1 /* Abstraction of GNU v2 abi.
3 Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008, 2009, 2010, 2011
4 Free Software Foundation, Inc.
6 Contributed by Daniel Berlin <dberlin@redhat.com>
8 This file is part of GDB.
10 This program is free software; you can redistribute it and/or modify
11 it under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 3 of the License, or
13 (at your option) any later version.
15 This program is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 GNU General Public License for more details.
20 You should have received a copy of the GNU General Public License
21 along with this program. If not, see <http://www.gnu.org/licenses/>. */
24 #include "gdb_string.h"
29 #include "gdb-demangle.h"
31 #include "cp-support.h"
32 #include "exceptions.h"
36 struct cp_abi_ops gnu_v2_abi_ops;
38 static int vb_match (struct type *, int, struct type *);
40 static enum dtor_kinds
41 gnuv2_is_destructor_name (const char *name)
43 if ((name[0] == '_' && is_cplus_marker (name[1]) && name[2] == '_')
44 || strncmp (name, "__dt__", 6) == 0)
45 return complete_object_dtor;
50 static enum ctor_kinds
51 gnuv2_is_constructor_name (const char *name)
53 if ((name[0] == '_' && name[1] == '_'
54 && (isdigit (name[2]) || strchr ("Qt", name[2])))
55 || strncmp (name, "__ct__", 6) == 0)
56 return complete_object_ctor;
62 gnuv2_is_vtable_name (const char *name)
64 return (((name)[0] == '_'
65 && (((name)[1] == 'V' && (name)[2] == 'T')
66 || ((name)[1] == 'v' && (name)[2] == 't'))
67 && is_cplus_marker ((name)[3])) ||
68 ((name)[0] == '_' && (name)[1] == '_'
69 && (name)[2] == 'v' && (name)[3] == 't' && (name)[4] == '_'));
73 gnuv2_is_operator_name (const char *name)
75 return strncmp (name, "operator", 8) == 0;
79 /* Return a virtual function as a value.
80 ARG1 is the object which provides the virtual function
81 table pointer. *ARG1P is side-effected in calling this function.
82 F is the list of member functions which contains the desired virtual
84 J is an index into F which provides the desired virtual function.
86 TYPE is the type in which F is located. */
88 gnuv2_virtual_fn_field (struct value **arg1p, struct fn_field * f, int j,
89 struct type * type, int offset)
91 struct value *arg1 = *arg1p;
92 struct type *type1 = check_typedef (value_type (arg1));
93 struct type *entry_type;
94 /* First, get the virtual function table pointer. That comes
95 with a strange type, so cast it to type `pointer to long' (which
96 should serve just fine as a function type). Then, index into
97 the table, and convert final value to appropriate function type. */
101 LONGEST vi = (LONGEST) TYPE_FN_FIELD_VOFFSET (f, j);
102 struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j);
103 struct type *context;
104 struct type *context_vptr_basetype;
105 int context_vptr_fieldno;
107 if (fcontext == NULL)
108 /* We don't have an fcontext (e.g. the program was compiled with
109 g++ version 1). Try to get the vtbl from the TYPE_VPTR_BASETYPE.
110 This won't work right for multiple inheritance, but at least we
111 should do as well as GDB 3.x did. */
112 fcontext = TYPE_VPTR_BASETYPE (type);
113 context = lookup_pointer_type (fcontext);
114 /* Now context is a pointer to the basetype containing the vtbl. */
115 if (TYPE_TARGET_TYPE (context) != type1)
117 struct value *tmp = value_cast (context, value_addr (arg1));
119 arg1 = value_ind (tmp);
120 type1 = check_typedef (value_type (arg1));
124 /* Now context is the basetype containing the vtbl. */
126 /* This type may have been defined before its virtual function table
127 was. If so, fill in the virtual function table entry for the
129 context_vptr_fieldno = get_vptr_fieldno (context, &context_vptr_basetype);
130 /* FIXME: What to do if vptr_fieldno is still -1? */
132 /* The virtual function table is now an array of structures
133 which have the form { int16 offset, delta; void *pfn; }. */
134 vtbl = value_primitive_field (arg1, 0, context_vptr_fieldno,
135 context_vptr_basetype);
137 /* With older versions of g++, the vtbl field pointed to an array
138 of structures. Nowadays it points directly to the structure. */
139 if (TYPE_CODE (value_type (vtbl)) == TYPE_CODE_PTR
140 && TYPE_CODE (TYPE_TARGET_TYPE (value_type (vtbl))) == TYPE_CODE_ARRAY)
142 /* Handle the case where the vtbl field points to an
143 array of structures. */
144 vtbl = value_ind (vtbl);
146 /* Index into the virtual function table. This is hard-coded because
147 looking up a field is not cheap, and it may be important to save
148 time, e.g. if the user has set a conditional breakpoint calling
149 a virtual function. */
150 entry = value_subscript (vtbl, vi);
154 /* Handle the case where the vtbl field points directly to a
156 vtbl = value_ptradd (vtbl, vi);
157 entry = value_ind (vtbl);
160 entry_type = check_typedef (value_type (entry));
162 if (TYPE_CODE (entry_type) == TYPE_CODE_STRUCT)
164 /* Move the `this' pointer according to the virtual function table. */
165 set_value_offset (arg1, value_offset (arg1)
166 + value_as_long (value_field (entry, 0)));
168 if (!value_lazy (arg1))
170 set_value_lazy (arg1, 1);
171 value_fetch_lazy (arg1);
174 vfn = value_field (entry, 2);
176 else if (TYPE_CODE (entry_type) == TYPE_CODE_PTR)
179 error (_("I'm confused: virtual function table has bad type"));
180 /* Reinstantiate the function pointer with the correct type. */
181 deprecated_set_value_type (vfn,
182 lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j)));
190 gnuv2_value_rtti_type (struct value *v, int *full, int *top, int *using_enc)
192 struct type *known_type;
193 struct type *rtti_type;
195 struct minimal_symbol *minsym;
196 char *demangled_name, *p;
198 struct type *known_type_vptr_basetype;
199 int known_type_vptr_fieldno;
208 /* Get declared type. */
209 known_type = value_type (v);
210 CHECK_TYPEDEF (known_type);
211 /* RTTI works only or class objects. */
212 if (TYPE_CODE (known_type) != TYPE_CODE_CLASS)
215 /* Plan on this changing in the future as i get around to setting
216 the vtables properly for G++ compiled stuff. Also, I'll be using
217 the type info functions, which are always right. Deal with it
220 /* Try to get the vptr basetype, fieldno. */
221 known_type_vptr_fieldno = get_vptr_fieldno (known_type,
222 &known_type_vptr_basetype);
224 /* If we can't find it, give up. */
225 if (known_type_vptr_fieldno < 0)
228 /* Make sure our basetype and known type match, otherwise, cast
229 so we can get at the vtable properly. */
230 btype = known_type_vptr_basetype;
231 CHECK_TYPEDEF (btype);
232 if (btype != known_type )
234 v = value_cast (btype, v);
238 /* We can't use value_ind here, because it would want to use RTTI, and
239 we'd waste a bunch of time figuring out we already know the type.
240 Besides, we don't care about the type, just the actual pointer. */
241 if (value_address (value_field (v, known_type_vptr_fieldno)) == 0)
244 vtbl = value_as_address (value_field (v, known_type_vptr_fieldno));
246 /* Try to find a symbol that is the vtable. */
247 minsym=lookup_minimal_symbol_by_pc(vtbl);
249 || (demangled_name=SYMBOL_LINKAGE_NAME (minsym))==NULL
250 || !is_vtable_name (demangled_name))
253 /* If we just skip the prefix, we get screwed by namespaces. */
254 demangled_name=cplus_demangle(demangled_name,DMGL_PARAMS|DMGL_ANSI);
255 p = strchr (demangled_name, ' ');
259 /* Lookup the type for the name. */
260 /* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */
261 rtti_type = cp_lookup_rtti_type (demangled_name, NULL);
262 if (rtti_type == NULL)
265 if (TYPE_N_BASECLASSES(rtti_type) > 1 && full && (*full) != 1)
268 *top = TYPE_BASECLASS_BITPOS (rtti_type,
269 TYPE_VPTR_FIELDNO(rtti_type)) / 8;
270 if (top && ((*top) >0))
272 if (TYPE_LENGTH(rtti_type) > TYPE_LENGTH(known_type))
293 /* Return true if the INDEXth field of TYPE is a virtual baseclass
294 pointer which is for the base class whose type is BASECLASS. */
297 vb_match (struct type *type, int index, struct type *basetype)
299 struct type *fieldtype;
300 char *name = TYPE_FIELD_NAME (type, index);
301 char *field_class_name = NULL;
305 /* gcc 2.4 uses _vb$. */
306 if (name[1] == 'v' && name[2] == 'b' && is_cplus_marker (name[3]))
307 field_class_name = name + 4;
308 /* gcc 2.5 will use __vb_. */
309 if (name[1] == '_' && name[2] == 'v' && name[3] == 'b' && name[4] == '_')
310 field_class_name = name + 5;
312 if (field_class_name == NULL)
313 /* This field is not a virtual base class pointer. */
316 /* It's a virtual baseclass pointer, now we just need to find out whether
317 it is for this baseclass. */
318 fieldtype = TYPE_FIELD_TYPE (type, index);
319 if (fieldtype == NULL
320 || TYPE_CODE (fieldtype) != TYPE_CODE_PTR)
321 /* "Can't happen". */
324 /* What we check for is that either the types are equal (needed for
325 nameless types) or have the same name. This is ugly, and a more
326 elegant solution should be devised (which would probably just push
327 the ugliness into symbol reading unless we change the stabs format). */
328 if (TYPE_TARGET_TYPE (fieldtype) == basetype)
331 if (TYPE_NAME (basetype) != NULL
332 && TYPE_NAME (TYPE_TARGET_TYPE (fieldtype)) != NULL
333 && strcmp (TYPE_NAME (basetype),
334 TYPE_NAME (TYPE_TARGET_TYPE (fieldtype))) == 0)
339 /* Compute the offset of the baseclass which is the INDEXth baseclass
340 of class TYPE, for value at VALADDR (in host) at ADDRESS (in
341 target). The result is the offset of the baseclass value relative
342 to (the address of)(ARG) + OFFSET. */
345 gnuv2_baseclass_offset (struct type *type, int index,
346 const bfd_byte *valaddr, int embedded_offset,
347 CORE_ADDR address, const struct value *val)
349 struct type *basetype = TYPE_BASECLASS (type, index);
351 if (BASETYPE_VIA_VIRTUAL (type, index))
353 /* Must hunt for the pointer to this virtual baseclass. */
354 int i, len = TYPE_NFIELDS (type);
355 int n_baseclasses = TYPE_N_BASECLASSES (type);
357 /* First look for the virtual baseclass pointer
359 for (i = n_baseclasses; i < len; i++)
361 if (vb_match (type, i, basetype))
363 struct type *field_type;
368 field_type = check_typedef (TYPE_FIELD_TYPE (type, i));
369 field_offset = TYPE_FIELD_BITPOS (type, i) / 8;
370 field_length = TYPE_LENGTH (field_type);
372 if (!value_bytes_available (val, embedded_offset + field_offset,
374 throw_error (NOT_AVAILABLE_ERROR,
375 _("Virtual baseclass pointer is not available"));
377 addr = unpack_pointer (field_type,
378 valaddr + embedded_offset + field_offset);
380 return addr - (LONGEST) address + embedded_offset;
383 /* Not in the fields, so try looking through the baseclasses. */
384 for (i = index + 1; i < n_baseclasses; i++)
386 /* Don't go through baseclass_offset, as that wraps
387 exceptions, thus, inner exceptions would be wrapped more
390 gnuv2_baseclass_offset (type, i, valaddr,
391 embedded_offset, address, val);
397 error (_("Baseclass offset not found"));
400 /* Baseclass is easily computed. */
401 return TYPE_BASECLASS_BITPOS (type, index) / 8;
405 init_gnuv2_ops (void)
407 gnu_v2_abi_ops.shortname = "gnu-v2";
408 gnu_v2_abi_ops.longname = "GNU G++ Version 2 ABI";
409 gnu_v2_abi_ops.doc = "G++ Version 2 ABI";
410 gnu_v2_abi_ops.is_destructor_name = gnuv2_is_destructor_name;
411 gnu_v2_abi_ops.is_constructor_name = gnuv2_is_constructor_name;
412 gnu_v2_abi_ops.is_vtable_name = gnuv2_is_vtable_name;
413 gnu_v2_abi_ops.is_operator_name = gnuv2_is_operator_name;
414 gnu_v2_abi_ops.virtual_fn_field = gnuv2_virtual_fn_field;
415 gnu_v2_abi_ops.rtti_type = gnuv2_value_rtti_type;
416 gnu_v2_abi_ops.baseclass_offset = gnuv2_baseclass_offset;
419 extern initialize_file_ftype _initialize_gnu_v2_abi; /* -Wmissing-prototypes */
422 _initialize_gnu_v2_abi (void)
425 register_cp_abi (&gnu_v2_abi_ops);
426 set_cp_abi_as_auto_default (gnu_v2_abi_ops.shortname);