1 /* Abstraction of GNU v2 abi. 2 3 Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008, 2009, 2010 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 32 #include <ctype.h> 33 34 struct cp_abi_ops gnu_v2_abi_ops; 35 36 static int vb_match (struct type *, int, struct type *); 37 38 static enum dtor_kinds 39 gnuv2_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 48 static enum ctor_kinds 49 gnuv2_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 59 static int 60 gnuv2_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 70 static int 71 gnuv2_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. */ 85 static struct value * 86 gnuv2_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 struct type *entry_type; 92 /* First, get the virtual function table pointer. That comes 93 with a strange type, so cast it to type `pointer to long' (which 94 should serve just fine as a function type). Then, index into 95 the table, and convert final value to appropriate function type. */ 96 struct value *entry; 97 struct value *vfn; 98 struct value *vtbl; 99 LONGEST vi = (LONGEST) TYPE_FN_FIELD_VOFFSET (f, j); 100 struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j); 101 struct type *context; 102 struct type *context_vptr_basetype; 103 int context_vptr_fieldno; 104 105 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)); 116 117 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 vtbl; 190 struct minimal_symbol *minsym; 191 char *demangled_name, *p; 192 struct type *btype; 193 struct type *known_type_vptr_basetype; 194 int known_type_vptr_fieldno; 195 196 if (full) 197 *full = 0; 198 if (top) 199 *top = -1; 200 if (using_enc) 201 *using_enc = 0; 202 203 /* Get declared type */ 204 known_type = value_type (v); 205 CHECK_TYPEDEF (known_type); 206 /* RTTI works only or class objects */ 207 if (TYPE_CODE (known_type) != TYPE_CODE_CLASS) 208 return NULL; 209 210 /* Plan on this changing in the future as i get around to setting 211 the vtables properly for G++ compiled stuff. Also, I'll be using 212 the type info functions, which are always right. Deal with it 213 until then. */ 214 215 /* Try to get the vptr basetype, fieldno. */ 216 known_type_vptr_fieldno = get_vptr_fieldno (known_type, 217 &known_type_vptr_basetype); 218 219 /* If we can't find it, give up. */ 220 if (known_type_vptr_fieldno < 0) 221 return NULL; 222 223 /* Make sure our basetype and known type match, otherwise, cast 224 so we can get at the vtable properly. 225 */ 226 btype = known_type_vptr_basetype; 227 CHECK_TYPEDEF (btype); 228 if (btype != known_type ) 229 { 230 v = value_cast (btype, v); 231 if (using_enc) 232 *using_enc=1; 233 } 234 /* 235 We can't use value_ind here, because it would want to use RTTI, and 236 we'd waste a bunch of time figuring out we already know the type. 237 Besides, we don't care about the type, just the actual pointer 238 */ 239 if (value_address (value_field (v, known_type_vptr_fieldno)) == 0) 240 return NULL; 241 242 vtbl = value_as_address (value_field (v, known_type_vptr_fieldno)); 243 244 /* Try to find a symbol that is the vtable */ 245 minsym=lookup_minimal_symbol_by_pc(vtbl); 246 if (minsym==NULL 247 || (demangled_name=SYMBOL_LINKAGE_NAME (minsym))==NULL 248 || !is_vtable_name (demangled_name)) 249 return NULL; 250 251 /* If we just skip the prefix, we get screwed by namespaces */ 252 demangled_name=cplus_demangle(demangled_name,DMGL_PARAMS|DMGL_ANSI); 253 p = strchr (demangled_name, ' '); 254 if (p) 255 *p = '\0'; 256 257 /* Lookup the type for the name */ 258 /* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */ 259 rtti_type = cp_lookup_rtti_type (demangled_name, NULL); 260 if (rtti_type == NULL) 261 return NULL; 262 263 if (TYPE_N_BASECLASSES(rtti_type) > 1 && full && (*full) != 1) 264 { 265 if (top) 266 *top=TYPE_BASECLASS_BITPOS(rtti_type,TYPE_VPTR_FIELDNO(rtti_type))/8; 267 if (top && ((*top) >0)) 268 { 269 if (TYPE_LENGTH(rtti_type) > TYPE_LENGTH(known_type)) 270 { 271 if (full) 272 *full=0; 273 } 274 else 275 { 276 if (full) 277 *full=1; 278 } 279 } 280 } 281 else 282 { 283 if (full) 284 *full=1; 285 } 286 287 return rtti_type; 288 } 289 290 /* Return true if the INDEXth field of TYPE is a virtual baseclass 291 pointer which is for the base class whose type is BASECLASS. */ 292 293 static int 294 vb_match (struct type *type, int index, struct type *basetype) 295 { 296 struct type *fieldtype; 297 char *name = TYPE_FIELD_NAME (type, index); 298 char *field_class_name = NULL; 299 300 if (*name != '_') 301 return 0; 302 /* gcc 2.4 uses _vb$. */ 303 if (name[1] == 'v' && name[2] == 'b' && is_cplus_marker (name[3])) 304 field_class_name = name + 4; 305 /* gcc 2.5 will use __vb_. */ 306 if (name[1] == '_' && name[2] == 'v' && name[3] == 'b' && name[4] == '_') 307 field_class_name = name + 5; 308 309 if (field_class_name == NULL) 310 /* This field is not a virtual base class pointer. */ 311 return 0; 312 313 /* It's a virtual baseclass pointer, now we just need to find out whether 314 it is for this baseclass. */ 315 fieldtype = TYPE_FIELD_TYPE (type, index); 316 if (fieldtype == NULL 317 || TYPE_CODE (fieldtype) != TYPE_CODE_PTR) 318 /* "Can't happen". */ 319 return 0; 320 321 /* What we check for is that either the types are equal (needed for 322 nameless types) or have the same name. This is ugly, and a more 323 elegant solution should be devised (which would probably just push 324 the ugliness into symbol reading unless we change the stabs format). */ 325 if (TYPE_TARGET_TYPE (fieldtype) == basetype) 326 return 1; 327 328 if (TYPE_NAME (basetype) != NULL 329 && TYPE_NAME (TYPE_TARGET_TYPE (fieldtype)) != NULL 330 && strcmp (TYPE_NAME (basetype), 331 TYPE_NAME (TYPE_TARGET_TYPE (fieldtype))) == 0) 332 return 1; 333 return 0; 334 } 335 336 /* Compute the offset of the baseclass which is 337 the INDEXth baseclass of class TYPE, 338 for value at VALADDR (in host) at ADDRESS (in target). 339 The result is the offset of the baseclass value relative 340 to (the address of)(ARG) + OFFSET. 341 342 -1 is returned on error. */ 343 344 static int 345 gnuv2_baseclass_offset (struct type *type, int index, 346 const bfd_byte *valaddr, CORE_ADDR address) 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 CORE_ADDR addr 363 = unpack_pointer (TYPE_FIELD_TYPE (type, i), 364 valaddr + (TYPE_FIELD_BITPOS (type, i) / 8)); 365 366 return addr - (LONGEST) address; 367 } 368 } 369 /* Not in the fields, so try looking through the baseclasses. */ 370 for (i = index + 1; i < n_baseclasses; i++) 371 { 372 int boffset = 373 baseclass_offset (type, i, valaddr, address); 374 375 if (boffset) 376 return boffset; 377 } 378 /* Not found. */ 379 return -1; 380 } 381 382 /* Baseclass is easily computed. */ 383 return TYPE_BASECLASS_BITPOS (type, index) / 8; 384 } 385 386 static void 387 init_gnuv2_ops (void) 388 { 389 gnu_v2_abi_ops.shortname = "gnu-v2"; 390 gnu_v2_abi_ops.longname = "GNU G++ Version 2 ABI"; 391 gnu_v2_abi_ops.doc = "G++ Version 2 ABI"; 392 gnu_v2_abi_ops.is_destructor_name = gnuv2_is_destructor_name; 393 gnu_v2_abi_ops.is_constructor_name = gnuv2_is_constructor_name; 394 gnu_v2_abi_ops.is_vtable_name = gnuv2_is_vtable_name; 395 gnu_v2_abi_ops.is_operator_name = gnuv2_is_operator_name; 396 gnu_v2_abi_ops.virtual_fn_field = gnuv2_virtual_fn_field; 397 gnu_v2_abi_ops.rtti_type = gnuv2_value_rtti_type; 398 gnu_v2_abi_ops.baseclass_offset = gnuv2_baseclass_offset; 399 } 400 401 extern initialize_file_ftype _initialize_gnu_v2_abi; /* -Wmissing-prototypes */ 402 403 void 404 _initialize_gnu_v2_abi (void) 405 { 406 init_gnuv2_ops (); 407 register_cp_abi (&gnu_v2_abi_ops); 408 set_cp_abi_as_auto_default (gnu_v2_abi_ops.shortname); 409 } 410