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gnu-v2-abi.c
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1/* Abstraction of GNU v2 abi.
2
3 Copyright (C) 2001-2023 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 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.
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
20 along with this program. If not, see <http://www.gnu.org/licenses/>. */
21
22#include "defs.h"
23#include "symtab.h"
24#include "gdbtypes.h"
25#include "value.h"
26#include "demangle.h"
27#include "gdb-demangle.h"
28#include "cp-abi.h"
29#include "cp-support.h"
30#include <ctype.h>
31
33
34static int vb_match (struct type *, int, struct type *);
35
36static enum dtor_kinds
38{
39 if ((name[0] == '_' && is_cplus_marker (name[1]) && name[2] == '_')
40 || startswith (name, "__dt__"))
42 else
43 return (enum dtor_kinds) 0;
44}
45
46static enum ctor_kinds
48{
49 if ((name[0] == '_' && name[1] == '_'
50 && (isdigit (name[2]) || strchr ("Qt", name[2])))
51 || startswith (name, "__ct__"))
53 else
54 return (enum ctor_kinds) 0;
55}
56
57static int
59{
60 return (((name)[0] == '_'
61 && (((name)[1] == 'V' && (name)[2] == 'T')
62 || ((name)[1] == 'v' && (name)[2] == 't'))
63 && is_cplus_marker ((name)[3])) ||
64 ((name)[0] == '_' && (name)[1] == '_'
65 && (name)[2] == 'v' && (name)[3] == 't' && (name)[4] == '_'));
66}
67
68static int
70{
71 return startswith (name, CP_OPERATOR_STR);
72}
73
74
75/* Return a virtual function as a value.
76 ARG1 is the object which provides the virtual function
77 table pointer. *ARG1P is side-effected in calling this function.
78 F is the list of member functions which contains the desired virtual
79 function.
80 J is an index into F which provides the desired virtual function.
81
82 TYPE is the type in which F is located. */
83static struct value *
84gnuv2_virtual_fn_field (struct value **arg1p, struct fn_field * f, int j,
85 struct type * type, int offset)
86{
87 struct value *arg1 = *arg1p;
88 struct type *type1 = check_typedef (value_type (arg1));
89 struct type *entry_type;
90 /* First, get the virtual function table pointer. That comes
91 with a strange type, so cast it to type `pointer to long' (which
92 should serve just fine as a function type). Then, index into
93 the table, and convert final value to appropriate function type. */
94 struct value *entry;
95 struct value *vfn;
96 struct value *vtbl;
97 LONGEST vi = (LONGEST) TYPE_FN_FIELD_VOFFSET (f, j);
98 struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j);
99 struct type *context;
100 struct type *context_vptr_basetype;
101 int context_vptr_fieldno;
102
103 if (fcontext == NULL)
104 /* We don't have an fcontext (e.g. the program was compiled with
105 g++ version 1). Try to get the vtbl from the TYPE_VPTR_BASETYPE.
106 This won't work right for multiple inheritance, but at least we
107 should do as well as GDB 3.x did. */
108 fcontext = TYPE_VPTR_BASETYPE (type);
109 context = lookup_pointer_type (fcontext);
110 /* Now context is a pointer to the basetype containing the vtbl. */
111 if (context->target_type () != type1)
112 {
113 struct value *tmp = value_cast (context, value_addr (arg1));
114
115 arg1 = value_ind (tmp);
116 type1 = check_typedef (value_type (arg1));
117 }
118
119 context = type1;
120 /* Now context is the basetype containing the vtbl. */
121
122 /* This type may have been defined before its virtual function table
123 was. If so, fill in the virtual function table entry for the
124 type now. */
125 context_vptr_fieldno = get_vptr_fieldno (context, &context_vptr_basetype);
126 /* FIXME: What to do if vptr_fieldno is still -1? */
127
128 /* The virtual function table is now an array of structures
129 which have the form { int16 offset, delta; void *pfn; }. */
130 vtbl = value_primitive_field (arg1, 0, context_vptr_fieldno,
131 context_vptr_basetype);
132
133 /* With older versions of g++, the vtbl field pointed to an array
134 of structures. Nowadays it points directly to the structure. */
135 if (value_type (vtbl)->code () == TYPE_CODE_PTR
136 && value_type (vtbl)->target_type ()->code () == TYPE_CODE_ARRAY)
137 {
138 /* Handle the case where the vtbl field points to an
139 array of structures. */
140 vtbl = value_ind (vtbl);
141
142 /* Index into the virtual function table. This is hard-coded because
143 looking up a field is not cheap, and it may be important to save
144 time, e.g. if the user has set a conditional breakpoint calling
145 a virtual function. */
146 entry = value_subscript (vtbl, vi);
147 }
148 else
149 {
150 /* Handle the case where the vtbl field points directly to a
151 structure. */
152 vtbl = value_ptradd (vtbl, vi);
153 entry = value_ind (vtbl);
154 }
155
156 entry_type = check_typedef (value_type (entry));
157
158 if (entry_type->code () == TYPE_CODE_STRUCT)
159 {
160 /* Move the `this' pointer according to the virtual function table. */
161 set_value_offset (arg1, value_offset (arg1)
162 + value_as_long (value_field (entry, 0)));
163
164 if (!value_lazy (arg1))
165 {
166 set_value_lazy (arg1, 1);
167 value_fetch_lazy (arg1);
168 }
169
170 vfn = value_field (entry, 2);
171 }
172 else if (entry_type->code () == TYPE_CODE_PTR)
173 vfn = entry;
174 else
175 error (_("I'm confused: virtual function table has bad type"));
176 /* Reinstantiate the function pointer with the correct type. */
179
180 *arg1p = arg1;
181 return vfn;
182}
183
184
185static struct type *
186gnuv2_value_rtti_type (struct value *v, int *full, LONGEST *top, int *using_enc)
187{
188 struct type *known_type;
189 struct type *rtti_type;
190 CORE_ADDR vtbl;
192 char *p;
193 const char *linkage_name;
194 struct type *btype;
195 struct type *known_type_vptr_basetype;
196 int known_type_vptr_fieldno;
197
198 if (full)
199 *full = 0;
200 if (top)
201 *top = -1;
202 if (using_enc)
203 *using_enc = 0;
204
205 /* Get declared type. */
206 known_type = value_type (v);
207 known_type = check_typedef (known_type);
208 /* RTTI works only or class objects. */
209 if (known_type->code () != TYPE_CODE_STRUCT)
210 return NULL;
211
212 /* Plan on this changing in the future as i get around to setting
213 the vtables properly for G++ compiled stuff. Also, I'll be using
214 the type info functions, which are always right. Deal with it
215 until then. */
216
217 /* Try to get the vptr basetype, fieldno. */
218 known_type_vptr_fieldno = get_vptr_fieldno (known_type,
219 &known_type_vptr_basetype);
220
221 /* If we can't find it, give up. */
222 if (known_type_vptr_fieldno < 0)
223 return NULL;
224
225 /* Make sure our basetype and known type match, otherwise, cast
226 so we can get at the vtable properly. */
227 btype = known_type_vptr_basetype;
228 btype = check_typedef (btype);
229 if (btype != known_type )
230 {
231 v = value_cast (btype, v);
232 if (using_enc)
233 *using_enc=1;
234 }
235 /* We can't use value_ind here, because it would want to use RTTI, and
236 we'd waste a bunch of time figuring out we already know the type.
237 Besides, we don't care about the type, just the actual pointer. */
238 if (value_address (value_field (v, known_type_vptr_fieldno)) == 0)
239 return NULL;
240
241 vtbl = value_as_address (value_field (v, known_type_vptr_fieldno));
242
243 /* Try to find a symbol that is the vtable. */
244 minsym=lookup_minimal_symbol_by_pc(vtbl);
245 if (minsym.minsym==NULL
246 || (linkage_name=minsym.minsym->linkage_name ())==NULL
247 || !is_vtable_name (linkage_name))
248 return NULL;
249
250 /* If we just skip the prefix, we get screwed by namespaces. */
251 gdb::unique_xmalloc_ptr<char> demangled_name
252 = gdb_demangle(linkage_name,DMGL_PARAMS|DMGL_ANSI);
253 p = strchr (demangled_name.get (), ' ');
254 if (p)
255 *p = '\0';
256
257 /* Lookup the type for the name. */
258 /* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */
259 rtti_type = cp_lookup_rtti_type (demangled_name.get (), NULL);
260 if (rtti_type == NULL)
261 return NULL;
262
263 if (TYPE_N_BASECLASSES(rtti_type) > 1 && full && (*full) != 1)
264 {
265 if (top)
266 *top = TYPE_BASECLASS_BITPOS (rtti_type,
267 TYPE_VPTR_FIELDNO(rtti_type)) / 8;
268 if (top && ((*top) >0))
269 {
270 if (rtti_type->length () > known_type->length ())
271 {
272 if (full)
273 *full=0;
274 }
275 else
276 {
277 if (full)
278 *full=1;
279 }
280 }
281 }
282 else
283 {
284 if (full)
285 *full=1;
286 }
287
288 return rtti_type;
289}
290
291/* Return true if the INDEXth field of TYPE is a virtual baseclass
292 pointer which is for the base class whose type is BASECLASS. */
293
294static int
295vb_match (struct type *type, int index, struct type *basetype)
296{
297 struct type *fieldtype;
298 const char *name = type->field (index).name ();
299 const char *field_class_name = NULL;
300
301 if (*name != '_')
302 return 0;
303 /* gcc 2.4 uses _vb$. */
304 if (name[1] == 'v' && name[2] == 'b' && is_cplus_marker (name[3]))
305 field_class_name = name + 4;
306 /* gcc 2.5 will use __vb_. */
307 if (name[1] == '_' && name[2] == 'v' && name[3] == 'b' && name[4] == '_')
308 field_class_name = name + 5;
309
310 if (field_class_name == NULL)
311 /* This field is not a virtual base class pointer. */
312 return 0;
313
314 /* It's a virtual baseclass pointer, now we just need to find out whether
315 it is for this baseclass. */
316 fieldtype = type->field (index).type ();
317 if (fieldtype == NULL
318 || fieldtype->code () != TYPE_CODE_PTR)
319 /* "Can't happen". */
320 return 0;
321
322 /* What we check for is that either the types are equal (needed for
323 nameless types) or have the same name. This is ugly, and a more
324 elegant solution should be devised (which would probably just push
325 the ugliness into symbol reading unless we change the stabs format). */
326 if (fieldtype->target_type () == basetype)
327 return 1;
328
329 if (basetype->name () != NULL
330 && fieldtype->target_type ()->name () != NULL
331 && strcmp (basetype->name (),
332 fieldtype->target_type ()->name ()) == 0)
333 return 1;
334 return 0;
335}
336
337/* Compute the offset of the baseclass which is the INDEXth baseclass
338 of class TYPE, for value at VALADDR (in host) at ADDRESS (in
339 target). The result is the offset of the baseclass value relative
340 to (the address of)(ARG) + OFFSET. */
341
342static int
343gnuv2_baseclass_offset (struct type *type, int index,
344 const bfd_byte *valaddr, LONGEST embedded_offset,
345 CORE_ADDR address, const struct value *val)
346{
347 struct type *basetype = TYPE_BASECLASS (type, index);
348
349 if (BASETYPE_VIA_VIRTUAL (type, index))
350 {
351 /* Must hunt for the pointer to this virtual baseclass. */
352 int i, len = type->num_fields ();
353 int n_baseclasses = TYPE_N_BASECLASSES (type);
354
355 /* First look for the virtual baseclass pointer
356 in the fields. */
357 for (i = n_baseclasses; i < len; i++)
358 {
359 if (vb_match (type, i, basetype))
360 {
361 struct type *field_type;
362 LONGEST field_offset;
363 int field_length;
364 CORE_ADDR addr;
365
366 field_type = check_typedef (type->field (i).type ());
367 field_offset = type->field (i).loc_bitpos () / 8;
368 field_length = field_type->length ();
369
370 if (!value_bytes_available (val, embedded_offset + field_offset,
371 field_length))
372 throw_error (NOT_AVAILABLE_ERROR,
373 _("Virtual baseclass pointer is not available"));
374
375 addr = unpack_pointer (field_type,
376 valaddr + embedded_offset + field_offset);
377
378 return addr - (LONGEST) address + embedded_offset;
379 }
380 }
381 /* Not in the fields, so try looking through the baseclasses. */
382 for (i = index + 1; i < n_baseclasses; i++)
383 {
384 /* Don't go through baseclass_offset, as that wraps
385 exceptions, thus, inner exceptions would be wrapped more
386 than once. */
387 int boffset =
388 gnuv2_baseclass_offset (type, i, valaddr,
389 embedded_offset, address, val);
390
391 if (boffset)
392 return boffset;
393 }
394
395 error (_("Baseclass offset not found"));
396 }
397
398 /* Baseclass is easily computed. */
399 return TYPE_BASECLASS_BITPOS (type, index) / 8;
400}
401
402static void
404{
405 gnu_v2_abi_ops.shortname = "gnu-v2";
406 gnu_v2_abi_ops.longname = "GNU G++ Version 2 ABI";
407 gnu_v2_abi_ops.doc = "G++ Version 2 ABI";
415}
416
418void
420{
423}
const char *const name
int code
Definition ada-lex.l:688
void f()
Definition 1.cc:36
int register_cp_abi(struct cp_abi_ops *abi)
Definition cp-abi.c:251
int is_vtable_name(const char *name)
Definition cp-abi.c:52
dtor_kinds
Definition cp-abi.h:61
@ complete_object_dtor
Definition cp-abi.h:69
ctor_kinds
Definition cp-abi.h:40
@ complete_object_ctor
Definition cp-abi.h:44
gdb::unique_xmalloc_ptr< char > gdb_demangle(const char *name, int options)
struct type * cp_lookup_rtti_type(const char *name, const struct block *block)
#define CP_OPERATOR_STR
Definition cp-support.h:53
bool is_cplus_marker(int c)
struct type * lookup_pointer_type(struct type *type)
Definition gdbtypes.c:402
int get_vptr_fieldno(struct type *type, struct type **basetypep)
Definition gdbtypes.c:2024
struct type * check_typedef(struct type *type)
Definition gdbtypes.c:3010
#define TYPE_VPTR_BASETYPE(thistype)
Definition gdbtypes.h:2084
#define TYPE_FN_FIELD_VOFFSET(thisfn, n)
Definition gdbtypes.h:2180
#define TYPE_FN_FIELD_TYPE(thisfn, n)
Definition gdbtypes.h:2170
#define TYPE_BASECLASS(thistype, index)
Definition gdbtypes.h:2107
#define TYPE_BASECLASS_BITPOS(thistype, index)
Definition gdbtypes.h:2110
#define TYPE_VPTR_FIELDNO(thistype)
Definition gdbtypes.h:2083
#define BASETYPE_VIA_VIRTUAL(thistype, index)
Definition gdbtypes.h:2115
#define TYPE_N_BASECLASSES(thistype)
Definition gdbtypes.h:2108
#define TYPE_FN_FIELD_FCONTEXT(thisfn, n)
Definition gdbtypes.h:2179
void _initialize_gnu_v2_abi()
Definition gnu-v2-abi.c:419
static int gnuv2_is_operator_name(const char *name)
Definition gnu-v2-abi.c:69
static enum ctor_kinds gnuv2_is_constructor_name(const char *name)
Definition gnu-v2-abi.c:47
static struct type * gnuv2_value_rtti_type(struct value *v, int *full, LONGEST *top, int *using_enc)
Definition gnu-v2-abi.c:186
static enum dtor_kinds gnuv2_is_destructor_name(const char *name)
Definition gnu-v2-abi.c:37
static struct value * gnuv2_virtual_fn_field(struct value **arg1p, struct fn_field *f, int j, struct type *type, int offset)
Definition gnu-v2-abi.c:84
static int gnuv2_is_vtable_name(const char *name)
Definition gnu-v2-abi.c:58
static cp_abi_ops gnu_v2_abi_ops
Definition gnu-v2-abi.c:32
static int vb_match(struct type *, int, struct type *)
Definition gnu-v2-abi.c:295
static int gnuv2_baseclass_offset(struct type *type, int index, const bfd_byte *valaddr, LONGEST embedded_offset, CORE_ADDR address, const struct value *val)
Definition gnu-v2-abi.c:343
static void init_gnuv2_ops(void)
Definition gnu-v2-abi.c:403
struct bound_minimal_symbol lookup_minimal_symbol_by_pc(CORE_ADDR pc)
Definition minsyms.c:977
struct minimal_symbol * minsym
Definition minsyms.h:49
const char * shortname
Definition cp-abi.h:218
int(* baseclass_offset)(struct type *type, int index, const bfd_byte *valaddr, LONGEST embedded_offset, CORE_ADDR address, const struct value *val)
Definition cp-abi.h:234
int(* is_vtable_name)(const char *name)
Definition cp-abi.h:226
enum ctor_kinds(* is_constructor_name)(const char *name)
Definition cp-abi.h:224
struct value *(* virtual_fn_field)(struct value **arg1p, struct fn_field *f, int j, struct type *type, int offset)
Definition cp-abi.h:228
enum dtor_kinds(* is_destructor_name)(const char *name)
Definition cp-abi.h:225
int(* is_operator_name)(const char *name)
Definition cp-abi.h:227
const char * longname
Definition cp-abi.h:219
const char * doc
Definition cp-abi.h:220
struct type *(* rtti_type)(struct value *v, int *full, LONGEST *top, int *using_enc)
Definition cp-abi.h:232
LONGEST loc_bitpos() const
Definition gdbtypes.h:586
const char * name() const
Definition gdbtypes.h:569
struct type * type() const
Definition gdbtypes.h:559
const char * linkage_name() const
Definition symtab.h:459
struct type * target_type() const
Definition gdbtypes.h:1000
type_code code() const
Definition gdbtypes.h:927
ULONGEST length() const
Definition gdbtypes.h:954
struct field & field(int idx) const
Definition gdbtypes.h:983
int num_fields() const
Definition gdbtypes.h:965
const char * name() const
Definition gdbtypes.h:939
Definition value.c:181
LONGEST offset
Definition value.c:281
struct value * value_subscript(struct value *array, LONGEST index)
Definition valarith.c:146
struct value * value_ptradd(struct value *arg1, LONGEST arg2)
Definition valarith.c:84
struct value * value_addr(struct value *arg1)
Definition valops.c:1543
struct value * value_cast(struct type *type, struct value *arg2)
Definition valops.c:408
struct value * value_ind(struct value *arg1)
Definition valops.c:1623
int value_bytes_available(const struct value *value, LONGEST offset, LONGEST length)
Definition value.c:391
struct type * value_type(const struct value *value)
Definition value.c:1109
LONGEST value_offset(const struct value *value)
Definition value.c:1120
int value_lazy(const struct value *value)
Definition value.c:1440
struct value * value_field(struct value *arg1, int fieldno)
Definition value.c:3229
CORE_ADDR unpack_pointer(struct type *type, const gdb_byte *valaddr)
Definition value.c:3012
CORE_ADDR value_as_address(struct value *val)
Definition value.c:2804
void value_fetch_lazy(struct value *val)
Definition value.c:4162
struct value * value_primitive_field(struct value *arg1, LONGEST offset, int fieldno, struct type *arg_type)
Definition value.c:3105
void set_value_offset(struct value *value, LONGEST offset)
Definition value.c:1125
CORE_ADDR value_address(const struct value *value)
Definition value.c:1607
LONGEST value_as_long(struct value *val)
Definition value.c:2791
void deprecated_set_value_type(struct value *value, struct type *type)
Definition value.c:1114
void set_value_lazy(struct value *value, int val)
Definition value.c:1446