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7ed49443 JB |
1 | /* Abstraction of GNU v3 abi. |
2 | Contributed by Jim Blandy <jimb@redhat.com> | |
451fbdda | 3 | |
0fb0cc75 | 4 | Copyright (C) 2001, 2002, 2003, 2005, 2006, 2007, 2008, 2009 |
0d5de010 | 5 | Free Software Foundation, Inc. |
7ed49443 JB |
6 | |
7 | This file is part of GDB. | |
8 | ||
a9762ec7 JB |
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. | |
7ed49443 JB |
13 | |
14 | This program is distributed in the hope that it will be useful, | |
15 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
17 | GNU General Public License for more details. | |
18 | ||
19 | You should have received a copy of the GNU General Public License | |
a9762ec7 | 20 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
7ed49443 JB |
21 | |
22 | #include "defs.h" | |
23 | #include "value.h" | |
24 | #include "cp-abi.h" | |
362ff856 | 25 | #include "cp-support.h" |
7ed49443 | 26 | #include "demangle.h" |
b18be20d | 27 | #include "objfiles.h" |
0d5de010 DJ |
28 | #include "valprint.h" |
29 | ||
3d499020 | 30 | #include "gdb_assert.h" |
5f8a3188 | 31 | #include "gdb_string.h" |
7ed49443 | 32 | |
b27b8843 | 33 | static struct cp_abi_ops gnu_v3_abi_ops; |
7ed49443 JB |
34 | |
35 | static int | |
36 | gnuv3_is_vtable_name (const char *name) | |
37 | { | |
38 | return strncmp (name, "_ZTV", 4) == 0; | |
39 | } | |
40 | ||
41 | static int | |
42 | gnuv3_is_operator_name (const char *name) | |
43 | { | |
44 | return strncmp (name, "operator", 8) == 0; | |
45 | } | |
46 | ||
47 | ||
ad4820ab UW |
48 | /* Determine architecture of class DOMAIN. This architecture is used |
49 | to query C++ ABI details (types, method pointer layout, etc.). | |
50 | ||
51 | Note that we assume DOMAIN must have been allocated with an OBJFILE; | |
52 | GDB does not provide any built-in class types. Thus we use the | |
53 | architecture of that OBJFILE to define the C++ ABI. */ | |
54 | ||
55 | static struct gdbarch * | |
56 | get_class_arch (struct type *domain) | |
57 | { | |
58 | gdb_assert (TYPE_CODE (domain) == TYPE_CODE_CLASS); | |
59 | gdb_assert (TYPE_OBJFILE (domain) != NULL); | |
60 | return get_objfile_arch (TYPE_OBJFILE (domain)); | |
61 | } | |
62 | ||
7ed49443 JB |
63 | /* To help us find the components of a vtable, we build ourselves a |
64 | GDB type object representing the vtable structure. Following the | |
65 | V3 ABI, it goes something like this: | |
66 | ||
67 | struct gdb_gnu_v3_abi_vtable { | |
68 | ||
69 | / * An array of virtual call and virtual base offsets. The real | |
70 | length of this array depends on the class hierarchy; we use | |
71 | negative subscripts to access the elements. Yucky, but | |
72 | better than the alternatives. * / | |
73 | ptrdiff_t vcall_and_vbase_offsets[0]; | |
74 | ||
75 | / * The offset from a virtual pointer referring to this table | |
76 | to the top of the complete object. * / | |
77 | ptrdiff_t offset_to_top; | |
78 | ||
79 | / * The type_info pointer for this class. This is really a | |
80 | std::type_info *, but GDB doesn't really look at the | |
81 | type_info object itself, so we don't bother to get the type | |
82 | exactly right. * / | |
83 | void *type_info; | |
84 | ||
85 | / * Virtual table pointers in objects point here. * / | |
86 | ||
87 | / * Virtual function pointers. Like the vcall/vbase array, the | |
88 | real length of this table depends on the class hierarchy. * / | |
89 | void (*virtual_functions[0]) (); | |
90 | ||
91 | }; | |
92 | ||
93 | The catch, of course, is that the exact layout of this table | |
94 | depends on the ABI --- word size, endianness, alignment, etc. So | |
95 | the GDB type object is actually a per-architecture kind of thing. | |
96 | ||
97 | vtable_type_gdbarch_data is a gdbarch per-architecture data pointer | |
98 | which refers to the struct type * for this structure, laid out | |
99 | appropriately for the architecture. */ | |
b27b8843 | 100 | static struct gdbarch_data *vtable_type_gdbarch_data; |
7ed49443 JB |
101 | |
102 | ||
103 | /* Human-readable names for the numbers of the fields above. */ | |
104 | enum { | |
105 | vtable_field_vcall_and_vbase_offsets, | |
106 | vtable_field_offset_to_top, | |
107 | vtable_field_type_info, | |
108 | vtable_field_virtual_functions | |
109 | }; | |
110 | ||
111 | ||
112 | /* Return a GDB type representing `struct gdb_gnu_v3_abi_vtable', | |
113 | described above, laid out appropriately for ARCH. | |
114 | ||
115 | We use this function as the gdbarch per-architecture data | |
9970f04b | 116 | initialization function. */ |
7ed49443 JB |
117 | static void * |
118 | build_gdb_vtable_type (struct gdbarch *arch) | |
119 | { | |
120 | struct type *t; | |
121 | struct field *field_list, *field; | |
122 | int offset; | |
123 | ||
124 | struct type *void_ptr_type | |
fde6c819 | 125 | = builtin_type (arch)->builtin_data_ptr; |
7ed49443 | 126 | struct type *ptr_to_void_fn_type |
fde6c819 | 127 | = builtin_type (arch)->builtin_func_ptr; |
7ed49443 JB |
128 | |
129 | /* ARCH can't give us the true ptrdiff_t type, so we guess. */ | |
130 | struct type *ptrdiff_type | |
819844ad | 131 | = init_type (TYPE_CODE_INT, |
9970f04b | 132 | gdbarch_ptr_bit (arch) / TARGET_CHAR_BIT, 0, |
7ed49443 JB |
133 | "ptrdiff_t", 0); |
134 | ||
135 | /* We assume no padding is necessary, since GDB doesn't know | |
136 | anything about alignment at the moment. If this assumption bites | |
137 | us, we should add a gdbarch method which, given a type, returns | |
138 | the alignment that type requires, and then use that here. */ | |
139 | ||
140 | /* Build the field list. */ | |
141 | field_list = xmalloc (sizeof (struct field [4])); | |
142 | memset (field_list, 0, sizeof (struct field [4])); | |
143 | field = &field_list[0]; | |
144 | offset = 0; | |
145 | ||
146 | /* ptrdiff_t vcall_and_vbase_offsets[0]; */ | |
147 | FIELD_NAME (*field) = "vcall_and_vbase_offsets"; | |
148 | FIELD_TYPE (*field) | |
149 | = create_array_type (0, ptrdiff_type, | |
6d84d3d8 | 150 | create_range_type (0, builtin_type_int32, 0, -1)); |
7ed49443 JB |
151 | FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT; |
152 | offset += TYPE_LENGTH (FIELD_TYPE (*field)); | |
153 | field++; | |
154 | ||
155 | /* ptrdiff_t offset_to_top; */ | |
156 | FIELD_NAME (*field) = "offset_to_top"; | |
157 | FIELD_TYPE (*field) = ptrdiff_type; | |
158 | FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT; | |
159 | offset += TYPE_LENGTH (FIELD_TYPE (*field)); | |
160 | field++; | |
161 | ||
162 | /* void *type_info; */ | |
163 | FIELD_NAME (*field) = "type_info"; | |
164 | FIELD_TYPE (*field) = void_ptr_type; | |
165 | FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT; | |
166 | offset += TYPE_LENGTH (FIELD_TYPE (*field)); | |
167 | field++; | |
168 | ||
169 | /* void (*virtual_functions[0]) (); */ | |
170 | FIELD_NAME (*field) = "virtual_functions"; | |
171 | FIELD_TYPE (*field) | |
172 | = create_array_type (0, ptr_to_void_fn_type, | |
6d84d3d8 | 173 | create_range_type (0, builtin_type_int32, 0, -1)); |
7ed49443 JB |
174 | FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT; |
175 | offset += TYPE_LENGTH (FIELD_TYPE (*field)); | |
176 | field++; | |
177 | ||
178 | /* We assumed in the allocation above that there were four fields. */ | |
3d499020 | 179 | gdb_assert (field == (field_list + 4)); |
7ed49443 JB |
180 | |
181 | t = init_type (TYPE_CODE_STRUCT, offset, 0, 0, 0); | |
182 | TYPE_NFIELDS (t) = field - field_list; | |
183 | TYPE_FIELDS (t) = field_list; | |
184 | TYPE_TAG_NAME (t) = "gdb_gnu_v3_abi_vtable"; | |
185 | ||
186 | return t; | |
187 | } | |
188 | ||
189 | ||
ed09d7da KB |
190 | /* Return the ptrdiff_t type used in the vtable type. */ |
191 | static struct type * | |
192 | vtable_ptrdiff_type (struct gdbarch *gdbarch) | |
193 | { | |
194 | struct type *vtable_type = gdbarch_data (gdbarch, vtable_type_gdbarch_data); | |
195 | ||
196 | /* The "offset_to_top" field has the appropriate (ptrdiff_t) type. */ | |
197 | return TYPE_FIELD_TYPE (vtable_type, vtable_field_offset_to_top); | |
198 | } | |
199 | ||
7ed49443 JB |
200 | /* Return the offset from the start of the imaginary `struct |
201 | gdb_gnu_v3_abi_vtable' object to the vtable's "address point" | |
202 | (i.e., where objects' virtual table pointers point). */ | |
203 | static int | |
ad4820ab | 204 | vtable_address_point_offset (struct gdbarch *gdbarch) |
7ed49443 | 205 | { |
ad4820ab | 206 | struct type *vtable_type = gdbarch_data (gdbarch, vtable_type_gdbarch_data); |
7ed49443 JB |
207 | |
208 | return (TYPE_FIELD_BITPOS (vtable_type, vtable_field_virtual_functions) | |
209 | / TARGET_CHAR_BIT); | |
210 | } | |
211 | ||
212 | ||
213 | static struct type * | |
214 | gnuv3_rtti_type (struct value *value, | |
215 | int *full_p, int *top_p, int *using_enc_p) | |
216 | { | |
ad4820ab UW |
217 | struct gdbarch *gdbarch; |
218 | struct type *vtable_type; | |
df407dfe | 219 | struct type *values_type = check_typedef (value_type (value)); |
7ed49443 JB |
220 | CORE_ADDR vtable_address; |
221 | struct value *vtable; | |
222 | struct minimal_symbol *vtable_symbol; | |
223 | const char *vtable_symbol_name; | |
224 | const char *class_name; | |
7ed49443 | 225 | struct type *run_time_type; |
21cfb3b6 | 226 | struct type *base_type; |
7ed49443 | 227 | LONGEST offset_to_top; |
81fe8080 DE |
228 | struct type *values_type_vptr_basetype; |
229 | int values_type_vptr_fieldno; | |
7ed49443 JB |
230 | |
231 | /* We only have RTTI for class objects. */ | |
df407dfe | 232 | if (TYPE_CODE (values_type) != TYPE_CODE_CLASS) |
7ed49443 JB |
233 | return NULL; |
234 | ||
ad4820ab UW |
235 | /* This routine may be called for Java types that do not have |
236 | a proper objfile. Just return NULL for those. */ | |
237 | if (!TYPE_OBJFILE (values_type) | |
238 | || !TYPE_OBJFILE (values_type)->obfd) | |
239 | return NULL; | |
240 | ||
241 | /* Determine architecture. */ | |
242 | gdbarch = get_class_arch (values_type); | |
243 | vtable_type = gdbarch_data (gdbarch, vtable_type_gdbarch_data); | |
244 | ||
df407dfe | 245 | /* If we can't find the virtual table pointer for values_type, we |
7ed49443 | 246 | can't find the RTTI. */ |
81fe8080 DE |
247 | values_type_vptr_fieldno = get_vptr_fieldno (values_type, |
248 | &values_type_vptr_basetype); | |
249 | if (values_type_vptr_fieldno == -1) | |
7ed49443 JB |
250 | return NULL; |
251 | ||
21cfb3b6 DJ |
252 | if (using_enc_p) |
253 | *using_enc_p = 0; | |
254 | ||
7ed49443 | 255 | /* Fetch VALUE's virtual table pointer, and tweak it to point at |
21cfb3b6 | 256 | an instance of our imaginary gdb_gnu_v3_abi_vtable structure. */ |
81fe8080 | 257 | base_type = check_typedef (values_type_vptr_basetype); |
df407dfe | 258 | if (values_type != base_type) |
21cfb3b6 DJ |
259 | { |
260 | value = value_cast (base_type, value); | |
261 | if (using_enc_p) | |
262 | *using_enc_p = 1; | |
263 | } | |
7ed49443 | 264 | vtable_address |
81fe8080 | 265 | = value_as_address (value_field (value, values_type_vptr_fieldno)); |
ad4820ab UW |
266 | vtable |
267 | = value_at_lazy (vtable_type, | |
268 | vtable_address - vtable_address_point_offset (gdbarch)); | |
7ed49443 JB |
269 | |
270 | /* Find the linker symbol for this vtable. */ | |
271 | vtable_symbol | |
42ae5230 | 272 | = lookup_minimal_symbol_by_pc (value_address (vtable) |
13c3b5f5 | 273 | + value_embedded_offset (vtable)); |
7ed49443 JB |
274 | if (! vtable_symbol) |
275 | return NULL; | |
276 | ||
277 | /* The symbol's demangled name should be something like "vtable for | |
278 | CLASS", where CLASS is the name of the run-time type of VALUE. | |
279 | If we didn't like this approach, we could instead look in the | |
280 | type_info object itself to get the class name. But this way | |
281 | should work just as well, and doesn't read target memory. */ | |
282 | vtable_symbol_name = SYMBOL_DEMANGLED_NAME (vtable_symbol); | |
98081e55 PB |
283 | if (vtable_symbol_name == NULL |
284 | || strncmp (vtable_symbol_name, "vtable for ", 11)) | |
f773fdbb | 285 | { |
8a3fe4f8 | 286 | warning (_("can't find linker symbol for virtual table for `%s' value"), |
df407dfe | 287 | TYPE_NAME (values_type)); |
f773fdbb | 288 | if (vtable_symbol_name) |
8a3fe4f8 | 289 | warning (_(" found `%s' instead"), vtable_symbol_name); |
f773fdbb JM |
290 | return NULL; |
291 | } | |
7ed49443 JB |
292 | class_name = vtable_symbol_name + 11; |
293 | ||
294 | /* Try to look up the class name as a type name. */ | |
362ff856 MC |
295 | /* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */ |
296 | run_time_type = cp_lookup_rtti_type (class_name, NULL); | |
297 | if (run_time_type == NULL) | |
298 | return NULL; | |
7ed49443 JB |
299 | |
300 | /* Get the offset from VALUE to the top of the complete object. | |
301 | NOTE: this is the reverse of the meaning of *TOP_P. */ | |
302 | offset_to_top | |
303 | = value_as_long (value_field (vtable, vtable_field_offset_to_top)); | |
304 | ||
305 | if (full_p) | |
13c3b5f5 | 306 | *full_p = (- offset_to_top == value_embedded_offset (value) |
4754a64e | 307 | && (TYPE_LENGTH (value_enclosing_type (value)) |
7ed49443 JB |
308 | >= TYPE_LENGTH (run_time_type))); |
309 | if (top_p) | |
310 | *top_p = - offset_to_top; | |
7ed49443 JB |
311 | |
312 | return run_time_type; | |
313 | } | |
314 | ||
0d5de010 DJ |
315 | /* Find the vtable for CONTAINER and return a value of the correct |
316 | vtable type for this architecture. */ | |
7ed49443 JB |
317 | |
318 | static struct value * | |
ad4820ab | 319 | gnuv3_get_vtable (struct gdbarch *gdbarch, struct value *container) |
7ed49443 | 320 | { |
ad4820ab | 321 | struct type *vtable_type = gdbarch_data (gdbarch, vtable_type_gdbarch_data); |
0d5de010 DJ |
322 | struct type *vtable_pointer_type; |
323 | struct value *vtable_pointer; | |
324 | CORE_ADDR vtable_pointer_address, vtable_address; | |
325 | ||
326 | /* We do not consult the debug information to find the virtual table. | |
327 | The ABI specifies that it is always at offset zero in any class, | |
328 | and debug information may not represent it. We won't issue an | |
329 | error if there's a class with virtual functions but no virtual table | |
330 | pointer, but something's already gone seriously wrong if that | |
331 | happens. | |
332 | ||
333 | We avoid using value_contents on principle, because the object might | |
334 | be large. */ | |
335 | ||
336 | /* Find the type "pointer to virtual table". */ | |
337 | vtable_pointer_type = lookup_pointer_type (vtable_type); | |
338 | ||
339 | /* Load it from the start of the class. */ | |
340 | vtable_pointer_address = value_as_address (value_addr (container)); | |
341 | vtable_pointer = value_at (vtable_pointer_type, vtable_pointer_address); | |
342 | vtable_address = value_as_address (vtable_pointer); | |
343 | ||
344 | /* Correct it to point at the start of the virtual table, rather | |
345 | than the address point. */ | |
346 | return value_at_lazy (vtable_type, | |
ad4820ab | 347 | vtable_address - vtable_address_point_offset (gdbarch)); |
0d5de010 | 348 | } |
7ed49443 | 349 | |
0d5de010 DJ |
350 | /* Return a function pointer for CONTAINER's VTABLE_INDEX'th virtual |
351 | function, of type FNTYPE. */ | |
7ed49443 | 352 | |
0d5de010 | 353 | static struct value * |
ad4820ab UW |
354 | gnuv3_get_virtual_fn (struct gdbarch *gdbarch, struct value *container, |
355 | struct type *fntype, int vtable_index) | |
0d5de010 | 356 | { |
ad4820ab | 357 | struct value *vtable = gnuv3_get_vtable (gdbarch, container); |
0d5de010 | 358 | struct value *vfn; |
7ed49443 JB |
359 | |
360 | /* Fetch the appropriate function pointer from the vtable. */ | |
361 | vfn = value_subscript (value_field (vtable, vtable_field_virtual_functions), | |
6d84d3d8 | 362 | value_from_longest (builtin_type_int32, vtable_index)); |
7ed49443 | 363 | |
0d5de010 DJ |
364 | /* If this architecture uses function descriptors directly in the vtable, |
365 | then the address of the vtable entry is actually a "function pointer" | |
366 | (i.e. points to the descriptor). We don't need to scale the index | |
367 | by the size of a function descriptor; GCC does that before outputing | |
368 | debug information. */ | |
ad4820ab | 369 | if (gdbarch_vtable_function_descriptors (gdbarch)) |
0d5de010 | 370 | vfn = value_addr (vfn); |
7ed49443 | 371 | |
0d5de010 DJ |
372 | /* Cast the function pointer to the appropriate type. */ |
373 | vfn = value_cast (lookup_pointer_type (fntype), vfn); | |
76b79d6e | 374 | |
7ed49443 JB |
375 | return vfn; |
376 | } | |
377 | ||
0d5de010 DJ |
378 | /* GNU v3 implementation of value_virtual_fn_field. See cp-abi.h |
379 | for a description of the arguments. */ | |
380 | ||
381 | static struct value * | |
382 | gnuv3_virtual_fn_field (struct value **value_p, | |
383 | struct fn_field *f, int j, | |
384 | struct type *vfn_base, int offset) | |
385 | { | |
386 | struct type *values_type = check_typedef (value_type (*value_p)); | |
ad4820ab | 387 | struct gdbarch *gdbarch; |
0d5de010 DJ |
388 | |
389 | /* Some simple sanity checks. */ | |
390 | if (TYPE_CODE (values_type) != TYPE_CODE_CLASS) | |
391 | error (_("Only classes can have virtual functions.")); | |
392 | ||
ad4820ab UW |
393 | /* Determine architecture. */ |
394 | gdbarch = get_class_arch (values_type); | |
395 | ||
0d5de010 DJ |
396 | /* Cast our value to the base class which defines this virtual |
397 | function. This takes care of any necessary `this' | |
398 | adjustments. */ | |
399 | if (vfn_base != values_type) | |
400 | *value_p = value_cast (vfn_base, *value_p); | |
401 | ||
ad4820ab | 402 | return gnuv3_get_virtual_fn (gdbarch, *value_p, TYPE_FN_FIELD_TYPE (f, j), |
0d5de010 DJ |
403 | TYPE_FN_FIELD_VOFFSET (f, j)); |
404 | } | |
405 | ||
1514d34e DJ |
406 | /* Compute the offset of the baseclass which is |
407 | the INDEXth baseclass of class TYPE, | |
408 | for value at VALADDR (in host) at ADDRESS (in target). | |
409 | The result is the offset of the baseclass value relative | |
410 | to (the address of)(ARG) + OFFSET. | |
411 | ||
412 | -1 is returned on error. */ | |
b9362cc7 | 413 | static int |
96ce45ca | 414 | gnuv3_baseclass_offset (struct type *type, int index, const bfd_byte *valaddr, |
1514d34e DJ |
415 | CORE_ADDR address) |
416 | { | |
ad4820ab UW |
417 | struct gdbarch *gdbarch; |
418 | struct type *vtable_type; | |
419 | struct type *ptr_type; | |
79d5b63a DJ |
420 | struct value *vtable; |
421 | struct type *vbasetype; | |
1514d34e DJ |
422 | struct value *offset_val, *vbase_array; |
423 | CORE_ADDR vtable_address; | |
424 | long int cur_base_offset, base_offset; | |
81fe8080 | 425 | int vbasetype_vptr_fieldno; |
1514d34e | 426 | |
ad4820ab UW |
427 | /* Determine architecture. */ |
428 | gdbarch = get_class_arch (type); | |
429 | vtable_type = gdbarch_data (gdbarch, vtable_type_gdbarch_data); | |
430 | ptr_type = builtin_type (gdbarch)->builtin_data_ptr; | |
431 | ||
1514d34e DJ |
432 | /* If it isn't a virtual base, this is easy. The offset is in the |
433 | type definition. */ | |
434 | if (!BASETYPE_VIA_VIRTUAL (type, index)) | |
435 | return TYPE_BASECLASS_BITPOS (type, index) / 8; | |
436 | ||
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 | |
441 | worthwhile. */ | |
442 | cur_base_offset = TYPE_BASECLASS_BITPOS (type, index) / 8; | |
ad4820ab | 443 | if (cur_base_offset >= - vtable_address_point_offset (gdbarch)) |
8a3fe4f8 | 444 | error (_("Expected a negative vbase offset (old compiler?)")); |
1514d34e | 445 | |
ad4820ab UW |
446 | cur_base_offset = cur_base_offset + vtable_address_point_offset (gdbarch); |
447 | if ((- cur_base_offset) % TYPE_LENGTH (ptr_type) != 0) | |
8a3fe4f8 | 448 | error (_("Misaligned vbase offset.")); |
ad4820ab | 449 | cur_base_offset = cur_base_offset / ((int) TYPE_LENGTH (ptr_type)); |
1514d34e DJ |
450 | |
451 | /* We're now looking for the cur_base_offset'th entry (negative index) | |
79d5b63a DJ |
452 | in the vcall_and_vbase_offsets array. We used to cast the object to |
453 | its TYPE_VPTR_BASETYPE, and reference the vtable as TYPE_VPTR_FIELDNO; | |
454 | however, that cast can not be done without calling baseclass_offset again | |
455 | if the TYPE_VPTR_BASETYPE is a virtual base class, as described in the | |
456 | v3 C++ ABI Section 2.4.I.2.b. Fortunately the ABI guarantees that the | |
457 | vtable pointer will be located at the beginning of the object, so we can | |
458 | bypass the casting. Verify that the TYPE_VPTR_FIELDNO is in fact at the | |
7ed85d26 DJ |
459 | start of whichever baseclass it resides in, as a sanity measure - iff |
460 | we have debugging information for that baseclass. */ | |
79d5b63a | 461 | |
392452f6 | 462 | vbasetype = check_typedef (TYPE_VPTR_BASETYPE (type)); |
81fe8080 | 463 | vbasetype_vptr_fieldno = get_vptr_fieldno (vbasetype, NULL); |
7ed85d26 | 464 | |
81fe8080 DE |
465 | if (vbasetype_vptr_fieldno >= 0 |
466 | && TYPE_FIELD_BITPOS (vbasetype, vbasetype_vptr_fieldno) != 0) | |
8a3fe4f8 | 467 | error (_("Illegal vptr offset in class %s"), |
79d5b63a DJ |
468 | TYPE_NAME (vbasetype) ? TYPE_NAME (vbasetype) : "<unknown>"); |
469 | ||
ad4820ab UW |
470 | vtable_address = value_as_address (value_at_lazy (ptr_type, address)); |
471 | vtable | |
472 | = value_at_lazy (vtable_type, | |
473 | vtable_address - vtable_address_point_offset (gdbarch)); | |
474 | offset_val = value_from_longest (builtin_type_int32, cur_base_offset); | |
1514d34e DJ |
475 | vbase_array = value_field (vtable, vtable_field_vcall_and_vbase_offsets); |
476 | base_offset = value_as_long (value_subscript (vbase_array, offset_val)); | |
477 | return base_offset; | |
478 | } | |
7ed49443 | 479 | |
0d5de010 DJ |
480 | /* Locate a virtual method in DOMAIN or its non-virtual base classes |
481 | which has virtual table index VOFFSET. The method has an associated | |
482 | "this" adjustment of ADJUSTMENT bytes. */ | |
483 | ||
2c0b251b | 484 | static const char * |
0d5de010 DJ |
485 | gnuv3_find_method_in (struct type *domain, CORE_ADDR voffset, |
486 | LONGEST adjustment) | |
487 | { | |
488 | int i; | |
489 | const char *physname; | |
490 | ||
491 | /* Search this class first. */ | |
492 | physname = NULL; | |
493 | if (adjustment == 0) | |
494 | { | |
495 | int len; | |
496 | ||
497 | len = TYPE_NFN_FIELDS (domain); | |
498 | for (i = 0; i < len; i++) | |
499 | { | |
500 | int len2, j; | |
501 | struct fn_field *f; | |
502 | ||
503 | f = TYPE_FN_FIELDLIST1 (domain, i); | |
504 | len2 = TYPE_FN_FIELDLIST_LENGTH (domain, i); | |
505 | ||
506 | check_stub_method_group (domain, i); | |
507 | for (j = 0; j < len2; j++) | |
508 | if (TYPE_FN_FIELD_VOFFSET (f, j) == voffset) | |
509 | return TYPE_FN_FIELD_PHYSNAME (f, j); | |
510 | } | |
511 | } | |
512 | ||
513 | /* Next search non-virtual bases. If it's in a virtual base, | |
514 | we're out of luck. */ | |
515 | for (i = 0; i < TYPE_N_BASECLASSES (domain); i++) | |
516 | { | |
517 | int pos; | |
518 | struct type *basetype; | |
519 | ||
520 | if (BASETYPE_VIA_VIRTUAL (domain, i)) | |
521 | continue; | |
522 | ||
523 | pos = TYPE_BASECLASS_BITPOS (domain, i) / 8; | |
524 | basetype = TYPE_FIELD_TYPE (domain, i); | |
525 | /* Recurse with a modified adjustment. We don't need to adjust | |
526 | voffset. */ | |
527 | if (adjustment >= pos && adjustment < pos + TYPE_LENGTH (basetype)) | |
528 | return gnuv3_find_method_in (basetype, voffset, adjustment - pos); | |
529 | } | |
530 | ||
531 | return NULL; | |
532 | } | |
533 | ||
fead6908 UW |
534 | /* Decode GNU v3 method pointer. */ |
535 | ||
536 | static int | |
ad4820ab UW |
537 | gnuv3_decode_method_ptr (struct gdbarch *gdbarch, |
538 | const gdb_byte *contents, | |
fead6908 UW |
539 | CORE_ADDR *value_p, |
540 | LONGEST *adjustment_p) | |
541 | { | |
ad4820ab | 542 | struct type *funcptr_type = builtin_type (gdbarch)->builtin_func_ptr; |
ed09d7da | 543 | struct type *offset_type = vtable_ptrdiff_type (gdbarch); |
fead6908 UW |
544 | CORE_ADDR ptr_value; |
545 | LONGEST voffset, adjustment; | |
546 | int vbit; | |
547 | ||
548 | /* Extract the pointer to member. The first element is either a pointer | |
549 | or a vtable offset. For pointers, we need to use extract_typed_address | |
550 | to allow the back-end to convert the pointer to a GDB address -- but | |
551 | vtable offsets we must handle as integers. At this point, we do not | |
552 | yet know which case we have, so we extract the value under both | |
553 | interpretations and choose the right one later on. */ | |
554 | ptr_value = extract_typed_address (contents, funcptr_type); | |
555 | voffset = extract_signed_integer (contents, TYPE_LENGTH (funcptr_type)); | |
556 | contents += TYPE_LENGTH (funcptr_type); | |
557 | adjustment = extract_signed_integer (contents, TYPE_LENGTH (offset_type)); | |
558 | ||
ad4820ab | 559 | if (!gdbarch_vbit_in_delta (gdbarch)) |
fead6908 UW |
560 | { |
561 | vbit = voffset & 1; | |
562 | voffset = voffset ^ vbit; | |
563 | } | |
564 | else | |
565 | { | |
566 | vbit = adjustment & 1; | |
567 | adjustment = adjustment >> 1; | |
568 | } | |
569 | ||
570 | *value_p = vbit? voffset : ptr_value; | |
571 | *adjustment_p = adjustment; | |
572 | return vbit; | |
573 | } | |
574 | ||
0d5de010 DJ |
575 | /* GNU v3 implementation of cplus_print_method_ptr. */ |
576 | ||
577 | static void | |
578 | gnuv3_print_method_ptr (const gdb_byte *contents, | |
579 | struct type *type, | |
580 | struct ui_file *stream) | |
581 | { | |
ad4820ab UW |
582 | struct type *domain = TYPE_DOMAIN_TYPE (type); |
583 | struct gdbarch *gdbarch = get_class_arch (domain); | |
0d5de010 DJ |
584 | CORE_ADDR ptr_value; |
585 | LONGEST adjustment; | |
0d5de010 DJ |
586 | int vbit; |
587 | ||
0d5de010 | 588 | /* Extract the pointer to member. */ |
ad4820ab | 589 | vbit = gnuv3_decode_method_ptr (gdbarch, contents, &ptr_value, &adjustment); |
0d5de010 DJ |
590 | |
591 | /* Check for NULL. */ | |
592 | if (ptr_value == 0 && vbit == 0) | |
593 | { | |
594 | fprintf_filtered (stream, "NULL"); | |
595 | return; | |
596 | } | |
597 | ||
598 | /* Search for a virtual method. */ | |
599 | if (vbit) | |
600 | { | |
601 | CORE_ADDR voffset; | |
602 | const char *physname; | |
603 | ||
604 | /* It's a virtual table offset, maybe in this class. Search | |
605 | for a field with the correct vtable offset. First convert it | |
606 | to an index, as used in TYPE_FN_FIELD_VOFFSET. */ | |
ed09d7da | 607 | voffset = ptr_value / TYPE_LENGTH (vtable_ptrdiff_type (gdbarch)); |
0d5de010 DJ |
608 | |
609 | physname = gnuv3_find_method_in (domain, voffset, adjustment); | |
610 | ||
611 | /* If we found a method, print that. We don't bother to disambiguate | |
612 | possible paths to the method based on the adjustment. */ | |
613 | if (physname) | |
614 | { | |
615 | char *demangled_name = cplus_demangle (physname, | |
616 | DMGL_ANSI | DMGL_PARAMS); | |
617 | if (demangled_name != NULL) | |
618 | { | |
619 | fprintf_filtered (stream, "&virtual "); | |
620 | fputs_filtered (demangled_name, stream); | |
621 | xfree (demangled_name); | |
622 | return; | |
623 | } | |
624 | } | |
625 | } | |
626 | ||
627 | /* We didn't find it; print the raw data. */ | |
628 | if (vbit) | |
629 | { | |
630 | fprintf_filtered (stream, "&virtual table offset "); | |
631 | print_longest (stream, 'd', 1, ptr_value); | |
632 | } | |
633 | else | |
634 | print_address_demangle (ptr_value, stream, demangle); | |
635 | ||
636 | if (adjustment) | |
637 | { | |
638 | fprintf_filtered (stream, ", this adjustment "); | |
639 | print_longest (stream, 'd', 1, adjustment); | |
640 | } | |
641 | } | |
642 | ||
643 | /* GNU v3 implementation of cplus_method_ptr_size. */ | |
644 | ||
645 | static int | |
ad4820ab | 646 | gnuv3_method_ptr_size (struct type *type) |
0d5de010 | 647 | { |
ad4820ab UW |
648 | struct type *domain_type = check_typedef (TYPE_DOMAIN_TYPE (type)); |
649 | struct gdbarch *gdbarch = get_class_arch (domain_type); | |
650 | return 2 * TYPE_LENGTH (builtin_type (gdbarch)->builtin_data_ptr); | |
0d5de010 DJ |
651 | } |
652 | ||
653 | /* GNU v3 implementation of cplus_make_method_ptr. */ | |
654 | ||
655 | static void | |
ad4820ab UW |
656 | gnuv3_make_method_ptr (struct type *type, gdb_byte *contents, |
657 | CORE_ADDR value, int is_virtual) | |
0d5de010 | 658 | { |
ad4820ab UW |
659 | struct type *domain_type = check_typedef (TYPE_DOMAIN_TYPE (type)); |
660 | struct gdbarch *gdbarch = get_class_arch (domain_type); | |
661 | int size = TYPE_LENGTH (builtin_type (gdbarch)->builtin_data_ptr); | |
0d5de010 DJ |
662 | |
663 | /* FIXME drow/2006-12-24: The adjustment of "this" is currently | |
664 | always zero, since the method pointer is of the correct type. | |
665 | But if the method pointer came from a base class, this is | |
666 | incorrect - it should be the offset to the base. The best | |
667 | fix might be to create the pointer to member pointing at the | |
668 | base class and cast it to the derived class, but that requires | |
669 | support for adjusting pointers to members when casting them - | |
670 | not currently supported by GDB. */ | |
671 | ||
ad4820ab | 672 | if (!gdbarch_vbit_in_delta (gdbarch)) |
0d5de010 DJ |
673 | { |
674 | store_unsigned_integer (contents, size, value | is_virtual); | |
675 | store_unsigned_integer (contents + size, size, 0); | |
676 | } | |
677 | else | |
678 | { | |
679 | store_unsigned_integer (contents, size, value); | |
680 | store_unsigned_integer (contents + size, size, is_virtual); | |
681 | } | |
682 | } | |
683 | ||
684 | /* GNU v3 implementation of cplus_method_ptr_to_value. */ | |
685 | ||
686 | static struct value * | |
687 | gnuv3_method_ptr_to_value (struct value **this_p, struct value *method_ptr) | |
688 | { | |
ad4820ab | 689 | struct gdbarch *gdbarch; |
0d5de010 DJ |
690 | const gdb_byte *contents = value_contents (method_ptr); |
691 | CORE_ADDR ptr_value; | |
ad4820ab | 692 | struct type *domain_type, *final_type, *method_type; |
0d5de010 DJ |
693 | LONGEST adjustment; |
694 | struct value *adjval; | |
695 | int vbit; | |
696 | ||
ad4820ab UW |
697 | domain_type = TYPE_DOMAIN_TYPE (check_typedef (value_type (method_ptr))); |
698 | final_type = lookup_pointer_type (domain_type); | |
0d5de010 DJ |
699 | |
700 | method_type = TYPE_TARGET_TYPE (check_typedef (value_type (method_ptr))); | |
701 | ||
fead6908 | 702 | /* Extract the pointer to member. */ |
ad4820ab UW |
703 | gdbarch = get_class_arch (domain_type); |
704 | vbit = gnuv3_decode_method_ptr (gdbarch, contents, &ptr_value, &adjustment); | |
0d5de010 DJ |
705 | |
706 | /* First convert THIS to match the containing type of the pointer to | |
707 | member. This cast may adjust the value of THIS. */ | |
708 | *this_p = value_cast (final_type, *this_p); | |
709 | ||
710 | /* Then apply whatever adjustment is necessary. This creates a somewhat | |
711 | strange pointer: it claims to have type FINAL_TYPE, but in fact it | |
712 | might not be a valid FINAL_TYPE. For instance, it might be a | |
713 | base class of FINAL_TYPE. And if it's not the primary base class, | |
714 | then printing it out as a FINAL_TYPE object would produce some pretty | |
715 | garbage. | |
716 | ||
717 | But we don't really know the type of the first argument in | |
718 | METHOD_TYPE either, which is why this happens. We can't | |
719 | dereference this later as a FINAL_TYPE, but once we arrive in the | |
720 | called method we'll have debugging information for the type of | |
721 | "this" - and that'll match the value we produce here. | |
722 | ||
723 | You can provoke this case by casting a Base::* to a Derived::*, for | |
724 | instance. */ | |
ad4820ab UW |
725 | *this_p = value_cast (builtin_type (gdbarch)->builtin_data_ptr, *this_p); |
726 | adjval = value_from_longest (builtin_type (gdbarch)->builtin_long, | |
727 | adjustment); | |
89eef114 | 728 | *this_p = value_ptradd (*this_p, adjval); |
0d5de010 DJ |
729 | *this_p = value_cast (final_type, *this_p); |
730 | ||
731 | if (vbit) | |
732 | { | |
ad4820ab | 733 | LONGEST voffset; |
ed09d7da | 734 | voffset = ptr_value / TYPE_LENGTH (vtable_ptrdiff_type (gdbarch)); |
ad4820ab UW |
735 | return gnuv3_get_virtual_fn (gdbarch, value_ind (*this_p), |
736 | method_type, voffset); | |
0d5de010 DJ |
737 | } |
738 | else | |
739 | return value_from_pointer (lookup_pointer_type (method_type), ptr_value); | |
740 | } | |
741 | ||
b18be20d DJ |
742 | /* Determine if we are currently in a C++ thunk. If so, get the address |
743 | of the routine we are thunking to and continue to there instead. */ | |
744 | ||
745 | static CORE_ADDR | |
52f729a7 | 746 | gnuv3_skip_trampoline (struct frame_info *frame, CORE_ADDR stop_pc) |
b18be20d DJ |
747 | { |
748 | CORE_ADDR real_stop_pc, method_stop_pc; | |
9970f04b | 749 | struct gdbarch *gdbarch = get_frame_arch (frame); |
b18be20d DJ |
750 | struct minimal_symbol *thunk_sym, *fn_sym; |
751 | struct obj_section *section; | |
752 | char *thunk_name, *fn_name; | |
753 | ||
9970f04b | 754 | real_stop_pc = gdbarch_skip_trampoline_code (gdbarch, frame, stop_pc); |
b18be20d DJ |
755 | if (real_stop_pc == 0) |
756 | real_stop_pc = stop_pc; | |
757 | ||
758 | /* Find the linker symbol for this potential thunk. */ | |
759 | thunk_sym = lookup_minimal_symbol_by_pc (real_stop_pc); | |
760 | section = find_pc_section (real_stop_pc); | |
761 | if (thunk_sym == NULL || section == NULL) | |
762 | return 0; | |
763 | ||
764 | /* The symbol's demangled name should be something like "virtual | |
765 | thunk to FUNCTION", where FUNCTION is the name of the function | |
766 | being thunked to. */ | |
767 | thunk_name = SYMBOL_DEMANGLED_NAME (thunk_sym); | |
768 | if (thunk_name == NULL || strstr (thunk_name, " thunk to ") == NULL) | |
769 | return 0; | |
770 | ||
771 | fn_name = strstr (thunk_name, " thunk to ") + strlen (" thunk to "); | |
772 | fn_sym = lookup_minimal_symbol (fn_name, NULL, section->objfile); | |
773 | if (fn_sym == NULL) | |
774 | return 0; | |
775 | ||
776 | method_stop_pc = SYMBOL_VALUE_ADDRESS (fn_sym); | |
e76f05fa | 777 | real_stop_pc = gdbarch_skip_trampoline_code |
9970f04b | 778 | (gdbarch, frame, method_stop_pc); |
b18be20d DJ |
779 | if (real_stop_pc == 0) |
780 | real_stop_pc = method_stop_pc; | |
781 | ||
782 | return real_stop_pc; | |
783 | } | |
784 | ||
41f1b697 DJ |
785 | /* Return nonzero if a type should be passed by reference. |
786 | ||
787 | The rule in the v3 ABI document comes from section 3.1.1. If the | |
788 | type has a non-trivial copy constructor or destructor, then the | |
789 | caller must make a copy (by calling the copy constructor if there | |
790 | is one or perform the copy itself otherwise), pass the address of | |
791 | the copy, and then destroy the temporary (if necessary). | |
792 | ||
793 | For return values with non-trivial copy constructors or | |
794 | destructors, space will be allocated in the caller, and a pointer | |
795 | will be passed as the first argument (preceding "this"). | |
796 | ||
797 | We don't have a bulletproof mechanism for determining whether a | |
798 | constructor or destructor is trivial. For GCC and DWARF2 debug | |
799 | information, we can check the artificial flag. | |
800 | ||
801 | We don't do anything with the constructors or destructors, | |
802 | but we have to get the argument passing right anyway. */ | |
803 | static int | |
804 | gnuv3_pass_by_reference (struct type *type) | |
805 | { | |
806 | int fieldnum, fieldelem; | |
807 | ||
808 | CHECK_TYPEDEF (type); | |
809 | ||
810 | /* We're only interested in things that can have methods. */ | |
811 | if (TYPE_CODE (type) != TYPE_CODE_STRUCT | |
812 | && TYPE_CODE (type) != TYPE_CODE_CLASS | |
813 | && TYPE_CODE (type) != TYPE_CODE_UNION) | |
814 | return 0; | |
815 | ||
816 | for (fieldnum = 0; fieldnum < TYPE_NFN_FIELDS (type); fieldnum++) | |
817 | for (fieldelem = 0; fieldelem < TYPE_FN_FIELDLIST_LENGTH (type, fieldnum); | |
818 | fieldelem++) | |
819 | { | |
820 | struct fn_field *fn = TYPE_FN_FIELDLIST1 (type, fieldnum); | |
821 | char *name = TYPE_FN_FIELDLIST_NAME (type, fieldnum); | |
822 | struct type *fieldtype = TYPE_FN_FIELD_TYPE (fn, fieldelem); | |
823 | ||
824 | /* If this function is marked as artificial, it is compiler-generated, | |
825 | and we assume it is trivial. */ | |
826 | if (TYPE_FN_FIELD_ARTIFICIAL (fn, fieldelem)) | |
827 | continue; | |
828 | ||
829 | /* If we've found a destructor, we must pass this by reference. */ | |
830 | if (name[0] == '~') | |
831 | return 1; | |
832 | ||
833 | /* If the mangled name of this method doesn't indicate that it | |
834 | is a constructor, we're not interested. | |
835 | ||
836 | FIXME drow/2007-09-23: We could do this using the name of | |
837 | the method and the name of the class instead of dealing | |
838 | with the mangled name. We don't have a convenient function | |
839 | to strip off both leading scope qualifiers and trailing | |
840 | template arguments yet. */ | |
841 | if (!is_constructor_name (TYPE_FN_FIELD_PHYSNAME (fn, fieldelem))) | |
842 | continue; | |
843 | ||
844 | /* If this method takes two arguments, and the second argument is | |
845 | a reference to this class, then it is a copy constructor. */ | |
846 | if (TYPE_NFIELDS (fieldtype) == 2 | |
847 | && TYPE_CODE (TYPE_FIELD_TYPE (fieldtype, 1)) == TYPE_CODE_REF | |
848 | && check_typedef (TYPE_TARGET_TYPE (TYPE_FIELD_TYPE (fieldtype, 1))) == type) | |
849 | return 1; | |
850 | } | |
851 | ||
852 | /* Even if all the constructors and destructors were artificial, one | |
853 | of them may have invoked a non-artificial constructor or | |
854 | destructor in a base class. If any base class needs to be passed | |
855 | by reference, so does this class. Similarly for members, which | |
856 | are constructed whenever this class is. We do not need to worry | |
857 | about recursive loops here, since we are only looking at members | |
858 | of complete class type. */ | |
859 | for (fieldnum = 0; fieldnum < TYPE_NFIELDS (type); fieldnum++) | |
860 | if (gnuv3_pass_by_reference (TYPE_FIELD_TYPE (type, fieldnum))) | |
861 | return 1; | |
862 | ||
863 | return 0; | |
864 | } | |
865 | ||
7ed49443 JB |
866 | static void |
867 | init_gnuv3_ops (void) | |
868 | { | |
030f20e1 | 869 | vtable_type_gdbarch_data = gdbarch_data_register_post_init (build_gdb_vtable_type); |
7ed49443 JB |
870 | |
871 | gnu_v3_abi_ops.shortname = "gnu-v3"; | |
872 | gnu_v3_abi_ops.longname = "GNU G++ Version 3 ABI"; | |
873 | gnu_v3_abi_ops.doc = "G++ Version 3 ABI"; | |
358777b0 EZ |
874 | gnu_v3_abi_ops.is_destructor_name = |
875 | (enum dtor_kinds (*) (const char *))is_gnu_v3_mangled_dtor; | |
876 | gnu_v3_abi_ops.is_constructor_name = | |
877 | (enum ctor_kinds (*) (const char *))is_gnu_v3_mangled_ctor; | |
7ed49443 JB |
878 | gnu_v3_abi_ops.is_vtable_name = gnuv3_is_vtable_name; |
879 | gnu_v3_abi_ops.is_operator_name = gnuv3_is_operator_name; | |
880 | gnu_v3_abi_ops.rtti_type = gnuv3_rtti_type; | |
881 | gnu_v3_abi_ops.virtual_fn_field = gnuv3_virtual_fn_field; | |
1514d34e | 882 | gnu_v3_abi_ops.baseclass_offset = gnuv3_baseclass_offset; |
0d5de010 DJ |
883 | gnu_v3_abi_ops.print_method_ptr = gnuv3_print_method_ptr; |
884 | gnu_v3_abi_ops.method_ptr_size = gnuv3_method_ptr_size; | |
885 | gnu_v3_abi_ops.make_method_ptr = gnuv3_make_method_ptr; | |
886 | gnu_v3_abi_ops.method_ptr_to_value = gnuv3_method_ptr_to_value; | |
b18be20d | 887 | gnu_v3_abi_ops.skip_trampoline = gnuv3_skip_trampoline; |
41f1b697 | 888 | gnu_v3_abi_ops.pass_by_reference = gnuv3_pass_by_reference; |
7ed49443 JB |
889 | } |
890 | ||
b9362cc7 | 891 | extern initialize_file_ftype _initialize_gnu_v3_abi; /* -Wmissing-prototypes */ |
7ed49443 JB |
892 | |
893 | void | |
894 | _initialize_gnu_v3_abi (void) | |
895 | { | |
896 | init_gnuv3_ops (); | |
897 | ||
fe1f4a5e | 898 | register_cp_abi (&gnu_v3_abi_ops); |
7ed49443 | 899 | } |