1/* Abstraction of GNU v2 abi. 2 3 Copyright (C) 2001, 2002, 2003, 2005, 2007 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 "gdb_string.h" 24#include "symtab.h" 25#include "gdbtypes.h" 26#include "value.h" 27#include "demangle.h" 28#include "cp-abi.h" 29#include "cp-support.h" 30#include "gnu-v2-abi.h" 31 32#include <ctype.h> 33 34struct cp_abi_ops gnu_v2_abi_ops; 35 36static int vb_match (struct type *, int, struct type *); 37 38static enum dtor_kinds 39gnuv2_is_destructor_name (const char *name) 40{ 41 if ((name[0] == '_' && is_cplus_marker (name[1]) && name[2] == '_') 42 || strncmp (name, "__dt__", 6) == 0) 43 return complete_object_dtor; 44 else 45 return 0; 46} 47 48static enum ctor_kinds 49gnuv2_is_constructor_name (const char *name) 50{ 51 if ((name[0] == '_' && name[1] == '_' 52 && (isdigit (name[2]) || strchr ("Qt", name[2]))) 53 || strncmp (name, "__ct__", 6) == 0) 54 return complete_object_ctor; 55 else 56 return 0; 57} 58 59static int 60gnuv2_is_vtable_name (const char *name) 61{ 62 return (((name)[0] == '_' 63 && (((name)[1] == 'V' && (name)[2] == 'T') 64 || ((name)[1] == 'v' && (name)[2] == 't')) 65 && is_cplus_marker ((name)[3])) || 66 ((name)[0] == '_' && (name)[1] == '_' 67 && (name)[2] == 'v' && (name)[3] == 't' && (name)[4] == '_')); 68} 69 70static int 71gnuv2_is_operator_name (const char *name) 72{ 73 return strncmp (name, "operator", 8) == 0; 74} 75 76 77/* Return a virtual function as a value. 78 ARG1 is the object which provides the virtual function 79 table pointer. *ARG1P is side-effected in calling this function. 80 F is the list of member functions which contains the desired virtual 81 function. 82 J is an index into F which provides the desired virtual function. 83 84 TYPE is the type in which F is located. */ 85static struct value * 86gnuv2_virtual_fn_field (struct value **arg1p, struct fn_field * f, int j, 87 struct type * type, int offset) 88{ 89 struct value *arg1 = *arg1p; 90 struct type *type1 = check_typedef (value_type (arg1)); 91 92 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. */ 98 struct value *entry; 99 struct value *vfn; 100 struct value *vtbl; 101 struct value *vi = value_from_longest (builtin_type_int, 102 (LONGEST) TYPE_FN_FIELD_VOFFSET (f, j)); 103 struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j); 104 struct type *context; 105 if (fcontext == NULL) 106 /* We don't have an fcontext (e.g. the program was compiled with 107 g++ version 1). Try to get the vtbl from the TYPE_VPTR_BASETYPE. 108 This won't work right for multiple inheritance, but at least we 109 should do as well as GDB 3.x did. */ 110 fcontext = TYPE_VPTR_BASETYPE (type); 111 context = lookup_pointer_type (fcontext); 112 /* Now context is a pointer to the basetype containing the vtbl. */ 113 if (TYPE_TARGET_TYPE (context) != type1) 114 { 115 struct value *tmp = value_cast (context, value_addr (arg1)); 116 arg1 = value_ind (tmp); 117 type1 = check_typedef (value_type (arg1)); 118 } 119 120 context = type1; 121 /* Now context is the basetype containing the vtbl. */ 122 123 /* This type may have been defined before its virtual function table 124 was. If so, fill in the virtual function table entry for the 125 type now. */ 126 if (TYPE_VPTR_FIELDNO (context) < 0) 127 fill_in_vptr_fieldno (context); 128 129 /* The virtual function table is now an array of structures 130 which have the form { int16 offset, delta; void *pfn; }. */ 131 vtbl = value_primitive_field (arg1, 0, TYPE_VPTR_FIELDNO (context), 132 TYPE_VPTR_BASETYPE (context)); 133 134 /* With older versions of g++, the vtbl field pointed to an array 135 of structures. Nowadays it points directly to the structure. */ 136 if (TYPE_CODE (value_type (vtbl)) == TYPE_CODE_PTR 137 && TYPE_CODE (TYPE_TARGET_TYPE (value_type (vtbl))) == TYPE_CODE_ARRAY) 138 { 139 /* Handle the case where the vtbl field points to an 140 array of structures. */ 141 vtbl = value_ind (vtbl); 142 143 /* Index into the virtual function table. This is hard-coded because 144 looking up a field is not cheap, and it may be important to save 145 time, e.g. if the user has set a conditional breakpoint calling 146 a virtual function. */ 147 entry = value_subscript (vtbl, vi); 148 } 149 else 150 { 151 /* Handle the case where the vtbl field points directly to a structure. */ 152 vtbl = value_add (vtbl, vi); 153 entry = value_ind (vtbl); 154 } 155 156 entry_type = check_typedef (value_type (entry)); 157 158 if (TYPE_CODE (entry_type) == TYPE_CODE_STRUCT) 159 { 160 /* Move the `this' pointer according to the virtual function table. */ 161 set_value_offset (arg1, value_offset (arg1) + value_as_long (value_field (entry, 0))); 162 163 if (!value_lazy (arg1)) 164 { 165 set_value_lazy (arg1, 1); 166 value_fetch_lazy (arg1); 167 } 168 169 vfn = value_field (entry, 2); 170 } 171 else if (TYPE_CODE (entry_type) == TYPE_CODE_PTR) 172 vfn = entry; 173 else 174 error (_("I'm confused: virtual function table has bad type")); 175 /* Reinstantiate the function pointer with the correct type. */ 176 deprecated_set_value_type (vfn, lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j))); 177 178 *arg1p = arg1; 179 return vfn; 180} 181 182 183static struct type * 184gnuv2_value_rtti_type (struct value *v, int *full, int *top, int *using_enc) 185{ 186 struct type *known_type; 187 struct type *rtti_type; 188 CORE_ADDR coreptr; 189 struct value *vp; 190 long top_offset = 0; 191 char rtti_type_name[256]; 192 CORE_ADDR vtbl; 193 struct minimal_symbol *minsym; 194 struct symbol *sym; 195 char *demangled_name, *p; 196 struct type *btype; 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 CHECK_TYPEDEF (known_type); 208 /* RTTI works only or class objects */ 209 if (TYPE_CODE (known_type) != TYPE_CODE_CLASS) 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 /* If the type has no vptr fieldno, try to get it filled in */ 218 if (TYPE_VPTR_FIELDNO(known_type) < 0) 219 fill_in_vptr_fieldno(known_type); 220 221 /* If we still can't find one, give up */ 222 if (TYPE_VPTR_FIELDNO(known_type) < 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 */ 228 btype = TYPE_VPTR_BASETYPE (known_type); 229 CHECK_TYPEDEF (btype); 230 if (btype != known_type ) 231 { 232 v = value_cast (btype, v); 233 if (using_enc) 234 *using_enc=1; 235 } 236 /* 237 We can't use value_ind here, because it would want to use RTTI, and 238 we'd waste a bunch of time figuring out we already know the type. 239 Besides, we don't care about the type, just the actual pointer 240 */ 241 if (VALUE_ADDRESS (value_field (v, TYPE_VPTR_FIELDNO (known_type))) == 0) 242 return NULL; 243 244 vtbl=value_as_address(value_field(v,TYPE_VPTR_FIELDNO(known_type))); 245 246 /* Try to find a symbol that is the vtable */ 247 minsym=lookup_minimal_symbol_by_pc(vtbl); 248 if (minsym==NULL 249 || (demangled_name=DEPRECATED_SYMBOL_NAME (minsym))==NULL 250 || !is_vtable_name (demangled_name)) 251 return NULL; 252 253 /* 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, ' '); 256 if (p) 257 *p = '\0'; 258 259 /* 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) 263 return NULL; 264 265 if (TYPE_N_BASECLASSES(rtti_type) > 1 && full && (*full) != 1) 266 { 267 if (top) 268 *top=TYPE_BASECLASS_BITPOS(rtti_type,TYPE_VPTR_FIELDNO(rtti_type))/8; 269 if (top && ((*top) >0)) 270 { 271 if (TYPE_LENGTH(rtti_type) > TYPE_LENGTH(known_type)) 272 { 273 if (full) 274 *full=0; 275 } 276 else 277 { 278 if (full) 279 *full=1; 280 } 281 } 282 } 283 else 284 { 285 if (full) 286 *full=1; 287 } 288 289 return rtti_type; 290} 291 292/* Return true if the INDEXth field of TYPE is a virtual baseclass 293 pointer which is for the base class whose type is BASECLASS. */ 294 295static int 296vb_match (struct type *type, int index, struct type *basetype) 297{ 298 struct type *fieldtype; 299 char *name = TYPE_FIELD_NAME (type, index); 300 char *field_class_name = NULL; 301 302 if (*name != '_') 303 return 0; 304 /* gcc 2.4 uses _vb$. */ 305 if (name[1] == 'v' && name[2] == 'b' && is_cplus_marker (name[3])) 306 field_class_name = name + 4; 307 /* gcc 2.5 will use __vb_. */ 308 if (name[1] == '_' && name[2] == 'v' && name[3] == 'b' && name[4] == '_') 309 field_class_name = name + 5; 310 311 if (field_class_name == NULL) 312 /* This field is not a virtual base class pointer. */ 313 return 0; 314 315 /* It's a virtual baseclass pointer, now we just need to find out whether 316 it is for this baseclass. */ 317 fieldtype = TYPE_FIELD_TYPE (type, index); 318 if (fieldtype == NULL 319 || TYPE_CODE (fieldtype) != TYPE_CODE_PTR) 320 /* "Can't happen". */ 321 return 0; 322 323 /* What we check for is that either the types are equal (needed for 324 nameless types) or have the same name. This is ugly, and a more 325 elegant solution should be devised (which would probably just push 326 the ugliness into symbol reading unless we change the stabs format). */ 327 if (TYPE_TARGET_TYPE (fieldtype) == basetype) 328 return 1; 329 330 if (TYPE_NAME (basetype) != NULL 331 && TYPE_NAME (TYPE_TARGET_TYPE (fieldtype)) != NULL 332 && strcmp (TYPE_NAME (basetype), 333 TYPE_NAME (TYPE_TARGET_TYPE (fieldtype))) == 0) 334 return 1; 335 return 0; 336} 337 338/* Compute the offset of the baseclass which is 339 the INDEXth baseclass of class TYPE, 340 for value at VALADDR (in host) at ADDRESS (in target). 341 The result is the offset of the baseclass value relative 342 to (the address of)(ARG) + OFFSET. 343 344 -1 is returned on error. */ 345 346int 347gnuv2_baseclass_offset (struct type *type, int index, 348 const bfd_byte *valaddr, CORE_ADDR address) 349{ 350 struct type *basetype = TYPE_BASECLASS (type, index); 351 352 if (BASETYPE_VIA_VIRTUAL (type, index)) 353 { 354 /* Must hunt for the pointer to this virtual baseclass. */ 355 int i, len = TYPE_NFIELDS (type); 356 int n_baseclasses = TYPE_N_BASECLASSES (type); 357 358 /* First look for the virtual baseclass pointer 359 in the fields. */ 360 for (i = n_baseclasses; i < len; i++) 361 { 362 if (vb_match (type, i, basetype)) 363 { 364 CORE_ADDR addr 365 = unpack_pointer (TYPE_FIELD_TYPE (type, i), 366 valaddr + (TYPE_FIELD_BITPOS (type, i) / 8)); 367 368 return addr - (LONGEST) address; 369 } 370 } 371 /* Not in the fields, so try looking through the baseclasses. */ 372 for (i = index + 1; i < n_baseclasses; i++) 373 { 374 int boffset = 375 baseclass_offset (type, i, valaddr, address); 376 if (boffset) 377 return boffset; 378 } 379 /* Not found. */ 380 return -1; 381 } 382 383 /* Baseclass is easily computed. */ 384 return TYPE_BASECLASS_BITPOS (type, index) / 8; 385} 386 387static void 388init_gnuv2_ops (void) 389{ 390 gnu_v2_abi_ops.shortname = "gnu-v2"; 391 gnu_v2_abi_ops.longname = "GNU G++ Version 2 ABI"; 392 gnu_v2_abi_ops.doc = "G++ Version 2 ABI"; 393 gnu_v2_abi_ops.is_destructor_name = gnuv2_is_destructor_name; 394 gnu_v2_abi_ops.is_constructor_name = gnuv2_is_constructor_name; 395 gnu_v2_abi_ops.is_vtable_name = gnuv2_is_vtable_name; 396 gnu_v2_abi_ops.is_operator_name = gnuv2_is_operator_name; 397 gnu_v2_abi_ops.virtual_fn_field = gnuv2_virtual_fn_field; 398 gnu_v2_abi_ops.rtti_type = gnuv2_value_rtti_type; 399 gnu_v2_abi_ops.baseclass_offset = gnuv2_baseclass_offset; 400} 401 402extern initialize_file_ftype _initialize_gnu_v2_abi; /* -Wmissing-prototypes */ 403 404void 405_initialize_gnu_v2_abi (void) 406{ 407 init_gnuv2_ops (); 408 register_cp_abi (&gnu_v2_abi_ops); 409 set_cp_abi_as_auto_default (gnu_v2_abi_ops.shortname); 410} 411