1 /* Abstraction of GNU v2 abi. 2 3 Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008, 2009 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 "gnu-v2-abi.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 arg1 = value_ind (tmp); 118 type1 = check_typedef (value_type (arg1)); 119 } 120 121 context = type1; 122 /* Now context is the basetype containing the vtbl. */ 123 124 /* This type may have been defined before its virtual function table 125 was. If so, fill in the virtual function table entry for the 126 type now. */ 127 context_vptr_fieldno = get_vptr_fieldno (context, &context_vptr_basetype); 128 /* FIXME: What to do if vptr_fieldno is still -1? */ 129 130 /* The virtual function table is now an array of structures 131 which have the form { int16 offset, delta; void *pfn; }. */ 132 vtbl = value_primitive_field (arg1, 0, context_vptr_fieldno, 133 context_vptr_basetype); 134 135 /* With older versions of g++, the vtbl field pointed to an array 136 of structures. Nowadays it points directly to the structure. */ 137 if (TYPE_CODE (value_type (vtbl)) == TYPE_CODE_PTR 138 && TYPE_CODE (TYPE_TARGET_TYPE (value_type (vtbl))) == TYPE_CODE_ARRAY) 139 { 140 /* Handle the case where the vtbl field points to an 141 array of structures. */ 142 vtbl = value_ind (vtbl); 143 144 /* Index into the virtual function table. This is hard-coded because 145 looking up a field is not cheap, and it may be important to save 146 time, e.g. if the user has set a conditional breakpoint calling 147 a virtual function. */ 148 entry = value_subscript (vtbl, vi); 149 } 150 else 151 { 152 /* Handle the case where the vtbl field points directly to a structure. */ 153 vtbl = value_ptradd (vtbl, vi); 154 entry = value_ind (vtbl); 155 } 156 157 entry_type = check_typedef (value_type (entry)); 158 159 if (TYPE_CODE (entry_type) == TYPE_CODE_STRUCT) 160 { 161 /* Move the `this' pointer according to the virtual function table. */ 162 set_value_offset (arg1, value_offset (arg1) + value_as_long (value_field (entry, 0))); 163 164 if (!value_lazy (arg1)) 165 { 166 set_value_lazy (arg1, 1); 167 value_fetch_lazy (arg1); 168 } 169 170 vfn = value_field (entry, 2); 171 } 172 else if (TYPE_CODE (entry_type) == TYPE_CODE_PTR) 173 vfn = entry; 174 else 175 error (_("I'm confused: virtual function table has bad type")); 176 /* Reinstantiate the function pointer with the correct type. */ 177 deprecated_set_value_type (vfn, lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j))); 178 179 *arg1p = arg1; 180 return vfn; 181 } 182 183 184 static struct type * 185 gnuv2_value_rtti_type (struct value *v, int *full, int *top, int *using_enc) 186 { 187 struct type *known_type; 188 struct type *rtti_type; 189 CORE_ADDR coreptr; 190 struct value *vp; 191 long top_offset = 0; 192 char rtti_type_name[256]; 193 CORE_ADDR vtbl; 194 struct minimal_symbol *minsym; 195 struct symbol *sym; 196 char *demangled_name, *p; 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 */ 231 btype = known_type_vptr_basetype; 232 CHECK_TYPEDEF (btype); 233 if (btype != known_type ) 234 { 235 v = value_cast (btype, v); 236 if (using_enc) 237 *using_enc=1; 238 } 239 /* 240 We can't use value_ind here, because it would want to use RTTI, and 241 we'd waste a bunch of time figuring out we already know the type. 242 Besides, we don't care about the type, just the actual pointer 243 */ 244 if (value_address (value_field (v, known_type_vptr_fieldno)) == 0) 245 return NULL; 246 247 vtbl = value_as_address (value_field (v, known_type_vptr_fieldno)); 248 249 /* Try to find a symbol that is the vtable */ 250 minsym=lookup_minimal_symbol_by_pc(vtbl); 251 if (minsym==NULL 252 || (demangled_name=SYMBOL_LINKAGE_NAME (minsym))==NULL 253 || !is_vtable_name (demangled_name)) 254 return NULL; 255 256 /* If we just skip the prefix, we get screwed by namespaces */ 257 demangled_name=cplus_demangle(demangled_name,DMGL_PARAMS|DMGL_ANSI); 258 p = strchr (demangled_name, ' '); 259 if (p) 260 *p = '\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. */ 297 298 static int 299 vb_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. */ 348 349 int 350 gnuv2_baseclass_offset (struct type *type, int index, 351 const bfd_byte *valaddr, 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 } 389 390 static void 391 init_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 } 404 405 extern initialize_file_ftype _initialize_gnu_v2_abi; /* -Wmissing-prototypes */ 406 407 void 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