1 /* Abstraction of GNU v3 abi.
2 Contributed by Jim Blandy <jimb@redhat.com>
4 Copyright (C) 2001-2016 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 "typeprint.h"
31 static struct cp_abi_ops gnu_v3_abi_ops;
33 /* A gdbarch key for std::type_info, in the event that it can't be
34 found in the debug info. */
36 static struct gdbarch_data *std_type_info_gdbarch_data;
40 gnuv3_is_vtable_name (const char *name)
42 return startswith (name, "_ZTV");
46 gnuv3_is_operator_name (const char *name)
48 return startswith (name, "operator");
52 /* To help us find the components of a vtable, we build ourselves a
53 GDB type object representing the vtable structure. Following the
54 V3 ABI, it goes something like this:
56 struct gdb_gnu_v3_abi_vtable {
58 / * An array of virtual call and virtual base offsets. The real
59 length of this array depends on the class hierarchy; we use
60 negative subscripts to access the elements. Yucky, but
61 better than the alternatives. * /
62 ptrdiff_t vcall_and_vbase_offsets[0];
64 / * The offset from a virtual pointer referring to this table
65 to the top of the complete object. * /
66 ptrdiff_t offset_to_top;
68 / * The type_info pointer for this class. This is really a
69 std::type_info *, but GDB doesn't really look at the
70 type_info object itself, so we don't bother to get the type
74 / * Virtual table pointers in objects point here. * /
76 / * Virtual function pointers. Like the vcall/vbase array, the
77 real length of this table depends on the class hierarchy. * /
78 void (*virtual_functions[0]) ();
82 The catch, of course, is that the exact layout of this table
83 depends on the ABI --- word size, endianness, alignment, etc. So
84 the GDB type object is actually a per-architecture kind of thing.
86 vtable_type_gdbarch_data is a gdbarch per-architecture data pointer
87 which refers to the struct type * for this structure, laid out
88 appropriately for the architecture. */
89 static struct gdbarch_data *vtable_type_gdbarch_data;
92 /* Human-readable names for the numbers of the fields above. */
94 vtable_field_vcall_and_vbase_offsets,
95 vtable_field_offset_to_top,
96 vtable_field_type_info,
97 vtable_field_virtual_functions
101 /* Return a GDB type representing `struct gdb_gnu_v3_abi_vtable',
102 described above, laid out appropriately for ARCH.
104 We use this function as the gdbarch per-architecture data
105 initialization function. */
107 build_gdb_vtable_type (struct gdbarch *arch)
110 struct field *field_list, *field;
113 struct type *void_ptr_type
114 = builtin_type (arch)->builtin_data_ptr;
115 struct type *ptr_to_void_fn_type
116 = builtin_type (arch)->builtin_func_ptr;
118 /* ARCH can't give us the true ptrdiff_t type, so we guess. */
119 struct type *ptrdiff_type
120 = arch_integer_type (arch, gdbarch_ptr_bit (arch), 0, "ptrdiff_t");
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. */
127 /* Build the field list. */
128 field_list = XCNEWVEC (struct field, 4);
129 field = &field_list[0];
132 /* ptrdiff_t vcall_and_vbase_offsets[0]; */
133 FIELD_NAME (*field) = "vcall_and_vbase_offsets";
134 FIELD_TYPE (*field) = lookup_array_range_type (ptrdiff_type, 0, -1);
135 SET_FIELD_BITPOS (*field, offset * TARGET_CHAR_BIT);
136 offset += TYPE_LENGTH (FIELD_TYPE (*field));
139 /* ptrdiff_t offset_to_top; */
140 FIELD_NAME (*field) = "offset_to_top";
141 FIELD_TYPE (*field) = ptrdiff_type;
142 SET_FIELD_BITPOS (*field, offset * TARGET_CHAR_BIT);
143 offset += TYPE_LENGTH (FIELD_TYPE (*field));
146 /* void *type_info; */
147 FIELD_NAME (*field) = "type_info";
148 FIELD_TYPE (*field) = void_ptr_type;
149 SET_FIELD_BITPOS (*field, offset * TARGET_CHAR_BIT);
150 offset += TYPE_LENGTH (FIELD_TYPE (*field));
153 /* void (*virtual_functions[0]) (); */
154 FIELD_NAME (*field) = "virtual_functions";
155 FIELD_TYPE (*field) = lookup_array_range_type (ptr_to_void_fn_type, 0, -1);
156 SET_FIELD_BITPOS (*field, offset * TARGET_CHAR_BIT);
157 offset += TYPE_LENGTH (FIELD_TYPE (*field));
160 /* We assumed in the allocation above that there were four fields. */
161 gdb_assert (field == (field_list + 4));
163 t = arch_type (arch, TYPE_CODE_STRUCT, offset, NULL);
164 TYPE_NFIELDS (t) = field - field_list;
165 TYPE_FIELDS (t) = field_list;
166 TYPE_TAG_NAME (t) = "gdb_gnu_v3_abi_vtable";
167 INIT_CPLUS_SPECIFIC (t);
169 return make_type_with_address_space (t, TYPE_INSTANCE_FLAG_CODE_SPACE);
173 /* Return the ptrdiff_t type used in the vtable type. */
175 vtable_ptrdiff_type (struct gdbarch *gdbarch)
177 struct type *vtable_type
178 = (struct type *) gdbarch_data (gdbarch, vtable_type_gdbarch_data);
180 /* The "offset_to_top" field has the appropriate (ptrdiff_t) type. */
181 return TYPE_FIELD_TYPE (vtable_type, vtable_field_offset_to_top);
184 /* Return the offset from the start of the imaginary `struct
185 gdb_gnu_v3_abi_vtable' object to the vtable's "address point"
186 (i.e., where objects' virtual table pointers point). */
188 vtable_address_point_offset (struct gdbarch *gdbarch)
190 struct type *vtable_type
191 = (struct type *) gdbarch_data (gdbarch, vtable_type_gdbarch_data);
193 return (TYPE_FIELD_BITPOS (vtable_type, vtable_field_virtual_functions)
198 /* Determine whether structure TYPE is a dynamic class. Cache the
202 gnuv3_dynamic_class (struct type *type)
204 int fieldnum, fieldelem;
206 type = check_typedef (type);
207 gdb_assert (TYPE_CODE (type) == TYPE_CODE_STRUCT
208 || TYPE_CODE (type) == TYPE_CODE_UNION);
210 if (TYPE_CODE (type) == TYPE_CODE_UNION)
213 if (TYPE_CPLUS_DYNAMIC (type))
214 return TYPE_CPLUS_DYNAMIC (type) == 1;
216 ALLOCATE_CPLUS_STRUCT_TYPE (type);
218 for (fieldnum = 0; fieldnum < TYPE_N_BASECLASSES (type); fieldnum++)
219 if (BASETYPE_VIA_VIRTUAL (type, fieldnum)
220 || gnuv3_dynamic_class (TYPE_FIELD_TYPE (type, fieldnum)))
222 TYPE_CPLUS_DYNAMIC (type) = 1;
226 for (fieldnum = 0; fieldnum < TYPE_NFN_FIELDS (type); fieldnum++)
227 for (fieldelem = 0; fieldelem < TYPE_FN_FIELDLIST_LENGTH (type, fieldnum);
230 struct fn_field *f = TYPE_FN_FIELDLIST1 (type, fieldnum);
232 if (TYPE_FN_FIELD_VIRTUAL_P (f, fieldelem))
234 TYPE_CPLUS_DYNAMIC (type) = 1;
239 TYPE_CPLUS_DYNAMIC (type) = -1;
243 /* Find the vtable for a value of CONTAINER_TYPE located at
244 CONTAINER_ADDR. Return a value of the correct vtable type for this
245 architecture, or NULL if CONTAINER does not have a vtable. */
247 static struct value *
248 gnuv3_get_vtable (struct gdbarch *gdbarch,
249 struct type *container_type, CORE_ADDR container_addr)
251 struct type *vtable_type
252 = (struct type *) gdbarch_data (gdbarch, vtable_type_gdbarch_data);
253 struct type *vtable_pointer_type;
254 struct value *vtable_pointer;
255 CORE_ADDR vtable_address;
257 container_type = check_typedef (container_type);
258 gdb_assert (TYPE_CODE (container_type) == TYPE_CODE_STRUCT);
260 /* If this type does not have a virtual table, don't read the first
262 if (!gnuv3_dynamic_class (container_type))
265 /* We do not consult the debug information to find the virtual table.
266 The ABI specifies that it is always at offset zero in any class,
267 and debug information may not represent it.
269 We avoid using value_contents on principle, because the object might
272 /* Find the type "pointer to virtual table". */
273 vtable_pointer_type = lookup_pointer_type (vtable_type);
275 /* Load it from the start of the class. */
276 vtable_pointer = value_at (vtable_pointer_type, container_addr);
277 vtable_address = value_as_address (vtable_pointer);
279 /* Correct it to point at the start of the virtual table, rather
280 than the address point. */
281 return value_at_lazy (vtable_type,
283 - vtable_address_point_offset (gdbarch));
288 gnuv3_rtti_type (struct value *value,
289 int *full_p, int *top_p, int *using_enc_p)
291 struct gdbarch *gdbarch;
292 struct type *values_type = check_typedef (value_type (value));
293 struct value *vtable;
294 struct minimal_symbol *vtable_symbol;
295 const char *vtable_symbol_name;
296 const char *class_name;
297 struct type *run_time_type;
298 LONGEST offset_to_top;
301 /* We only have RTTI for class objects. */
302 if (TYPE_CODE (values_type) != TYPE_CODE_STRUCT)
305 /* Java doesn't have RTTI following the C++ ABI. */
306 if (TYPE_CPLUS_REALLY_JAVA (values_type))
309 /* Determine architecture. */
310 gdbarch = get_type_arch (values_type);
315 vtable = gnuv3_get_vtable (gdbarch, values_type,
316 value_as_address (value_addr (value)));
320 /* Find the linker symbol for this vtable. */
322 = lookup_minimal_symbol_by_pc (value_address (vtable)
323 + value_embedded_offset (vtable)).minsym;
327 /* The symbol's demangled name should be something like "vtable for
328 CLASS", where CLASS is the name of the run-time type of VALUE.
329 If we didn't like this approach, we could instead look in the
330 type_info object itself to get the class name. But this way
331 should work just as well, and doesn't read target memory. */
332 vtable_symbol_name = MSYMBOL_DEMANGLED_NAME (vtable_symbol);
333 if (vtable_symbol_name == NULL
334 || !startswith (vtable_symbol_name, "vtable for "))
336 warning (_("can't find linker symbol for virtual table for `%s' value"),
337 TYPE_SAFE_NAME (values_type));
338 if (vtable_symbol_name)
339 warning (_(" found `%s' instead"), vtable_symbol_name);
342 class_name = vtable_symbol_name + 11;
344 /* Strip off @plt and version suffixes. */
345 atsign = strchr (class_name, '@');
350 copy = (char *) alloca (atsign - class_name + 1);
351 memcpy (copy, class_name, atsign - class_name);
352 copy[atsign - class_name] = '\0';
356 /* Try to look up the class name as a type name. */
357 /* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */
358 run_time_type = cp_lookup_rtti_type (class_name, NULL);
359 if (run_time_type == NULL)
362 /* Get the offset from VALUE to the top of the complete object.
363 NOTE: this is the reverse of the meaning of *TOP_P. */
365 = value_as_long (value_field (vtable, vtable_field_offset_to_top));
368 *full_p = (- offset_to_top == value_embedded_offset (value)
369 && (TYPE_LENGTH (value_enclosing_type (value))
370 >= TYPE_LENGTH (run_time_type)));
372 *top_p = - offset_to_top;
373 return run_time_type;
376 /* Return a function pointer for CONTAINER's VTABLE_INDEX'th virtual
377 function, of type FNTYPE. */
379 static struct value *
380 gnuv3_get_virtual_fn (struct gdbarch *gdbarch, struct value *container,
381 struct type *fntype, int vtable_index)
383 struct value *vtable, *vfn;
385 /* Every class with virtual functions must have a vtable. */
386 vtable = gnuv3_get_vtable (gdbarch, value_type (container),
387 value_as_address (value_addr (container)));
388 gdb_assert (vtable != NULL);
390 /* Fetch the appropriate function pointer from the vtable. */
391 vfn = value_subscript (value_field (vtable, vtable_field_virtual_functions),
394 /* If this architecture uses function descriptors directly in the vtable,
395 then the address of the vtable entry is actually a "function pointer"
396 (i.e. points to the descriptor). We don't need to scale the index
397 by the size of a function descriptor; GCC does that before outputing
398 debug information. */
399 if (gdbarch_vtable_function_descriptors (gdbarch))
400 vfn = value_addr (vfn);
402 /* Cast the function pointer to the appropriate type. */
403 vfn = value_cast (lookup_pointer_type (fntype), vfn);
408 /* GNU v3 implementation of value_virtual_fn_field. See cp-abi.h
409 for a description of the arguments. */
411 static struct value *
412 gnuv3_virtual_fn_field (struct value **value_p,
413 struct fn_field *f, int j,
414 struct type *vfn_base, int offset)
416 struct type *values_type = check_typedef (value_type (*value_p));
417 struct gdbarch *gdbarch;
419 /* Some simple sanity checks. */
420 if (TYPE_CODE (values_type) != TYPE_CODE_STRUCT)
421 error (_("Only classes can have virtual functions."));
423 /* Determine architecture. */
424 gdbarch = get_type_arch (values_type);
426 /* Cast our value to the base class which defines this virtual
427 function. This takes care of any necessary `this'
429 if (vfn_base != values_type)
430 *value_p = value_cast (vfn_base, *value_p);
432 return gnuv3_get_virtual_fn (gdbarch, *value_p, TYPE_FN_FIELD_TYPE (f, j),
433 TYPE_FN_FIELD_VOFFSET (f, j));
436 /* Compute the offset of the baseclass which is
437 the INDEXth baseclass of class TYPE,
438 for value at VALADDR (in host) at ADDRESS (in target).
439 The result is the offset of the baseclass value relative
440 to (the address of)(ARG) + OFFSET.
442 -1 is returned on error. */
445 gnuv3_baseclass_offset (struct type *type, int index,
446 const bfd_byte *valaddr, int embedded_offset,
447 CORE_ADDR address, const struct value *val)
449 struct gdbarch *gdbarch;
450 struct type *ptr_type;
451 struct value *vtable;
452 struct value *vbase_array;
453 long int cur_base_offset, base_offset;
455 /* Determine architecture. */
456 gdbarch = get_type_arch (type);
457 ptr_type = builtin_type (gdbarch)->builtin_data_ptr;
459 /* If it isn't a virtual base, this is easy. The offset is in the
460 type definition. Likewise for Java, which doesn't really have
461 virtual inheritance in the C++ sense. */
462 if (!BASETYPE_VIA_VIRTUAL (type, index) || TYPE_CPLUS_REALLY_JAVA (type))
463 return TYPE_BASECLASS_BITPOS (type, index) / 8;
465 /* To access a virtual base, we need to use the vbase offset stored in
466 our vtable. Recent GCC versions provide this information. If it isn't
467 available, we could get what we needed from RTTI, or from drawing the
468 complete inheritance graph based on the debug info. Neither is
470 cur_base_offset = TYPE_BASECLASS_BITPOS (type, index) / 8;
471 if (cur_base_offset >= - vtable_address_point_offset (gdbarch))
472 error (_("Expected a negative vbase offset (old compiler?)"));
474 cur_base_offset = cur_base_offset + vtable_address_point_offset (gdbarch);
475 if ((- cur_base_offset) % TYPE_LENGTH (ptr_type) != 0)
476 error (_("Misaligned vbase offset."));
477 cur_base_offset = cur_base_offset / ((int) TYPE_LENGTH (ptr_type));
479 vtable = gnuv3_get_vtable (gdbarch, type, address + embedded_offset);
480 gdb_assert (vtable != NULL);
481 vbase_array = value_field (vtable, vtable_field_vcall_and_vbase_offsets);
482 base_offset = value_as_long (value_subscript (vbase_array, cur_base_offset));
486 /* Locate a virtual method in DOMAIN or its non-virtual base classes
487 which has virtual table index VOFFSET. The method has an associated
488 "this" adjustment of ADJUSTMENT bytes. */
491 gnuv3_find_method_in (struct type *domain, CORE_ADDR voffset,
496 /* Search this class first. */
501 len = TYPE_NFN_FIELDS (domain);
502 for (i = 0; i < len; i++)
507 f = TYPE_FN_FIELDLIST1 (domain, i);
508 len2 = TYPE_FN_FIELDLIST_LENGTH (domain, i);
510 check_stub_method_group (domain, i);
511 for (j = 0; j < len2; j++)
512 if (TYPE_FN_FIELD_VOFFSET (f, j) == voffset)
513 return TYPE_FN_FIELD_PHYSNAME (f, j);
517 /* Next search non-virtual bases. If it's in a virtual base,
518 we're out of luck. */
519 for (i = 0; i < TYPE_N_BASECLASSES (domain); i++)
522 struct type *basetype;
524 if (BASETYPE_VIA_VIRTUAL (domain, i))
527 pos = TYPE_BASECLASS_BITPOS (domain, i) / 8;
528 basetype = TYPE_FIELD_TYPE (domain, i);
529 /* Recurse with a modified adjustment. We don't need to adjust
531 if (adjustment >= pos && adjustment < pos + TYPE_LENGTH (basetype))
532 return gnuv3_find_method_in (basetype, voffset, adjustment - pos);
538 /* Decode GNU v3 method pointer. */
541 gnuv3_decode_method_ptr (struct gdbarch *gdbarch,
542 const gdb_byte *contents,
544 LONGEST *adjustment_p)
546 struct type *funcptr_type = builtin_type (gdbarch)->builtin_func_ptr;
547 struct type *offset_type = vtable_ptrdiff_type (gdbarch);
548 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
550 LONGEST voffset, adjustment;
553 /* Extract the pointer to member. The first element is either a pointer
554 or a vtable offset. For pointers, we need to use extract_typed_address
555 to allow the back-end to convert the pointer to a GDB address -- but
556 vtable offsets we must handle as integers. At this point, we do not
557 yet know which case we have, so we extract the value under both
558 interpretations and choose the right one later on. */
559 ptr_value = extract_typed_address (contents, funcptr_type);
560 voffset = extract_signed_integer (contents,
561 TYPE_LENGTH (funcptr_type), byte_order);
562 contents += TYPE_LENGTH (funcptr_type);
563 adjustment = extract_signed_integer (contents,
564 TYPE_LENGTH (offset_type), byte_order);
566 if (!gdbarch_vbit_in_delta (gdbarch))
569 voffset = voffset ^ vbit;
573 vbit = adjustment & 1;
574 adjustment = adjustment >> 1;
577 *value_p = vbit? voffset : ptr_value;
578 *adjustment_p = adjustment;
582 /* GNU v3 implementation of cplus_print_method_ptr. */
585 gnuv3_print_method_ptr (const gdb_byte *contents,
587 struct ui_file *stream)
589 struct type *self_type = TYPE_SELF_TYPE (type);
590 struct gdbarch *gdbarch = get_type_arch (self_type);
595 /* Extract the pointer to member. */
596 vbit = gnuv3_decode_method_ptr (gdbarch, contents, &ptr_value, &adjustment);
598 /* Check for NULL. */
599 if (ptr_value == 0 && vbit == 0)
601 fprintf_filtered (stream, "NULL");
605 /* Search for a virtual method. */
609 const char *physname;
611 /* It's a virtual table offset, maybe in this class. Search
612 for a field with the correct vtable offset. First convert it
613 to an index, as used in TYPE_FN_FIELD_VOFFSET. */
614 voffset = ptr_value / TYPE_LENGTH (vtable_ptrdiff_type (gdbarch));
616 physname = gnuv3_find_method_in (self_type, voffset, adjustment);
618 /* If we found a method, print that. We don't bother to disambiguate
619 possible paths to the method based on the adjustment. */
622 char *demangled_name = gdb_demangle (physname,
623 DMGL_ANSI | DMGL_PARAMS);
625 fprintf_filtered (stream, "&virtual ");
626 if (demangled_name == NULL)
627 fputs_filtered (physname, stream);
630 fputs_filtered (demangled_name, stream);
631 xfree (demangled_name);
636 else if (ptr_value != 0)
638 /* Found a non-virtual function: print out the type. */
639 fputs_filtered ("(", stream);
640 c_print_type (type, "", stream, -1, 0, &type_print_raw_options);
641 fputs_filtered (") ", stream);
644 /* We didn't find it; print the raw data. */
647 fprintf_filtered (stream, "&virtual table offset ");
648 print_longest (stream, 'd', 1, ptr_value);
652 struct value_print_options opts;
654 get_user_print_options (&opts);
655 print_address_demangle (&opts, gdbarch, ptr_value, stream, demangle);
660 fprintf_filtered (stream, ", this adjustment ");
661 print_longest (stream, 'd', 1, adjustment);
665 /* GNU v3 implementation of cplus_method_ptr_size. */
668 gnuv3_method_ptr_size (struct type *type)
670 struct gdbarch *gdbarch = get_type_arch (type);
672 return 2 * TYPE_LENGTH (builtin_type (gdbarch)->builtin_data_ptr);
675 /* GNU v3 implementation of cplus_make_method_ptr. */
678 gnuv3_make_method_ptr (struct type *type, gdb_byte *contents,
679 CORE_ADDR value, int is_virtual)
681 struct gdbarch *gdbarch = get_type_arch (type);
682 int size = TYPE_LENGTH (builtin_type (gdbarch)->builtin_data_ptr);
683 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
685 /* FIXME drow/2006-12-24: The adjustment of "this" is currently
686 always zero, since the method pointer is of the correct type.
687 But if the method pointer came from a base class, this is
688 incorrect - it should be the offset to the base. The best
689 fix might be to create the pointer to member pointing at the
690 base class and cast it to the derived class, but that requires
691 support for adjusting pointers to members when casting them -
692 not currently supported by GDB. */
694 if (!gdbarch_vbit_in_delta (gdbarch))
696 store_unsigned_integer (contents, size, byte_order, value | is_virtual);
697 store_unsigned_integer (contents + size, size, byte_order, 0);
701 store_unsigned_integer (contents, size, byte_order, value);
702 store_unsigned_integer (contents + size, size, byte_order, is_virtual);
706 /* GNU v3 implementation of cplus_method_ptr_to_value. */
708 static struct value *
709 gnuv3_method_ptr_to_value (struct value **this_p, struct value *method_ptr)
711 struct gdbarch *gdbarch;
712 const gdb_byte *contents = value_contents (method_ptr);
714 struct type *self_type, *final_type, *method_type;
718 self_type = TYPE_SELF_TYPE (check_typedef (value_type (method_ptr)));
719 final_type = lookup_pointer_type (self_type);
721 method_type = TYPE_TARGET_TYPE (check_typedef (value_type (method_ptr)));
723 /* Extract the pointer to member. */
724 gdbarch = get_type_arch (self_type);
725 vbit = gnuv3_decode_method_ptr (gdbarch, contents, &ptr_value, &adjustment);
727 /* First convert THIS to match the containing type of the pointer to
728 member. This cast may adjust the value of THIS. */
729 *this_p = value_cast (final_type, *this_p);
731 /* Then apply whatever adjustment is necessary. This creates a somewhat
732 strange pointer: it claims to have type FINAL_TYPE, but in fact it
733 might not be a valid FINAL_TYPE. For instance, it might be a
734 base class of FINAL_TYPE. And if it's not the primary base class,
735 then printing it out as a FINAL_TYPE object would produce some pretty
738 But we don't really know the type of the first argument in
739 METHOD_TYPE either, which is why this happens. We can't
740 dereference this later as a FINAL_TYPE, but once we arrive in the
741 called method we'll have debugging information for the type of
742 "this" - and that'll match the value we produce here.
744 You can provoke this case by casting a Base::* to a Derived::*, for
746 *this_p = value_cast (builtin_type (gdbarch)->builtin_data_ptr, *this_p);
747 *this_p = value_ptradd (*this_p, adjustment);
748 *this_p = value_cast (final_type, *this_p);
754 voffset = ptr_value / TYPE_LENGTH (vtable_ptrdiff_type (gdbarch));
755 return gnuv3_get_virtual_fn (gdbarch, value_ind (*this_p),
756 method_type, voffset);
759 return value_from_pointer (lookup_pointer_type (method_type), ptr_value);
762 /* Objects of this type are stored in a hash table and a vector when
763 printing the vtables for a class. */
765 struct value_and_voffset
767 /* The value representing the object. */
770 /* The maximum vtable offset we've found for any object at this
771 offset in the outermost object. */
775 typedef struct value_and_voffset *value_and_voffset_p;
776 DEF_VEC_P (value_and_voffset_p);
778 /* Hash function for value_and_voffset. */
781 hash_value_and_voffset (const void *p)
783 const struct value_and_voffset *o = (const struct value_and_voffset *) p;
785 return value_address (o->value) + value_embedded_offset (o->value);
788 /* Equality function for value_and_voffset. */
791 eq_value_and_voffset (const void *a, const void *b)
793 const struct value_and_voffset *ova = (const struct value_and_voffset *) a;
794 const struct value_and_voffset *ovb = (const struct value_and_voffset *) b;
796 return (value_address (ova->value) + value_embedded_offset (ova->value)
797 == value_address (ovb->value) + value_embedded_offset (ovb->value));
800 /* qsort comparison function for value_and_voffset. */
803 compare_value_and_voffset (const void *a, const void *b)
805 const struct value_and_voffset * const *ova
806 = (const struct value_and_voffset * const *) a;
807 CORE_ADDR addra = (value_address ((*ova)->value)
808 + value_embedded_offset ((*ova)->value));
809 const struct value_and_voffset * const *ovb
810 = (const struct value_and_voffset * const *) b;
811 CORE_ADDR addrb = (value_address ((*ovb)->value)
812 + value_embedded_offset ((*ovb)->value));
821 /* A helper function used when printing vtables. This determines the
822 key (most derived) sub-object at each address and also computes the
823 maximum vtable offset seen for the corresponding vtable. Updates
824 OFFSET_HASH and OFFSET_VEC with a new value_and_voffset object, if
825 needed. VALUE is the object to examine. */
828 compute_vtable_size (htab_t offset_hash,
829 VEC (value_and_voffset_p) **offset_vec,
833 struct type *type = check_typedef (value_type (value));
835 struct value_and_voffset search_vo, *current_vo;
837 gdb_assert (TYPE_CODE (type) == TYPE_CODE_STRUCT);
839 /* If the object is not dynamic, then we are done; as it cannot have
840 dynamic base types either. */
841 if (!gnuv3_dynamic_class (type))
844 /* Update the hash and the vec, if needed. */
845 search_vo.value = value;
846 slot = htab_find_slot (offset_hash, &search_vo, INSERT);
848 current_vo = (struct value_and_voffset *) *slot;
851 current_vo = XNEW (struct value_and_voffset);
852 current_vo->value = value;
853 current_vo->max_voffset = -1;
855 VEC_safe_push (value_and_voffset_p, *offset_vec, current_vo);
858 /* Update the value_and_voffset object with the highest vtable
859 offset from this class. */
860 for (i = 0; i < TYPE_NFN_FIELDS (type); ++i)
863 struct fn_field *fn = TYPE_FN_FIELDLIST1 (type, i);
865 for (j = 0; j < TYPE_FN_FIELDLIST_LENGTH (type, i); ++j)
867 if (TYPE_FN_FIELD_VIRTUAL_P (fn, j))
869 int voffset = TYPE_FN_FIELD_VOFFSET (fn, j);
871 if (voffset > current_vo->max_voffset)
872 current_vo->max_voffset = voffset;
877 /* Recurse into base classes. */
878 for (i = 0; i < TYPE_N_BASECLASSES (type); ++i)
879 compute_vtable_size (offset_hash, offset_vec, value_field (value, i));
882 /* Helper for gnuv3_print_vtable that prints a single vtable. */
885 print_one_vtable (struct gdbarch *gdbarch, struct value *value,
887 struct value_print_options *opts)
890 struct type *type = check_typedef (value_type (value));
891 struct value *vtable;
894 vtable = gnuv3_get_vtable (gdbarch, type,
895 value_address (value)
896 + value_embedded_offset (value));
897 vt_addr = value_address (value_field (vtable,
898 vtable_field_virtual_functions));
900 printf_filtered (_("vtable for '%s' @ %s (subobject @ %s):\n"),
901 TYPE_SAFE_NAME (type),
902 paddress (gdbarch, vt_addr),
903 paddress (gdbarch, (value_address (value)
904 + value_embedded_offset (value))));
906 for (i = 0; i <= max_voffset; ++i)
908 /* Initialize it just to avoid a GCC false warning. */
913 printf_filtered ("[%d]: ", i);
915 vfn = value_subscript (value_field (vtable,
916 vtable_field_virtual_functions),
919 if (gdbarch_vtable_function_descriptors (gdbarch))
920 vfn = value_addr (vfn);
924 addr = value_as_address (vfn);
926 CATCH (ex, RETURN_MASK_ERROR)
928 printf_filtered (_("<error: %s>"), ex.message);
934 print_function_pointer_address (opts, gdbarch, addr, gdb_stdout);
935 printf_filtered ("\n");
939 /* Implementation of the print_vtable method. */
942 gnuv3_print_vtable (struct value *value)
944 struct gdbarch *gdbarch;
946 struct value *vtable;
947 struct value_print_options opts;
949 struct cleanup *cleanup;
950 VEC (value_and_voffset_p) *result_vec = NULL;
951 struct value_and_voffset *iter;
954 value = coerce_ref (value);
955 type = check_typedef (value_type (value));
956 if (TYPE_CODE (type) == TYPE_CODE_PTR)
958 value = value_ind (value);
959 type = check_typedef (value_type (value));
962 get_user_print_options (&opts);
964 /* Respect 'set print object'. */
965 if (opts.objectprint)
967 value = value_full_object (value, NULL, 0, 0, 0);
968 type = check_typedef (value_type (value));
971 gdbarch = get_type_arch (type);
974 if (TYPE_CODE (type) == TYPE_CODE_STRUCT)
975 vtable = gnuv3_get_vtable (gdbarch, type,
976 value_as_address (value_addr (value)));
980 printf_filtered (_("This object does not have a virtual function table\n"));
984 offset_hash = htab_create_alloc (1, hash_value_and_voffset,
985 eq_value_and_voffset,
986 xfree, xcalloc, xfree);
987 cleanup = make_cleanup_htab_delete (offset_hash);
988 make_cleanup (VEC_cleanup (value_and_voffset_p), &result_vec);
990 compute_vtable_size (offset_hash, &result_vec, value);
992 qsort (VEC_address (value_and_voffset_p, result_vec),
993 VEC_length (value_and_voffset_p, result_vec),
994 sizeof (value_and_voffset_p),
995 compare_value_and_voffset);
998 for (i = 0; VEC_iterate (value_and_voffset_p, result_vec, i, iter); ++i)
1000 if (iter->max_voffset >= 0)
1003 printf_filtered ("\n");
1004 print_one_vtable (gdbarch, iter->value, iter->max_voffset, &opts);
1009 do_cleanups (cleanup);
1012 /* Return a GDB type representing `struct std::type_info', laid out
1013 appropriately for ARCH.
1015 We use this function as the gdbarch per-architecture data
1016 initialization function. */
1019 build_std_type_info_type (struct gdbarch *arch)
1022 struct field *field_list, *field;
1024 struct type *void_ptr_type
1025 = builtin_type (arch)->builtin_data_ptr;
1026 struct type *char_type
1027 = builtin_type (arch)->builtin_char;
1028 struct type *char_ptr_type
1029 = make_pointer_type (make_cv_type (1, 0, char_type, NULL), NULL);
1031 field_list = XCNEWVEC (struct field, 2);
1032 field = &field_list[0];
1036 FIELD_NAME (*field) = "_vptr.type_info";
1037 FIELD_TYPE (*field) = void_ptr_type;
1038 SET_FIELD_BITPOS (*field, offset * TARGET_CHAR_BIT);
1039 offset += TYPE_LENGTH (FIELD_TYPE (*field));
1043 FIELD_NAME (*field) = "__name";
1044 FIELD_TYPE (*field) = char_ptr_type;
1045 SET_FIELD_BITPOS (*field, offset * TARGET_CHAR_BIT);
1046 offset += TYPE_LENGTH (FIELD_TYPE (*field));
1049 gdb_assert (field == (field_list + 2));
1051 t = arch_type (arch, TYPE_CODE_STRUCT, offset, NULL);
1052 TYPE_NFIELDS (t) = field - field_list;
1053 TYPE_FIELDS (t) = field_list;
1054 TYPE_TAG_NAME (t) = "gdb_gnu_v3_type_info";
1055 INIT_CPLUS_SPECIFIC (t);
1060 /* Implement the 'get_typeid_type' method. */
1062 static struct type *
1063 gnuv3_get_typeid_type (struct gdbarch *gdbarch)
1065 struct symbol *typeinfo;
1066 struct type *typeinfo_type;
1068 typeinfo = lookup_symbol ("std::type_info", NULL, STRUCT_DOMAIN,
1070 if (typeinfo == NULL)
1072 = (struct type *) gdbarch_data (gdbarch, std_type_info_gdbarch_data);
1074 typeinfo_type = SYMBOL_TYPE (typeinfo);
1076 return typeinfo_type;
1079 /* Implement the 'get_typeid' method. */
1081 static struct value *
1082 gnuv3_get_typeid (struct value *value)
1084 struct type *typeinfo_type;
1086 struct gdbarch *gdbarch;
1087 struct cleanup *cleanup;
1088 struct value *result;
1089 char *type_name, *canonical;
1091 /* We have to handle values a bit trickily here, to allow this code
1092 to work properly with non_lvalue values that are really just
1094 if (value_lval_const (value) == lval_memory)
1095 value = coerce_ref (value);
1097 type = check_typedef (value_type (value));
1099 /* In the non_lvalue case, a reference might have slipped through
1101 if (TYPE_CODE (type) == TYPE_CODE_REF)
1102 type = check_typedef (TYPE_TARGET_TYPE (type));
1104 /* Ignore top-level cv-qualifiers. */
1105 type = make_cv_type (0, 0, type, NULL);
1106 gdbarch = get_type_arch (type);
1108 type_name = type_to_string (type);
1109 if (type_name == NULL)
1110 error (_("cannot find typeinfo for unnamed type"));
1111 cleanup = make_cleanup (xfree, type_name);
1113 /* We need to canonicalize the type name here, because we do lookups
1114 using the demangled name, and so we must match the format it
1115 uses. E.g., GDB tends to use "const char *" as a type name, but
1116 the demangler uses "char const *". */
1117 canonical = cp_canonicalize_string (type_name);
1118 if (canonical != NULL)
1120 make_cleanup (xfree, canonical);
1121 type_name = canonical;
1124 typeinfo_type = gnuv3_get_typeid_type (gdbarch);
1126 /* We check for lval_memory because in the "typeid (type-id)" case,
1127 the type is passed via a not_lval value object. */
1128 if (TYPE_CODE (type) == TYPE_CODE_STRUCT
1129 && value_lval_const (value) == lval_memory
1130 && gnuv3_dynamic_class (type))
1132 struct value *vtable, *typeinfo_value;
1133 CORE_ADDR address = value_address (value) + value_embedded_offset (value);
1135 vtable = gnuv3_get_vtable (gdbarch, type, address);
1137 error (_("cannot find typeinfo for object of type '%s'"), type_name);
1138 typeinfo_value = value_field (vtable, vtable_field_type_info);
1139 result = value_ind (value_cast (make_pointer_type (typeinfo_type, NULL),
1145 struct bound_minimal_symbol minsym;
1147 sym_name = concat ("typeinfo for ", type_name, (char *) NULL);
1148 make_cleanup (xfree, sym_name);
1149 minsym = lookup_minimal_symbol (sym_name, NULL, NULL);
1151 if (minsym.minsym == NULL)
1152 error (_("could not find typeinfo symbol for '%s'"), type_name);
1154 result = value_at_lazy (typeinfo_type, BMSYMBOL_VALUE_ADDRESS (minsym));
1157 do_cleanups (cleanup);
1161 /* Implement the 'get_typename_from_type_info' method. */
1164 gnuv3_get_typename_from_type_info (struct value *type_info_ptr)
1166 struct gdbarch *gdbarch = get_type_arch (value_type (type_info_ptr));
1167 struct bound_minimal_symbol typeinfo_sym;
1169 const char *symname;
1170 const char *class_name;
1173 addr = value_as_address (type_info_ptr);
1174 typeinfo_sym = lookup_minimal_symbol_by_pc (addr);
1175 if (typeinfo_sym.minsym == NULL)
1176 error (_("could not find minimal symbol for typeinfo address %s"),
1177 paddress (gdbarch, addr));
1179 #define TYPEINFO_PREFIX "typeinfo for "
1180 #define TYPEINFO_PREFIX_LEN (sizeof (TYPEINFO_PREFIX) - 1)
1181 symname = MSYMBOL_DEMANGLED_NAME (typeinfo_sym.minsym);
1182 if (symname == NULL || strncmp (symname, TYPEINFO_PREFIX,
1183 TYPEINFO_PREFIX_LEN))
1184 error (_("typeinfo symbol '%s' has unexpected name"),
1185 MSYMBOL_LINKAGE_NAME (typeinfo_sym.minsym));
1186 class_name = symname + TYPEINFO_PREFIX_LEN;
1188 /* Strip off @plt and version suffixes. */
1189 atsign = strchr (class_name, '@');
1191 return savestring (class_name, atsign - class_name);
1192 return xstrdup (class_name);
1195 /* Implement the 'get_type_from_type_info' method. */
1197 static struct type *
1198 gnuv3_get_type_from_type_info (struct value *type_info_ptr)
1201 struct cleanup *cleanup;
1202 struct value *type_val;
1203 struct expression *expr;
1204 struct type *result;
1206 type_name = gnuv3_get_typename_from_type_info (type_info_ptr);
1207 cleanup = make_cleanup (xfree, type_name);
1209 /* We have to parse the type name, since in general there is not a
1210 symbol for a type. This is somewhat bogus since there may be a
1211 mis-parse. Another approach might be to re-use the demangler's
1212 internal form to reconstruct the type somehow. */
1214 expr = parse_expression (type_name);
1215 make_cleanup (xfree, expr);
1217 type_val = evaluate_type (expr);
1218 result = value_type (type_val);
1220 do_cleanups (cleanup);
1224 /* Determine if we are currently in a C++ thunk. If so, get the address
1225 of the routine we are thunking to and continue to there instead. */
1228 gnuv3_skip_trampoline (struct frame_info *frame, CORE_ADDR stop_pc)
1230 CORE_ADDR real_stop_pc, method_stop_pc, func_addr;
1231 struct gdbarch *gdbarch = get_frame_arch (frame);
1232 struct bound_minimal_symbol thunk_sym, fn_sym;
1233 struct obj_section *section;
1234 const char *thunk_name, *fn_name;
1236 real_stop_pc = gdbarch_skip_trampoline_code (gdbarch, frame, stop_pc);
1237 if (real_stop_pc == 0)
1238 real_stop_pc = stop_pc;
1240 /* Find the linker symbol for this potential thunk. */
1241 thunk_sym = lookup_minimal_symbol_by_pc (real_stop_pc);
1242 section = find_pc_section (real_stop_pc);
1243 if (thunk_sym.minsym == NULL || section == NULL)
1246 /* The symbol's demangled name should be something like "virtual
1247 thunk to FUNCTION", where FUNCTION is the name of the function
1248 being thunked to. */
1249 thunk_name = MSYMBOL_DEMANGLED_NAME (thunk_sym.minsym);
1250 if (thunk_name == NULL || strstr (thunk_name, " thunk to ") == NULL)
1253 fn_name = strstr (thunk_name, " thunk to ") + strlen (" thunk to ");
1254 fn_sym = lookup_minimal_symbol (fn_name, NULL, section->objfile);
1255 if (fn_sym.minsym == NULL)
1258 method_stop_pc = BMSYMBOL_VALUE_ADDRESS (fn_sym);
1260 /* Some targets have minimal symbols pointing to function descriptors
1261 (powerpc 64 for example). Make sure to retrieve the address
1262 of the real function from the function descriptor before passing on
1263 the address to other layers of GDB. */
1264 func_addr = gdbarch_convert_from_func_ptr_addr (gdbarch, method_stop_pc,
1267 method_stop_pc = func_addr;
1269 real_stop_pc = gdbarch_skip_trampoline_code
1270 (gdbarch, frame, method_stop_pc);
1271 if (real_stop_pc == 0)
1272 real_stop_pc = method_stop_pc;
1274 return real_stop_pc;
1277 /* Return nonzero if a type should be passed by reference.
1279 The rule in the v3 ABI document comes from section 3.1.1. If the
1280 type has a non-trivial copy constructor or destructor, then the
1281 caller must make a copy (by calling the copy constructor if there
1282 is one or perform the copy itself otherwise), pass the address of
1283 the copy, and then destroy the temporary (if necessary).
1285 For return values with non-trivial copy constructors or
1286 destructors, space will be allocated in the caller, and a pointer
1287 will be passed as the first argument (preceding "this").
1289 We don't have a bulletproof mechanism for determining whether a
1290 constructor or destructor is trivial. For GCC and DWARF2 debug
1291 information, we can check the artificial flag.
1293 We don't do anything with the constructors or destructors,
1294 but we have to get the argument passing right anyway. */
1296 gnuv3_pass_by_reference (struct type *type)
1298 int fieldnum, fieldelem;
1300 type = check_typedef (type);
1302 /* We're only interested in things that can have methods. */
1303 if (TYPE_CODE (type) != TYPE_CODE_STRUCT
1304 && TYPE_CODE (type) != TYPE_CODE_UNION)
1307 /* A dynamic class has a non-trivial copy constructor.
1308 See c++98 section 12.8 Copying class objects [class.copy]. */
1309 if (gnuv3_dynamic_class (type))
1312 for (fieldnum = 0; fieldnum < TYPE_NFN_FIELDS (type); fieldnum++)
1313 for (fieldelem = 0; fieldelem < TYPE_FN_FIELDLIST_LENGTH (type, fieldnum);
1316 struct fn_field *fn = TYPE_FN_FIELDLIST1 (type, fieldnum);
1317 const char *name = TYPE_FN_FIELDLIST_NAME (type, fieldnum);
1318 struct type *fieldtype = TYPE_FN_FIELD_TYPE (fn, fieldelem);
1320 /* If this function is marked as artificial, it is compiler-generated,
1321 and we assume it is trivial. */
1322 if (TYPE_FN_FIELD_ARTIFICIAL (fn, fieldelem))
1325 /* If we've found a destructor, we must pass this by reference. */
1329 /* If the mangled name of this method doesn't indicate that it
1330 is a constructor, we're not interested.
1332 FIXME drow/2007-09-23: We could do this using the name of
1333 the method and the name of the class instead of dealing
1334 with the mangled name. We don't have a convenient function
1335 to strip off both leading scope qualifiers and trailing
1336 template arguments yet. */
1337 if (!is_constructor_name (TYPE_FN_FIELD_PHYSNAME (fn, fieldelem))
1338 && !TYPE_FN_FIELD_CONSTRUCTOR (fn, fieldelem))
1341 /* If this method takes two arguments, and the second argument is
1342 a reference to this class, then it is a copy constructor. */
1343 if (TYPE_NFIELDS (fieldtype) == 2)
1345 struct type *arg_type = TYPE_FIELD_TYPE (fieldtype, 1);
1347 if (TYPE_CODE (arg_type) == TYPE_CODE_REF)
1349 struct type *arg_target_type;
1351 arg_target_type = check_typedef (TYPE_TARGET_TYPE (arg_type));
1352 if (class_types_same_p (arg_target_type, type))
1358 /* Even if all the constructors and destructors were artificial, one
1359 of them may have invoked a non-artificial constructor or
1360 destructor in a base class. If any base class needs to be passed
1361 by reference, so does this class. Similarly for members, which
1362 are constructed whenever this class is. We do not need to worry
1363 about recursive loops here, since we are only looking at members
1364 of complete class type. Also ignore any static members. */
1365 for (fieldnum = 0; fieldnum < TYPE_NFIELDS (type); fieldnum++)
1366 if (! field_is_static (&TYPE_FIELD (type, fieldnum))
1367 && gnuv3_pass_by_reference (TYPE_FIELD_TYPE (type, fieldnum)))
1374 init_gnuv3_ops (void)
1376 vtable_type_gdbarch_data
1377 = gdbarch_data_register_post_init (build_gdb_vtable_type);
1378 std_type_info_gdbarch_data
1379 = gdbarch_data_register_post_init (build_std_type_info_type);
1381 gnu_v3_abi_ops.shortname = "gnu-v3";
1382 gnu_v3_abi_ops.longname = "GNU G++ Version 3 ABI";
1383 gnu_v3_abi_ops.doc = "G++ Version 3 ABI";
1384 gnu_v3_abi_ops.is_destructor_name =
1385 (enum dtor_kinds (*) (const char *))is_gnu_v3_mangled_dtor;
1386 gnu_v3_abi_ops.is_constructor_name =
1387 (enum ctor_kinds (*) (const char *))is_gnu_v3_mangled_ctor;
1388 gnu_v3_abi_ops.is_vtable_name = gnuv3_is_vtable_name;
1389 gnu_v3_abi_ops.is_operator_name = gnuv3_is_operator_name;
1390 gnu_v3_abi_ops.rtti_type = gnuv3_rtti_type;
1391 gnu_v3_abi_ops.virtual_fn_field = gnuv3_virtual_fn_field;
1392 gnu_v3_abi_ops.baseclass_offset = gnuv3_baseclass_offset;
1393 gnu_v3_abi_ops.print_method_ptr = gnuv3_print_method_ptr;
1394 gnu_v3_abi_ops.method_ptr_size = gnuv3_method_ptr_size;
1395 gnu_v3_abi_ops.make_method_ptr = gnuv3_make_method_ptr;
1396 gnu_v3_abi_ops.method_ptr_to_value = gnuv3_method_ptr_to_value;
1397 gnu_v3_abi_ops.print_vtable = gnuv3_print_vtable;
1398 gnu_v3_abi_ops.get_typeid = gnuv3_get_typeid;
1399 gnu_v3_abi_ops.get_typeid_type = gnuv3_get_typeid_type;
1400 gnu_v3_abi_ops.get_type_from_type_info = gnuv3_get_type_from_type_info;
1401 gnu_v3_abi_ops.get_typename_from_type_info
1402 = gnuv3_get_typename_from_type_info;
1403 gnu_v3_abi_ops.skip_trampoline = gnuv3_skip_trampoline;
1404 gnu_v3_abi_ops.pass_by_reference = gnuv3_pass_by_reference;
1407 extern initialize_file_ftype _initialize_gnu_v3_abi; /* -Wmissing-prototypes */
1410 _initialize_gnu_v3_abi (void)
1414 register_cp_abi (&gnu_v3_abi_ops);
1415 set_cp_abi_as_auto_default (gnu_v3_abi_ops.shortname);