1 /* Abstraction of GNU v2 abi. 2 3 Copyright (C) 2001-2013 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 "gdb-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 const char *linkage_name; 197 struct type *btype; 198 struct type *known_type_vptr_basetype; 199 int known_type_vptr_fieldno; 200 201 if (full) 202 *full = 0; 203 if (top) 204 *top = -1; 205 if (using_enc) 206 *using_enc = 0; 207 208 /* 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) 213 return NULL; 214 215 /* 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 218 until then. */ 219 220 /* Try to get the vptr basetype, fieldno. */ 221 known_type_vptr_fieldno = get_vptr_fieldno (known_type, 222 &known_type_vptr_basetype); 223 224 /* If we can't find it, give up. */ 225 if (known_type_vptr_fieldno < 0) 226 return NULL; 227 228 /* 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 ) 233 { 234 v = value_cast (btype, v); 235 if (using_enc) 236 *using_enc=1; 237 } 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) 242 return NULL; 243 244 vtbl = value_as_address (value_field (v, known_type_vptr_fieldno)); 245 246 /* Try to find a symbol that is the vtable. */ 247 minsym=lookup_minimal_symbol_by_pc(vtbl); 248 if (minsym==NULL 249 || (linkage_name=SYMBOL_LINKAGE_NAME (minsym))==NULL 250 || !is_vtable_name (linkage_name)) 251 return NULL; 252 253 /* If we just skip the prefix, we get screwed by namespaces. */ 254 demangled_name=cplus_demangle(linkage_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, 269 TYPE_VPTR_FIELDNO(rtti_type)) / 8; 270 if (top && ((*top) >0)) 271 { 272 if (TYPE_LENGTH(rtti_type) > TYPE_LENGTH(known_type)) 273 { 274 if (full) 275 *full=0; 276 } 277 else 278 { 279 if (full) 280 *full=1; 281 } 282 } 283 } 284 else 285 { 286 if (full) 287 *full=1; 288 } 289 290 return rtti_type; 291 } 292 293 /* Return true if the INDEXth field of TYPE is a virtual baseclass 294 pointer which is for the base class whose type is BASECLASS. */ 295 296 static int 297 vb_match (struct type *type, int index, struct type *basetype) 298 { 299 struct type *fieldtype; 300 const char *name = TYPE_FIELD_NAME (type, index); 301 const char *field_class_name = NULL; 302 303 if (*name != '_') 304 return 0; 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; 311 312 if (field_class_name == NULL) 313 /* This field is not a virtual base class pointer. */ 314 return 0; 315 316 /* 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". */ 322 return 0; 323 324 /* 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) 329 return 1; 330 331 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) 335 return 1; 336 return 0; 337 } 338 339 /* 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. */ 343 344 static int 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) 348 { 349 struct type *basetype = TYPE_BASECLASS (type, index); 350 351 if (BASETYPE_VIA_VIRTUAL (type, index)) 352 { 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); 356 357 /* First look for the virtual baseclass pointer 358 in the fields. */ 359 for (i = n_baseclasses; i < len; i++) 360 { 361 if (vb_match (type, i, basetype)) 362 { 363 struct type *field_type; 364 int field_offset; 365 int field_length; 366 CORE_ADDR addr; 367 368 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); 371 372 if (!value_bytes_available (val, embedded_offset + field_offset, 373 field_length)) 374 throw_error (NOT_AVAILABLE_ERROR, 375 _("Virtual baseclass pointer is not available")); 376 377 addr = unpack_pointer (field_type, 378 valaddr + embedded_offset + field_offset); 379 380 return addr - (LONGEST) address + embedded_offset; 381 } 382 } 383 /* Not in the fields, so try looking through the baseclasses. */ 384 for (i = index + 1; i < n_baseclasses; i++) 385 { 386 /* Don't go through baseclass_offset, as that wraps 387 exceptions, thus, inner exceptions would be wrapped more 388 than once. */ 389 int boffset = 390 gnuv2_baseclass_offset (type, i, valaddr, 391 embedded_offset, address, val); 392 393 if (boffset) 394 return boffset; 395 } 396 397 error (_("Baseclass offset not found")); 398 } 399 400 /* Baseclass is easily computed. */ 401 return TYPE_BASECLASS_BITPOS (type, index) / 8; 402 } 403 404 static void 405 init_gnuv2_ops (void) 406 { 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; 417 } 418 419 extern initialize_file_ftype _initialize_gnu_v2_abi; /* -Wmissing-prototypes */ 420 421 void 422 _initialize_gnu_v2_abi (void) 423 { 424 init_gnuv2_ops (); 425 register_cp_abi (&gnu_v2_abi_ops); 426 } 427