1 /* Abstraction of GNU v2 abi.
3 Copyright (C) 2001-2022 Free Software Foundation, Inc.
5 Contributed by Daniel Berlin <dberlin@redhat.com>
7 This file is part of GDB.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program. If not, see <http://www.gnu.org/licenses/>. */
27 #include "gdb-demangle.h"
29 #include "cp-support.h"
32 static cp_abi_ops gnu_v2_abi_ops
;
34 static int vb_match (struct type
*, int, struct type
*);
36 static enum dtor_kinds
37 gnuv2_is_destructor_name (const char *name
)
39 if ((name
[0] == '_' && is_cplus_marker (name
[1]) && name
[2] == '_')
40 || startswith (name
, "__dt__"))
41 return complete_object_dtor
;
43 return (enum dtor_kinds
) 0;
46 static enum ctor_kinds
47 gnuv2_is_constructor_name (const char *name
)
49 if ((name
[0] == '_' && name
[1] == '_'
50 && (isdigit (name
[2]) || strchr ("Qt", name
[2])))
51 || startswith (name
, "__ct__"))
52 return complete_object_ctor
;
54 return (enum ctor_kinds
) 0;
58 gnuv2_is_vtable_name (const char *name
)
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] == '_'));
69 gnuv2_is_operator_name (const char *name
)
71 return startswith (name
, CP_OPERATOR_STR
);
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
80 J is an index into F which provides the desired virtual function.
82 TYPE is the type in which F is located. */
84 gnuv2_virtual_fn_field (struct value
**arg1p
, struct fn_field
* f
, int j
,
85 struct type
* type
, int offset
)
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. */
97 LONGEST vi
= (LONGEST
) TYPE_FN_FIELD_VOFFSET (f
, j
);
98 struct type
*fcontext
= TYPE_FN_FIELD_FCONTEXT (f
, j
);
100 struct type
*context_vptr_basetype
;
101 int context_vptr_fieldno
;
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 (TYPE_TARGET_TYPE (context
) != type1
)
113 struct value
*tmp
= value_cast (context
, value_addr (arg1
));
115 arg1
= value_ind (tmp
);
116 type1
= check_typedef (value_type (arg1
));
120 /* Now context is the basetype containing the vtbl. */
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
125 context_vptr_fieldno
= get_vptr_fieldno (context
, &context_vptr_basetype
);
126 /* FIXME: What to do if vptr_fieldno is still -1? */
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
);
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 && TYPE_TARGET_TYPE (value_type (vtbl
))->code () == TYPE_CODE_ARRAY
)
138 /* Handle the case where the vtbl field points to an
139 array of structures. */
140 vtbl
= value_ind (vtbl
);
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
);
150 /* Handle the case where the vtbl field points directly to a
152 vtbl
= value_ptradd (vtbl
, vi
);
153 entry
= value_ind (vtbl
);
156 entry_type
= check_typedef (value_type (entry
));
158 if (entry_type
->code () == TYPE_CODE_STRUCT
)
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)));
164 if (!value_lazy (arg1
))
166 set_value_lazy (arg1
, 1);
167 value_fetch_lazy (arg1
);
170 vfn
= value_field (entry
, 2);
172 else if (entry_type
->code () == TYPE_CODE_PTR
)
175 error (_("I'm confused: virtual function table has bad type"));
176 /* Reinstantiate the function pointer with the correct type. */
177 deprecated_set_value_type (vfn
,
178 lookup_pointer_type (TYPE_FN_FIELD_TYPE (f
, j
)));
186 gnuv2_value_rtti_type (struct value
*v
, int *full
, LONGEST
*top
, int *using_enc
)
188 struct type
*known_type
;
189 struct type
*rtti_type
;
191 struct bound_minimal_symbol minsym
;
193 const char *linkage_name
;
195 struct type
*known_type_vptr_basetype
;
196 int known_type_vptr_fieldno
;
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
)
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
217 /* Try to get the vptr basetype, fieldno. */
218 known_type_vptr_fieldno
= get_vptr_fieldno (known_type
,
219 &known_type_vptr_basetype
);
221 /* If we can't find it, give up. */
222 if (known_type_vptr_fieldno
< 0)
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
)
231 v
= value_cast (btype
, v
);
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)
241 vtbl
= value_as_address (value_field (v
, known_type_vptr_fieldno
));
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
))
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 (), ' ');
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
)
263 if (TYPE_N_BASECLASSES(rtti_type
) > 1 && full
&& (*full
) != 1)
266 *top
= TYPE_BASECLASS_BITPOS (rtti_type
,
267 TYPE_VPTR_FIELDNO(rtti_type
)) / 8;
268 if (top
&& ((*top
) >0))
270 if (TYPE_LENGTH(rtti_type
) > TYPE_LENGTH(known_type
))
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. */
295 vb_match (struct type
*type
, int index
, struct type
*basetype
)
297 struct type
*fieldtype
;
298 const char *name
= type
->field (index
).name ();
299 const char *field_class_name
= NULL
;
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;
310 if (field_class_name
== NULL
)
311 /* This field is not a virtual base class pointer. */
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". */
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 (TYPE_TARGET_TYPE (fieldtype
) == basetype
)
329 if (basetype
->name () != NULL
330 && TYPE_TARGET_TYPE (fieldtype
)->name () != NULL
331 && strcmp (basetype
->name (),
332 TYPE_TARGET_TYPE (fieldtype
)->name ()) == 0)
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. */
343 gnuv2_baseclass_offset (struct type
*type
, int index
,
344 const bfd_byte
*valaddr
, LONGEST embedded_offset
,
345 CORE_ADDR address
, const struct value
*val
)
347 struct type
*basetype
= TYPE_BASECLASS (type
, index
);
349 if (BASETYPE_VIA_VIRTUAL (type
, index
))
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
);
355 /* First look for the virtual baseclass pointer
357 for (i
= n_baseclasses
; i
< len
; i
++)
359 if (vb_match (type
, i
, basetype
))
361 struct type
*field_type
;
362 LONGEST field_offset
;
366 field_type
= check_typedef (type
->field (i
).type ());
367 field_offset
= type
->field (i
).loc_bitpos () / 8;
368 field_length
= TYPE_LENGTH (field_type
);
370 if (!value_bytes_available (val
, embedded_offset
+ field_offset
,
372 throw_error (NOT_AVAILABLE_ERROR
,
373 _("Virtual baseclass pointer is not available"));
375 addr
= unpack_pointer (field_type
,
376 valaddr
+ embedded_offset
+ field_offset
);
378 return addr
- (LONGEST
) address
+ embedded_offset
;
381 /* Not in the fields, so try looking through the baseclasses. */
382 for (i
= index
+ 1; i
< n_baseclasses
; i
++)
384 /* Don't go through baseclass_offset, as that wraps
385 exceptions, thus, inner exceptions would be wrapped more
388 gnuv2_baseclass_offset (type
, i
, valaddr
,
389 embedded_offset
, address
, val
);
395 error (_("Baseclass offset not found"));
398 /* Baseclass is easily computed. */
399 return TYPE_BASECLASS_BITPOS (type
, index
) / 8;
403 init_gnuv2_ops (void)
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";
408 gnu_v2_abi_ops
.is_destructor_name
= gnuv2_is_destructor_name
;
409 gnu_v2_abi_ops
.is_constructor_name
= gnuv2_is_constructor_name
;
410 gnu_v2_abi_ops
.is_vtable_name
= gnuv2_is_vtable_name
;
411 gnu_v2_abi_ops
.is_operator_name
= gnuv2_is_operator_name
;
412 gnu_v2_abi_ops
.virtual_fn_field
= gnuv2_virtual_fn_field
;
413 gnu_v2_abi_ops
.rtti_type
= gnuv2_value_rtti_type
;
414 gnu_v2_abi_ops
.baseclass_offset
= gnuv2_baseclass_offset
;
417 void _initialize_gnu_v2_abi ();
419 _initialize_gnu_v2_abi ()
422 register_cp_abi (&gnu_v2_abi_ops
);