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7ed49443 JB |
1 | /* Abstraction of GNU v3 abi. |
2 | Contributed by Jim Blandy <jimb@redhat.com> | |
451fbdda | 3 | |
6aba47ca | 4 | Copyright (C) 2001, 2002, 2003, 2005, 2006, 2007 |
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 | ||
48 | /* To help us find the components of a vtable, we build ourselves a | |
49 | GDB type object representing the vtable structure. Following the | |
50 | V3 ABI, it goes something like this: | |
51 | ||
52 | struct gdb_gnu_v3_abi_vtable { | |
53 | ||
54 | / * An array of virtual call and virtual base offsets. The real | |
55 | length of this array depends on the class hierarchy; we use | |
56 | negative subscripts to access the elements. Yucky, but | |
57 | better than the alternatives. * / | |
58 | ptrdiff_t vcall_and_vbase_offsets[0]; | |
59 | ||
60 | / * The offset from a virtual pointer referring to this table | |
61 | to the top of the complete object. * / | |
62 | ptrdiff_t offset_to_top; | |
63 | ||
64 | / * The type_info pointer for this class. This is really a | |
65 | std::type_info *, but GDB doesn't really look at the | |
66 | type_info object itself, so we don't bother to get the type | |
67 | exactly right. * / | |
68 | void *type_info; | |
69 | ||
70 | / * Virtual table pointers in objects point here. * / | |
71 | ||
72 | / * Virtual function pointers. Like the vcall/vbase array, the | |
73 | real length of this table depends on the class hierarchy. * / | |
74 | void (*virtual_functions[0]) (); | |
75 | ||
76 | }; | |
77 | ||
78 | The catch, of course, is that the exact layout of this table | |
79 | depends on the ABI --- word size, endianness, alignment, etc. So | |
80 | the GDB type object is actually a per-architecture kind of thing. | |
81 | ||
82 | vtable_type_gdbarch_data is a gdbarch per-architecture data pointer | |
83 | which refers to the struct type * for this structure, laid out | |
84 | appropriately for the architecture. */ | |
b27b8843 | 85 | static struct gdbarch_data *vtable_type_gdbarch_data; |
7ed49443 JB |
86 | |
87 | ||
88 | /* Human-readable names for the numbers of the fields above. */ | |
89 | enum { | |
90 | vtable_field_vcall_and_vbase_offsets, | |
91 | vtable_field_offset_to_top, | |
92 | vtable_field_type_info, | |
93 | vtable_field_virtual_functions | |
94 | }; | |
95 | ||
96 | ||
97 | /* Return a GDB type representing `struct gdb_gnu_v3_abi_vtable', | |
98 | described above, laid out appropriately for ARCH. | |
99 | ||
100 | We use this function as the gdbarch per-architecture data | |
101 | initialization function. We assume that the gdbarch framework | |
102 | calls the per-architecture data initialization functions after it | |
103 | sets current_gdbarch to the new architecture. */ | |
104 | static void * | |
105 | build_gdb_vtable_type (struct gdbarch *arch) | |
106 | { | |
107 | struct type *t; | |
108 | struct field *field_list, *field; | |
109 | int offset; | |
110 | ||
111 | struct type *void_ptr_type | |
112 | = lookup_pointer_type (builtin_type_void); | |
113 | struct type *ptr_to_void_fn_type | |
114 | = lookup_pointer_type (lookup_function_type (builtin_type_void)); | |
115 | ||
116 | /* ARCH can't give us the true ptrdiff_t type, so we guess. */ | |
117 | struct type *ptrdiff_type | |
819844ad UW |
118 | = init_type (TYPE_CODE_INT, |
119 | gdbarch_ptr_bit (current_gdbarch) / TARGET_CHAR_BIT, 0, | |
7ed49443 JB |
120 | "ptrdiff_t", 0); |
121 | ||
122 | /* We assume no padding is necessary, since GDB doesn't know | |
123 | anything about alignment at the moment. If this assumption bites | |
124 | us, we should add a gdbarch method which, given a type, returns | |
125 | the alignment that type requires, and then use that here. */ | |
126 | ||
127 | /* Build the field list. */ | |
128 | field_list = xmalloc (sizeof (struct field [4])); | |
129 | memset (field_list, 0, sizeof (struct field [4])); | |
130 | field = &field_list[0]; | |
131 | offset = 0; | |
132 | ||
133 | /* ptrdiff_t vcall_and_vbase_offsets[0]; */ | |
134 | FIELD_NAME (*field) = "vcall_and_vbase_offsets"; | |
135 | FIELD_TYPE (*field) | |
136 | = create_array_type (0, ptrdiff_type, | |
137 | create_range_type (0, builtin_type_int, 0, -1)); | |
138 | FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT; | |
139 | offset += TYPE_LENGTH (FIELD_TYPE (*field)); | |
140 | field++; | |
141 | ||
142 | /* ptrdiff_t offset_to_top; */ | |
143 | FIELD_NAME (*field) = "offset_to_top"; | |
144 | FIELD_TYPE (*field) = ptrdiff_type; | |
145 | FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT; | |
146 | offset += TYPE_LENGTH (FIELD_TYPE (*field)); | |
147 | field++; | |
148 | ||
149 | /* void *type_info; */ | |
150 | FIELD_NAME (*field) = "type_info"; | |
151 | FIELD_TYPE (*field) = void_ptr_type; | |
152 | FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT; | |
153 | offset += TYPE_LENGTH (FIELD_TYPE (*field)); | |
154 | field++; | |
155 | ||
156 | /* void (*virtual_functions[0]) (); */ | |
157 | FIELD_NAME (*field) = "virtual_functions"; | |
158 | FIELD_TYPE (*field) | |
159 | = create_array_type (0, ptr_to_void_fn_type, | |
160 | create_range_type (0, builtin_type_int, 0, -1)); | |
161 | FIELD_BITPOS (*field) = offset * TARGET_CHAR_BIT; | |
162 | offset += TYPE_LENGTH (FIELD_TYPE (*field)); | |
163 | field++; | |
164 | ||
165 | /* We assumed in the allocation above that there were four fields. */ | |
3d499020 | 166 | gdb_assert (field == (field_list + 4)); |
7ed49443 JB |
167 | |
168 | t = init_type (TYPE_CODE_STRUCT, offset, 0, 0, 0); | |
169 | TYPE_NFIELDS (t) = field - field_list; | |
170 | TYPE_FIELDS (t) = field_list; | |
171 | TYPE_TAG_NAME (t) = "gdb_gnu_v3_abi_vtable"; | |
172 | ||
173 | return t; | |
174 | } | |
175 | ||
176 | ||
177 | /* Return the offset from the start of the imaginary `struct | |
178 | gdb_gnu_v3_abi_vtable' object to the vtable's "address point" | |
179 | (i.e., where objects' virtual table pointers point). */ | |
180 | static int | |
5ae5f592 | 181 | vtable_address_point_offset (void) |
7ed49443 | 182 | { |
451fbdda AC |
183 | struct type *vtable_type = gdbarch_data (current_gdbarch, |
184 | vtable_type_gdbarch_data); | |
7ed49443 JB |
185 | |
186 | return (TYPE_FIELD_BITPOS (vtable_type, vtable_field_virtual_functions) | |
187 | / TARGET_CHAR_BIT); | |
188 | } | |
189 | ||
190 | ||
191 | static struct type * | |
192 | gnuv3_rtti_type (struct value *value, | |
193 | int *full_p, int *top_p, int *using_enc_p) | |
194 | { | |
451fbdda AC |
195 | struct type *vtable_type = gdbarch_data (current_gdbarch, |
196 | vtable_type_gdbarch_data); | |
df407dfe | 197 | struct type *values_type = check_typedef (value_type (value)); |
7ed49443 JB |
198 | CORE_ADDR vtable_address; |
199 | struct value *vtable; | |
200 | struct minimal_symbol *vtable_symbol; | |
201 | const char *vtable_symbol_name; | |
202 | const char *class_name; | |
7ed49443 | 203 | struct type *run_time_type; |
21cfb3b6 | 204 | struct type *base_type; |
7ed49443 JB |
205 | LONGEST offset_to_top; |
206 | ||
207 | /* We only have RTTI for class objects. */ | |
df407dfe | 208 | if (TYPE_CODE (values_type) != TYPE_CODE_CLASS) |
7ed49443 JB |
209 | return NULL; |
210 | ||
df407dfe | 211 | /* If we can't find the virtual table pointer for values_type, we |
7ed49443 | 212 | can't find the RTTI. */ |
df407dfe AC |
213 | fill_in_vptr_fieldno (values_type); |
214 | if (TYPE_VPTR_FIELDNO (values_type) == -1) | |
7ed49443 JB |
215 | return NULL; |
216 | ||
21cfb3b6 DJ |
217 | if (using_enc_p) |
218 | *using_enc_p = 0; | |
219 | ||
7ed49443 | 220 | /* Fetch VALUE's virtual table pointer, and tweak it to point at |
21cfb3b6 | 221 | an instance of our imaginary gdb_gnu_v3_abi_vtable structure. */ |
df407dfe AC |
222 | base_type = check_typedef (TYPE_VPTR_BASETYPE (values_type)); |
223 | if (values_type != base_type) | |
21cfb3b6 DJ |
224 | { |
225 | value = value_cast (base_type, value); | |
226 | if (using_enc_p) | |
227 | *using_enc_p = 1; | |
228 | } | |
7ed49443 | 229 | vtable_address |
df407dfe | 230 | = value_as_address (value_field (value, TYPE_VPTR_FIELDNO (values_type))); |
7ed49443 | 231 | vtable = value_at_lazy (vtable_type, |
00a4c844 | 232 | vtable_address - vtable_address_point_offset ()); |
7ed49443 JB |
233 | |
234 | /* Find the linker symbol for this vtable. */ | |
235 | vtable_symbol | |
236 | = lookup_minimal_symbol_by_pc (VALUE_ADDRESS (vtable) | |
df407dfe | 237 | + value_offset (vtable) |
13c3b5f5 | 238 | + value_embedded_offset (vtable)); |
7ed49443 JB |
239 | if (! vtable_symbol) |
240 | return NULL; | |
241 | ||
242 | /* The symbol's demangled name should be something like "vtable for | |
243 | CLASS", where CLASS is the name of the run-time type of VALUE. | |
244 | If we didn't like this approach, we could instead look in the | |
245 | type_info object itself to get the class name. But this way | |
246 | should work just as well, and doesn't read target memory. */ | |
247 | vtable_symbol_name = SYMBOL_DEMANGLED_NAME (vtable_symbol); | |
98081e55 PB |
248 | if (vtable_symbol_name == NULL |
249 | || strncmp (vtable_symbol_name, "vtable for ", 11)) | |
f773fdbb | 250 | { |
8a3fe4f8 | 251 | warning (_("can't find linker symbol for virtual table for `%s' value"), |
df407dfe | 252 | TYPE_NAME (values_type)); |
f773fdbb | 253 | if (vtable_symbol_name) |
8a3fe4f8 | 254 | warning (_(" found `%s' instead"), vtable_symbol_name); |
f773fdbb JM |
255 | return NULL; |
256 | } | |
7ed49443 JB |
257 | class_name = vtable_symbol_name + 11; |
258 | ||
259 | /* Try to look up the class name as a type name. */ | |
362ff856 MC |
260 | /* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */ |
261 | run_time_type = cp_lookup_rtti_type (class_name, NULL); | |
262 | if (run_time_type == NULL) | |
263 | return NULL; | |
7ed49443 JB |
264 | |
265 | /* Get the offset from VALUE to the top of the complete object. | |
266 | NOTE: this is the reverse of the meaning of *TOP_P. */ | |
267 | offset_to_top | |
268 | = value_as_long (value_field (vtable, vtable_field_offset_to_top)); | |
269 | ||
270 | if (full_p) | |
13c3b5f5 | 271 | *full_p = (- offset_to_top == value_embedded_offset (value) |
4754a64e | 272 | && (TYPE_LENGTH (value_enclosing_type (value)) |
7ed49443 JB |
273 | >= TYPE_LENGTH (run_time_type))); |
274 | if (top_p) | |
275 | *top_p = - offset_to_top; | |
7ed49443 JB |
276 | |
277 | return run_time_type; | |
278 | } | |
279 | ||
0d5de010 DJ |
280 | /* Find the vtable for CONTAINER and return a value of the correct |
281 | vtable type for this architecture. */ | |
7ed49443 JB |
282 | |
283 | static struct value * | |
0d5de010 | 284 | gnuv3_get_vtable (struct value *container) |
7ed49443 | 285 | { |
451fbdda AC |
286 | struct type *vtable_type = gdbarch_data (current_gdbarch, |
287 | vtable_type_gdbarch_data); | |
0d5de010 DJ |
288 | struct type *vtable_pointer_type; |
289 | struct value *vtable_pointer; | |
290 | CORE_ADDR vtable_pointer_address, vtable_address; | |
291 | ||
292 | /* We do not consult the debug information to find the virtual table. | |
293 | The ABI specifies that it is always at offset zero in any class, | |
294 | and debug information may not represent it. We won't issue an | |
295 | error if there's a class with virtual functions but no virtual table | |
296 | pointer, but something's already gone seriously wrong if that | |
297 | happens. | |
298 | ||
299 | We avoid using value_contents on principle, because the object might | |
300 | be large. */ | |
301 | ||
302 | /* Find the type "pointer to virtual table". */ | |
303 | vtable_pointer_type = lookup_pointer_type (vtable_type); | |
304 | ||
305 | /* Load it from the start of the class. */ | |
306 | vtable_pointer_address = value_as_address (value_addr (container)); | |
307 | vtable_pointer = value_at (vtable_pointer_type, vtable_pointer_address); | |
308 | vtable_address = value_as_address (vtable_pointer); | |
309 | ||
310 | /* Correct it to point at the start of the virtual table, rather | |
311 | than the address point. */ | |
312 | return value_at_lazy (vtable_type, | |
313 | vtable_address - vtable_address_point_offset ()); | |
314 | } | |
7ed49443 | 315 | |
0d5de010 DJ |
316 | /* Return a function pointer for CONTAINER's VTABLE_INDEX'th virtual |
317 | function, of type FNTYPE. */ | |
7ed49443 | 318 | |
0d5de010 DJ |
319 | static struct value * |
320 | gnuv3_get_virtual_fn (struct value *container, struct type *fntype, | |
321 | int vtable_index) | |
322 | { | |
323 | struct value *vtable = gnuv3_get_vtable (container); | |
324 | struct value *vfn; | |
7ed49443 JB |
325 | |
326 | /* Fetch the appropriate function pointer from the vtable. */ | |
327 | vfn = value_subscript (value_field (vtable, vtable_field_virtual_functions), | |
0d5de010 | 328 | value_from_longest (builtin_type_int, vtable_index)); |
7ed49443 | 329 | |
0d5de010 DJ |
330 | /* If this architecture uses function descriptors directly in the vtable, |
331 | then the address of the vtable entry is actually a "function pointer" | |
332 | (i.e. points to the descriptor). We don't need to scale the index | |
333 | by the size of a function descriptor; GCC does that before outputing | |
334 | debug information. */ | |
335 | if (gdbarch_vtable_function_descriptors (current_gdbarch)) | |
336 | vfn = value_addr (vfn); | |
7ed49443 | 337 | |
0d5de010 DJ |
338 | /* Cast the function pointer to the appropriate type. */ |
339 | vfn = value_cast (lookup_pointer_type (fntype), vfn); | |
76b79d6e | 340 | |
7ed49443 JB |
341 | return vfn; |
342 | } | |
343 | ||
0d5de010 DJ |
344 | /* GNU v3 implementation of value_virtual_fn_field. See cp-abi.h |
345 | for a description of the arguments. */ | |
346 | ||
347 | static struct value * | |
348 | gnuv3_virtual_fn_field (struct value **value_p, | |
349 | struct fn_field *f, int j, | |
350 | struct type *vfn_base, int offset) | |
351 | { | |
352 | struct type *values_type = check_typedef (value_type (*value_p)); | |
353 | ||
354 | /* Some simple sanity checks. */ | |
355 | if (TYPE_CODE (values_type) != TYPE_CODE_CLASS) | |
356 | error (_("Only classes can have virtual functions.")); | |
357 | ||
358 | /* Cast our value to the base class which defines this virtual | |
359 | function. This takes care of any necessary `this' | |
360 | adjustments. */ | |
361 | if (vfn_base != values_type) | |
362 | *value_p = value_cast (vfn_base, *value_p); | |
363 | ||
364 | return gnuv3_get_virtual_fn (*value_p, TYPE_FN_FIELD_TYPE (f, j), | |
365 | TYPE_FN_FIELD_VOFFSET (f, j)); | |
366 | } | |
367 | ||
1514d34e DJ |
368 | /* Compute the offset of the baseclass which is |
369 | the INDEXth baseclass of class TYPE, | |
370 | for value at VALADDR (in host) at ADDRESS (in target). | |
371 | The result is the offset of the baseclass value relative | |
372 | to (the address of)(ARG) + OFFSET. | |
373 | ||
374 | -1 is returned on error. */ | |
b9362cc7 | 375 | static int |
96ce45ca | 376 | gnuv3_baseclass_offset (struct type *type, int index, const bfd_byte *valaddr, |
1514d34e DJ |
377 | CORE_ADDR address) |
378 | { | |
451fbdda AC |
379 | struct type *vtable_type = gdbarch_data (current_gdbarch, |
380 | vtable_type_gdbarch_data); | |
79d5b63a DJ |
381 | struct value *vtable; |
382 | struct type *vbasetype; | |
1514d34e DJ |
383 | struct value *offset_val, *vbase_array; |
384 | CORE_ADDR vtable_address; | |
385 | long int cur_base_offset, base_offset; | |
1514d34e DJ |
386 | |
387 | /* If it isn't a virtual base, this is easy. The offset is in the | |
388 | type definition. */ | |
389 | if (!BASETYPE_VIA_VIRTUAL (type, index)) | |
390 | return TYPE_BASECLASS_BITPOS (type, index) / 8; | |
391 | ||
392 | /* To access a virtual base, we need to use the vbase offset stored in | |
393 | our vtable. Recent GCC versions provide this information. If it isn't | |
394 | available, we could get what we needed from RTTI, or from drawing the | |
395 | complete inheritance graph based on the debug info. Neither is | |
396 | worthwhile. */ | |
397 | cur_base_offset = TYPE_BASECLASS_BITPOS (type, index) / 8; | |
398 | if (cur_base_offset >= - vtable_address_point_offset ()) | |
8a3fe4f8 | 399 | error (_("Expected a negative vbase offset (old compiler?)")); |
1514d34e DJ |
400 | |
401 | cur_base_offset = cur_base_offset + vtable_address_point_offset (); | |
402 | if ((- cur_base_offset) % TYPE_LENGTH (builtin_type_void_data_ptr) != 0) | |
8a3fe4f8 | 403 | error (_("Misaligned vbase offset.")); |
1514d34e DJ |
404 | cur_base_offset = cur_base_offset |
405 | / ((int) TYPE_LENGTH (builtin_type_void_data_ptr)); | |
406 | ||
407 | /* We're now looking for the cur_base_offset'th entry (negative index) | |
79d5b63a DJ |
408 | in the vcall_and_vbase_offsets array. We used to cast the object to |
409 | its TYPE_VPTR_BASETYPE, and reference the vtable as TYPE_VPTR_FIELDNO; | |
410 | however, that cast can not be done without calling baseclass_offset again | |
411 | if the TYPE_VPTR_BASETYPE is a virtual base class, as described in the | |
412 | v3 C++ ABI Section 2.4.I.2.b. Fortunately the ABI guarantees that the | |
413 | vtable pointer will be located at the beginning of the object, so we can | |
414 | bypass the casting. Verify that the TYPE_VPTR_FIELDNO is in fact at the | |
7ed85d26 DJ |
415 | start of whichever baseclass it resides in, as a sanity measure - iff |
416 | we have debugging information for that baseclass. */ | |
79d5b63a DJ |
417 | |
418 | vbasetype = TYPE_VPTR_BASETYPE (type); | |
7ed85d26 DJ |
419 | if (TYPE_VPTR_FIELDNO (vbasetype) < 0) |
420 | fill_in_vptr_fieldno (vbasetype); | |
421 | ||
422 | if (TYPE_VPTR_FIELDNO (vbasetype) >= 0 | |
423 | && TYPE_FIELD_BITPOS (vbasetype, TYPE_VPTR_FIELDNO (vbasetype)) != 0) | |
8a3fe4f8 | 424 | error (_("Illegal vptr offset in class %s"), |
79d5b63a DJ |
425 | TYPE_NAME (vbasetype) ? TYPE_NAME (vbasetype) : "<unknown>"); |
426 | ||
427 | vtable_address = value_as_address (value_at_lazy (builtin_type_void_data_ptr, | |
00a4c844 | 428 | address)); |
1514d34e | 429 | vtable = value_at_lazy (vtable_type, |
00a4c844 | 430 | vtable_address - vtable_address_point_offset ()); |
1514d34e DJ |
431 | offset_val = value_from_longest(builtin_type_int, cur_base_offset); |
432 | vbase_array = value_field (vtable, vtable_field_vcall_and_vbase_offsets); | |
433 | base_offset = value_as_long (value_subscript (vbase_array, offset_val)); | |
434 | return base_offset; | |
435 | } | |
7ed49443 | 436 | |
0d5de010 DJ |
437 | /* Locate a virtual method in DOMAIN or its non-virtual base classes |
438 | which has virtual table index VOFFSET. The method has an associated | |
439 | "this" adjustment of ADJUSTMENT bytes. */ | |
440 | ||
441 | const char * | |
442 | gnuv3_find_method_in (struct type *domain, CORE_ADDR voffset, | |
443 | LONGEST adjustment) | |
444 | { | |
445 | int i; | |
446 | const char *physname; | |
447 | ||
448 | /* Search this class first. */ | |
449 | physname = NULL; | |
450 | if (adjustment == 0) | |
451 | { | |
452 | int len; | |
453 | ||
454 | len = TYPE_NFN_FIELDS (domain); | |
455 | for (i = 0; i < len; i++) | |
456 | { | |
457 | int len2, j; | |
458 | struct fn_field *f; | |
459 | ||
460 | f = TYPE_FN_FIELDLIST1 (domain, i); | |
461 | len2 = TYPE_FN_FIELDLIST_LENGTH (domain, i); | |
462 | ||
463 | check_stub_method_group (domain, i); | |
464 | for (j = 0; j < len2; j++) | |
465 | if (TYPE_FN_FIELD_VOFFSET (f, j) == voffset) | |
466 | return TYPE_FN_FIELD_PHYSNAME (f, j); | |
467 | } | |
468 | } | |
469 | ||
470 | /* Next search non-virtual bases. If it's in a virtual base, | |
471 | we're out of luck. */ | |
472 | for (i = 0; i < TYPE_N_BASECLASSES (domain); i++) | |
473 | { | |
474 | int pos; | |
475 | struct type *basetype; | |
476 | ||
477 | if (BASETYPE_VIA_VIRTUAL (domain, i)) | |
478 | continue; | |
479 | ||
480 | pos = TYPE_BASECLASS_BITPOS (domain, i) / 8; | |
481 | basetype = TYPE_FIELD_TYPE (domain, i); | |
482 | /* Recurse with a modified adjustment. We don't need to adjust | |
483 | voffset. */ | |
484 | if (adjustment >= pos && adjustment < pos + TYPE_LENGTH (basetype)) | |
485 | return gnuv3_find_method_in (basetype, voffset, adjustment - pos); | |
486 | } | |
487 | ||
488 | return NULL; | |
489 | } | |
490 | ||
491 | /* GNU v3 implementation of cplus_print_method_ptr. */ | |
492 | ||
493 | static void | |
494 | gnuv3_print_method_ptr (const gdb_byte *contents, | |
495 | struct type *type, | |
496 | struct ui_file *stream) | |
497 | { | |
498 | CORE_ADDR ptr_value; | |
499 | LONGEST adjustment; | |
500 | struct type *domain; | |
501 | int vbit; | |
502 | ||
503 | domain = TYPE_DOMAIN_TYPE (type); | |
504 | ||
505 | /* Extract the pointer to member. */ | |
506 | ptr_value = extract_typed_address (contents, builtin_type_void_func_ptr); | |
507 | contents += TYPE_LENGTH (builtin_type_void_func_ptr); | |
508 | adjustment = extract_signed_integer (contents, | |
509 | TYPE_LENGTH (builtin_type_long)); | |
510 | ||
511 | if (!gdbarch_vbit_in_delta (current_gdbarch)) | |
512 | { | |
513 | vbit = ptr_value & 1; | |
514 | ptr_value = ptr_value ^ vbit; | |
515 | } | |
516 | else | |
517 | { | |
518 | vbit = adjustment & 1; | |
519 | adjustment = adjustment >> 1; | |
520 | } | |
521 | ||
522 | /* Check for NULL. */ | |
523 | if (ptr_value == 0 && vbit == 0) | |
524 | { | |
525 | fprintf_filtered (stream, "NULL"); | |
526 | return; | |
527 | } | |
528 | ||
529 | /* Search for a virtual method. */ | |
530 | if (vbit) | |
531 | { | |
532 | CORE_ADDR voffset; | |
533 | const char *physname; | |
534 | ||
535 | /* It's a virtual table offset, maybe in this class. Search | |
536 | for a field with the correct vtable offset. First convert it | |
537 | to an index, as used in TYPE_FN_FIELD_VOFFSET. */ | |
538 | voffset = ptr_value / TYPE_LENGTH (builtin_type_long); | |
539 | ||
540 | physname = gnuv3_find_method_in (domain, voffset, adjustment); | |
541 | ||
542 | /* If we found a method, print that. We don't bother to disambiguate | |
543 | possible paths to the method based on the adjustment. */ | |
544 | if (physname) | |
545 | { | |
546 | char *demangled_name = cplus_demangle (physname, | |
547 | DMGL_ANSI | DMGL_PARAMS); | |
548 | if (demangled_name != NULL) | |
549 | { | |
550 | fprintf_filtered (stream, "&virtual "); | |
551 | fputs_filtered (demangled_name, stream); | |
552 | xfree (demangled_name); | |
553 | return; | |
554 | } | |
555 | } | |
556 | } | |
557 | ||
558 | /* We didn't find it; print the raw data. */ | |
559 | if (vbit) | |
560 | { | |
561 | fprintf_filtered (stream, "&virtual table offset "); | |
562 | print_longest (stream, 'd', 1, ptr_value); | |
563 | } | |
564 | else | |
565 | print_address_demangle (ptr_value, stream, demangle); | |
566 | ||
567 | if (adjustment) | |
568 | { | |
569 | fprintf_filtered (stream, ", this adjustment "); | |
570 | print_longest (stream, 'd', 1, adjustment); | |
571 | } | |
572 | } | |
573 | ||
574 | /* GNU v3 implementation of cplus_method_ptr_size. */ | |
575 | ||
576 | static int | |
577 | gnuv3_method_ptr_size (void) | |
578 | { | |
579 | return 2 * TYPE_LENGTH (builtin_type_void_data_ptr); | |
580 | } | |
581 | ||
582 | /* GNU v3 implementation of cplus_make_method_ptr. */ | |
583 | ||
584 | static void | |
585 | gnuv3_make_method_ptr (gdb_byte *contents, CORE_ADDR value, int is_virtual) | |
586 | { | |
587 | int size = TYPE_LENGTH (builtin_type_void_data_ptr); | |
588 | ||
589 | /* FIXME drow/2006-12-24: The adjustment of "this" is currently | |
590 | always zero, since the method pointer is of the correct type. | |
591 | But if the method pointer came from a base class, this is | |
592 | incorrect - it should be the offset to the base. The best | |
593 | fix might be to create the pointer to member pointing at the | |
594 | base class and cast it to the derived class, but that requires | |
595 | support for adjusting pointers to members when casting them - | |
596 | not currently supported by GDB. */ | |
597 | ||
598 | if (!gdbarch_vbit_in_delta (current_gdbarch)) | |
599 | { | |
600 | store_unsigned_integer (contents, size, value | is_virtual); | |
601 | store_unsigned_integer (contents + size, size, 0); | |
602 | } | |
603 | else | |
604 | { | |
605 | store_unsigned_integer (contents, size, value); | |
606 | store_unsigned_integer (contents + size, size, is_virtual); | |
607 | } | |
608 | } | |
609 | ||
610 | /* GNU v3 implementation of cplus_method_ptr_to_value. */ | |
611 | ||
612 | static struct value * | |
613 | gnuv3_method_ptr_to_value (struct value **this_p, struct value *method_ptr) | |
614 | { | |
615 | const gdb_byte *contents = value_contents (method_ptr); | |
616 | CORE_ADDR ptr_value; | |
617 | struct type *final_type, *method_type; | |
618 | LONGEST adjustment; | |
619 | struct value *adjval; | |
620 | int vbit; | |
621 | ||
622 | final_type = TYPE_DOMAIN_TYPE (check_typedef (value_type (method_ptr))); | |
623 | final_type = lookup_pointer_type (final_type); | |
624 | ||
625 | method_type = TYPE_TARGET_TYPE (check_typedef (value_type (method_ptr))); | |
626 | ||
627 | ptr_value = extract_typed_address (contents, builtin_type_void_func_ptr); | |
628 | contents += TYPE_LENGTH (builtin_type_void_func_ptr); | |
629 | adjustment = extract_signed_integer (contents, | |
630 | TYPE_LENGTH (builtin_type_long)); | |
631 | ||
632 | if (!gdbarch_vbit_in_delta (current_gdbarch)) | |
633 | { | |
634 | vbit = ptr_value & 1; | |
635 | ptr_value = ptr_value ^ vbit; | |
636 | } | |
637 | else | |
638 | { | |
639 | vbit = adjustment & 1; | |
640 | adjustment = adjustment >> 1; | |
641 | } | |
642 | ||
643 | /* First convert THIS to match the containing type of the pointer to | |
644 | member. This cast may adjust the value of THIS. */ | |
645 | *this_p = value_cast (final_type, *this_p); | |
646 | ||
647 | /* Then apply whatever adjustment is necessary. This creates a somewhat | |
648 | strange pointer: it claims to have type FINAL_TYPE, but in fact it | |
649 | might not be a valid FINAL_TYPE. For instance, it might be a | |
650 | base class of FINAL_TYPE. And if it's not the primary base class, | |
651 | then printing it out as a FINAL_TYPE object would produce some pretty | |
652 | garbage. | |
653 | ||
654 | But we don't really know the type of the first argument in | |
655 | METHOD_TYPE either, which is why this happens. We can't | |
656 | dereference this later as a FINAL_TYPE, but once we arrive in the | |
657 | called method we'll have debugging information for the type of | |
658 | "this" - and that'll match the value we produce here. | |
659 | ||
660 | You can provoke this case by casting a Base::* to a Derived::*, for | |
661 | instance. */ | |
662 | *this_p = value_cast (builtin_type_void_data_ptr, *this_p); | |
663 | adjval = value_from_longest (builtin_type_long, adjustment); | |
664 | *this_p = value_add (*this_p, adjval); | |
665 | *this_p = value_cast (final_type, *this_p); | |
666 | ||
667 | if (vbit) | |
668 | { | |
669 | LONGEST voffset = ptr_value / TYPE_LENGTH (builtin_type_long); | |
670 | return gnuv3_get_virtual_fn (value_ind (*this_p), method_type, voffset); | |
671 | } | |
672 | else | |
673 | return value_from_pointer (lookup_pointer_type (method_type), ptr_value); | |
674 | } | |
675 | ||
b18be20d DJ |
676 | /* Determine if we are currently in a C++ thunk. If so, get the address |
677 | of the routine we are thunking to and continue to there instead. */ | |
678 | ||
679 | static CORE_ADDR | |
52f729a7 | 680 | gnuv3_skip_trampoline (struct frame_info *frame, CORE_ADDR stop_pc) |
b18be20d DJ |
681 | { |
682 | CORE_ADDR real_stop_pc, method_stop_pc; | |
683 | struct minimal_symbol *thunk_sym, *fn_sym; | |
684 | struct obj_section *section; | |
685 | char *thunk_name, *fn_name; | |
686 | ||
52f729a7 UW |
687 | real_stop_pc = gdbarch_skip_trampoline_code |
688 | (current_gdbarch, frame, stop_pc); | |
b18be20d DJ |
689 | if (real_stop_pc == 0) |
690 | real_stop_pc = stop_pc; | |
691 | ||
692 | /* Find the linker symbol for this potential thunk. */ | |
693 | thunk_sym = lookup_minimal_symbol_by_pc (real_stop_pc); | |
694 | section = find_pc_section (real_stop_pc); | |
695 | if (thunk_sym == NULL || section == NULL) | |
696 | return 0; | |
697 | ||
698 | /* The symbol's demangled name should be something like "virtual | |
699 | thunk to FUNCTION", where FUNCTION is the name of the function | |
700 | being thunked to. */ | |
701 | thunk_name = SYMBOL_DEMANGLED_NAME (thunk_sym); | |
702 | if (thunk_name == NULL || strstr (thunk_name, " thunk to ") == NULL) | |
703 | return 0; | |
704 | ||
705 | fn_name = strstr (thunk_name, " thunk to ") + strlen (" thunk to "); | |
706 | fn_sym = lookup_minimal_symbol (fn_name, NULL, section->objfile); | |
707 | if (fn_sym == NULL) | |
708 | return 0; | |
709 | ||
710 | method_stop_pc = SYMBOL_VALUE_ADDRESS (fn_sym); | |
e76f05fa | 711 | real_stop_pc = gdbarch_skip_trampoline_code |
52f729a7 | 712 | (current_gdbarch, frame, method_stop_pc); |
b18be20d DJ |
713 | if (real_stop_pc == 0) |
714 | real_stop_pc = method_stop_pc; | |
715 | ||
716 | return real_stop_pc; | |
717 | } | |
718 | ||
41f1b697 DJ |
719 | /* Return nonzero if a type should be passed by reference. |
720 | ||
721 | The rule in the v3 ABI document comes from section 3.1.1. If the | |
722 | type has a non-trivial copy constructor or destructor, then the | |
723 | caller must make a copy (by calling the copy constructor if there | |
724 | is one or perform the copy itself otherwise), pass the address of | |
725 | the copy, and then destroy the temporary (if necessary). | |
726 | ||
727 | For return values with non-trivial copy constructors or | |
728 | destructors, space will be allocated in the caller, and a pointer | |
729 | will be passed as the first argument (preceding "this"). | |
730 | ||
731 | We don't have a bulletproof mechanism for determining whether a | |
732 | constructor or destructor is trivial. For GCC and DWARF2 debug | |
733 | information, we can check the artificial flag. | |
734 | ||
735 | We don't do anything with the constructors or destructors, | |
736 | but we have to get the argument passing right anyway. */ | |
737 | static int | |
738 | gnuv3_pass_by_reference (struct type *type) | |
739 | { | |
740 | int fieldnum, fieldelem; | |
741 | ||
742 | CHECK_TYPEDEF (type); | |
743 | ||
744 | /* We're only interested in things that can have methods. */ | |
745 | if (TYPE_CODE (type) != TYPE_CODE_STRUCT | |
746 | && TYPE_CODE (type) != TYPE_CODE_CLASS | |
747 | && TYPE_CODE (type) != TYPE_CODE_UNION) | |
748 | return 0; | |
749 | ||
750 | for (fieldnum = 0; fieldnum < TYPE_NFN_FIELDS (type); fieldnum++) | |
751 | for (fieldelem = 0; fieldelem < TYPE_FN_FIELDLIST_LENGTH (type, fieldnum); | |
752 | fieldelem++) | |
753 | { | |
754 | struct fn_field *fn = TYPE_FN_FIELDLIST1 (type, fieldnum); | |
755 | char *name = TYPE_FN_FIELDLIST_NAME (type, fieldnum); | |
756 | struct type *fieldtype = TYPE_FN_FIELD_TYPE (fn, fieldelem); | |
757 | ||
758 | /* If this function is marked as artificial, it is compiler-generated, | |
759 | and we assume it is trivial. */ | |
760 | if (TYPE_FN_FIELD_ARTIFICIAL (fn, fieldelem)) | |
761 | continue; | |
762 | ||
763 | /* If we've found a destructor, we must pass this by reference. */ | |
764 | if (name[0] == '~') | |
765 | return 1; | |
766 | ||
767 | /* If the mangled name of this method doesn't indicate that it | |
768 | is a constructor, we're not interested. | |
769 | ||
770 | FIXME drow/2007-09-23: We could do this using the name of | |
771 | the method and the name of the class instead of dealing | |
772 | with the mangled name. We don't have a convenient function | |
773 | to strip off both leading scope qualifiers and trailing | |
774 | template arguments yet. */ | |
775 | if (!is_constructor_name (TYPE_FN_FIELD_PHYSNAME (fn, fieldelem))) | |
776 | continue; | |
777 | ||
778 | /* If this method takes two arguments, and the second argument is | |
779 | a reference to this class, then it is a copy constructor. */ | |
780 | if (TYPE_NFIELDS (fieldtype) == 2 | |
781 | && TYPE_CODE (TYPE_FIELD_TYPE (fieldtype, 1)) == TYPE_CODE_REF | |
782 | && check_typedef (TYPE_TARGET_TYPE (TYPE_FIELD_TYPE (fieldtype, 1))) == type) | |
783 | return 1; | |
784 | } | |
785 | ||
786 | /* Even if all the constructors and destructors were artificial, one | |
787 | of them may have invoked a non-artificial constructor or | |
788 | destructor in a base class. If any base class needs to be passed | |
789 | by reference, so does this class. Similarly for members, which | |
790 | are constructed whenever this class is. We do not need to worry | |
791 | about recursive loops here, since we are only looking at members | |
792 | of complete class type. */ | |
793 | for (fieldnum = 0; fieldnum < TYPE_NFIELDS (type); fieldnum++) | |
794 | if (gnuv3_pass_by_reference (TYPE_FIELD_TYPE (type, fieldnum))) | |
795 | return 1; | |
796 | ||
797 | return 0; | |
798 | } | |
799 | ||
7ed49443 JB |
800 | static void |
801 | init_gnuv3_ops (void) | |
802 | { | |
030f20e1 | 803 | vtable_type_gdbarch_data = gdbarch_data_register_post_init (build_gdb_vtable_type); |
7ed49443 JB |
804 | |
805 | gnu_v3_abi_ops.shortname = "gnu-v3"; | |
806 | gnu_v3_abi_ops.longname = "GNU G++ Version 3 ABI"; | |
807 | gnu_v3_abi_ops.doc = "G++ Version 3 ABI"; | |
358777b0 EZ |
808 | gnu_v3_abi_ops.is_destructor_name = |
809 | (enum dtor_kinds (*) (const char *))is_gnu_v3_mangled_dtor; | |
810 | gnu_v3_abi_ops.is_constructor_name = | |
811 | (enum ctor_kinds (*) (const char *))is_gnu_v3_mangled_ctor; | |
7ed49443 JB |
812 | gnu_v3_abi_ops.is_vtable_name = gnuv3_is_vtable_name; |
813 | gnu_v3_abi_ops.is_operator_name = gnuv3_is_operator_name; | |
814 | gnu_v3_abi_ops.rtti_type = gnuv3_rtti_type; | |
815 | gnu_v3_abi_ops.virtual_fn_field = gnuv3_virtual_fn_field; | |
1514d34e | 816 | gnu_v3_abi_ops.baseclass_offset = gnuv3_baseclass_offset; |
0d5de010 DJ |
817 | gnu_v3_abi_ops.print_method_ptr = gnuv3_print_method_ptr; |
818 | gnu_v3_abi_ops.method_ptr_size = gnuv3_method_ptr_size; | |
819 | gnu_v3_abi_ops.make_method_ptr = gnuv3_make_method_ptr; | |
820 | gnu_v3_abi_ops.method_ptr_to_value = gnuv3_method_ptr_to_value; | |
b18be20d | 821 | gnu_v3_abi_ops.skip_trampoline = gnuv3_skip_trampoline; |
41f1b697 | 822 | gnu_v3_abi_ops.pass_by_reference = gnuv3_pass_by_reference; |
7ed49443 JB |
823 | } |
824 | ||
b9362cc7 | 825 | extern initialize_file_ftype _initialize_gnu_v3_abi; /* -Wmissing-prototypes */ |
7ed49443 JB |
826 | |
827 | void | |
828 | _initialize_gnu_v3_abi (void) | |
829 | { | |
830 | init_gnuv3_ops (); | |
831 | ||
fe1f4a5e | 832 | register_cp_abi (&gnu_v3_abi_ops); |
7ed49443 | 833 | } |