| 1 | /* Abstraction of GNU v2 abi. |
| 2 | |
| 3 | Copyright (C) 2001-2020 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 "symtab.h" |
| 24 | #include "gdbtypes.h" |
| 25 | #include "value.h" |
| 26 | #include "demangle.h" |
| 27 | #include "gdb-demangle.h" |
| 28 | #include "cp-abi.h" |
| 29 | #include "cp-support.h" |
| 30 | #include <ctype.h> |
| 31 | |
| 32 | struct cp_abi_ops gnu_v2_abi_ops; |
| 33 | |
| 34 | static int vb_match (struct type *, int, struct type *); |
| 35 | |
| 36 | static enum dtor_kinds |
| 37 | gnuv2_is_destructor_name (const char *name) |
| 38 | { |
| 39 | if ((name[0] == '_' && is_cplus_marker (name[1]) && name[2] == '_') |
| 40 | || startswith (name, "__dt__")) |
| 41 | return complete_object_dtor; |
| 42 | else |
| 43 | return (enum dtor_kinds) 0; |
| 44 | } |
| 45 | |
| 46 | static enum ctor_kinds |
| 47 | gnuv2_is_constructor_name (const char *name) |
| 48 | { |
| 49 | if ((name[0] == '_' && name[1] == '_' |
| 50 | && (isdigit (name[2]) || strchr ("Qt", name[2]))) |
| 51 | || startswith (name, "__ct__")) |
| 52 | return complete_object_ctor; |
| 53 | else |
| 54 | return (enum ctor_kinds) 0; |
| 55 | } |
| 56 | |
| 57 | static int |
| 58 | gnuv2_is_vtable_name (const char *name) |
| 59 | { |
| 60 | return (((name)[0] == '_' |
| 61 | && (((name)[1] == 'V' && (name)[2] == 'T') |
| 62 | || ((name)[1] == 'v' && (name)[2] == 't')) |
| 63 | && is_cplus_marker ((name)[3])) || |
| 64 | ((name)[0] == '_' && (name)[1] == '_' |
| 65 | && (name)[2] == 'v' && (name)[3] == 't' && (name)[4] == '_')); |
| 66 | } |
| 67 | |
| 68 | static int |
| 69 | gnuv2_is_operator_name (const char *name) |
| 70 | { |
| 71 | return startswith (name, CP_OPERATOR_STR); |
| 72 | } |
| 73 | |
| 74 | \f |
| 75 | /* Return a virtual function as a value. |
| 76 | ARG1 is the object which provides the virtual function |
| 77 | table pointer. *ARG1P is side-effected in calling this function. |
| 78 | F is the list of member functions which contains the desired virtual |
| 79 | function. |
| 80 | J is an index into F which provides the desired virtual function. |
| 81 | |
| 82 | TYPE is the type in which F is located. */ |
| 83 | static struct value * |
| 84 | gnuv2_virtual_fn_field (struct value **arg1p, struct fn_field * f, int j, |
| 85 | struct type * type, int offset) |
| 86 | { |
| 87 | struct value *arg1 = *arg1p; |
| 88 | struct type *type1 = check_typedef (value_type (arg1)); |
| 89 | struct type *entry_type; |
| 90 | /* First, get the virtual function table pointer. That comes |
| 91 | with a strange type, so cast it to type `pointer to long' (which |
| 92 | should serve just fine as a function type). Then, index into |
| 93 | the table, and convert final value to appropriate function type. */ |
| 94 | struct value *entry; |
| 95 | struct value *vfn; |
| 96 | struct value *vtbl; |
| 97 | LONGEST vi = (LONGEST) TYPE_FN_FIELD_VOFFSET (f, j); |
| 98 | struct type *fcontext = TYPE_FN_FIELD_FCONTEXT (f, j); |
| 99 | struct type *context; |
| 100 | struct type *context_vptr_basetype; |
| 101 | int context_vptr_fieldno; |
| 102 | |
| 103 | if (fcontext == NULL) |
| 104 | /* We don't have an fcontext (e.g. the program was compiled with |
| 105 | g++ version 1). Try to get the vtbl from the TYPE_VPTR_BASETYPE. |
| 106 | This won't work right for multiple inheritance, but at least we |
| 107 | should do as well as GDB 3.x did. */ |
| 108 | fcontext = TYPE_VPTR_BASETYPE (type); |
| 109 | context = lookup_pointer_type (fcontext); |
| 110 | /* Now context is a pointer to the basetype containing the vtbl. */ |
| 111 | if (TYPE_TARGET_TYPE (context) != type1) |
| 112 | { |
| 113 | struct value *tmp = value_cast (context, value_addr (arg1)); |
| 114 | |
| 115 | arg1 = value_ind (tmp); |
| 116 | type1 = check_typedef (value_type (arg1)); |
| 117 | } |
| 118 | |
| 119 | context = type1; |
| 120 | /* Now context is the basetype containing the vtbl. */ |
| 121 | |
| 122 | /* This type may have been defined before its virtual function table |
| 123 | was. If so, fill in the virtual function table entry for the |
| 124 | type now. */ |
| 125 | context_vptr_fieldno = get_vptr_fieldno (context, &context_vptr_basetype); |
| 126 | /* FIXME: What to do if vptr_fieldno is still -1? */ |
| 127 | |
| 128 | /* The virtual function table is now an array of structures |
| 129 | which have the form { int16 offset, delta; void *pfn; }. */ |
| 130 | vtbl = value_primitive_field (arg1, 0, context_vptr_fieldno, |
| 131 | context_vptr_basetype); |
| 132 | |
| 133 | /* With older versions of g++, the vtbl field pointed to an array |
| 134 | of structures. Nowadays it points directly to the structure. */ |
| 135 | if (TYPE_CODE (value_type (vtbl)) == TYPE_CODE_PTR |
| 136 | && TYPE_CODE (TYPE_TARGET_TYPE (value_type (vtbl))) == TYPE_CODE_ARRAY) |
| 137 | { |
| 138 | /* Handle the case where the vtbl field points to an |
| 139 | array of structures. */ |
| 140 | vtbl = value_ind (vtbl); |
| 141 | |
| 142 | /* Index into the virtual function table. This is hard-coded because |
| 143 | looking up a field is not cheap, and it may be important to save |
| 144 | time, e.g. if the user has set a conditional breakpoint calling |
| 145 | a virtual function. */ |
| 146 | entry = value_subscript (vtbl, vi); |
| 147 | } |
| 148 | else |
| 149 | { |
| 150 | /* Handle the case where the vtbl field points directly to a |
| 151 | structure. */ |
| 152 | vtbl = value_ptradd (vtbl, vi); |
| 153 | entry = value_ind (vtbl); |
| 154 | } |
| 155 | |
| 156 | entry_type = check_typedef (value_type (entry)); |
| 157 | |
| 158 | if (TYPE_CODE (entry_type) == TYPE_CODE_STRUCT) |
| 159 | { |
| 160 | /* Move the `this' pointer according to the virtual function table. */ |
| 161 | set_value_offset (arg1, value_offset (arg1) |
| 162 | + 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, |
| 178 | lookup_pointer_type (TYPE_FN_FIELD_TYPE (f, j))); |
| 179 | |
| 180 | *arg1p = arg1; |
| 181 | return vfn; |
| 182 | } |
| 183 | |
| 184 | |
| 185 | static struct type * |
| 186 | gnuv2_value_rtti_type (struct value *v, int *full, LONGEST *top, int *using_enc) |
| 187 | { |
| 188 | struct type *known_type; |
| 189 | struct type *rtti_type; |
| 190 | CORE_ADDR vtbl; |
| 191 | struct bound_minimal_symbol minsym; |
| 192 | char *demangled_name, *p; |
| 193 | const char *linkage_name; |
| 194 | struct type *btype; |
| 195 | struct type *known_type_vptr_basetype; |
| 196 | int known_type_vptr_fieldno; |
| 197 | |
| 198 | if (full) |
| 199 | *full = 0; |
| 200 | if (top) |
| 201 | *top = -1; |
| 202 | if (using_enc) |
| 203 | *using_enc = 0; |
| 204 | |
| 205 | /* Get declared type. */ |
| 206 | known_type = value_type (v); |
| 207 | known_type = check_typedef (known_type); |
| 208 | /* RTTI works only or class objects. */ |
| 209 | if (TYPE_CODE (known_type) != TYPE_CODE_STRUCT) |
| 210 | return NULL; |
| 211 | |
| 212 | /* Plan on this changing in the future as i get around to setting |
| 213 | the vtables properly for G++ compiled stuff. Also, I'll be using |
| 214 | the type info functions, which are always right. Deal with it |
| 215 | until then. */ |
| 216 | |
| 217 | /* Try to get the vptr basetype, fieldno. */ |
| 218 | known_type_vptr_fieldno = get_vptr_fieldno (known_type, |
| 219 | &known_type_vptr_basetype); |
| 220 | |
| 221 | /* If we can't find it, give up. */ |
| 222 | if (known_type_vptr_fieldno < 0) |
| 223 | return NULL; |
| 224 | |
| 225 | /* Make sure our basetype and known type match, otherwise, cast |
| 226 | so we can get at the vtable properly. */ |
| 227 | btype = known_type_vptr_basetype; |
| 228 | btype = check_typedef (btype); |
| 229 | if (btype != known_type ) |
| 230 | { |
| 231 | v = value_cast (btype, v); |
| 232 | if (using_enc) |
| 233 | *using_enc=1; |
| 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 | if (value_address (value_field (v, known_type_vptr_fieldno)) == 0) |
| 239 | return NULL; |
| 240 | |
| 241 | vtbl = value_as_address (value_field (v, known_type_vptr_fieldno)); |
| 242 | |
| 243 | /* Try to find a symbol that is the vtable. */ |
| 244 | minsym=lookup_minimal_symbol_by_pc(vtbl); |
| 245 | if (minsym.minsym==NULL |
| 246 | || (linkage_name=minsym.minsym->linkage_name ())==NULL |
| 247 | || !is_vtable_name (linkage_name)) |
| 248 | return NULL; |
| 249 | |
| 250 | /* If we just skip the prefix, we get screwed by namespaces. */ |
| 251 | demangled_name=gdb_demangle(linkage_name,DMGL_PARAMS|DMGL_ANSI); |
| 252 | p = strchr (demangled_name, ' '); |
| 253 | if (p) |
| 254 | *p = '\0'; |
| 255 | |
| 256 | /* Lookup the type for the name. */ |
| 257 | /* FIXME: chastain/2003-11-26: block=NULL is bogus. See pr gdb/1465. */ |
| 258 | rtti_type = cp_lookup_rtti_type (demangled_name, NULL); |
| 259 | if (rtti_type == NULL) |
| 260 | return NULL; |
| 261 | |
| 262 | if (TYPE_N_BASECLASSES(rtti_type) > 1 && full && (*full) != 1) |
| 263 | { |
| 264 | if (top) |
| 265 | *top = TYPE_BASECLASS_BITPOS (rtti_type, |
| 266 | 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 | const char *name = TYPE_FIELD_NAME (type, index); |
| 298 | const 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 the INDEXth baseclass |
| 337 | of class TYPE, for value at VALADDR (in host) at ADDRESS (in |
| 338 | target). The result is the offset of the baseclass value relative |
| 339 | to (the address of)(ARG) + OFFSET. */ |
| 340 | |
| 341 | static int |
| 342 | gnuv2_baseclass_offset (struct type *type, int index, |
| 343 | const bfd_byte *valaddr, LONGEST embedded_offset, |
| 344 | CORE_ADDR address, const struct value *val) |
| 345 | { |
| 346 | struct type *basetype = TYPE_BASECLASS (type, index); |
| 347 | |
| 348 | if (BASETYPE_VIA_VIRTUAL (type, index)) |
| 349 | { |
| 350 | /* Must hunt for the pointer to this virtual baseclass. */ |
| 351 | int i, len = TYPE_NFIELDS (type); |
| 352 | int n_baseclasses = TYPE_N_BASECLASSES (type); |
| 353 | |
| 354 | /* First look for the virtual baseclass pointer |
| 355 | in the fields. */ |
| 356 | for (i = n_baseclasses; i < len; i++) |
| 357 | { |
| 358 | if (vb_match (type, i, basetype)) |
| 359 | { |
| 360 | struct type *field_type; |
| 361 | LONGEST field_offset; |
| 362 | int field_length; |
| 363 | CORE_ADDR addr; |
| 364 | |
| 365 | field_type = check_typedef (TYPE_FIELD_TYPE (type, i)); |
| 366 | field_offset = TYPE_FIELD_BITPOS (type, i) / 8; |
| 367 | field_length = TYPE_LENGTH (field_type); |
| 368 | |
| 369 | if (!value_bytes_available (val, embedded_offset + field_offset, |
| 370 | field_length)) |
| 371 | throw_error (NOT_AVAILABLE_ERROR, |
| 372 | _("Virtual baseclass pointer is not available")); |
| 373 | |
| 374 | addr = unpack_pointer (field_type, |
| 375 | valaddr + embedded_offset + field_offset); |
| 376 | |
| 377 | return addr - (LONGEST) address + embedded_offset; |
| 378 | } |
| 379 | } |
| 380 | /* Not in the fields, so try looking through the baseclasses. */ |
| 381 | for (i = index + 1; i < n_baseclasses; i++) |
| 382 | { |
| 383 | /* Don't go through baseclass_offset, as that wraps |
| 384 | exceptions, thus, inner exceptions would be wrapped more |
| 385 | than once. */ |
| 386 | int boffset = |
| 387 | gnuv2_baseclass_offset (type, i, valaddr, |
| 388 | embedded_offset, address, val); |
| 389 | |
| 390 | if (boffset) |
| 391 | return boffset; |
| 392 | } |
| 393 | |
| 394 | error (_("Baseclass offset not found")); |
| 395 | } |
| 396 | |
| 397 | /* Baseclass is easily computed. */ |
| 398 | return TYPE_BASECLASS_BITPOS (type, index) / 8; |
| 399 | } |
| 400 | |
| 401 | static void |
| 402 | init_gnuv2_ops (void) |
| 403 | { |
| 404 | gnu_v2_abi_ops.shortname = "gnu-v2"; |
| 405 | gnu_v2_abi_ops.longname = "GNU G++ Version 2 ABI"; |
| 406 | gnu_v2_abi_ops.doc = "G++ Version 2 ABI"; |
| 407 | gnu_v2_abi_ops.is_destructor_name = gnuv2_is_destructor_name; |
| 408 | gnu_v2_abi_ops.is_constructor_name = gnuv2_is_constructor_name; |
| 409 | gnu_v2_abi_ops.is_vtable_name = gnuv2_is_vtable_name; |
| 410 | gnu_v2_abi_ops.is_operator_name = gnuv2_is_operator_name; |
| 411 | gnu_v2_abi_ops.virtual_fn_field = gnuv2_virtual_fn_field; |
| 412 | gnu_v2_abi_ops.rtti_type = gnuv2_value_rtti_type; |
| 413 | gnu_v2_abi_ops.baseclass_offset = gnuv2_baseclass_offset; |
| 414 | } |
| 415 | |
| 416 | void |
| 417 | _initialize_gnu_v2_abi (void) |
| 418 | { |
| 419 | init_gnuv2_ops (); |
| 420 | register_cp_abi (&gnu_v2_abi_ops); |
| 421 | } |