1 /* Abstraction of GNU v2 abi. 2 3 Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008, 2009, 2010, 2011 4 Free Software Foundation, Inc. 5 6 Contributed by Daniel Berlin <dberlin@redhat.com> 7 8 This file is part of GDB. 9 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. 14 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. 19 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/>. */ 22 23 #include "defs.h" 24 #include "gdb_string.h" 25 #include "symtab.h" 26 #include "gdbtypes.h" 27 #include "value.h" 28 #include "demangle.h" 29 #include "cp-abi.h" 30 #include "cp-support.h" 31 #include "exceptions.h" 32 33 #include <ctype.h> 34 35 struct cp_abi_ops gnu_v2_abi_ops; 36 37 static int vb_match (struct type *, int, struct type *); 38 39 static enum dtor_kinds 40 gnuv2_is_destructor_name (const char *name) 41 { 42 if ((name[0] == '_' && is_cplus_marker (name[1]) && name[2] == '_') 43 || strncmp (name, "__dt__", 6) == 0) 44 return complete_object_dtor; 45 else 46 return 0; 47 } 48 49 static enum ctor_kinds 50 gnuv2_is_constructor_name (const char *name) 51 { 52 if ((name[0] == '_' && name[1] == '_' 53 && (isdigit (name[2]) || strchr ("Qt", name[2]))) 54 || strncmp (name, "__ct__", 6) == 0) 55 return complete_object_ctor; 56 else 57 return 0; 58 } 59 60 static int 61 gnuv2_is_vtable_name (const char *name) 62 { 63 return (((name)[0] == '_' 64 && (((name)[1] == 'V' && (name)[2] == 'T') 65 || ((name)[1] == 'v' && (name)[2] == 't')) 66 && is_cplus_marker ((name)[3])) || 67 ((name)[0] == '_' && (name)[1] == '_' 68 && (name)[2] == 'v' && (name)[3] == 't' && (name)[4] == '_')); 69 } 70 71 static int 72 gnuv2_is_operator_name (const char *name) 73 { 74 return strncmp (name, "operator", 8) == 0; 75 } 76 77 78 /* Return a virtual function as a value. 79 ARG1 is the object which provides the virtual function 80 table pointer. *ARG1P is side-effected in calling this function. 81 F is the list of member functions which contains the desired virtual 82 function. 83 J is an index into F which provides the desired virtual function. 84 85 TYPE is the type in which F is located. */ 86 static struct value * 87 gnuv2_virtual_fn_field (struct value **arg1p, struct fn_field * f, int j, 88 struct type * type, int offset) 89 { 90 struct value *arg1 = *arg1p; 91 struct type *type1 = check_typedef (value_type (arg1)); 92 struct type *entry_type; 93 /* First, get the virtual function table pointer. That comes 94 with a strange type, so cast it to type `pointer to long' (which 95 should serve just fine as a function type). Then, index into 96 the table, and convert final value to appropriate function type. */ 97 struct value *entry; 98 struct value *vfn; 99 struct value *vtbl; 100 LONGEST vi = (LONGEST) TYPE_FN_FIELD_VOFFSET (f, j); 101 struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j); 102 struct type *context; 103 struct type *context_vptr_basetype; 104 int context_vptr_fieldno; 105 106 if (fcontext == NULL) 107 /* We don't have an fcontext (e.g. the program was compiled with 108 g++ version 1). Try to get the vtbl from the TYPE_VPTR_BASETYPE. 109 This won't work right for multiple inheritance, but at least we 110 should do as well as GDB 3.x did. */ 111 fcontext = TYPE_VPTR_BASETYPE (type); 112 context = lookup_pointer_type (fcontext); 113 /* Now context is a pointer to the basetype containing the vtbl. */ 114 if (TYPE_TARGET_TYPE (context) != type1) 115 { 116 struct value *tmp = value_cast (context, value_addr (arg1)); 117 118 arg1 = value_ind (tmp); 119 type1 = check_typedef (value_type (arg1)); 120 } 121 122 context = type1; 123 /* Now context is the basetype containing the vtbl. */ 124 125 /* This type may have been defined before its virtual function table 126 was. If so, fill in the virtual function table entry for the 127 type now. */ 128 context_vptr_fieldno = get_vptr_fieldno (context, &context_vptr_basetype); 129 /* FIXME: What to do if vptr_fieldno is still -1? */ 130 131 /* The virtual function table is now an array of structures 132 which have the form { int16 offset, delta; void *pfn; }. */ 133 vtbl = value_primitive_field (arg1, 0, context_vptr_fieldno, 134 context_vptr_basetype); 135 136 /* With older versions of g++, the vtbl field pointed to an array 137 of structures. Nowadays it points directly to the structure. */ 138 if (TYPE_CODE (value_type (vtbl)) == TYPE_CODE_PTR 139 && TYPE_CODE (TYPE_TARGET_TYPE (value_type (vtbl))) == TYPE_CODE_ARRAY) 140 { 141 /* Handle the case where the vtbl field points to an 142 array of structures. */ 143 vtbl = value_ind (vtbl); 144 145 /* Index into the virtual function table. This is hard-coded because 146 looking up a field is not cheap, and it may be important to save 147 time, e.g. if the user has set a conditional breakpoint calling 148 a virtual function. */ 149 entry = value_subscript (vtbl, vi); 150 } 151 else 152 { 153 /* Handle the case where the vtbl field points directly to a 154 structure. */ 155 vtbl = value_ptradd (vtbl, vi); 156 entry = value_ind (vtbl); 157 } 158 159 entry_type = check_typedef (value_type (entry)); 160 161 if (TYPE_CODE (entry_type) == TYPE_CODE_STRUCT) 162 { 163 /* Move the `this' pointer according to the virtual function table. */ 164 set_value_offset (arg1, value_offset (arg1) 165 + value_as_long (value_field (entry, 0))); 166 167 if (!value_lazy (arg1)) 168 { 169 set_value_lazy (arg1, 1); 170 value_fetch_lazy (arg1); 171 } 172 173 vfn = value_field (entry, 2); 174 } 175 else if (TYPE_CODE (entry_type) == TYPE_CODE_PTR) 176 vfn = entry; 177 else 178 error (_("I'm confused: virtual function table has bad type")); 179 /* Reinstantiate the function pointer with the correct type. */ 180 deprecated_set_value_type (vfn, 181 lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j))); 182 183 *arg1p = arg1; 184 return vfn; 185 } 186 187 188 static struct type * 189 gnuv2_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 vtbl; 194 struct minimal_symbol *minsym; 195 char *demangled_name, *p; 196 struct type *btype; 197 struct type *known_type_vptr_basetype; 198 int known_type_vptr_fieldno; 199 200 if (full) 201 *full = 0; 202 if (top) 203 *top = -1; 204 if (using_enc) 205 *using_enc = 0; 206 207 /* Get declared type. */ 208 known_type = value_type (v); 209 CHECK_TYPEDEF (known_type); 210 /* RTTI works only or class objects. */ 211 if (TYPE_CODE (known_type) != TYPE_CODE_CLASS) 212 return NULL; 213 214 /* Plan on this changing in the future as i get around to setting 215 the vtables properly for G++ compiled stuff. Also, I'll be using 216 the type info functions, which are always right. Deal with it 217 until then. */ 218 219 /* Try to get the vptr basetype, fieldno. */ 220 known_type_vptr_fieldno = get_vptr_fieldno (known_type, 221 &known_type_vptr_basetype); 222 223 /* If we can't find it, give up. */ 224 if (known_type_vptr_fieldno < 0) 225 return NULL; 226 227 /* Make sure our basetype and known type match, otherwise, cast 228 so we can get at the vtable properly. */ 229 btype = known_type_vptr_basetype; 230 CHECK_TYPEDEF (btype); 231 if (btype != known_type ) 232 { 233 v = value_cast (btype, v); 234 if (using_enc) 235 *using_enc=1; 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 if (value_address (value_field (v, known_type_vptr_fieldno)) == 0) 241 return NULL; 242 243 vtbl = value_as_address (value_field (v, known_type_vptr_fieldno)); 244 245 /* Try to find a symbol that is the vtable. */ 246 minsym=lookup_minimal_symbol_by_pc(vtbl); 247 if (minsym==NULL 248 || (demangled_name=SYMBOL_LINKAGE_NAME (minsym))==NULL 249 || !is_vtable_name (demangled_name)) 250 return NULL; 251 252 /* If we just skip the prefix, we get screwed by namespaces. */ 253 demangled_name=cplus_demangle(demangled_name,DMGL_PARAMS|DMGL_ANSI); 254 p = strchr (demangled_name, ' '); 255 if (p) 256 *p = '\0'; 257 258 /* Lookup the type for the name. */ 259 /* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */ 260 rtti_type = cp_lookup_rtti_type (demangled_name, NULL); 261 if (rtti_type == NULL) 262 return NULL; 263 264 if (TYPE_N_BASECLASSES(rtti_type) > 1 && full && (*full) != 1) 265 { 266 if (top) 267 *top = TYPE_BASECLASS_BITPOS (rtti_type, 268 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. */ 294 295 static int 296 vb_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 the INDEXth baseclass 339 of class TYPE, for value at VALADDR (in host) at ADDRESS (in 340 target). The result is the offset of the baseclass value relative 341 to (the address of)(ARG) + OFFSET. */ 342 343 static int 344 gnuv2_baseclass_offset (struct type *type, int index, 345 const bfd_byte *valaddr, int embedded_offset, 346 CORE_ADDR address, const struct value *val) 347 { 348 struct type *basetype = TYPE_BASECLASS (type, index); 349 350 if (BASETYPE_VIA_VIRTUAL (type, index)) 351 { 352 /* Must hunt for the pointer to this virtual baseclass. */ 353 int i, len = TYPE_NFIELDS (type); 354 int n_baseclasses = TYPE_N_BASECLASSES (type); 355 356 /* First look for the virtual baseclass pointer 357 in the fields. */ 358 for (i = n_baseclasses; i < len; i++) 359 { 360 if (vb_match (type, i, basetype)) 361 { 362 struct type *field_type; 363 int field_offset; 364 int field_length; 365 CORE_ADDR addr; 366 367 field_type = check_typedef (TYPE_FIELD_TYPE (type, i)); 368 field_offset = TYPE_FIELD_BITPOS (type, i) / 8; 369 field_length = TYPE_LENGTH (field_type); 370 371 if (!value_bytes_available (val, embedded_offset + field_offset, 372 field_length)) 373 throw_error (NOT_AVAILABLE_ERROR, 374 _("Virtual baseclass pointer is not available")); 375 376 addr = unpack_pointer (field_type, 377 valaddr + embedded_offset + field_offset); 378 379 return addr - (LONGEST) address + embedded_offset; 380 } 381 } 382 /* Not in the fields, so try looking through the baseclasses. */ 383 for (i = index + 1; i < n_baseclasses; i++) 384 { 385 /* Don't go through baseclass_offset, as that wraps 386 exceptions, thus, inner exceptions would be wrapped more 387 than once. */ 388 int boffset = 389 gnuv2_baseclass_offset (type, i, valaddr, 390 embedded_offset, address, val); 391 392 if (boffset) 393 return boffset; 394 } 395 396 error (_("Baseclass offset not found")); 397 } 398 399 /* Baseclass is easily computed. */ 400 return TYPE_BASECLASS_BITPOS (type, index) / 8; 401 } 402 403 static void 404 init_gnuv2_ops (void) 405 { 406 gnu_v2_abi_ops.shortname = "gnu-v2"; 407 gnu_v2_abi_ops.longname = "GNU G++ Version 2 ABI"; 408 gnu_v2_abi_ops.doc = "G++ Version 2 ABI"; 409 gnu_v2_abi_ops.is_destructor_name = gnuv2_is_destructor_name; 410 gnu_v2_abi_ops.is_constructor_name = gnuv2_is_constructor_name; 411 gnu_v2_abi_ops.is_vtable_name = gnuv2_is_vtable_name; 412 gnu_v2_abi_ops.is_operator_name = gnuv2_is_operator_name; 413 gnu_v2_abi_ops.virtual_fn_field = gnuv2_virtual_fn_field; 414 gnu_v2_abi_ops.rtti_type = gnuv2_value_rtti_type; 415 gnu_v2_abi_ops.baseclass_offset = gnuv2_baseclass_offset; 416 } 417 418 extern initialize_file_ftype _initialize_gnu_v2_abi; /* -Wmissing-prototypes */ 419 420 void 421 _initialize_gnu_v2_abi (void) 422 { 423 init_gnuv2_ops (); 424 register_cp_abi (&gnu_v2_abi_ops); 425 set_cp_abi_as_auto_default (gnu_v2_abi_ops.shortname); 426 } 427