1 /* Abstraction of GNU v3 abi.
2 Contributed by Jim Blandy <jimb@redhat.com>
4 Copyright (C) 2001-2003, 2005-2012 Free Software Foundation, Inc.
6 This file is part of GDB.
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program. If not, see <http://www.gnu.org/licenses/>. */
24 #include "cp-support.h"
29 #include "exceptions.h"
31 #include "gdb_assert.h"
32 #include "gdb_string.h"
34 static struct cp_abi_ops gnu_v3_abi_ops;
37 gnuv3_is_vtable_name (const char *name)
39 return strncmp (name, "_ZTV", 4) == 0;
43 gnuv3_is_operator_name (const char *name)
45 return strncmp (name, "operator", 8) == 0;
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:
53 struct gdb_gnu_v3_abi_vtable {
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];
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;
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
71 / * Virtual table pointers in objects point here. * /
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]) ();
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.
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;
89 /* Human-readable names for the numbers of the fields above. */
91 vtable_field_vcall_and_vbase_offsets,
92 vtable_field_offset_to_top,
93 vtable_field_type_info,
94 vtable_field_virtual_functions
98 /* Return a GDB type representing `struct gdb_gnu_v3_abi_vtable',
99 described above, laid out appropriately for ARCH.
101 We use this function as the gdbarch per-architecture data
102 initialization function. */
104 build_gdb_vtable_type (struct gdbarch *arch)
107 struct field *field_list, *field;
110 struct type *void_ptr_type
111 = builtin_type (arch)->builtin_data_ptr;
112 struct type *ptr_to_void_fn_type
113 = builtin_type (arch)->builtin_func_ptr;
115 /* ARCH can't give us the true ptrdiff_t type, so we guess. */
116 struct type *ptrdiff_type
117 = arch_integer_type (arch, gdbarch_ptr_bit (arch), 0, "ptrdiff_t");
119 /* We assume no padding is necessary, since GDB doesn't know
120 anything about alignment at the moment. If this assumption bites
121 us, we should add a gdbarch method which, given a type, returns
122 the alignment that type requires, and then use that here. */
124 /* Build the field list. */
125 field_list = xmalloc (sizeof (struct field [4]));
126 memset (field_list, 0, sizeof (struct field [4]));
127 field = &field_list[0];
130 /* ptrdiff_t vcall_and_vbase_offsets[0]; */
131 FIELD_NAME (*field) = "vcall_and_vbase_offsets";
132 FIELD_TYPE (*field) = lookup_array_range_type (ptrdiff_type, 0, -1);
133 FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
134 offset += TYPE_LENGTH (FIELD_TYPE (*field));
137 /* ptrdiff_t offset_to_top; */
138 FIELD_NAME (*field) = "offset_to_top";
139 FIELD_TYPE (*field) = ptrdiff_type;
140 FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
141 offset += TYPE_LENGTH (FIELD_TYPE (*field));
144 /* void *type_info; */
145 FIELD_NAME (*field) = "type_info";
146 FIELD_TYPE (*field) = void_ptr_type;
147 FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
148 offset += TYPE_LENGTH (FIELD_TYPE (*field));
151 /* void (*virtual_functions[0]) (); */
152 FIELD_NAME (*field) = "virtual_functions";
153 FIELD_TYPE (*field) = lookup_array_range_type (ptr_to_void_fn_type, 0, -1);
154 FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT;
155 offset += TYPE_LENGTH (FIELD_TYPE (*field));
158 /* We assumed in the allocation above that there were four fields. */
159 gdb_assert (field == (field_list + 4));
161 t = arch_type (arch, TYPE_CODE_STRUCT, offset, NULL);
162 TYPE_NFIELDS (t) = field - field_list;
163 TYPE_FIELDS (t) = field_list;
164 TYPE_TAG_NAME (t) = "gdb_gnu_v3_abi_vtable";
165 INIT_CPLUS_SPECIFIC (t);
171 /* Return the ptrdiff_t type used in the vtable type. */
173 vtable_ptrdiff_type (struct gdbarch *gdbarch)
175 struct type *vtable_type = gdbarch_data (gdbarch, vtable_type_gdbarch_data);
177 /* The "offset_to_top" field has the appropriate (ptrdiff_t) type. */
178 return TYPE_FIELD_TYPE (vtable_type, vtable_field_offset_to_top);
181 /* Return the offset from the start of the imaginary `struct
182 gdb_gnu_v3_abi_vtable' object to the vtable's "address point"
183 (i.e., where objects' virtual table pointers point). */
185 vtable_address_point_offset (struct gdbarch *gdbarch)
187 struct type *vtable_type = gdbarch_data (gdbarch, vtable_type_gdbarch_data);
189 return (TYPE_FIELD_BITPOS (vtable_type, vtable_field_virtual_functions)
194 /* Determine whether structure TYPE is a dynamic class. Cache the
198 gnuv3_dynamic_class (struct type *type)
200 int fieldnum, fieldelem;
202 if (TYPE_CPLUS_DYNAMIC (type))
203 return TYPE_CPLUS_DYNAMIC (type) == 1;
205 ALLOCATE_CPLUS_STRUCT_TYPE (type);
207 for (fieldnum = 0; fieldnum < TYPE_N_BASECLASSES (type); fieldnum++)
208 if (BASETYPE_VIA_VIRTUAL (type, fieldnum)
209 || gnuv3_dynamic_class (TYPE_FIELD_TYPE (type, fieldnum)))
211 TYPE_CPLUS_DYNAMIC (type) = 1;
215 for (fieldnum = 0; fieldnum < TYPE_NFN_FIELDS (type); fieldnum++)
216 for (fieldelem = 0; fieldelem < TYPE_FN_FIELDLIST_LENGTH (type, fieldnum);
219 struct fn_field *f = TYPE_FN_FIELDLIST1 (type, fieldnum);
221 if (TYPE_FN_FIELD_VIRTUAL_P (f, fieldelem))
223 TYPE_CPLUS_DYNAMIC (type) = 1;
228 TYPE_CPLUS_DYNAMIC (type) = -1;
232 /* Find the vtable for a value of CONTAINER_TYPE located at
233 CONTAINER_ADDR. Return a value of the correct vtable type for this
234 architecture, or NULL if CONTAINER does not have a vtable. */
236 static struct value *
237 gnuv3_get_vtable (struct gdbarch *gdbarch,
238 struct type *container_type, CORE_ADDR container_addr)
240 struct type *vtable_type = gdbarch_data (gdbarch,
241 vtable_type_gdbarch_data);
242 struct type *vtable_pointer_type;
243 struct value *vtable_pointer;
244 CORE_ADDR vtable_address;
246 /* If this type does not have a virtual table, don't read the first
248 if (!gnuv3_dynamic_class (check_typedef (container_type)))
251 /* We do not consult the debug information to find the virtual table.
252 The ABI specifies that it is always at offset zero in any class,
253 and debug information may not represent it.
255 We avoid using value_contents on principle, because the object might
258 /* Find the type "pointer to virtual table". */
259 vtable_pointer_type = lookup_pointer_type (vtable_type);
261 /* Load it from the start of the class. */
262 vtable_pointer = value_at (vtable_pointer_type, container_addr);
263 vtable_address = value_as_address (vtable_pointer);
265 /* Correct it to point at the start of the virtual table, rather
266 than the address point. */
267 return value_at_lazy (vtable_type,
269 - vtable_address_point_offset (gdbarch));
274 gnuv3_rtti_type (struct value *value,
275 int *full_p, int *top_p, int *using_enc_p)
277 struct gdbarch *gdbarch;
278 struct type *values_type = check_typedef (value_type (value));
279 struct value *vtable;
280 struct minimal_symbol *vtable_symbol;
281 const char *vtable_symbol_name;
282 const char *class_name;
283 struct type *run_time_type;
284 LONGEST offset_to_top;
286 /* We only have RTTI for class objects. */
287 if (TYPE_CODE (values_type) != TYPE_CODE_CLASS)
290 /* Java doesn't have RTTI following the C++ ABI. */
291 if (TYPE_CPLUS_REALLY_JAVA (values_type))
294 /* Determine architecture. */
295 gdbarch = get_type_arch (values_type);
300 vtable = gnuv3_get_vtable (gdbarch, value_type (value),
301 value_as_address (value_addr (value)));
305 /* Find the linker symbol for this vtable. */
307 = lookup_minimal_symbol_by_pc (value_address (vtable)
308 + value_embedded_offset (vtable));
312 /* The symbol's demangled name should be something like "vtable for
313 CLASS", where CLASS is the name of the run-time type of VALUE.
314 If we didn't like this approach, we could instead look in the
315 type_info object itself to get the class name. But this way
316 should work just as well, and doesn't read target memory. */
317 vtable_symbol_name = SYMBOL_DEMANGLED_NAME (vtable_symbol);
318 if (vtable_symbol_name == NULL
319 || strncmp (vtable_symbol_name, "vtable for ", 11))
321 warning (_("can't find linker symbol for virtual table for `%s' value"),
322 TYPE_SAFE_NAME (values_type));
323 if (vtable_symbol_name)
324 warning (_(" found `%s' instead"), vtable_symbol_name);
327 class_name = vtable_symbol_name + 11;
329 /* Try to look up the class name as a type name. */
330 /* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */
331 run_time_type = cp_lookup_rtti_type (class_name, NULL);
332 if (run_time_type == NULL)
335 /* Get the offset from VALUE to the top of the complete object.
336 NOTE: this is the reverse of the meaning of *TOP_P. */
338 = value_as_long (value_field (vtable, vtable_field_offset_to_top));
341 *full_p = (- offset_to_top == value_embedded_offset (value)
342 && (TYPE_LENGTH (value_enclosing_type (value))
343 >= TYPE_LENGTH (run_time_type)));
345 *top_p = - offset_to_top;
346 return run_time_type;
349 /* Return a function pointer for CONTAINER's VTABLE_INDEX'th virtual
350 function, of type FNTYPE. */
352 static struct value *
353 gnuv3_get_virtual_fn (struct gdbarch *gdbarch, struct value *container,
354 struct type *fntype, int vtable_index)
356 struct value *vtable, *vfn;
358 /* Every class with virtual functions must have a vtable. */
359 vtable = gnuv3_get_vtable (gdbarch, value_type (container),
360 value_as_address (value_addr (container)));
361 gdb_assert (vtable != NULL);
363 /* Fetch the appropriate function pointer from the vtable. */
364 vfn = value_subscript (value_field (vtable, vtable_field_virtual_functions),
367 /* If this architecture uses function descriptors directly in the vtable,
368 then the address of the vtable entry is actually a "function pointer"
369 (i.e. points to the descriptor). We don't need to scale the index
370 by the size of a function descriptor; GCC does that before outputing
371 debug information. */
372 if (gdbarch_vtable_function_descriptors (gdbarch))
373 vfn = value_addr (vfn);
375 /* Cast the function pointer to the appropriate type. */
376 vfn = value_cast (lookup_pointer_type (fntype), vfn);
381 /* GNU v3 implementation of value_virtual_fn_field. See cp-abi.h
382 for a description of the arguments. */
384 static struct value *
385 gnuv3_virtual_fn_field (struct value **value_p,
386 struct fn_field *f, int j,
387 struct type *vfn_base, int offset)
389 struct type *values_type = check_typedef (value_type (*value_p));
390 struct gdbarch *gdbarch;
392 /* Some simple sanity checks. */
393 if (TYPE_CODE (values_type) != TYPE_CODE_CLASS)
394 error (_("Only classes can have virtual functions."));
396 /* Determine architecture. */
397 gdbarch = get_type_arch (values_type);
399 /* Cast our value to the base class which defines this virtual
400 function. This takes care of any necessary `this'
402 if (vfn_base != values_type)
403 *value_p = value_cast (vfn_base, *value_p);
405 return gnuv3_get_virtual_fn (gdbarch, *value_p, TYPE_FN_FIELD_TYPE (f, j),
406 TYPE_FN_FIELD_VOFFSET (f, j));
409 /* Compute the offset of the baseclass which is
410 the INDEXth baseclass of class TYPE,
411 for value at VALADDR (in host) at ADDRESS (in target).
412 The result is the offset of the baseclass value relative
413 to (the address of)(ARG) + OFFSET.
415 -1 is returned on error. */
418 gnuv3_baseclass_offset (struct type *type, int index,
419 const bfd_byte *valaddr, int embedded_offset,
420 CORE_ADDR address, const struct value *val)
422 struct gdbarch *gdbarch;
423 struct type *ptr_type;
424 struct value *vtable;
425 struct value *vbase_array;
426 long int cur_base_offset, base_offset;
428 /* Determine architecture. */
429 gdbarch = get_type_arch (type);
430 ptr_type = builtin_type (gdbarch)->builtin_data_ptr;
432 /* If it isn't a virtual base, this is easy. The offset is in the
434 if (!BASETYPE_VIA_VIRTUAL (type, index))
435 return TYPE_BASECLASS_BITPOS (type, index) / 8;
437 /* To access a virtual base, we need to use the vbase offset stored in
438 our vtable. Recent GCC versions provide this information. If it isn't
439 available, we could get what we needed from RTTI, or from drawing the
440 complete inheritance graph based on the debug info. Neither is
442 cur_base_offset = TYPE_BASECLASS_BITPOS (type, index) / 8;
443 if (cur_base_offset >= - vtable_address_point_offset (gdbarch))
444 error (_("Expected a negative vbase offset (old compiler?)"));
446 cur_base_offset = cur_base_offset + vtable_address_point_offset (gdbarch);
447 if ((- cur_base_offset) % TYPE_LENGTH (ptr_type) != 0)
448 error (_("Misaligned vbase offset."));
449 cur_base_offset = cur_base_offset / ((int) TYPE_LENGTH (ptr_type));
451 vtable = gnuv3_get_vtable (gdbarch, type, address + embedded_offset);
452 gdb_assert (vtable != NULL);
453 vbase_array = value_field (vtable, vtable_field_vcall_and_vbase_offsets);
454 base_offset = value_as_long (value_subscript (vbase_array, cur_base_offset));
458 /* Locate a virtual method in DOMAIN or its non-virtual base classes
459 which has virtual table index VOFFSET. The method has an associated
460 "this" adjustment of ADJUSTMENT bytes. */
463 gnuv3_find_method_in (struct type *domain, CORE_ADDR voffset,
468 /* Search this class first. */
473 len = TYPE_NFN_FIELDS (domain);
474 for (i = 0; i < len; i++)
479 f = TYPE_FN_FIELDLIST1 (domain, i);
480 len2 = TYPE_FN_FIELDLIST_LENGTH (domain, i);
482 check_stub_method_group (domain, i);
483 for (j = 0; j < len2; j++)
484 if (TYPE_FN_FIELD_VOFFSET (f, j) == voffset)
485 return TYPE_FN_FIELD_PHYSNAME (f, j);
489 /* Next search non-virtual bases. If it's in a virtual base,
490 we're out of luck. */
491 for (i = 0; i < TYPE_N_BASECLASSES (domain); i++)
494 struct type *basetype;
496 if (BASETYPE_VIA_VIRTUAL (domain, i))
499 pos = TYPE_BASECLASS_BITPOS (domain, i) / 8;
500 basetype = TYPE_FIELD_TYPE (domain, i);
501 /* Recurse with a modified adjustment. We don't need to adjust
503 if (adjustment >= pos && adjustment < pos + TYPE_LENGTH (basetype))
504 return gnuv3_find_method_in (basetype, voffset, adjustment - pos);
510 /* Decode GNU v3 method pointer. */
513 gnuv3_decode_method_ptr (struct gdbarch *gdbarch,
514 const gdb_byte *contents,
516 LONGEST *adjustment_p)
518 struct type *funcptr_type = builtin_type (gdbarch)->builtin_func_ptr;
519 struct type *offset_type = vtable_ptrdiff_type (gdbarch);
520 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
522 LONGEST voffset, adjustment;
525 /* Extract the pointer to member. The first element is either a pointer
526 or a vtable offset. For pointers, we need to use extract_typed_address
527 to allow the back-end to convert the pointer to a GDB address -- but
528 vtable offsets we must handle as integers. At this point, we do not
529 yet know which case we have, so we extract the value under both
530 interpretations and choose the right one later on. */
531 ptr_value = extract_typed_address (contents, funcptr_type);
532 voffset = extract_signed_integer (contents,
533 TYPE_LENGTH (funcptr_type), byte_order);
534 contents += TYPE_LENGTH (funcptr_type);
535 adjustment = extract_signed_integer (contents,
536 TYPE_LENGTH (offset_type), byte_order);
538 if (!gdbarch_vbit_in_delta (gdbarch))
541 voffset = voffset ^ vbit;
545 vbit = adjustment & 1;
546 adjustment = adjustment >> 1;
549 *value_p = vbit? voffset : ptr_value;
550 *adjustment_p = adjustment;
554 /* GNU v3 implementation of cplus_print_method_ptr. */
557 gnuv3_print_method_ptr (const gdb_byte *contents,
559 struct ui_file *stream)
561 struct type *domain = TYPE_DOMAIN_TYPE (type);
562 struct gdbarch *gdbarch = get_type_arch (domain);
567 /* Extract the pointer to member. */
568 vbit = gnuv3_decode_method_ptr (gdbarch, contents, &ptr_value, &adjustment);
570 /* Check for NULL. */
571 if (ptr_value == 0 && vbit == 0)
573 fprintf_filtered (stream, "NULL");
577 /* Search for a virtual method. */
581 const char *physname;
583 /* It's a virtual table offset, maybe in this class. Search
584 for a field with the correct vtable offset. First convert it
585 to an index, as used in TYPE_FN_FIELD_VOFFSET. */
586 voffset = ptr_value / TYPE_LENGTH (vtable_ptrdiff_type (gdbarch));
588 physname = gnuv3_find_method_in (domain, voffset, adjustment);
590 /* If we found a method, print that. We don't bother to disambiguate
591 possible paths to the method based on the adjustment. */
594 char *demangled_name = cplus_demangle (physname,
595 DMGL_ANSI | DMGL_PARAMS);
597 fprintf_filtered (stream, "&virtual ");
598 if (demangled_name == NULL)
599 fputs_filtered (physname, stream);
602 fputs_filtered (demangled_name, stream);
603 xfree (demangled_name);
608 else if (ptr_value != 0)
610 /* Found a non-virtual function: print out the type. */
611 fputs_filtered ("(", stream);
612 c_print_type (type, "", stream, -1, 0);
613 fputs_filtered (") ", stream);
616 /* We didn't find it; print the raw data. */
619 fprintf_filtered (stream, "&virtual table offset ");
620 print_longest (stream, 'd', 1, ptr_value);
623 print_address_demangle (gdbarch, ptr_value, stream, demangle);
627 fprintf_filtered (stream, ", this adjustment ");
628 print_longest (stream, 'd', 1, adjustment);
632 /* GNU v3 implementation of cplus_method_ptr_size. */
635 gnuv3_method_ptr_size (struct type *type)
637 struct gdbarch *gdbarch = get_type_arch (type);
639 return 2 * TYPE_LENGTH (builtin_type (gdbarch)->builtin_data_ptr);
642 /* GNU v3 implementation of cplus_make_method_ptr. */
645 gnuv3_make_method_ptr (struct type *type, gdb_byte *contents,
646 CORE_ADDR value, int is_virtual)
648 struct gdbarch *gdbarch = get_type_arch (type);
649 int size = TYPE_LENGTH (builtin_type (gdbarch)->builtin_data_ptr);
650 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
652 /* FIXME drow/2006-12-24: The adjustment of "this" is currently
653 always zero, since the method pointer is of the correct type.
654 But if the method pointer came from a base class, this is
655 incorrect - it should be the offset to the base. The best
656 fix might be to create the pointer to member pointing at the
657 base class and cast it to the derived class, but that requires
658 support for adjusting pointers to members when casting them -
659 not currently supported by GDB. */
661 if (!gdbarch_vbit_in_delta (gdbarch))
663 store_unsigned_integer (contents, size, byte_order, value | is_virtual);
664 store_unsigned_integer (contents + size, size, byte_order, 0);
668 store_unsigned_integer (contents, size, byte_order, value);
669 store_unsigned_integer (contents + size, size, byte_order, is_virtual);
673 /* GNU v3 implementation of cplus_method_ptr_to_value. */
675 static struct value *
676 gnuv3_method_ptr_to_value (struct value **this_p, struct value *method_ptr)
678 struct gdbarch *gdbarch;
679 const gdb_byte *contents = value_contents (method_ptr);
681 struct type *domain_type, *final_type, *method_type;
685 domain_type = TYPE_DOMAIN_TYPE (check_typedef (value_type (method_ptr)));
686 final_type = lookup_pointer_type (domain_type);
688 method_type = TYPE_TARGET_TYPE (check_typedef (value_type (method_ptr)));
690 /* Extract the pointer to member. */
691 gdbarch = get_type_arch (domain_type);
692 vbit = gnuv3_decode_method_ptr (gdbarch, contents, &ptr_value, &adjustment);
694 /* First convert THIS to match the containing type of the pointer to
695 member. This cast may adjust the value of THIS. */
696 *this_p = value_cast (final_type, *this_p);
698 /* Then apply whatever adjustment is necessary. This creates a somewhat
699 strange pointer: it claims to have type FINAL_TYPE, but in fact it
700 might not be a valid FINAL_TYPE. For instance, it might be a
701 base class of FINAL_TYPE. And if it's not the primary base class,
702 then printing it out as a FINAL_TYPE object would produce some pretty
705 But we don't really know the type of the first argument in
706 METHOD_TYPE either, which is why this happens. We can't
707 dereference this later as a FINAL_TYPE, but once we arrive in the
708 called method we'll have debugging information for the type of
709 "this" - and that'll match the value we produce here.
711 You can provoke this case by casting a Base::* to a Derived::*, for
713 *this_p = value_cast (builtin_type (gdbarch)->builtin_data_ptr, *this_p);
714 *this_p = value_ptradd (*this_p, adjustment);
715 *this_p = value_cast (final_type, *this_p);
721 voffset = ptr_value / TYPE_LENGTH (vtable_ptrdiff_type (gdbarch));
722 return gnuv3_get_virtual_fn (gdbarch, value_ind (*this_p),
723 method_type, voffset);
726 return value_from_pointer (lookup_pointer_type (method_type), ptr_value);
729 /* Objects of this type are stored in a hash table and a vector when
730 printing the vtables for a class. */
732 struct value_and_voffset
734 /* The value representing the object. */
737 /* The maximum vtable offset we've found for any object at this
738 offset in the outermost object. */
742 typedef struct value_and_voffset *value_and_voffset_p;
743 DEF_VEC_P (value_and_voffset_p);
745 /* Hash function for value_and_voffset. */
748 hash_value_and_voffset (const void *p)
750 const struct value_and_voffset *o = p;
752 return value_address (o->value) + value_embedded_offset (o->value);
755 /* Equality function for value_and_voffset. */
758 eq_value_and_voffset (const void *a, const void *b)
760 const struct value_and_voffset *ova = a;
761 const struct value_and_voffset *ovb = b;
763 return (value_address (ova->value) + value_embedded_offset (ova->value)
764 == value_address (ovb->value) + value_embedded_offset (ovb->value));
767 /* qsort comparison function for value_and_voffset. */
770 compare_value_and_voffset (const void *a, const void *b)
772 const struct value_and_voffset * const *ova = a;
773 CORE_ADDR addra = (value_address ((*ova)->value)
774 + value_embedded_offset ((*ova)->value));
775 const struct value_and_voffset * const *ovb = b;
776 CORE_ADDR addrb = (value_address ((*ovb)->value)
777 + value_embedded_offset ((*ovb)->value));
786 /* A helper function used when printing vtables. This determines the
787 key (most derived) sub-object at each address and also computes the
788 maximum vtable offset seen for the corresponding vtable. Updates
789 OFFSET_HASH and OFFSET_VEC with a new value_and_voffset object, if
790 needed. VALUE is the object to examine. */
793 compute_vtable_size (htab_t offset_hash,
794 VEC (value_and_voffset_p) **offset_vec,
798 struct type *type = check_typedef (value_type (value));
800 struct value_and_voffset search_vo, *current_vo;
801 CORE_ADDR addr = value_address (value) + value_embedded_offset (value);
803 /* If the object is not dynamic, then we are done; as it cannot have
804 dynamic base types either. */
805 if (!gnuv3_dynamic_class (type))
808 /* Update the hash and the vec, if needed. */
809 search_vo.value = value;
810 slot = htab_find_slot (offset_hash, &search_vo, INSERT);
815 current_vo = XNEW (struct value_and_voffset);
816 current_vo->value = value;
817 current_vo->max_voffset = -1;
819 VEC_safe_push (value_and_voffset_p, *offset_vec, current_vo);
822 /* Update the value_and_voffset object with the highest vtable
823 offset from this class. */
824 for (i = 0; i < TYPE_NFN_FIELDS (type); ++i)
827 struct fn_field *fn = TYPE_FN_FIELDLIST1 (type, i);
829 for (j = 0; j < TYPE_FN_FIELDLIST_LENGTH (type, i); ++j)
831 if (TYPE_FN_FIELD_VIRTUAL_P (fn, j))
833 int voffset = TYPE_FN_FIELD_VOFFSET (fn, j);
835 if (voffset > current_vo->max_voffset)
836 current_vo->max_voffset = voffset;
841 /* Recurse into base classes. */
842 for (i = 0; i < TYPE_N_BASECLASSES (type); ++i)
843 compute_vtable_size (offset_hash, offset_vec, value_field (value, i));
846 /* Helper for gnuv3_print_vtable that prints a single vtable. */
849 print_one_vtable (struct gdbarch *gdbarch, struct value *value,
851 struct value_print_options *opts)
854 struct type *type = check_typedef (value_type (value));
855 struct value *vtable;
858 vtable = gnuv3_get_vtable (gdbarch, type,
859 value_address (value)
860 + value_embedded_offset (value));
861 vt_addr = value_address (value_field (vtable,
862 vtable_field_virtual_functions));
864 printf_filtered (_("vtable for '%s' @ %s (subobject @ %s):\n"),
865 TYPE_SAFE_NAME (type),
866 paddress (gdbarch, vt_addr),
867 paddress (gdbarch, (value_address (value)
868 + value_embedded_offset (value))));
870 for (i = 0; i <= max_voffset; ++i)
874 volatile struct gdb_exception ex;
876 printf_filtered ("[%d]: ", i);
878 vfn = value_subscript (value_field (vtable,
879 vtable_field_virtual_functions),
882 if (gdbarch_vtable_function_descriptors (gdbarch))
883 vfn = value_addr (vfn);
885 TRY_CATCH (ex, RETURN_MASK_ERROR)
887 addr = value_as_address (vfn);
890 printf_filtered (_("<error: %s>"), ex.message);
892 print_function_pointer_address (gdbarch, addr, gdb_stdout,
894 printf_filtered ("\n");
898 /* Implementation of the print_vtable method. */
901 gnuv3_print_vtable (struct value *value)
903 struct gdbarch *gdbarch;
905 struct value *vtable;
906 struct value_print_options opts;
908 struct cleanup *cleanup;
909 VEC (value_and_voffset_p) *result_vec;
910 struct value_and_voffset *iter;
913 value = coerce_ref (value);
914 type = check_typedef (value_type (value));
915 if (TYPE_CODE (type) == TYPE_CODE_PTR)
917 value = value_ind (value);
918 type = check_typedef (value_type (value));
921 get_user_print_options (&opts);
923 /* Respect 'set print object'. */
924 if (opts.objectprint)
926 value = value_full_object (value, NULL, 0, 0, 0);
927 type = check_typedef (value_type (value));
930 gdbarch = get_type_arch (type);
931 vtable = gnuv3_get_vtable (gdbarch, type,
932 value_as_address (value_addr (value)));
936 printf_filtered (_("This object does not have a virtual function table\n"));
940 offset_hash = htab_create_alloc (1, hash_value_and_voffset,
941 eq_value_and_voffset,
942 xfree, xcalloc, xfree);
943 cleanup = make_cleanup_htab_delete (offset_hash);
944 make_cleanup (VEC_cleanup (value_and_voffset_p), &result_vec);
946 compute_vtable_size (offset_hash, &result_vec, value);
948 qsort (VEC_address (value_and_voffset_p, result_vec),
949 VEC_length (value_and_voffset_p, result_vec),
950 sizeof (value_and_voffset_p),
951 compare_value_and_voffset);
954 for (i = 0; VEC_iterate (value_and_voffset_p, result_vec, i, iter); ++i)
956 if (iter->max_voffset >= 0)
959 printf_filtered ("\n");
960 print_one_vtable (gdbarch, iter->value, iter->max_voffset, &opts);
965 do_cleanups (cleanup);
968 /* Determine if we are currently in a C++ thunk. If so, get the address
969 of the routine we are thunking to and continue to there instead. */
972 gnuv3_skip_trampoline (struct frame_info *frame, CORE_ADDR stop_pc)
974 CORE_ADDR real_stop_pc, method_stop_pc;
975 struct gdbarch *gdbarch = get_frame_arch (frame);
976 struct minimal_symbol *thunk_sym, *fn_sym;
977 struct obj_section *section;
978 const char *thunk_name, *fn_name;
980 real_stop_pc = gdbarch_skip_trampoline_code (gdbarch, frame, stop_pc);
981 if (real_stop_pc == 0)
982 real_stop_pc = stop_pc;
984 /* Find the linker symbol for this potential thunk. */
985 thunk_sym = lookup_minimal_symbol_by_pc (real_stop_pc);
986 section = find_pc_section (real_stop_pc);
987 if (thunk_sym == NULL || section == NULL)
990 /* The symbol's demangled name should be something like "virtual
991 thunk to FUNCTION", where FUNCTION is the name of the function
993 thunk_name = SYMBOL_DEMANGLED_NAME (thunk_sym);
994 if (thunk_name == NULL || strstr (thunk_name, " thunk to ") == NULL)
997 fn_name = strstr (thunk_name, " thunk to ") + strlen (" thunk to ");
998 fn_sym = lookup_minimal_symbol (fn_name, NULL, section->objfile);
1002 method_stop_pc = SYMBOL_VALUE_ADDRESS (fn_sym);
1003 real_stop_pc = gdbarch_skip_trampoline_code
1004 (gdbarch, frame, method_stop_pc);
1005 if (real_stop_pc == 0)
1006 real_stop_pc = method_stop_pc;
1008 return real_stop_pc;
1011 /* Return nonzero if a type should be passed by reference.
1013 The rule in the v3 ABI document comes from section 3.1.1. If the
1014 type has a non-trivial copy constructor or destructor, then the
1015 caller must make a copy (by calling the copy constructor if there
1016 is one or perform the copy itself otherwise), pass the address of
1017 the copy, and then destroy the temporary (if necessary).
1019 For return values with non-trivial copy constructors or
1020 destructors, space will be allocated in the caller, and a pointer
1021 will be passed as the first argument (preceding "this").
1023 We don't have a bulletproof mechanism for determining whether a
1024 constructor or destructor is trivial. For GCC and DWARF2 debug
1025 information, we can check the artificial flag.
1027 We don't do anything with the constructors or destructors,
1028 but we have to get the argument passing right anyway. */
1030 gnuv3_pass_by_reference (struct type *type)
1032 int fieldnum, fieldelem;
1034 CHECK_TYPEDEF (type);
1036 /* We're only interested in things that can have methods. */
1037 if (TYPE_CODE (type) != TYPE_CODE_STRUCT
1038 && TYPE_CODE (type) != TYPE_CODE_CLASS
1039 && TYPE_CODE (type) != TYPE_CODE_UNION)
1042 for (fieldnum = 0; fieldnum < TYPE_NFN_FIELDS (type); fieldnum++)
1043 for (fieldelem = 0; fieldelem < TYPE_FN_FIELDLIST_LENGTH (type, fieldnum);
1046 struct fn_field *fn = TYPE_FN_FIELDLIST1 (type, fieldnum);
1047 const char *name = TYPE_FN_FIELDLIST_NAME (type, fieldnum);
1048 struct type *fieldtype = TYPE_FN_FIELD_TYPE (fn, fieldelem);
1050 /* If this function is marked as artificial, it is compiler-generated,
1051 and we assume it is trivial. */
1052 if (TYPE_FN_FIELD_ARTIFICIAL (fn, fieldelem))
1055 /* If we've found a destructor, we must pass this by reference. */
1059 /* If the mangled name of this method doesn't indicate that it
1060 is a constructor, we're not interested.
1062 FIXME drow/2007-09-23: We could do this using the name of
1063 the method and the name of the class instead of dealing
1064 with the mangled name. We don't have a convenient function
1065 to strip off both leading scope qualifiers and trailing
1066 template arguments yet. */
1067 if (!is_constructor_name (TYPE_FN_FIELD_PHYSNAME (fn, fieldelem)))
1070 /* If this method takes two arguments, and the second argument is
1071 a reference to this class, then it is a copy constructor. */
1072 if (TYPE_NFIELDS (fieldtype) == 2
1073 && TYPE_CODE (TYPE_FIELD_TYPE (fieldtype, 1)) == TYPE_CODE_REF
1074 && check_typedef (TYPE_TARGET_TYPE (TYPE_FIELD_TYPE (fieldtype,
1079 /* Even if all the constructors and destructors were artificial, one
1080 of them may have invoked a non-artificial constructor or
1081 destructor in a base class. If any base class needs to be passed
1082 by reference, so does this class. Similarly for members, which
1083 are constructed whenever this class is. We do not need to worry
1084 about recursive loops here, since we are only looking at members
1085 of complete class type. Also ignore any static members. */
1086 for (fieldnum = 0; fieldnum < TYPE_NFIELDS (type); fieldnum++)
1087 if (! field_is_static (&TYPE_FIELD (type, fieldnum))
1088 && gnuv3_pass_by_reference (TYPE_FIELD_TYPE (type, fieldnum)))
1095 init_gnuv3_ops (void)
1097 vtable_type_gdbarch_data
1098 = gdbarch_data_register_post_init (build_gdb_vtable_type);
1100 gnu_v3_abi_ops.shortname = "gnu-v3";
1101 gnu_v3_abi_ops.longname = "GNU G++ Version 3 ABI";
1102 gnu_v3_abi_ops.doc = "G++ Version 3 ABI";
1103 gnu_v3_abi_ops.is_destructor_name =
1104 (enum dtor_kinds (*) (const char *))is_gnu_v3_mangled_dtor;
1105 gnu_v3_abi_ops.is_constructor_name =
1106 (enum ctor_kinds (*) (const char *))is_gnu_v3_mangled_ctor;
1107 gnu_v3_abi_ops.is_vtable_name = gnuv3_is_vtable_name;
1108 gnu_v3_abi_ops.is_operator_name = gnuv3_is_operator_name;
1109 gnu_v3_abi_ops.rtti_type = gnuv3_rtti_type;
1110 gnu_v3_abi_ops.virtual_fn_field = gnuv3_virtual_fn_field;
1111 gnu_v3_abi_ops.baseclass_offset = gnuv3_baseclass_offset;
1112 gnu_v3_abi_ops.print_method_ptr = gnuv3_print_method_ptr;
1113 gnu_v3_abi_ops.method_ptr_size = gnuv3_method_ptr_size;
1114 gnu_v3_abi_ops.make_method_ptr = gnuv3_make_method_ptr;
1115 gnu_v3_abi_ops.method_ptr_to_value = gnuv3_method_ptr_to_value;
1116 gnu_v3_abi_ops.print_vtable = gnuv3_print_vtable;
1117 gnu_v3_abi_ops.skip_trampoline = gnuv3_skip_trampoline;
1118 gnu_v3_abi_ops.pass_by_reference = gnuv3_pass_by_reference;
1121 extern initialize_file_ftype _initialize_gnu_v3_abi; /* -Wmissing-prototypes */
1124 _initialize_gnu_v3_abi (void)
1128 register_cp_abi (&gnu_v3_abi_ops);