1/* Abstraction of GNU v2 abi. 2 3 Copyright 2001, 2002, 2003 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 35#include <ctype.h> 36 37struct cp_abi_ops gnu_v2_abi_ops; 38 39static int vb_match (struct type *, int, struct type *); 40int gnuv2_baseclass_offset (struct type *type, int index, char *valaddr, 41 CORE_ADDR address); 42 43static enum dtor_kinds 44gnuv2_is_destructor_name (const char *name) 45{ 46 if ((name[0] == '_' && is_cplus_marker (name[1]) && name[2] == '_') 47 || strncmp (name, "__dt__", 6) == 0) 48 return complete_object_dtor; 49 else 50 return 0; 51} 52 53static enum ctor_kinds 54gnuv2_is_constructor_name (const char *name) 55{ 56 if ((name[0] == '_' && name[1] == '_' 57 && (isdigit (name[2]) || strchr ("Qt", name[2]))) 58 || strncmp (name, "__ct__", 6) == 0) 59 return complete_object_ctor; 60 else 61 return 0; 62} 63 64static int 65gnuv2_is_vtable_name (const char *name) 66{ 67 return (((name)[0] == '_' 68 && (((name)[1] == 'V' && (name)[2] == 'T') 69 || ((name)[1] == 'v' && (name)[2] == 't')) 70 && is_cplus_marker ((name)[3])) || 71 ((name)[0] == '_' && (name)[1] == '_' 72 && (name)[2] == 'v' && (name)[3] == 't' && (name)[4] == '_')); 73} 74 75static int 76gnuv2_is_operator_name (const char *name) 77{ 78 return strncmp (name, "operator", 8) == 0; 79} 80 81 82/* Return a virtual function as a value. 83 ARG1 is the object which provides the virtual function 84 table pointer. *ARG1P is side-effected in calling this function. 85 F is the list of member functions which contains the desired virtual 86 function. 87 J is an index into F which provides the desired virtual function. 88 89 TYPE is the type in which F is located. */ 90static struct value * 91gnuv2_virtual_fn_field (struct value **arg1p, struct fn_field * f, int j, 92 struct type * type, int offset) 93{ 94 struct value *arg1 = *arg1p; 95 struct type *type1 = check_typedef (VALUE_TYPE (arg1)); 96 97 98 struct type *entry_type; 99 /* First, get the virtual function table pointer. That comes 100 with a strange type, so cast it to type `pointer to long' (which 101 should serve just fine as a function type). Then, index into 102 the table, and convert final value to appropriate function type. */ 103 struct value *entry; 104 struct value *vfn; 105 struct value *vtbl; 106 struct value *vi = value_from_longest (builtin_type_int, 107 (LONGEST) TYPE_FN_FIELD_VOFFSET (f, j)); 108 struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j); 109 struct type *context; 110 if (fcontext == NULL) 111 /* We don't have an fcontext (e.g. the program was compiled with 112 g++ version 1). Try to get the vtbl from the TYPE_VPTR_BASETYPE. 113 This won't work right for multiple inheritance, but at least we 114 should do as well as GDB 3.x did. */ 115 fcontext = TYPE_VPTR_BASETYPE (type); 116 context = lookup_pointer_type (fcontext); 117 /* Now context is a pointer to the basetype containing the vtbl. */ 118 if (TYPE_TARGET_TYPE (context) != type1) 119 { 120 struct value *tmp = value_cast (context, value_addr (arg1)); 121 arg1 = value_ind (tmp); 122 type1 = check_typedef (VALUE_TYPE (arg1)); 123 } 124 125 context = type1; 126 /* Now context is the basetype containing the vtbl. */ 127 128 /* This type may have been defined before its virtual function table 129 was. If so, fill in the virtual function table entry for the 130 type now. */ 131 if (TYPE_VPTR_FIELDNO (context) < 0) 132 fill_in_vptr_fieldno (context); 133 134 /* The virtual function table is now an array of structures 135 which have the form { int16 offset, delta; void *pfn; }. */ 136 vtbl = value_primitive_field (arg1, 0, TYPE_VPTR_FIELDNO (context), 137 TYPE_VPTR_BASETYPE (context)); 138 139 /* With older versions of g++, the vtbl field pointed to an array 140 of structures. Nowadays it points directly to the structure. */ 141 if (TYPE_CODE (VALUE_TYPE (vtbl)) == TYPE_CODE_PTR 142 && TYPE_CODE (TYPE_TARGET_TYPE (VALUE_TYPE (vtbl))) == TYPE_CODE_ARRAY) 143 { 144 /* Handle the case where the vtbl field points to an 145 array of structures. */ 146 vtbl = value_ind (vtbl); 147 148 /* Index into the virtual function table. This is hard-coded because 149 looking up a field is not cheap, and it may be important to save 150 time, e.g. if the user has set a conditional breakpoint calling 151 a virtual function. */ 152 entry = value_subscript (vtbl, vi); 153 } 154 else 155 { 156 /* Handle the case where the vtbl field points directly to a structure. */ 157 vtbl = value_add (vtbl, vi); 158 entry = value_ind (vtbl); 159 } 160 161 entry_type = check_typedef (VALUE_TYPE (entry)); 162 163 if (TYPE_CODE (entry_type) == TYPE_CODE_STRUCT) 164 { 165 /* Move the `this' pointer according to the virtual function table. */ 166 VALUE_OFFSET (arg1) += value_as_long (value_field (entry, 0)); 167 168 if (!VALUE_LAZY (arg1)) 169 { 170 VALUE_LAZY (arg1) = 1; 171 value_fetch_lazy (arg1); 172 } 173 174 vfn = value_field (entry, 2); 175 } 176 else if (TYPE_CODE (entry_type) == TYPE_CODE_PTR) 177 vfn = entry; 178 else 179 error ("I'm confused: virtual function table has bad type"); 180 /* Reinstantiate the function pointer with the correct type. */ 181 VALUE_TYPE (vfn) = lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j)); 182 183 *arg1p = arg1; 184 return vfn; 185} 186 187 188static struct type * 189gnuv2_value_rtti_type (struct value *v, int *full, int *top, int *using_enc) 190{ 191 struct type *known_type; 192 struct type *rtti_type; 193 CORE_ADDR coreptr; 194 struct value *vp; 195 long top_offset = 0; 196 char rtti_type_name[256]; 197 CORE_ADDR vtbl; 198 struct minimal_symbol *minsym; 199 struct symbol *sym; 200 char *demangled_name; 201 struct type *btype; 202 203 if (full) 204 *full = 0; 205 if (top) 206 *top = -1; 207 if (using_enc) 208 *using_enc = 0; 209 210 /* Get declared type */ 211 known_type = VALUE_TYPE (v); 212 CHECK_TYPEDEF (known_type); 213 /* RTTI works only or class objects */ 214 if (TYPE_CODE (known_type) != TYPE_CODE_CLASS) 215 return NULL; 216 217 /* Plan on this changing in the future as i get around to setting 218 the vtables properly for G++ compiled stuff. Also, I'll be using 219 the type info functions, which are always right. Deal with it 220 until then. */ 221 222 /* If the type has no vptr fieldno, try to get it filled in */ 223 if (TYPE_VPTR_FIELDNO(known_type) < 0) 224 fill_in_vptr_fieldno(known_type); 225 226 /* If we still can't find one, give up */ 227 if (TYPE_VPTR_FIELDNO(known_type) < 0) 228 return NULL; 229 230 /* Make sure our basetype and known type match, otherwise, cast 231 so we can get at the vtable properly. 232 */ 233 btype = TYPE_VPTR_BASETYPE (known_type); 234 CHECK_TYPEDEF (btype); 235 if (btype != known_type ) 236 { 237 v = value_cast (btype, v); 238 if (using_enc) 239 *using_enc=1; 240 } 241 /* 242 We can't use value_ind here, because it would want to use RTTI, and 243 we'd waste a bunch of time figuring out we already know the type. 244 Besides, we don't care about the type, just the actual pointer 245 */ 246 if (VALUE_ADDRESS (value_field (v, TYPE_VPTR_FIELDNO (known_type))) == 0) 247 return NULL; 248 249 vtbl=value_as_address(value_field(v,TYPE_VPTR_FIELDNO(known_type))); 250 251 /* Try to find a symbol that is the vtable */ 252 minsym=lookup_minimal_symbol_by_pc(vtbl); 253 if (minsym==NULL 254 || (demangled_name=DEPRECATED_SYMBOL_NAME (minsym))==NULL 255 || !is_vtable_name (demangled_name)) 256 return NULL; 257 258 /* If we just skip the prefix, we get screwed by namespaces */ 259 demangled_name=cplus_demangle(demangled_name,DMGL_PARAMS|DMGL_ANSI); 260 *(strchr(demangled_name,' '))=0; 261 262 /* Lookup the type for the name */ 263 /* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */ 264 rtti_type = cp_lookup_rtti_type (demangled_name, NULL); 265 if (rtti_type == NULL) 266 return NULL; 267 268 if (TYPE_N_BASECLASSES(rtti_type) > 1 && full && (*full) != 1) 269 { 270 if (top) 271 *top=TYPE_BASECLASS_BITPOS(rtti_type,TYPE_VPTR_FIELDNO(rtti_type))/8; 272 if (top && ((*top) >0)) 273 { 274 if (TYPE_LENGTH(rtti_type) > TYPE_LENGTH(known_type)) 275 { 276 if (full) 277 *full=0; 278 } 279 else 280 { 281 if (full) 282 *full=1; 283 } 284 } 285 } 286 else 287 { 288 if (full) 289 *full=1; 290 } 291 292 return rtti_type; 293} 294 295/* Return true if the INDEXth field of TYPE is a virtual baseclass 296 pointer which is for the base class whose type is BASECLASS. */ 297 298static int 299vb_match (struct type *type, int index, struct type *basetype) 300{ 301 struct type *fieldtype; 302 char *name = TYPE_FIELD_NAME (type, index); 303 char *field_class_name = NULL; 304 305 if (*name != '_') 306 return 0; 307 /* gcc 2.4 uses _vb$. */ 308 if (name[1] == 'v' && name[2] == 'b' && is_cplus_marker (name[3])) 309 field_class_name = name + 4; 310 /* gcc 2.5 will use __vb_. */ 311 if (name[1] == '_' && name[2] == 'v' && name[3] == 'b' && name[4] == '_') 312 field_class_name = name + 5; 313 314 if (field_class_name == NULL) 315 /* This field is not a virtual base class pointer. */ 316 return 0; 317 318 /* It's a virtual baseclass pointer, now we just need to find out whether 319 it is for this baseclass. */ 320 fieldtype = TYPE_FIELD_TYPE (type, index); 321 if (fieldtype == NULL 322 || TYPE_CODE (fieldtype) != TYPE_CODE_PTR) 323 /* "Can't happen". */ 324 return 0; 325 326 /* What we check for is that either the types are equal (needed for 327 nameless types) or have the same name. This is ugly, and a more 328 elegant solution should be devised (which would probably just push 329 the ugliness into symbol reading unless we change the stabs format). */ 330 if (TYPE_TARGET_TYPE (fieldtype) == basetype) 331 return 1; 332 333 if (TYPE_NAME (basetype) != NULL 334 && TYPE_NAME (TYPE_TARGET_TYPE (fieldtype)) != NULL 335 && strcmp (TYPE_NAME (basetype), 336 TYPE_NAME (TYPE_TARGET_TYPE (fieldtype))) == 0) 337 return 1; 338 return 0; 339} 340 341/* Compute the offset of the baseclass which is 342 the INDEXth baseclass of class TYPE, 343 for value at VALADDR (in host) at ADDRESS (in target). 344 The result is the offset of the baseclass value relative 345 to (the address of)(ARG) + OFFSET. 346 347 -1 is returned on error. */ 348 349int 350gnuv2_baseclass_offset (struct type *type, int index, char *valaddr, 351 CORE_ADDR address) 352{ 353 struct type *basetype = TYPE_BASECLASS (type, index); 354 355 if (BASETYPE_VIA_VIRTUAL (type, index)) 356 { 357 /* Must hunt for the pointer to this virtual baseclass. */ 358 int i, len = TYPE_NFIELDS (type); 359 int n_baseclasses = TYPE_N_BASECLASSES (type); 360 361 /* First look for the virtual baseclass pointer 362 in the fields. */ 363 for (i = n_baseclasses; i < len; i++) 364 { 365 if (vb_match (type, i, basetype)) 366 { 367 CORE_ADDR addr 368 = unpack_pointer (TYPE_FIELD_TYPE (type, i), 369 valaddr + (TYPE_FIELD_BITPOS (type, i) / 8)); 370 371 return addr - (LONGEST) address; 372 } 373 } 374 /* Not in the fields, so try looking through the baseclasses. */ 375 for (i = index + 1; i < n_baseclasses; i++) 376 { 377 int boffset = 378 baseclass_offset (type, i, valaddr, address); 379 if (boffset) 380 return boffset; 381 } 382 /* Not found. */ 383 return -1; 384 } 385 386 /* Baseclass is easily computed. */ 387 return TYPE_BASECLASS_BITPOS (type, index) / 8; 388} 389 390static void 391init_gnuv2_ops (void) 392{ 393 gnu_v2_abi_ops.shortname = "gnu-v2"; 394 gnu_v2_abi_ops.longname = "GNU G++ Version 2 ABI"; 395 gnu_v2_abi_ops.doc = "G++ Version 2 ABI"; 396 gnu_v2_abi_ops.is_destructor_name = gnuv2_is_destructor_name; 397 gnu_v2_abi_ops.is_constructor_name = gnuv2_is_constructor_name; 398 gnu_v2_abi_ops.is_vtable_name = gnuv2_is_vtable_name; 399 gnu_v2_abi_ops.is_operator_name = gnuv2_is_operator_name; 400 gnu_v2_abi_ops.virtual_fn_field = gnuv2_virtual_fn_field; 401 gnu_v2_abi_ops.rtti_type = gnuv2_value_rtti_type; 402 gnu_v2_abi_ops.baseclass_offset = gnuv2_baseclass_offset; 403} 404 405extern initialize_file_ftype _initialize_gnu_v2_abi; /* -Wmissing-prototypes */ 406 407void 408_initialize_gnu_v2_abi (void) 409{ 410 init_gnuv2_ops (); 411 register_cp_abi (&gnu_v2_abi_ops); 412 set_cp_abi_as_auto_default (gnu_v2_abi_ops.shortname); 413} 414