect - it should be the offset to the base. The best
593 fix might be to create the pointer to member pointing at the
594 base class and cast it to the derived class, but that requires
595 support for adjusting pointers to members when casting them -
596 not currently supported by GDB. */
597
598 if (!gdbarch_vbit_in_delta (current_gdbarch))
599 {
600 store_unsigned_integer (contents, size, value | is_virtual);
601 store_unsigned_integer (contents + size, size, 0);
602 }
603 else
604 {
605 store_unsigned_integer (contents, size, value);
606 store_unsigned_integer (contents + size, size, is_virtual);
607 }
608 }
609
610 /* GNU v3 implementation of cplus_method_ptr_to_value. */
611
612 static struct value *
613 gnuv3_method_ptr_to_value (struct value **this_p, struct value *method_ptr)
614 {
615 const gdb_byte *contents = value_contents (method_ptr);
616 CORE_ADDR ptr_value;
617 struct type *final_type, *method_type;
618 LONGEST adjustment;
619 struct value *adjval;
620 int vbit;
621
622 final_type = TYPE_DOMAIN_TYPE (check_typedef (value_type (method_ptr)));
623 final_type = lookup_pointer_type (final_type);
624
625 method_type = TYPE_TARGET_TYPE (check_typedef (value_type (method_ptr)));
626
627 ptr_value = extract_typed_address (contents, builtin_type_void_func_ptr);
628 contents += TYPE_LENGTH (builtin_type_void_func_ptr);
629 adjustment = extract_signed_integer (contents,
630 TYPE_LENGTH (builtin_type_long));
631
632 if (!gdbarch_vbit_in_delta (current_gdbarch))
633 {
634 vbit = ptr_value & 1;
635 ptr_value = ptr_value ^ vbit;
636 }
637 else
638 {
639 vbit = adjustment & 1;
640 adjustment = adjustment >> 1;
641 }
642
643 /* First convert THIS to match the containing type of the pointer to
644 member. This cast may adjust the value of THIS. */
645 *this_p = value_cast (final_type, *this_p);
646
647 /* Then apply whatever adjustment is necessary. This creates a somewhat
648 strange pointer: it claims to have type FINAL_TYPE, but in fact it
649 might not be a valid FINAL_TYPE. For instance, it might be a
650 base class of FINAL_TYPE. And if it's not the primary base class,
651 then printing it out as a FINAL_TYPE object would produce some pretty
652 garbage.
653
654 But we don't really know the type of the first argument in
655 METHOD_TYPE either, which is why this happens. We can't
656 dereference this later as a FINAL_TYPE, but once we arrive in the
657 called method we'll have debugging information for the type of
658 "this" - and that'll match the value we produce here.
659
660 You can provoke this case by casting a Base::* to a Derived::*, for
661 instance. */
662 *this_p = value_cast (builtin_type_void_data_ptr, *this_p);
663 adjval = value_from_longest (builtin_type_long, adjustment);
664 *this_p = value_add (*this_p, adjval);
665 *this_p = value_cast (final_type, *this_p);
666
667 if (vbit)
668 {
669 LONGEST voffset = ptr_value / TYPE_LENGTH (builtin_type_long);
670 return gnuv3_get_virtual_fn (value_ind (*this_p), method_type, voffset);
671 }
672 else
673 return value_from_pointer (lookup_pointer_type (method_type), ptr_value);
674 }
675
676 static void
677 init_gnuv3_ops (void)
678 {
679 vtable_type_gdbarch_data = gdbarch_data_register_post_init (build_gdb_vtable_type);
680
681 gnu_v3_abi_ops.shortname = "gnu-v3";
682 gnu_v3_abi_ops.longname = "GNU G++ Version 3 ABI";
683 gnu_v3_abi_ops.doc = "G++ Version 3 ABI";
684 gnu_v3_abi_ops.is_destructor_name =
685 (enum dtor_kinds (*) (const char *))is_gnu_v3_mangled_dtor;
686 gnu_v3_abi_ops.is_constructor_name =
687 (enum ctor_kinds (*) (const char *))is_gnu_v3_mangled_ctor;
688 gnu_v3_abi_ops.is_vtable_name = gnuv3_is_vtable_name;
689 gnu_v3_abi_ops.is_operator_name = gnuv3_is_operator_name;
690 gnu_v3_abi_ops.rtti_type = gnuv3_rtti_type;
691 gnu_v3_abi_ops.virtual_fn_field = gnuv3_virtual_fn_field;
692 gnu_v3_abi_ops.baseclass_offset = gnuv3_baseclass_offset;
693 gnu_v3_abi_ops.print_method_ptr = gnuv3_print_method_ptr;
694 gnu_v3_abi_ops.method_ptr_size = gnuv3_method_ptr_size;
695 gnu_v3_abi_ops.make_method_ptr = gnuv3_make_method_ptr;
696 gnu_v3_abi_ops.method_ptr_to_value = gnuv3_method_ptr_to_value;
697 }
698
699 extern initialize_file_ftype _initialize_gnu_v3_abi; /* -Wmissing-prototypes */
700
701 void
702 _initialize_gnu_v3_abi (void)
703 {
704 init_gnuv3_ops ();
705
706 register_cp_abi (&gnu_v3_abi_ops);
707 }