1 /* Abstraction of GNU v2 abi.
2
3 Copyright 2001, 2002, 2003, 2005 Free Software Foundation, Inc.
4
5 Contributed by Daniel Berlin <dberlin@redhat.com>
6
7 This file is part of GDB.
8
9 This program is free software; you can redistribute it and/or
10 modify
11 it under the terms of the GNU General Public License as published
12 by
13 the Free Software Foundation; either version 2 of the License, or
14 (at your option) any later version.
15
16 This program is distributed in the hope that it will be useful,
17 but WITHOUT ANY WARRANTY; without even the implied warranty of
18 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 GNU General Public License for more details.
20
21 You should have received a copy of the GNU General Public License
22 along with this program; if not, write to the Free Software
23 Foundation, Inc., 59 Temple Place - Suite 330,
24 Boston, MA 02111-1307, USA. */
25
26 #include "defs.h"
27 #include "gdb_string.h"
28 #include "symtab.h"
29 #include "gdbtypes.h"
30 #include "value.h"
31 #include "demangle.h"
32 #include "cp-abi.h"
33 #include "cp-support.h"
34 #include "gnu-v2-abi.h"
35
36 #include <ctype.h>
37
38 struct cp_abi_ops gnu_v2_abi_ops;
39
40 static int vb_match (struct type *, int, struct type *);
41
42 static enum dtor_kinds
gnuv2_is_destructor_name(const char * name)43 gnuv2_is_destructor_name (const char *name)
44 {
45 if ((name[0] == '_' && is_cplus_marker (name[1]) && name[2] == '_')
46 || strncmp (name, "__dt__", 6) == 0)
47 return complete_object_dtor;
48 else
49 return 0;
50 }
51
52 static enum ctor_kinds
gnuv2_is_constructor_name(const char * name)53 gnuv2_is_constructor_name (const char *name)
54 {
55 if ((name[0] == '_' && name[1] == '_'
56 && (isdigit (name[2]) || strchr ("Qt", name[2])))
57 || strncmp (name, "__ct__", 6) == 0)
58 return complete_object_ctor;
59 else
60 return 0;
61 }
62
63 static int
gnuv2_is_vtable_name(const char * name)64 gnuv2_is_vtable_name (const char *name)
65 {
66 return (((name)[0] == '_'
67 && (((name)[1] == 'V' && (name)[2] == 'T')
68 || ((name)[1] == 'v' && (name)[2] == 't'))
69 && is_cplus_marker ((name)[3])) ||
70 ((name)[0] == '_' && (name)[1] == '_'
71 && (name)[2] == 'v' && (name)[3] == 't' && (name)[4] == '_'));
72 }
73
74 static int
gnuv2_is_operator_name(const char * name)75 gnuv2_is_operator_name (const char *name)
76 {
77 return strncmp (name, "operator", 8) == 0;
78 }
79
80
81 /* Return a virtual function as a value.
82 ARG1 is the object which provides the virtual function
83 table pointer. *ARG1P is side-effected in calling this function.
84 F is the list of member functions which contains the desired virtual
85 function.
86 J is an index into F which provides the desired virtual function.
87
88 TYPE is the type in which F is located. */
89 static struct value *
gnuv2_virtual_fn_field(struct value ** arg1p,struct fn_field * f,int j,struct type * type,int offset)90 gnuv2_virtual_fn_field (struct value **arg1p, struct fn_field * f, int j,
91 struct type * type, int offset)
92 {
93 struct value *arg1 = *arg1p;
94 struct type *type1 = check_typedef (value_type (arg1));
95
96
97 struct type *entry_type;
98 /* First, get the virtual function table pointer. That comes
99 with a strange type, so cast it to type `pointer to long' (which
100 should serve just fine as a function type). Then, index into
101 the table, and convert final value to appropriate function type. */
102 struct value *entry;
103 struct value *vfn;
104 struct value *vtbl;
105 struct value *vi = value_from_longest (builtin_type_int,
106 (LONGEST) TYPE_FN_FIELD_VOFFSET (f, j));
107 struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j);
108 struct type *context;
109 if (fcontext == NULL)
110 /* We don't have an fcontext (e.g. the program was compiled with
111 g++ version 1). Try to get the vtbl from the TYPE_VPTR_BASETYPE.
112 This won't work right for multiple inheritance, but at least we
113 should do as well as GDB 3.x did. */
114 fcontext = TYPE_VPTR_BASETYPE (type);
115 context = lookup_pointer_type (fcontext);
116 /* Now context is a pointer to the basetype containing the vtbl. */
117 if (TYPE_TARGET_TYPE (context) != type1)
118 {
119 struct value *tmp = value_cast (context, value_addr (arg1));
120 arg1 = value_ind (tmp);
121 type1 = check_typedef (value_type (arg1));
122 }
123
124 context = type1;
125 /* Now context is the basetype containing the vtbl. */
126
127 /* This type may have been defined before its virtual function table
128 was. If so, fill in the virtual function table entry for the
129 type now. */
130 if (TYPE_VPTR_FIELDNO (context) < 0)
131 fill_in_vptr_fieldno (context);
132
133 /* The virtual function table is now an array of structures
134 which have the form { int16 offset, delta; void *pfn; }. */
135 vtbl = value_primitive_field (arg1, 0, TYPE_VPTR_FIELDNO (context),
136 TYPE_VPTR_BASETYPE (context));
137
138 /* With older versions of g++, the vtbl field pointed to an array
139 of structures. Nowadays it points directly to the structure. */
140 if (TYPE_CODE (value_type (vtbl)) == TYPE_CODE_PTR
141 && TYPE_CODE (TYPE_TARGET_TYPE (value_type (vtbl))) == TYPE_CODE_ARRAY)
142 {
143 /* Handle the case where the vtbl field points to an
144 array of structures. */
145 vtbl = value_ind (vtbl);
146
147 /* Index into the virtual function table. This is hard-coded because
148 looking up a field is not cheap, and it may be important to save
149 time, e.g. if the user has set a conditional breakpoint calling
150 a virtual function. */
151 entry = value_subscript (vtbl, vi);
152 }
153 else
154 {
155 /* Handle the case where the vtbl field points directly to a structure. */
156 vtbl = value_add (vtbl, vi);
157 entry = value_ind (vtbl);
158 }
159
160 entry_type = check_typedef (value_type (entry));
161
162 if (TYPE_CODE (entry_type) == TYPE_CODE_STRUCT)
163 {
164 /* Move the `this' pointer according to the virtual function table. */
165 set_value_offset (arg1, value_offset (arg1) + value_as_long (value_field (entry, 0)));
166
167 if (!value_lazy (arg1))
168 {
169 set_value_lazy (arg1, 1);
170 value_fetch_lazy (arg1);
171 }
172
173 vfn = value_field (entry, 2);
174 }
175 else if (TYPE_CODE (entry_type) == TYPE_CODE_PTR)
176 vfn = entry;
177 else
178 error (_("I'm confused: virtual function table has bad type"));
179 /* Reinstantiate the function pointer with the correct type. */
180 deprecated_set_value_type (vfn, lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j)));
181
182 *arg1p = arg1;
183 return vfn;
184 }
185
186
187 static struct type *
gnuv2_value_rtti_type(struct value * v,int * full,int * top,int * using_enc)188 gnuv2_value_rtti_type (struct value *v, int *full, int *top, int *using_enc)
189 {
190 struct type *known_type;
191 struct type *rtti_type;
192 CORE_ADDR coreptr;
193 struct value *vp;
194 long top_offset = 0;
195 char rtti_type_name[256];
196 CORE_ADDR vtbl;
197 struct minimal_symbol *minsym;
198 struct symbol *sym;
199 char *demangled_name;
200 struct type *btype;
201
202 if (full)
203 *full = 0;
204 if (top)
205 *top = -1;
206 if (using_enc)
207 *using_enc = 0;
208
209 /* Get declared type */
210 known_type = value_type (v);
211 CHECK_TYPEDEF (known_type);
212 /* RTTI works only or class objects */
213 if (TYPE_CODE (known_type) != TYPE_CODE_CLASS)
214 return NULL;
215
216 /* Plan on this changing in the future as i get around to setting
217 the vtables properly for G++ compiled stuff. Also, I'll be using
218 the type info functions, which are always right. Deal with it
219 until then. */
220
221 /* If the type has no vptr fieldno, try to get it filled in */
222 if (TYPE_VPTR_FIELDNO(known_type) < 0)
223 fill_in_vptr_fieldno(known_type);
224
225 /* If we still can't find one, give up */
226 if (TYPE_VPTR_FIELDNO(known_type) < 0)
227 return NULL;
228
229 /* Make sure our basetype and known type match, otherwise, cast
230 so we can get at the vtable properly.
231 */
232 btype = TYPE_VPTR_BASETYPE (known_type);
233 CHECK_TYPEDEF (btype);
234 if (btype != known_type )
235 {
236 v = value_cast (btype, v);
237 if (using_enc)
238 *using_enc=1;
239 }
240 /*
241 We can't use value_ind here, because it would want to use RTTI, and
242 we'd waste a bunch of time figuring out we already know the type.
243 Besides, we don't care about the type, just the actual pointer
244 */
245 if (VALUE_ADDRESS (value_field (v, TYPE_VPTR_FIELDNO (known_type))) == 0)
246 return NULL;
247
248 vtbl=value_as_address(value_field(v,TYPE_VPTR_FIELDNO(known_type)));
249
250 /* Try to find a symbol that is the vtable */
251 minsym=lookup_minimal_symbol_by_pc(vtbl);
252 if (minsym==NULL
253 || (demangled_name=DEPRECATED_SYMBOL_NAME (minsym))==NULL
254 || !is_vtable_name (demangled_name))
255 return NULL;
256
257 /* If we just skip the prefix, we get screwed by namespaces */
258 demangled_name=cplus_demangle(demangled_name,DMGL_PARAMS|DMGL_ANSI);
259 *(strchr(demangled_name,' '))=0;
260
261 /* Lookup the type for the name */
262 /* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */
263 rtti_type = cp_lookup_rtti_type (demangled_name, NULL);
264 if (rtti_type == NULL)
265 return NULL;
266
267 if (TYPE_N_BASECLASSES(rtti_type) > 1 && full && (*full) != 1)
268 {
269 if (top)
270 *top=TYPE_BASECLASS_BITPOS(rtti_type,TYPE_VPTR_FIELDNO(rtti_type))/8;
271 if (top && ((*top) >0))
272 {
273 if (TYPE_LENGTH(rtti_type) > TYPE_LENGTH(known_type))
274 {
275 if (full)
276 *full=0;
277 }
278 else
279 {
280 if (full)
281 *full=1;
282 }
283 }
284 }
285 else
286 {
287 if (full)
288 *full=1;
289 }
290
291 return rtti_type;
292 }
293
294 /* Return true if the INDEXth field of TYPE is a virtual baseclass
295 pointer which is for the base class whose type is BASECLASS. */
296
297 static int
vb_match(struct type * type,int index,struct type * basetype)298 vb_match (struct type *type, int index, struct type *basetype)
299 {
300 struct type *fieldtype;
301 char *name = TYPE_FIELD_NAME (type, index);
302 char *field_class_name = NULL;
303
304 if (*name != '_')
305 return 0;
306 /* gcc 2.4 uses _vb$. */
307 if (name[1] == 'v' && name[2] == 'b' && is_cplus_marker (name[3]))
308 field_class_name = name + 4;
309 /* gcc 2.5 will use __vb_. */
310 if (name[1] == '_' && name[2] == 'v' && name[3] == 'b' && name[4] == '_')
311 field_class_name = name + 5;
312
313 if (field_class_name == NULL)
314 /* This field is not a virtual base class pointer. */
315 return 0;
316
317 /* It's a virtual baseclass pointer, now we just need to find out whether
318 it is for this baseclass. */
319 fieldtype = TYPE_FIELD_TYPE (type, index);
320 if (fieldtype == NULL
321 || TYPE_CODE (fieldtype) != TYPE_CODE_PTR)
322 /* "Can't happen". */
323 return 0;
324
325 /* What we check for is that either the types are equal (needed for
326 nameless types) or have the same name. This is ugly, and a more
327 elegant solution should be devised (which would probably just push
328 the ugliness into symbol reading unless we change the stabs format). */
329 if (TYPE_TARGET_TYPE (fieldtype) == basetype)
330 return 1;
331
332 if (TYPE_NAME (basetype) != NULL
333 && TYPE_NAME (TYPE_TARGET_TYPE (fieldtype)) != NULL
334 && strcmp (TYPE_NAME (basetype),
335 TYPE_NAME (TYPE_TARGET_TYPE (fieldtype))) == 0)
336 return 1;
337 return 0;
338 }
339
340 /* Compute the offset of the baseclass which is
341 the INDEXth baseclass of class TYPE,
342 for value at VALADDR (in host) at ADDRESS (in target).
343 The result is the offset of the baseclass value relative
344 to (the address of)(ARG) + OFFSET.
345
346 -1 is returned on error. */
347
348 int
gnuv2_baseclass_offset(struct type * type,int index,const bfd_byte * valaddr,CORE_ADDR address)349 gnuv2_baseclass_offset (struct type *type, int index,
350 const bfd_byte *valaddr, CORE_ADDR address)
351 {
352 struct type *basetype = TYPE_BASECLASS (type, index);
353
354 if (BASETYPE_VIA_VIRTUAL (type, index))
355 {
356 /* Must hunt for the pointer to this virtual baseclass. */
357 int i, len = TYPE_NFIELDS (type);
358 int n_baseclasses = TYPE_N_BASECLASSES (type);
359
360 /* First look for the virtual baseclass pointer
361 in the fields. */
362 for (i = n_baseclasses; i < len; i++)
363 {
364 if (vb_match (type, i, basetype))
365 {
366 CORE_ADDR addr
367 = unpack_pointer (TYPE_FIELD_TYPE (type, i),
368 valaddr + (TYPE_FIELD_BITPOS (type, i) / 8));
369
370 return addr - (LONGEST) address;
371 }
372 }
373 /* Not in the fields, so try looking through the baseclasses. */
374 for (i = index + 1; i < n_baseclasses; i++)
375 {
376 int boffset =
377 baseclass_offset (type, i, valaddr, address);
378 if (boffset)
379 return boffset;
380 }
381 /* Not found. */
382 return -1;
383 }
384
385 /* Baseclass is easily computed. */
386 return TYPE_BASECLASS_BITPOS (type, index) / 8;
387 }
388
389 static void
init_gnuv2_ops(void)390 init_gnuv2_ops (void)
391 {
392 gnu_v2_abi_ops.shortname = "gnu-v2";
393 gnu_v2_abi_ops.longname = "GNU G++ Version 2 ABI";
394 gnu_v2_abi_ops.doc = "G++ Version 2 ABI";
395 gnu_v2_abi_ops.is_destructor_name = gnuv2_is_destructor_name;
396 gnu_v2_abi_ops.is_constructor_name = gnuv2_is_constructor_name;
397 gnu_v2_abi_ops.is_vtable_name = gnuv2_is_vtable_name;
398 gnu_v2_abi_ops.is_operator_name = gnuv2_is_operator_name;
399 gnu_v2_abi_ops.virtual_fn_field = gnuv2_virtual_fn_field;
400 gnu_v2_abi_ops.rtti_type = gnuv2_value_rtti_type;
401 gnu_v2_abi_ops.baseclass_offset = gnuv2_baseclass_offset;
402 }
403
404 extern initialize_file_ftype _initialize_gnu_v2_abi; /* -Wmissing-prototypes */
405
406 void
_initialize_gnu_v2_abi(void)407 _initialize_gnu_v2_abi (void)
408 {
409 init_gnuv2_ops ();
410 register_cp_abi (&gnu_v2_abi_ops);
411 set_cp_abi_as_auto_default (gnu_v2_abi_ops.shortname);
412 }
413