1 /* Abstraction of GNU v3 abi.
2 Contributed by Jim Blandy <jimb@redhat.com>
4 Copyright (C) 2001, 2002, 2003, 2005, 2006, 2007, 2008, 2009, 2010, 2011
5 Free Software Foundation, Inc.
7 This file is part of GDB.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or
12 (at your option) any later version.
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.
19 You should have received a copy of the GNU General Public License
20 along with this program. If not, see <http://www.gnu.org/licenses/>. */
25 #include "cp-support.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 /* Determine architecture. */
291 gdbarch
= get_type_arch (values_type
);
296 vtable
= gnuv3_get_vtable (gdbarch
, value_type (value
),
297 value_as_address (value_addr (value
)));
301 /* Find the linker symbol for this vtable. */
303 = lookup_minimal_symbol_by_pc (value_address (vtable
)
304 + value_embedded_offset (vtable
));
308 /* The symbol's demangled name should be something like "vtable for
309 CLASS", where CLASS is the name of the run-time type of VALUE.
310 If we didn't like this approach, we could instead look in the
311 type_info object itself to get the class name. But this way
312 should work just as well, and doesn't read target memory. */
313 vtable_symbol_name
= SYMBOL_DEMANGLED_NAME (vtable_symbol
);
314 if (vtable_symbol_name
== NULL
315 || strncmp (vtable_symbol_name
, "vtable for ", 11))
317 warning (_("can't find linker symbol for virtual table for `%s' value"),
318 TYPE_NAME (values_type
));
319 if (vtable_symbol_name
)
320 warning (_(" found `%s' instead"), vtable_symbol_name
);
323 class_name
= vtable_symbol_name
+ 11;
325 /* Try to look up the class name as a type name. */
326 /* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */
327 run_time_type
= cp_lookup_rtti_type (class_name
, NULL
);
328 if (run_time_type
== NULL
)
331 /* Get the offset from VALUE to the top of the complete object.
332 NOTE: this is the reverse of the meaning of *TOP_P. */
334 = value_as_long (value_field (vtable
, vtable_field_offset_to_top
));
337 *full_p
= (- offset_to_top
== value_embedded_offset (value
)
338 && (TYPE_LENGTH (value_enclosing_type (value
))
339 >= TYPE_LENGTH (run_time_type
)));
341 *top_p
= - offset_to_top
;
342 return run_time_type
;
345 /* Return a function pointer for CONTAINER's VTABLE_INDEX'th virtual
346 function, of type FNTYPE. */
348 static struct value
*
349 gnuv3_get_virtual_fn (struct gdbarch
*gdbarch
, struct value
*container
,
350 struct type
*fntype
, int vtable_index
)
352 struct value
*vtable
, *vfn
;
354 /* Every class with virtual functions must have a vtable. */
355 vtable
= gnuv3_get_vtable (gdbarch
, value_type (container
),
356 value_as_address (value_addr (container
)));
357 gdb_assert (vtable
!= NULL
);
359 /* Fetch the appropriate function pointer from the vtable. */
360 vfn
= value_subscript (value_field (vtable
, vtable_field_virtual_functions
),
363 /* If this architecture uses function descriptors directly in the vtable,
364 then the address of the vtable entry is actually a "function pointer"
365 (i.e. points to the descriptor). We don't need to scale the index
366 by the size of a function descriptor; GCC does that before outputing
367 debug information. */
368 if (gdbarch_vtable_function_descriptors (gdbarch
))
369 vfn
= value_addr (vfn
);
371 /* Cast the function pointer to the appropriate type. */
372 vfn
= value_cast (lookup_pointer_type (fntype
), vfn
);
377 /* GNU v3 implementation of value_virtual_fn_field. See cp-abi.h
378 for a description of the arguments. */
380 static struct value
*
381 gnuv3_virtual_fn_field (struct value
**value_p
,
382 struct fn_field
*f
, int j
,
383 struct type
*vfn_base
, int offset
)
385 struct type
*values_type
= check_typedef (value_type (*value_p
));
386 struct gdbarch
*gdbarch
;
388 /* Some simple sanity checks. */
389 if (TYPE_CODE (values_type
) != TYPE_CODE_CLASS
)
390 error (_("Only classes can have virtual functions."));
392 /* Determine architecture. */
393 gdbarch
= get_type_arch (values_type
);
395 /* Cast our value to the base class which defines this virtual
396 function. This takes care of any necessary `this'
398 if (vfn_base
!= values_type
)
399 *value_p
= value_cast (vfn_base
, *value_p
);
401 return gnuv3_get_virtual_fn (gdbarch
, *value_p
, TYPE_FN_FIELD_TYPE (f
, j
),
402 TYPE_FN_FIELD_VOFFSET (f
, j
));
405 /* Compute the offset of the baseclass which is
406 the INDEXth baseclass of class TYPE,
407 for value at VALADDR (in host) at ADDRESS (in target).
408 The result is the offset of the baseclass value relative
409 to (the address of)(ARG) + OFFSET.
411 -1 is returned on error. */
414 gnuv3_baseclass_offset (struct type
*type
, int index
,
415 const bfd_byte
*valaddr
, int embedded_offset
,
416 CORE_ADDR address
, const struct value
*val
)
418 struct gdbarch
*gdbarch
;
419 struct type
*ptr_type
;
420 struct value
*vtable
;
421 struct value
*vbase_array
;
422 long int cur_base_offset
, base_offset
;
424 /* Determine architecture. */
425 gdbarch
= get_type_arch (type
);
426 ptr_type
= builtin_type (gdbarch
)->builtin_data_ptr
;
428 /* If it isn't a virtual base, this is easy. The offset is in the
430 if (!BASETYPE_VIA_VIRTUAL (type
, index
))
431 return TYPE_BASECLASS_BITPOS (type
, index
) / 8;
433 /* To access a virtual base, we need to use the vbase offset stored in
434 our vtable. Recent GCC versions provide this information. If it isn't
435 available, we could get what we needed from RTTI, or from drawing the
436 complete inheritance graph based on the debug info. Neither is
438 cur_base_offset
= TYPE_BASECLASS_BITPOS (type
, index
) / 8;
439 if (cur_base_offset
>= - vtable_address_point_offset (gdbarch
))
440 error (_("Expected a negative vbase offset (old compiler?)"));
442 cur_base_offset
= cur_base_offset
+ vtable_address_point_offset (gdbarch
);
443 if ((- cur_base_offset
) % TYPE_LENGTH (ptr_type
) != 0)
444 error (_("Misaligned vbase offset."));
445 cur_base_offset
= cur_base_offset
/ ((int) TYPE_LENGTH (ptr_type
));
447 vtable
= gnuv3_get_vtable (gdbarch
, type
, address
+ embedded_offset
);
448 gdb_assert (vtable
!= NULL
);
449 vbase_array
= value_field (vtable
, vtable_field_vcall_and_vbase_offsets
);
450 base_offset
= value_as_long (value_subscript (vbase_array
, cur_base_offset
));
454 /* Locate a virtual method in DOMAIN or its non-virtual base classes
455 which has virtual table index VOFFSET. The method has an associated
456 "this" adjustment of ADJUSTMENT bytes. */
459 gnuv3_find_method_in (struct type
*domain
, CORE_ADDR voffset
,
464 /* Search this class first. */
469 len
= TYPE_NFN_FIELDS (domain
);
470 for (i
= 0; i
< len
; i
++)
475 f
= TYPE_FN_FIELDLIST1 (domain
, i
);
476 len2
= TYPE_FN_FIELDLIST_LENGTH (domain
, i
);
478 check_stub_method_group (domain
, i
);
479 for (j
= 0; j
< len2
; j
++)
480 if (TYPE_FN_FIELD_VOFFSET (f
, j
) == voffset
)
481 return TYPE_FN_FIELD_PHYSNAME (f
, j
);
485 /* Next search non-virtual bases. If it's in a virtual base,
486 we're out of luck. */
487 for (i
= 0; i
< TYPE_N_BASECLASSES (domain
); i
++)
490 struct type
*basetype
;
492 if (BASETYPE_VIA_VIRTUAL (domain
, i
))
495 pos
= TYPE_BASECLASS_BITPOS (domain
, i
) / 8;
496 basetype
= TYPE_FIELD_TYPE (domain
, i
);
497 /* Recurse with a modified adjustment. We don't need to adjust
499 if (adjustment
>= pos
&& adjustment
< pos
+ TYPE_LENGTH (basetype
))
500 return gnuv3_find_method_in (basetype
, voffset
, adjustment
- pos
);
506 /* Decode GNU v3 method pointer. */
509 gnuv3_decode_method_ptr (struct gdbarch
*gdbarch
,
510 const gdb_byte
*contents
,
512 LONGEST
*adjustment_p
)
514 struct type
*funcptr_type
= builtin_type (gdbarch
)->builtin_func_ptr
;
515 struct type
*offset_type
= vtable_ptrdiff_type (gdbarch
);
516 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
518 LONGEST voffset
, adjustment
;
521 /* Extract the pointer to member. The first element is either a pointer
522 or a vtable offset. For pointers, we need to use extract_typed_address
523 to allow the back-end to convert the pointer to a GDB address -- but
524 vtable offsets we must handle as integers. At this point, we do not
525 yet know which case we have, so we extract the value under both
526 interpretations and choose the right one later on. */
527 ptr_value
= extract_typed_address (contents
, funcptr_type
);
528 voffset
= extract_signed_integer (contents
,
529 TYPE_LENGTH (funcptr_type
), byte_order
);
530 contents
+= TYPE_LENGTH (funcptr_type
);
531 adjustment
= extract_signed_integer (contents
,
532 TYPE_LENGTH (offset_type
), byte_order
);
534 if (!gdbarch_vbit_in_delta (gdbarch
))
537 voffset
= voffset
^ vbit
;
541 vbit
= adjustment
& 1;
542 adjustment
= adjustment
>> 1;
545 *value_p
= vbit
? voffset
: ptr_value
;
546 *adjustment_p
= adjustment
;
550 /* GNU v3 implementation of cplus_print_method_ptr. */
553 gnuv3_print_method_ptr (const gdb_byte
*contents
,
555 struct ui_file
*stream
)
557 struct type
*domain
= TYPE_DOMAIN_TYPE (type
);
558 struct gdbarch
*gdbarch
= get_type_arch (domain
);
563 /* Extract the pointer to member. */
564 vbit
= gnuv3_decode_method_ptr (gdbarch
, contents
, &ptr_value
, &adjustment
);
566 /* Check for NULL. */
567 if (ptr_value
== 0 && vbit
== 0)
569 fprintf_filtered (stream
, "NULL");
573 /* Search for a virtual method. */
577 const char *physname
;
579 /* It's a virtual table offset, maybe in this class. Search
580 for a field with the correct vtable offset. First convert it
581 to an index, as used in TYPE_FN_FIELD_VOFFSET. */
582 voffset
= ptr_value
/ TYPE_LENGTH (vtable_ptrdiff_type (gdbarch
));
584 physname
= gnuv3_find_method_in (domain
, voffset
, adjustment
);
586 /* If we found a method, print that. We don't bother to disambiguate
587 possible paths to the method based on the adjustment. */
590 char *demangled_name
= cplus_demangle (physname
,
591 DMGL_ANSI
| DMGL_PARAMS
);
593 fprintf_filtered (stream
, "&virtual ");
594 if (demangled_name
== NULL
)
595 fputs_filtered (physname
, stream
);
598 fputs_filtered (demangled_name
, stream
);
599 xfree (demangled_name
);
604 else if (ptr_value
!= 0)
606 /* Found a non-virtual function: print out the type. */
607 fputs_filtered ("(", stream
);
608 c_print_type (type
, "", stream
, -1, 0);
609 fputs_filtered (") ", stream
);
612 /* We didn't find it; print the raw data. */
615 fprintf_filtered (stream
, "&virtual table offset ");
616 print_longest (stream
, 'd', 1, ptr_value
);
619 print_address_demangle (gdbarch
, ptr_value
, stream
, demangle
);
623 fprintf_filtered (stream
, ", this adjustment ");
624 print_longest (stream
, 'd', 1, adjustment
);
628 /* GNU v3 implementation of cplus_method_ptr_size. */
631 gnuv3_method_ptr_size (struct type
*type
)
633 struct gdbarch
*gdbarch
= get_type_arch (type
);
635 return 2 * TYPE_LENGTH (builtin_type (gdbarch
)->builtin_data_ptr
);
638 /* GNU v3 implementation of cplus_make_method_ptr. */
641 gnuv3_make_method_ptr (struct type
*type
, gdb_byte
*contents
,
642 CORE_ADDR value
, int is_virtual
)
644 struct gdbarch
*gdbarch
= get_type_arch (type
);
645 int size
= TYPE_LENGTH (builtin_type (gdbarch
)->builtin_data_ptr
);
646 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
648 /* FIXME drow/2006-12-24: The adjustment of "this" is currently
649 always zero, since the method pointer is of the correct type.
650 But if the method pointer came from a base class, this is
651 incorrect - it should be the offset to the base. The best
652 fix might be to create the pointer to member pointing at the
653 base class and cast it to the derived class, but that requires
654 support for adjusting pointers to members when casting them -
655 not currently supported by GDB. */
657 if (!gdbarch_vbit_in_delta (gdbarch
))
659 store_unsigned_integer (contents
, size
, byte_order
, value
| is_virtual
);
660 store_unsigned_integer (contents
+ size
, size
, byte_order
, 0);
664 store_unsigned_integer (contents
, size
, byte_order
, value
);
665 store_unsigned_integer (contents
+ size
, size
, byte_order
, is_virtual
);
669 /* GNU v3 implementation of cplus_method_ptr_to_value. */
671 static struct value
*
672 gnuv3_method_ptr_to_value (struct value
**this_p
, struct value
*method_ptr
)
674 struct gdbarch
*gdbarch
;
675 const gdb_byte
*contents
= value_contents (method_ptr
);
677 struct type
*domain_type
, *final_type
, *method_type
;
681 domain_type
= TYPE_DOMAIN_TYPE (check_typedef (value_type (method_ptr
)));
682 final_type
= lookup_pointer_type (domain_type
);
684 method_type
= TYPE_TARGET_TYPE (check_typedef (value_type (method_ptr
)));
686 /* Extract the pointer to member. */
687 gdbarch
= get_type_arch (domain_type
);
688 vbit
= gnuv3_decode_method_ptr (gdbarch
, contents
, &ptr_value
, &adjustment
);
690 /* First convert THIS to match the containing type of the pointer to
691 member. This cast may adjust the value of THIS. */
692 *this_p
= value_cast (final_type
, *this_p
);
694 /* Then apply whatever adjustment is necessary. This creates a somewhat
695 strange pointer: it claims to have type FINAL_TYPE, but in fact it
696 might not be a valid FINAL_TYPE. For instance, it might be a
697 base class of FINAL_TYPE. And if it's not the primary base class,
698 then printing it out as a FINAL_TYPE object would produce some pretty
701 But we don't really know the type of the first argument in
702 METHOD_TYPE either, which is why this happens. We can't
703 dereference this later as a FINAL_TYPE, but once we arrive in the
704 called method we'll have debugging information for the type of
705 "this" - and that'll match the value we produce here.
707 You can provoke this case by casting a Base::* to a Derived::*, for
709 *this_p
= value_cast (builtin_type (gdbarch
)->builtin_data_ptr
, *this_p
);
710 *this_p
= value_ptradd (*this_p
, adjustment
);
711 *this_p
= value_cast (final_type
, *this_p
);
717 voffset
= ptr_value
/ TYPE_LENGTH (vtable_ptrdiff_type (gdbarch
));
718 return gnuv3_get_virtual_fn (gdbarch
, value_ind (*this_p
),
719 method_type
, voffset
);
722 return value_from_pointer (lookup_pointer_type (method_type
), ptr_value
);
725 /* Determine if we are currently in a C++ thunk. If so, get the address
726 of the routine we are thunking to and continue to there instead. */
729 gnuv3_skip_trampoline (struct frame_info
*frame
, CORE_ADDR stop_pc
)
731 CORE_ADDR real_stop_pc
, method_stop_pc
;
732 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
733 struct minimal_symbol
*thunk_sym
, *fn_sym
;
734 struct obj_section
*section
;
735 char *thunk_name
, *fn_name
;
737 real_stop_pc
= gdbarch_skip_trampoline_code (gdbarch
, frame
, stop_pc
);
738 if (real_stop_pc
== 0)
739 real_stop_pc
= stop_pc
;
741 /* Find the linker symbol for this potential thunk. */
742 thunk_sym
= lookup_minimal_symbol_by_pc (real_stop_pc
);
743 section
= find_pc_section (real_stop_pc
);
744 if (thunk_sym
== NULL
|| section
== NULL
)
747 /* The symbol's demangled name should be something like "virtual
748 thunk to FUNCTION", where FUNCTION is the name of the function
750 thunk_name
= SYMBOL_DEMANGLED_NAME (thunk_sym
);
751 if (thunk_name
== NULL
|| strstr (thunk_name
, " thunk to ") == NULL
)
754 fn_name
= strstr (thunk_name
, " thunk to ") + strlen (" thunk to ");
755 fn_sym
= lookup_minimal_symbol (fn_name
, NULL
, section
->objfile
);
759 method_stop_pc
= SYMBOL_VALUE_ADDRESS (fn_sym
);
760 real_stop_pc
= gdbarch_skip_trampoline_code
761 (gdbarch
, frame
, method_stop_pc
);
762 if (real_stop_pc
== 0)
763 real_stop_pc
= method_stop_pc
;
768 /* Return nonzero if a type should be passed by reference.
770 The rule in the v3 ABI document comes from section 3.1.1. If the
771 type has a non-trivial copy constructor or destructor, then the
772 caller must make a copy (by calling the copy constructor if there
773 is one or perform the copy itself otherwise), pass the address of
774 the copy, and then destroy the temporary (if necessary).
776 For return values with non-trivial copy constructors or
777 destructors, space will be allocated in the caller, and a pointer
778 will be passed as the first argument (preceding "this").
780 We don't have a bulletproof mechanism for determining whether a
781 constructor or destructor is trivial. For GCC and DWARF2 debug
782 information, we can check the artificial flag.
784 We don't do anything with the constructors or destructors,
785 but we have to get the argument passing right anyway. */
787 gnuv3_pass_by_reference (struct type
*type
)
789 int fieldnum
, fieldelem
;
791 CHECK_TYPEDEF (type
);
793 /* We're only interested in things that can have methods. */
794 if (TYPE_CODE (type
) != TYPE_CODE_STRUCT
795 && TYPE_CODE (type
) != TYPE_CODE_CLASS
796 && TYPE_CODE (type
) != TYPE_CODE_UNION
)
799 for (fieldnum
= 0; fieldnum
< TYPE_NFN_FIELDS (type
); fieldnum
++)
800 for (fieldelem
= 0; fieldelem
< TYPE_FN_FIELDLIST_LENGTH (type
, fieldnum
);
803 struct fn_field
*fn
= TYPE_FN_FIELDLIST1 (type
, fieldnum
);
804 char *name
= TYPE_FN_FIELDLIST_NAME (type
, fieldnum
);
805 struct type
*fieldtype
= TYPE_FN_FIELD_TYPE (fn
, fieldelem
);
807 /* If this function is marked as artificial, it is compiler-generated,
808 and we assume it is trivial. */
809 if (TYPE_FN_FIELD_ARTIFICIAL (fn
, fieldelem
))
812 /* If we've found a destructor, we must pass this by reference. */
816 /* If the mangled name of this method doesn't indicate that it
817 is a constructor, we're not interested.
819 FIXME drow/2007-09-23: We could do this using the name of
820 the method and the name of the class instead of dealing
821 with the mangled name. We don't have a convenient function
822 to strip off both leading scope qualifiers and trailing
823 template arguments yet. */
824 if (!is_constructor_name (TYPE_FN_FIELD_PHYSNAME (fn
, fieldelem
)))
827 /* If this method takes two arguments, and the second argument is
828 a reference to this class, then it is a copy constructor. */
829 if (TYPE_NFIELDS (fieldtype
) == 2
830 && TYPE_CODE (TYPE_FIELD_TYPE (fieldtype
, 1)) == TYPE_CODE_REF
831 && check_typedef (TYPE_TARGET_TYPE (TYPE_FIELD_TYPE (fieldtype
,
836 /* Even if all the constructors and destructors were artificial, one
837 of them may have invoked a non-artificial constructor or
838 destructor in a base class. If any base class needs to be passed
839 by reference, so does this class. Similarly for members, which
840 are constructed whenever this class is. We do not need to worry
841 about recursive loops here, since we are only looking at members
842 of complete class type. Also ignore any static members. */
843 for (fieldnum
= 0; fieldnum
< TYPE_NFIELDS (type
); fieldnum
++)
844 if (! field_is_static (&TYPE_FIELD (type
, fieldnum
))
845 && gnuv3_pass_by_reference (TYPE_FIELD_TYPE (type
, fieldnum
)))
852 init_gnuv3_ops (void)
854 vtable_type_gdbarch_data
855 = gdbarch_data_register_post_init (build_gdb_vtable_type
);
857 gnu_v3_abi_ops
.shortname
= "gnu-v3";
858 gnu_v3_abi_ops
.longname
= "GNU G++ Version 3 ABI";
859 gnu_v3_abi_ops
.doc
= "G++ Version 3 ABI";
860 gnu_v3_abi_ops
.is_destructor_name
=
861 (enum dtor_kinds (*) (const char *))is_gnu_v3_mangled_dtor
;
862 gnu_v3_abi_ops
.is_constructor_name
=
863 (enum ctor_kinds (*) (const char *))is_gnu_v3_mangled_ctor
;
864 gnu_v3_abi_ops
.is_vtable_name
= gnuv3_is_vtable_name
;
865 gnu_v3_abi_ops
.is_operator_name
= gnuv3_is_operator_name
;
866 gnu_v3_abi_ops
.rtti_type
= gnuv3_rtti_type
;
867 gnu_v3_abi_ops
.virtual_fn_field
= gnuv3_virtual_fn_field
;
868 gnu_v3_abi_ops
.baseclass_offset
= gnuv3_baseclass_offset
;
869 gnu_v3_abi_ops
.print_method_ptr
= gnuv3_print_method_ptr
;
870 gnu_v3_abi_ops
.method_ptr_size
= gnuv3_method_ptr_size
;
871 gnu_v3_abi_ops
.make_method_ptr
= gnuv3_make_method_ptr
;
872 gnu_v3_abi_ops
.method_ptr_to_value
= gnuv3_method_ptr_to_value
;
873 gnu_v3_abi_ops
.skip_trampoline
= gnuv3_skip_trampoline
;
874 gnu_v3_abi_ops
.pass_by_reference
= gnuv3_pass_by_reference
;
877 extern initialize_file_ftype _initialize_gnu_v3_abi
; /* -Wmissing-prototypes */
880 _initialize_gnu_v3_abi (void)
884 register_cp_abi (&gnu_v3_abi_ops
);