| 1 | /* Find a variable's value in memory, for GDB, the GNU debugger. |
| 2 | |
| 3 | Copyright (C) 1986-2016 Free Software Foundation, Inc. |
| 4 | |
| 5 | This file is part of GDB. |
| 6 | |
| 7 | This program is free software; you can redistribute it and/or modify |
| 8 | it under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 3 of the License, or |
| 10 | (at your option) any later version. |
| 11 | |
| 12 | This program is distributed in the hope that it will be useful, |
| 13 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | GNU General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 19 | |
| 20 | #include "defs.h" |
| 21 | #include "symtab.h" |
| 22 | #include "gdbtypes.h" |
| 23 | #include "frame.h" |
| 24 | #include "value.h" |
| 25 | #include "gdbcore.h" |
| 26 | #include "inferior.h" |
| 27 | #include "target.h" |
| 28 | #include "floatformat.h" |
| 29 | #include "symfile.h" /* for overlay functions */ |
| 30 | #include "regcache.h" |
| 31 | #include "user-regs.h" |
| 32 | #include "block.h" |
| 33 | #include "objfiles.h" |
| 34 | #include "language.h" |
| 35 | #include "dwarf2loc.h" |
| 36 | |
| 37 | /* Basic byte-swapping routines. All 'extract' functions return a |
| 38 | host-format integer from a target-format integer at ADDR which is |
| 39 | LEN bytes long. */ |
| 40 | |
| 41 | #if TARGET_CHAR_BIT != 8 || HOST_CHAR_BIT != 8 |
| 42 | /* 8 bit characters are a pretty safe assumption these days, so we |
| 43 | assume it throughout all these swapping routines. If we had to deal with |
| 44 | 9 bit characters, we would need to make len be in bits and would have |
| 45 | to re-write these routines... */ |
| 46 | you lose |
| 47 | #endif |
| 48 | |
| 49 | LONGEST |
| 50 | extract_signed_integer (const gdb_byte *addr, int len, |
| 51 | enum bfd_endian byte_order) |
| 52 | { |
| 53 | LONGEST retval; |
| 54 | const unsigned char *p; |
| 55 | const unsigned char *startaddr = addr; |
| 56 | const unsigned char *endaddr = startaddr + len; |
| 57 | |
| 58 | if (len > (int) sizeof (LONGEST)) |
| 59 | error (_("\ |
| 60 | That operation is not available on integers of more than %d bytes."), |
| 61 | (int) sizeof (LONGEST)); |
| 62 | |
| 63 | /* Start at the most significant end of the integer, and work towards |
| 64 | the least significant. */ |
| 65 | if (byte_order == BFD_ENDIAN_BIG) |
| 66 | { |
| 67 | p = startaddr; |
| 68 | /* Do the sign extension once at the start. */ |
| 69 | retval = ((LONGEST) * p ^ 0x80) - 0x80; |
| 70 | for (++p; p < endaddr; ++p) |
| 71 | retval = (retval << 8) | *p; |
| 72 | } |
| 73 | else |
| 74 | { |
| 75 | p = endaddr - 1; |
| 76 | /* Do the sign extension once at the start. */ |
| 77 | retval = ((LONGEST) * p ^ 0x80) - 0x80; |
| 78 | for (--p; p >= startaddr; --p) |
| 79 | retval = (retval << 8) | *p; |
| 80 | } |
| 81 | return retval; |
| 82 | } |
| 83 | |
| 84 | ULONGEST |
| 85 | extract_unsigned_integer (const gdb_byte *addr, int len, |
| 86 | enum bfd_endian byte_order) |
| 87 | { |
| 88 | ULONGEST retval; |
| 89 | const unsigned char *p; |
| 90 | const unsigned char *startaddr = addr; |
| 91 | const unsigned char *endaddr = startaddr + len; |
| 92 | |
| 93 | if (len > (int) sizeof (ULONGEST)) |
| 94 | error (_("\ |
| 95 | That operation is not available on integers of more than %d bytes."), |
| 96 | (int) sizeof (ULONGEST)); |
| 97 | |
| 98 | /* Start at the most significant end of the integer, and work towards |
| 99 | the least significant. */ |
| 100 | retval = 0; |
| 101 | if (byte_order == BFD_ENDIAN_BIG) |
| 102 | { |
| 103 | for (p = startaddr; p < endaddr; ++p) |
| 104 | retval = (retval << 8) | *p; |
| 105 | } |
| 106 | else |
| 107 | { |
| 108 | for (p = endaddr - 1; p >= startaddr; --p) |
| 109 | retval = (retval << 8) | *p; |
| 110 | } |
| 111 | return retval; |
| 112 | } |
| 113 | |
| 114 | /* Sometimes a long long unsigned integer can be extracted as a |
| 115 | LONGEST value. This is done so that we can print these values |
| 116 | better. If this integer can be converted to a LONGEST, this |
| 117 | function returns 1 and sets *PVAL. Otherwise it returns 0. */ |
| 118 | |
| 119 | int |
| 120 | extract_long_unsigned_integer (const gdb_byte *addr, int orig_len, |
| 121 | enum bfd_endian byte_order, LONGEST *pval) |
| 122 | { |
| 123 | const gdb_byte *p; |
| 124 | const gdb_byte *first_addr; |
| 125 | int len; |
| 126 | |
| 127 | len = orig_len; |
| 128 | if (byte_order == BFD_ENDIAN_BIG) |
| 129 | { |
| 130 | for (p = addr; |
| 131 | len > (int) sizeof (LONGEST) && p < addr + orig_len; |
| 132 | p++) |
| 133 | { |
| 134 | if (*p == 0) |
| 135 | len--; |
| 136 | else |
| 137 | break; |
| 138 | } |
| 139 | first_addr = p; |
| 140 | } |
| 141 | else |
| 142 | { |
| 143 | first_addr = addr; |
| 144 | for (p = addr + orig_len - 1; |
| 145 | len > (int) sizeof (LONGEST) && p >= addr; |
| 146 | p--) |
| 147 | { |
| 148 | if (*p == 0) |
| 149 | len--; |
| 150 | else |
| 151 | break; |
| 152 | } |
| 153 | } |
| 154 | |
| 155 | if (len <= (int) sizeof (LONGEST)) |
| 156 | { |
| 157 | *pval = (LONGEST) extract_unsigned_integer (first_addr, |
| 158 | sizeof (LONGEST), |
| 159 | byte_order); |
| 160 | return 1; |
| 161 | } |
| 162 | |
| 163 | return 0; |
| 164 | } |
| 165 | |
| 166 | |
| 167 | /* Treat the bytes at BUF as a pointer of type TYPE, and return the |
| 168 | address it represents. */ |
| 169 | CORE_ADDR |
| 170 | extract_typed_address (const gdb_byte *buf, struct type *type) |
| 171 | { |
| 172 | if (TYPE_CODE (type) != TYPE_CODE_PTR |
| 173 | && TYPE_CODE (type) != TYPE_CODE_REF) |
| 174 | internal_error (__FILE__, __LINE__, |
| 175 | _("extract_typed_address: " |
| 176 | "type is not a pointer or reference")); |
| 177 | |
| 178 | return gdbarch_pointer_to_address (get_type_arch (type), type, buf); |
| 179 | } |
| 180 | |
| 181 | /* All 'store' functions accept a host-format integer and store a |
| 182 | target-format integer at ADDR which is LEN bytes long. */ |
| 183 | |
| 184 | void |
| 185 | store_signed_integer (gdb_byte *addr, int len, |
| 186 | enum bfd_endian byte_order, LONGEST val) |
| 187 | { |
| 188 | gdb_byte *p; |
| 189 | gdb_byte *startaddr = addr; |
| 190 | gdb_byte *endaddr = startaddr + len; |
| 191 | |
| 192 | /* Start at the least significant end of the integer, and work towards |
| 193 | the most significant. */ |
| 194 | if (byte_order == BFD_ENDIAN_BIG) |
| 195 | { |
| 196 | for (p = endaddr - 1; p >= startaddr; --p) |
| 197 | { |
| 198 | *p = val & 0xff; |
| 199 | val >>= 8; |
| 200 | } |
| 201 | } |
| 202 | else |
| 203 | { |
| 204 | for (p = startaddr; p < endaddr; ++p) |
| 205 | { |
| 206 | *p = val & 0xff; |
| 207 | val >>= 8; |
| 208 | } |
| 209 | } |
| 210 | } |
| 211 | |
| 212 | void |
| 213 | store_unsigned_integer (gdb_byte *addr, int len, |
| 214 | enum bfd_endian byte_order, ULONGEST val) |
| 215 | { |
| 216 | unsigned char *p; |
| 217 | unsigned char *startaddr = (unsigned char *) addr; |
| 218 | unsigned char *endaddr = startaddr + len; |
| 219 | |
| 220 | /* Start at the least significant end of the integer, and work towards |
| 221 | the most significant. */ |
| 222 | if (byte_order == BFD_ENDIAN_BIG) |
| 223 | { |
| 224 | for (p = endaddr - 1; p >= startaddr; --p) |
| 225 | { |
| 226 | *p = val & 0xff; |
| 227 | val >>= 8; |
| 228 | } |
| 229 | } |
| 230 | else |
| 231 | { |
| 232 | for (p = startaddr; p < endaddr; ++p) |
| 233 | { |
| 234 | *p = val & 0xff; |
| 235 | val >>= 8; |
| 236 | } |
| 237 | } |
| 238 | } |
| 239 | |
| 240 | /* Store the address ADDR as a pointer of type TYPE at BUF, in target |
| 241 | form. */ |
| 242 | void |
| 243 | store_typed_address (gdb_byte *buf, struct type *type, CORE_ADDR addr) |
| 244 | { |
| 245 | if (TYPE_CODE (type) != TYPE_CODE_PTR |
| 246 | && TYPE_CODE (type) != TYPE_CODE_REF) |
| 247 | internal_error (__FILE__, __LINE__, |
| 248 | _("store_typed_address: " |
| 249 | "type is not a pointer or reference")); |
| 250 | |
| 251 | gdbarch_address_to_pointer (get_type_arch (type), type, buf, addr); |
| 252 | } |
| 253 | |
| 254 | |
| 255 | |
| 256 | /* Return a `value' with the contents of (virtual or cooked) register |
| 257 | REGNUM as found in the specified FRAME. The register's type is |
| 258 | determined by register_type(). */ |
| 259 | |
| 260 | struct value * |
| 261 | value_of_register (int regnum, struct frame_info *frame) |
| 262 | { |
| 263 | struct gdbarch *gdbarch = get_frame_arch (frame); |
| 264 | struct value *reg_val; |
| 265 | |
| 266 | /* User registers lie completely outside of the range of normal |
| 267 | registers. Catch them early so that the target never sees them. */ |
| 268 | if (regnum >= gdbarch_num_regs (gdbarch) |
| 269 | + gdbarch_num_pseudo_regs (gdbarch)) |
| 270 | return value_of_user_reg (regnum, frame); |
| 271 | |
| 272 | reg_val = value_of_register_lazy (frame, regnum); |
| 273 | value_fetch_lazy (reg_val); |
| 274 | return reg_val; |
| 275 | } |
| 276 | |
| 277 | /* Return a `value' with the contents of (virtual or cooked) register |
| 278 | REGNUM as found in the specified FRAME. The register's type is |
| 279 | determined by register_type(). The value is not fetched. */ |
| 280 | |
| 281 | struct value * |
| 282 | value_of_register_lazy (struct frame_info *frame, int regnum) |
| 283 | { |
| 284 | struct gdbarch *gdbarch = get_frame_arch (frame); |
| 285 | struct value *reg_val; |
| 286 | |
| 287 | gdb_assert (regnum < (gdbarch_num_regs (gdbarch) |
| 288 | + gdbarch_num_pseudo_regs (gdbarch))); |
| 289 | |
| 290 | /* We should have a valid (i.e. non-sentinel) frame. */ |
| 291 | gdb_assert (frame_id_p (get_frame_id (frame))); |
| 292 | |
| 293 | reg_val = allocate_value_lazy (register_type (gdbarch, regnum)); |
| 294 | VALUE_LVAL (reg_val) = lval_register; |
| 295 | VALUE_REGNUM (reg_val) = regnum; |
| 296 | VALUE_FRAME_ID (reg_val) = get_frame_id (frame); |
| 297 | return reg_val; |
| 298 | } |
| 299 | |
| 300 | /* Given a pointer of type TYPE in target form in BUF, return the |
| 301 | address it represents. */ |
| 302 | CORE_ADDR |
| 303 | unsigned_pointer_to_address (struct gdbarch *gdbarch, |
| 304 | struct type *type, const gdb_byte *buf) |
| 305 | { |
| 306 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 307 | |
| 308 | return extract_unsigned_integer (buf, TYPE_LENGTH (type), byte_order); |
| 309 | } |
| 310 | |
| 311 | CORE_ADDR |
| 312 | signed_pointer_to_address (struct gdbarch *gdbarch, |
| 313 | struct type *type, const gdb_byte *buf) |
| 314 | { |
| 315 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 316 | |
| 317 | return extract_signed_integer (buf, TYPE_LENGTH (type), byte_order); |
| 318 | } |
| 319 | |
| 320 | /* Given an address, store it as a pointer of type TYPE in target |
| 321 | format in BUF. */ |
| 322 | void |
| 323 | unsigned_address_to_pointer (struct gdbarch *gdbarch, struct type *type, |
| 324 | gdb_byte *buf, CORE_ADDR addr) |
| 325 | { |
| 326 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 327 | |
| 328 | store_unsigned_integer (buf, TYPE_LENGTH (type), byte_order, addr); |
| 329 | } |
| 330 | |
| 331 | void |
| 332 | address_to_signed_pointer (struct gdbarch *gdbarch, struct type *type, |
| 333 | gdb_byte *buf, CORE_ADDR addr) |
| 334 | { |
| 335 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 336 | |
| 337 | store_signed_integer (buf, TYPE_LENGTH (type), byte_order, addr); |
| 338 | } |
| 339 | \f |
| 340 | /* Will calling read_var_value or locate_var_value on SYM end |
| 341 | up caring what frame it is being evaluated relative to? SYM must |
| 342 | be non-NULL. */ |
| 343 | int |
| 344 | symbol_read_needs_frame (struct symbol *sym) |
| 345 | { |
| 346 | if (SYMBOL_COMPUTED_OPS (sym) != NULL) |
| 347 | return SYMBOL_COMPUTED_OPS (sym)->read_needs_frame (sym); |
| 348 | |
| 349 | switch (SYMBOL_CLASS (sym)) |
| 350 | { |
| 351 | /* All cases listed explicitly so that gcc -Wall will detect it if |
| 352 | we failed to consider one. */ |
| 353 | case LOC_COMPUTED: |
| 354 | gdb_assert_not_reached (_("LOC_COMPUTED variable missing a method")); |
| 355 | |
| 356 | case LOC_REGISTER: |
| 357 | case LOC_ARG: |
| 358 | case LOC_REF_ARG: |
| 359 | case LOC_REGPARM_ADDR: |
| 360 | case LOC_LOCAL: |
| 361 | return 1; |
| 362 | |
| 363 | case LOC_UNDEF: |
| 364 | case LOC_CONST: |
| 365 | case LOC_STATIC: |
| 366 | case LOC_TYPEDEF: |
| 367 | |
| 368 | case LOC_LABEL: |
| 369 | /* Getting the address of a label can be done independently of the block, |
| 370 | even if some *uses* of that address wouldn't work so well without |
| 371 | the right frame. */ |
| 372 | |
| 373 | case LOC_BLOCK: |
| 374 | case LOC_CONST_BYTES: |
| 375 | case LOC_UNRESOLVED: |
| 376 | case LOC_OPTIMIZED_OUT: |
| 377 | return 0; |
| 378 | } |
| 379 | return 1; |
| 380 | } |
| 381 | |
| 382 | /* Private data to be used with minsym_lookup_iterator_cb. */ |
| 383 | |
| 384 | struct minsym_lookup_data |
| 385 | { |
| 386 | /* The name of the minimal symbol we are searching for. */ |
| 387 | const char *name; |
| 388 | |
| 389 | /* The field where the callback should store the minimal symbol |
| 390 | if found. It should be initialized to NULL before the search |
| 391 | is started. */ |
| 392 | struct bound_minimal_symbol result; |
| 393 | }; |
| 394 | |
| 395 | /* A callback function for gdbarch_iterate_over_objfiles_in_search_order. |
| 396 | It searches by name for a minimal symbol within the given OBJFILE. |
| 397 | The arguments are passed via CB_DATA, which in reality is a pointer |
| 398 | to struct minsym_lookup_data. */ |
| 399 | |
| 400 | static int |
| 401 | minsym_lookup_iterator_cb (struct objfile *objfile, void *cb_data) |
| 402 | { |
| 403 | struct minsym_lookup_data *data = (struct minsym_lookup_data *) cb_data; |
| 404 | |
| 405 | gdb_assert (data->result.minsym == NULL); |
| 406 | |
| 407 | data->result = lookup_minimal_symbol (data->name, NULL, objfile); |
| 408 | |
| 409 | /* The iterator should stop iff a match was found. */ |
| 410 | return (data->result.minsym != NULL); |
| 411 | } |
| 412 | |
| 413 | /* Given static link expression and the frame it lives in, look for the frame |
| 414 | the static links points to and return it. Return NULL if we could not find |
| 415 | such a frame. */ |
| 416 | |
| 417 | static struct frame_info * |
| 418 | follow_static_link (struct frame_info *frame, |
| 419 | const struct dynamic_prop *static_link) |
| 420 | { |
| 421 | CORE_ADDR upper_frame_base; |
| 422 | |
| 423 | if (!dwarf2_evaluate_property (static_link, frame, NULL, &upper_frame_base)) |
| 424 | return NULL; |
| 425 | |
| 426 | /* Now climb up the stack frame until we reach the frame we are interested |
| 427 | in. */ |
| 428 | for (; frame != NULL; frame = get_prev_frame (frame)) |
| 429 | { |
| 430 | struct symbol *framefunc = get_frame_function (frame); |
| 431 | |
| 432 | /* Stacks can be quite deep: give the user a chance to stop this. */ |
| 433 | QUIT; |
| 434 | |
| 435 | /* If we don't know how to compute FRAME's base address, don't give up: |
| 436 | maybe the frame we are looking for is upper in the stace frame. */ |
| 437 | if (framefunc != NULL |
| 438 | && SYMBOL_BLOCK_OPS (framefunc)->get_frame_base != NULL |
| 439 | && (SYMBOL_BLOCK_OPS (framefunc)->get_frame_base (framefunc, frame) |
| 440 | == upper_frame_base)) |
| 441 | break; |
| 442 | } |
| 443 | |
| 444 | return frame; |
| 445 | } |
| 446 | |
| 447 | /* Assuming VAR is a symbol that can be reached from FRAME thanks to lexical |
| 448 | rules, look for the frame that is actually hosting VAR and return it. If, |
| 449 | for some reason, we found no such frame, return NULL. |
| 450 | |
| 451 | This kind of computation is necessary to correctly handle lexically nested |
| 452 | functions. |
| 453 | |
| 454 | Note that in some cases, we know what scope VAR comes from but we cannot |
| 455 | reach the specific frame that hosts the instance of VAR we are looking for. |
| 456 | For backward compatibility purposes (with old compilers), we then look for |
| 457 | the first frame that can host it. */ |
| 458 | |
| 459 | static struct frame_info * |
| 460 | get_hosting_frame (struct symbol *var, const struct block *var_block, |
| 461 | struct frame_info *frame) |
| 462 | { |
| 463 | const struct block *frame_block = NULL; |
| 464 | |
| 465 | if (!symbol_read_needs_frame (var)) |
| 466 | return NULL; |
| 467 | |
| 468 | /* Some symbols for local variables have no block: this happens when they are |
| 469 | not produced by a debug information reader, for instance when GDB creates |
| 470 | synthetic symbols. Without block information, we must assume they are |
| 471 | local to FRAME. In this case, there is nothing to do. */ |
| 472 | else if (var_block == NULL) |
| 473 | return frame; |
| 474 | |
| 475 | /* We currently assume that all symbols with a location list need a frame. |
| 476 | This is true in practice because selecting the location description |
| 477 | requires to compute the CFA, hence requires a frame. However we have |
| 478 | tests that embed global/static symbols with null location lists. |
| 479 | We want to get <optimized out> instead of <frame required> when evaluating |
| 480 | them so return a frame instead of raising an error. */ |
| 481 | else if (var_block == block_global_block (var_block) |
| 482 | || var_block == block_static_block (var_block)) |
| 483 | return frame; |
| 484 | |
| 485 | /* We have to handle the "my_func::my_local_var" notation. This requires us |
| 486 | to look for upper frames when we find no block for the current frame: here |
| 487 | and below, handle when frame_block == NULL. */ |
| 488 | if (frame != NULL) |
| 489 | frame_block = get_frame_block (frame, NULL); |
| 490 | |
| 491 | /* Climb up the call stack until reaching the frame we are looking for. */ |
| 492 | while (frame != NULL && frame_block != var_block) |
| 493 | { |
| 494 | /* Stacks can be quite deep: give the user a chance to stop this. */ |
| 495 | QUIT; |
| 496 | |
| 497 | if (frame_block == NULL) |
| 498 | { |
| 499 | frame = get_prev_frame (frame); |
| 500 | if (frame == NULL) |
| 501 | break; |
| 502 | frame_block = get_frame_block (frame, NULL); |
| 503 | } |
| 504 | |
| 505 | /* If we failed to find the proper frame, fallback to the heuristic |
| 506 | method below. */ |
| 507 | else if (frame_block == block_global_block (frame_block)) |
| 508 | { |
| 509 | frame = NULL; |
| 510 | break; |
| 511 | } |
| 512 | |
| 513 | /* Assuming we have a block for this frame: if we are at the function |
| 514 | level, the immediate upper lexical block is in an outer function: |
| 515 | follow the static link. */ |
| 516 | else if (BLOCK_FUNCTION (frame_block)) |
| 517 | { |
| 518 | const struct dynamic_prop *static_link |
| 519 | = block_static_link (frame_block); |
| 520 | int could_climb_up = 0; |
| 521 | |
| 522 | if (static_link != NULL) |
| 523 | { |
| 524 | frame = follow_static_link (frame, static_link); |
| 525 | if (frame != NULL) |
| 526 | { |
| 527 | frame_block = get_frame_block (frame, NULL); |
| 528 | could_climb_up = frame_block != NULL; |
| 529 | } |
| 530 | } |
| 531 | if (!could_climb_up) |
| 532 | { |
| 533 | frame = NULL; |
| 534 | break; |
| 535 | } |
| 536 | } |
| 537 | |
| 538 | else |
| 539 | /* We must be in some function nested lexical block. Just get the |
| 540 | outer block: both must share the same frame. */ |
| 541 | frame_block = BLOCK_SUPERBLOCK (frame_block); |
| 542 | } |
| 543 | |
| 544 | /* Old compilers may not provide a static link, or they may provide an |
| 545 | invalid one. For such cases, fallback on the old way to evaluate |
| 546 | non-local references: just climb up the call stack and pick the first |
| 547 | frame that contains the variable we are looking for. */ |
| 548 | if (frame == NULL) |
| 549 | { |
| 550 | frame = block_innermost_frame (var_block); |
| 551 | if (frame == NULL) |
| 552 | { |
| 553 | if (BLOCK_FUNCTION (var_block) |
| 554 | && !block_inlined_p (var_block) |
| 555 | && SYMBOL_PRINT_NAME (BLOCK_FUNCTION (var_block))) |
| 556 | error (_("No frame is currently executing in block %s."), |
| 557 | SYMBOL_PRINT_NAME (BLOCK_FUNCTION (var_block))); |
| 558 | else |
| 559 | error (_("No frame is currently executing in specified" |
| 560 | " block")); |
| 561 | } |
| 562 | } |
| 563 | |
| 564 | return frame; |
| 565 | } |
| 566 | |
| 567 | /* A default implementation for the "la_read_var_value" hook in |
| 568 | the language vector which should work in most situations. */ |
| 569 | |
| 570 | struct value * |
| 571 | default_read_var_value (struct symbol *var, const struct block *var_block, |
| 572 | struct frame_info *frame) |
| 573 | { |
| 574 | struct value *v; |
| 575 | struct type *type = SYMBOL_TYPE (var); |
| 576 | CORE_ADDR addr; |
| 577 | |
| 578 | /* Call check_typedef on our type to make sure that, if TYPE is |
| 579 | a TYPE_CODE_TYPEDEF, its length is set to the length of the target type |
| 580 | instead of zero. However, we do not replace the typedef type by the |
| 581 | target type, because we want to keep the typedef in order to be able to |
| 582 | set the returned value type description correctly. */ |
| 583 | check_typedef (type); |
| 584 | |
| 585 | if (symbol_read_needs_frame (var)) |
| 586 | gdb_assert (frame != NULL); |
| 587 | |
| 588 | if (frame != NULL) |
| 589 | frame = get_hosting_frame (var, var_block, frame); |
| 590 | |
| 591 | if (SYMBOL_COMPUTED_OPS (var) != NULL) |
| 592 | return SYMBOL_COMPUTED_OPS (var)->read_variable (var, frame); |
| 593 | |
| 594 | switch (SYMBOL_CLASS (var)) |
| 595 | { |
| 596 | case LOC_CONST: |
| 597 | if (is_dynamic_type (type)) |
| 598 | { |
| 599 | /* Value is a constant byte-sequence and needs no memory access. */ |
| 600 | type = resolve_dynamic_type (type, NULL, /* Unused address. */ 0); |
| 601 | } |
| 602 | /* Put the constant back in target format. */ |
| 603 | v = allocate_value (type); |
| 604 | store_signed_integer (value_contents_raw (v), TYPE_LENGTH (type), |
| 605 | gdbarch_byte_order (get_type_arch (type)), |
| 606 | (LONGEST) SYMBOL_VALUE (var)); |
| 607 | VALUE_LVAL (v) = not_lval; |
| 608 | return v; |
| 609 | |
| 610 | case LOC_LABEL: |
| 611 | /* Put the constant back in target format. */ |
| 612 | v = allocate_value (type); |
| 613 | if (overlay_debugging) |
| 614 | { |
| 615 | CORE_ADDR addr |
| 616 | = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var), |
| 617 | SYMBOL_OBJ_SECTION (symbol_objfile (var), |
| 618 | var)); |
| 619 | |
| 620 | store_typed_address (value_contents_raw (v), type, addr); |
| 621 | } |
| 622 | else |
| 623 | store_typed_address (value_contents_raw (v), type, |
| 624 | SYMBOL_VALUE_ADDRESS (var)); |
| 625 | VALUE_LVAL (v) = not_lval; |
| 626 | return v; |
| 627 | |
| 628 | case LOC_CONST_BYTES: |
| 629 | if (is_dynamic_type (type)) |
| 630 | { |
| 631 | /* Value is a constant byte-sequence and needs no memory access. */ |
| 632 | type = resolve_dynamic_type (type, NULL, /* Unused address. */ 0); |
| 633 | } |
| 634 | v = allocate_value (type); |
| 635 | memcpy (value_contents_raw (v), SYMBOL_VALUE_BYTES (var), |
| 636 | TYPE_LENGTH (type)); |
| 637 | VALUE_LVAL (v) = not_lval; |
| 638 | return v; |
| 639 | |
| 640 | case LOC_STATIC: |
| 641 | if (overlay_debugging) |
| 642 | addr = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var), |
| 643 | SYMBOL_OBJ_SECTION (symbol_objfile (var), |
| 644 | var)); |
| 645 | else |
| 646 | addr = SYMBOL_VALUE_ADDRESS (var); |
| 647 | break; |
| 648 | |
| 649 | case LOC_ARG: |
| 650 | addr = get_frame_args_address (frame); |
| 651 | if (!addr) |
| 652 | error (_("Unknown argument list address for `%s'."), |
| 653 | SYMBOL_PRINT_NAME (var)); |
| 654 | addr += SYMBOL_VALUE (var); |
| 655 | break; |
| 656 | |
| 657 | case LOC_REF_ARG: |
| 658 | { |
| 659 | struct value *ref; |
| 660 | CORE_ADDR argref; |
| 661 | |
| 662 | argref = get_frame_args_address (frame); |
| 663 | if (!argref) |
| 664 | error (_("Unknown argument list address for `%s'."), |
| 665 | SYMBOL_PRINT_NAME (var)); |
| 666 | argref += SYMBOL_VALUE (var); |
| 667 | ref = value_at (lookup_pointer_type (type), argref); |
| 668 | addr = value_as_address (ref); |
| 669 | break; |
| 670 | } |
| 671 | |
| 672 | case LOC_LOCAL: |
| 673 | addr = get_frame_locals_address (frame); |
| 674 | addr += SYMBOL_VALUE (var); |
| 675 | break; |
| 676 | |
| 677 | case LOC_TYPEDEF: |
| 678 | error (_("Cannot look up value of a typedef `%s'."), |
| 679 | SYMBOL_PRINT_NAME (var)); |
| 680 | break; |
| 681 | |
| 682 | case LOC_BLOCK: |
| 683 | if (overlay_debugging) |
| 684 | addr = symbol_overlayed_address |
| 685 | (BLOCK_START (SYMBOL_BLOCK_VALUE (var)), |
| 686 | SYMBOL_OBJ_SECTION (symbol_objfile (var), var)); |
| 687 | else |
| 688 | addr = BLOCK_START (SYMBOL_BLOCK_VALUE (var)); |
| 689 | break; |
| 690 | |
| 691 | case LOC_REGISTER: |
| 692 | case LOC_REGPARM_ADDR: |
| 693 | { |
| 694 | int regno = SYMBOL_REGISTER_OPS (var) |
| 695 | ->register_number (var, get_frame_arch (frame)); |
| 696 | struct value *regval; |
| 697 | |
| 698 | if (SYMBOL_CLASS (var) == LOC_REGPARM_ADDR) |
| 699 | { |
| 700 | regval = value_from_register (lookup_pointer_type (type), |
| 701 | regno, |
| 702 | frame); |
| 703 | |
| 704 | if (regval == NULL) |
| 705 | error (_("Value of register variable not available for `%s'."), |
| 706 | SYMBOL_PRINT_NAME (var)); |
| 707 | |
| 708 | addr = value_as_address (regval); |
| 709 | } |
| 710 | else |
| 711 | { |
| 712 | regval = value_from_register (type, regno, frame); |
| 713 | |
| 714 | if (regval == NULL) |
| 715 | error (_("Value of register variable not available for `%s'."), |
| 716 | SYMBOL_PRINT_NAME (var)); |
| 717 | return regval; |
| 718 | } |
| 719 | } |
| 720 | break; |
| 721 | |
| 722 | case LOC_COMPUTED: |
| 723 | gdb_assert_not_reached (_("LOC_COMPUTED variable missing a method")); |
| 724 | |
| 725 | case LOC_UNRESOLVED: |
| 726 | { |
| 727 | struct minsym_lookup_data lookup_data; |
| 728 | struct minimal_symbol *msym; |
| 729 | struct obj_section *obj_section; |
| 730 | |
| 731 | memset (&lookup_data, 0, sizeof (lookup_data)); |
| 732 | lookup_data.name = SYMBOL_LINKAGE_NAME (var); |
| 733 | |
| 734 | gdbarch_iterate_over_objfiles_in_search_order |
| 735 | (symbol_arch (var), |
| 736 | minsym_lookup_iterator_cb, &lookup_data, |
| 737 | symbol_objfile (var)); |
| 738 | msym = lookup_data.result.minsym; |
| 739 | |
| 740 | /* If we can't find the minsym there's a problem in the symbol info. |
| 741 | The symbol exists in the debug info, but it's missing in the minsym |
| 742 | table. */ |
| 743 | if (msym == NULL) |
| 744 | { |
| 745 | const char *flavour_name |
| 746 | = objfile_flavour_name (symbol_objfile (var)); |
| 747 | |
| 748 | /* We can't get here unless we've opened the file, so flavour_name |
| 749 | can't be NULL. */ |
| 750 | gdb_assert (flavour_name != NULL); |
| 751 | error (_("Missing %s symbol \"%s\"."), |
| 752 | flavour_name, SYMBOL_LINKAGE_NAME (var)); |
| 753 | } |
| 754 | obj_section = MSYMBOL_OBJ_SECTION (lookup_data.result.objfile, msym); |
| 755 | /* Relocate address, unless there is no section or the variable is |
| 756 | a TLS variable. */ |
| 757 | if (obj_section == NULL |
| 758 | || (obj_section->the_bfd_section->flags & SEC_THREAD_LOCAL) != 0) |
| 759 | addr = MSYMBOL_VALUE_RAW_ADDRESS (msym); |
| 760 | else |
| 761 | addr = BMSYMBOL_VALUE_ADDRESS (lookup_data.result); |
| 762 | if (overlay_debugging) |
| 763 | addr = symbol_overlayed_address (addr, obj_section); |
| 764 | /* Determine address of TLS variable. */ |
| 765 | if (obj_section |
| 766 | && (obj_section->the_bfd_section->flags & SEC_THREAD_LOCAL) != 0) |
| 767 | addr = target_translate_tls_address (obj_section->objfile, addr); |
| 768 | } |
| 769 | break; |
| 770 | |
| 771 | case LOC_OPTIMIZED_OUT: |
| 772 | return allocate_optimized_out_value (type); |
| 773 | |
| 774 | default: |
| 775 | error (_("Cannot look up value of a botched symbol `%s'."), |
| 776 | SYMBOL_PRINT_NAME (var)); |
| 777 | break; |
| 778 | } |
| 779 | |
| 780 | v = value_at_lazy (type, addr); |
| 781 | return v; |
| 782 | } |
| 783 | |
| 784 | /* Calls VAR's language la_read_var_value hook with the given arguments. */ |
| 785 | |
| 786 | struct value * |
| 787 | read_var_value (struct symbol *var, const struct block *var_block, |
| 788 | struct frame_info *frame) |
| 789 | { |
| 790 | const struct language_defn *lang = language_def (SYMBOL_LANGUAGE (var)); |
| 791 | |
| 792 | gdb_assert (lang != NULL); |
| 793 | gdb_assert (lang->la_read_var_value != NULL); |
| 794 | |
| 795 | return lang->la_read_var_value (var, var_block, frame); |
| 796 | } |
| 797 | |
| 798 | /* Install default attributes for register values. */ |
| 799 | |
| 800 | struct value * |
| 801 | default_value_from_register (struct gdbarch *gdbarch, struct type *type, |
| 802 | int regnum, struct frame_id frame_id) |
| 803 | { |
| 804 | int len = TYPE_LENGTH (type); |
| 805 | struct value *value = allocate_value (type); |
| 806 | |
| 807 | VALUE_LVAL (value) = lval_register; |
| 808 | VALUE_FRAME_ID (value) = frame_id; |
| 809 | VALUE_REGNUM (value) = regnum; |
| 810 | |
| 811 | /* Any structure stored in more than one register will always be |
| 812 | an integral number of registers. Otherwise, you need to do |
| 813 | some fiddling with the last register copied here for little |
| 814 | endian machines. */ |
| 815 | if (gdbarch_byte_order (gdbarch) == BFD_ENDIAN_BIG |
| 816 | && len < register_size (gdbarch, regnum)) |
| 817 | /* Big-endian, and we want less than full size. */ |
| 818 | set_value_offset (value, register_size (gdbarch, regnum) - len); |
| 819 | else |
| 820 | set_value_offset (value, 0); |
| 821 | |
| 822 | return value; |
| 823 | } |
| 824 | |
| 825 | /* VALUE must be an lval_register value. If regnum is the value's |
| 826 | associated register number, and len the length of the values type, |
| 827 | read one or more registers in FRAME, starting with register REGNUM, |
| 828 | until we've read LEN bytes. |
| 829 | |
| 830 | If any of the registers we try to read are optimized out, then mark the |
| 831 | complete resulting value as optimized out. */ |
| 832 | |
| 833 | void |
| 834 | read_frame_register_value (struct value *value, struct frame_info *frame) |
| 835 | { |
| 836 | struct gdbarch *gdbarch = get_frame_arch (frame); |
| 837 | int offset = 0; |
| 838 | int reg_offset = value_offset (value); |
| 839 | int regnum = VALUE_REGNUM (value); |
| 840 | int len = type_length_units (check_typedef (value_type (value))); |
| 841 | |
| 842 | gdb_assert (VALUE_LVAL (value) == lval_register); |
| 843 | |
| 844 | /* Skip registers wholly inside of REG_OFFSET. */ |
| 845 | while (reg_offset >= register_size (gdbarch, regnum)) |
| 846 | { |
| 847 | reg_offset -= register_size (gdbarch, regnum); |
| 848 | regnum++; |
| 849 | } |
| 850 | |
| 851 | /* Copy the data. */ |
| 852 | while (len > 0) |
| 853 | { |
| 854 | struct value *regval = get_frame_register_value (frame, regnum); |
| 855 | int reg_len = type_length_units (value_type (regval)) - reg_offset; |
| 856 | |
| 857 | /* If the register length is larger than the number of bytes |
| 858 | remaining to copy, then only copy the appropriate bytes. */ |
| 859 | if (reg_len > len) |
| 860 | reg_len = len; |
| 861 | |
| 862 | value_contents_copy (value, offset, regval, reg_offset, reg_len); |
| 863 | |
| 864 | offset += reg_len; |
| 865 | len -= reg_len; |
| 866 | reg_offset = 0; |
| 867 | regnum++; |
| 868 | } |
| 869 | } |
| 870 | |
| 871 | /* Return a value of type TYPE, stored in register REGNUM, in frame FRAME. */ |
| 872 | |
| 873 | struct value * |
| 874 | value_from_register (struct type *type, int regnum, struct frame_info *frame) |
| 875 | { |
| 876 | struct gdbarch *gdbarch = get_frame_arch (frame); |
| 877 | struct type *type1 = check_typedef (type); |
| 878 | struct value *v; |
| 879 | |
| 880 | if (gdbarch_convert_register_p (gdbarch, regnum, type1)) |
| 881 | { |
| 882 | int optim, unavail, ok; |
| 883 | |
| 884 | /* The ISA/ABI need to something weird when obtaining the |
| 885 | specified value from this register. It might need to |
| 886 | re-order non-adjacent, starting with REGNUM (see MIPS and |
| 887 | i386). It might need to convert the [float] register into |
| 888 | the corresponding [integer] type (see Alpha). The assumption |
| 889 | is that gdbarch_register_to_value populates the entire value |
| 890 | including the location. */ |
| 891 | v = allocate_value (type); |
| 892 | VALUE_LVAL (v) = lval_register; |
| 893 | VALUE_FRAME_ID (v) = get_frame_id (frame); |
| 894 | VALUE_REGNUM (v) = regnum; |
| 895 | ok = gdbarch_register_to_value (gdbarch, frame, regnum, type1, |
| 896 | value_contents_raw (v), &optim, |
| 897 | &unavail); |
| 898 | |
| 899 | if (!ok) |
| 900 | { |
| 901 | if (optim) |
| 902 | mark_value_bytes_optimized_out (v, 0, TYPE_LENGTH (type)); |
| 903 | if (unavail) |
| 904 | mark_value_bytes_unavailable (v, 0, TYPE_LENGTH (type)); |
| 905 | } |
| 906 | } |
| 907 | else |
| 908 | { |
| 909 | /* Construct the value. */ |
| 910 | v = gdbarch_value_from_register (gdbarch, type, |
| 911 | regnum, get_frame_id (frame)); |
| 912 | |
| 913 | /* Get the data. */ |
| 914 | read_frame_register_value (v, frame); |
| 915 | } |
| 916 | |
| 917 | return v; |
| 918 | } |
| 919 | |
| 920 | /* Return contents of register REGNUM in frame FRAME as address. |
| 921 | Will abort if register value is not available. */ |
| 922 | |
| 923 | CORE_ADDR |
| 924 | address_from_register (int regnum, struct frame_info *frame) |
| 925 | { |
| 926 | struct gdbarch *gdbarch = get_frame_arch (frame); |
| 927 | struct type *type = builtin_type (gdbarch)->builtin_data_ptr; |
| 928 | struct value *value; |
| 929 | CORE_ADDR result; |
| 930 | int regnum_max_excl = (gdbarch_num_regs (gdbarch) |
| 931 | + gdbarch_num_pseudo_regs (gdbarch)); |
| 932 | |
| 933 | if (regnum < 0 || regnum >= regnum_max_excl) |
| 934 | error (_("Invalid register #%d, expecting 0 <= # < %d"), regnum, |
| 935 | regnum_max_excl); |
| 936 | |
| 937 | /* This routine may be called during early unwinding, at a time |
| 938 | where the ID of FRAME is not yet known. Calling value_from_register |
| 939 | would therefore abort in get_frame_id. However, since we only need |
| 940 | a temporary value that is never used as lvalue, we actually do not |
| 941 | really need to set its VALUE_FRAME_ID. Therefore, we re-implement |
| 942 | the core of value_from_register, but use the null_frame_id. */ |
| 943 | |
| 944 | /* Some targets require a special conversion routine even for plain |
| 945 | pointer types. Avoid constructing a value object in those cases. */ |
| 946 | if (gdbarch_convert_register_p (gdbarch, regnum, type)) |
| 947 | { |
| 948 | gdb_byte *buf = (gdb_byte *) alloca (TYPE_LENGTH (type)); |
| 949 | int optim, unavail, ok; |
| 950 | |
| 951 | ok = gdbarch_register_to_value (gdbarch, frame, regnum, type, |
| 952 | buf, &optim, &unavail); |
| 953 | if (!ok) |
| 954 | { |
| 955 | /* This function is used while computing a location expression. |
| 956 | Complain about the value being optimized out, rather than |
| 957 | letting value_as_address complain about some random register |
| 958 | the expression depends on not being saved. */ |
| 959 | error_value_optimized_out (); |
| 960 | } |
| 961 | |
| 962 | return unpack_long (type, buf); |
| 963 | } |
| 964 | |
| 965 | value = gdbarch_value_from_register (gdbarch, type, regnum, null_frame_id); |
| 966 | read_frame_register_value (value, frame); |
| 967 | |
| 968 | if (value_optimized_out (value)) |
| 969 | { |
| 970 | /* This function is used while computing a location expression. |
| 971 | Complain about the value being optimized out, rather than |
| 972 | letting value_as_address complain about some random register |
| 973 | the expression depends on not being saved. */ |
| 974 | error_value_optimized_out (); |
| 975 | } |
| 976 | |
| 977 | result = value_as_address (value); |
| 978 | release_value (value); |
| 979 | value_free (value); |
| 980 | |
| 981 | return result; |
| 982 | } |
| 983 | |