| 1 | /* Find a variable's value in memory, for GDB, the GNU debugger. |
| 2 | |
| 3 | Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, |
| 4 | 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2003, 2004, 2005 Free |
| 5 | Software Foundation, Inc. |
| 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 2 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, write to the Free Software |
| 21 | Foundation, Inc., 59 Temple Place - Suite 330, |
| 22 | Boston, MA 02111-1307, USA. */ |
| 23 | |
| 24 | #include "defs.h" |
| 25 | #include "symtab.h" |
| 26 | #include "gdbtypes.h" |
| 27 | #include "frame.h" |
| 28 | #include "value.h" |
| 29 | #include "gdbcore.h" |
| 30 | #include "inferior.h" |
| 31 | #include "target.h" |
| 32 | #include "gdb_string.h" |
| 33 | #include "gdb_assert.h" |
| 34 | #include "floatformat.h" |
| 35 | #include "symfile.h" /* for overlay functions */ |
| 36 | #include "regcache.h" |
| 37 | #include "user-regs.h" |
| 38 | #include "block.h" |
| 39 | |
| 40 | /* Basic byte-swapping routines. GDB has needed these for a long time... |
| 41 | All extract a target-format integer at ADDR which is LEN bytes long. */ |
| 42 | |
| 43 | #if TARGET_CHAR_BIT != 8 || HOST_CHAR_BIT != 8 |
| 44 | /* 8 bit characters are a pretty safe assumption these days, so we |
| 45 | assume it throughout all these swapping routines. If we had to deal with |
| 46 | 9 bit characters, we would need to make len be in bits and would have |
| 47 | to re-write these routines... */ |
| 48 | you lose |
| 49 | #endif |
| 50 | |
| 51 | LONGEST |
| 52 | extract_signed_integer (const gdb_byte *addr, int len) |
| 53 | { |
| 54 | LONGEST retval; |
| 55 | const unsigned char *p; |
| 56 | const unsigned char *startaddr = addr; |
| 57 | const unsigned char *endaddr = startaddr + len; |
| 58 | |
| 59 | if (len > (int) sizeof (LONGEST)) |
| 60 | error (_("\ |
| 61 | That operation is not available on integers of more than %d bytes."), |
| 62 | (int) sizeof (LONGEST)); |
| 63 | |
| 64 | /* Start at the most significant end of the integer, and work towards |
| 65 | the least significant. */ |
| 66 | if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG) |
| 67 | { |
| 68 | p = startaddr; |
| 69 | /* Do the sign extension once at the start. */ |
| 70 | retval = ((LONGEST) * p ^ 0x80) - 0x80; |
| 71 | for (++p; p < endaddr; ++p) |
| 72 | retval = (retval << 8) | *p; |
| 73 | } |
| 74 | else |
| 75 | { |
| 76 | p = endaddr - 1; |
| 77 | /* Do the sign extension once at the start. */ |
| 78 | retval = ((LONGEST) * p ^ 0x80) - 0x80; |
| 79 | for (--p; p >= startaddr; --p) |
| 80 | retval = (retval << 8) | *p; |
| 81 | } |
| 82 | return retval; |
| 83 | } |
| 84 | |
| 85 | ULONGEST |
| 86 | extract_unsigned_integer (const gdb_byte *addr, int len) |
| 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 (TARGET_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 | LONGEST *pval) |
| 122 | { |
| 123 | const gdb_byte *p; |
| 124 | const gdb_byte *first_addr; |
| 125 | int len; |
| 126 | |
| 127 | len = orig_len; |
| 128 | if (TARGET_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 | return 1; |
| 160 | } |
| 161 | |
| 162 | return 0; |
| 163 | } |
| 164 | |
| 165 | |
| 166 | /* Treat the bytes at BUF as a pointer of type TYPE, and return the |
| 167 | address it represents. */ |
| 168 | CORE_ADDR |
| 169 | extract_typed_address (const gdb_byte *buf, struct type *type) |
| 170 | { |
| 171 | if (TYPE_CODE (type) != TYPE_CODE_PTR |
| 172 | && TYPE_CODE (type) != TYPE_CODE_REF) |
| 173 | internal_error (__FILE__, __LINE__, |
| 174 | _("extract_typed_address: " |
| 175 | "type is not a pointer or reference")); |
| 176 | |
| 177 | return POINTER_TO_ADDRESS (type, buf); |
| 178 | } |
| 179 | |
| 180 | |
| 181 | void |
| 182 | store_signed_integer (gdb_byte *addr, int len, LONGEST val) |
| 183 | { |
| 184 | gdb_byte *p; |
| 185 | gdb_byte *startaddr = addr; |
| 186 | gdb_byte *endaddr = startaddr + len; |
| 187 | |
| 188 | /* Start at the least significant end of the integer, and work towards |
| 189 | the most significant. */ |
| 190 | if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG) |
| 191 | { |
| 192 | for (p = endaddr - 1; p >= startaddr; --p) |
| 193 | { |
| 194 | *p = val & 0xff; |
| 195 | val >>= 8; |
| 196 | } |
| 197 | } |
| 198 | else |
| 199 | { |
| 200 | for (p = startaddr; p < endaddr; ++p) |
| 201 | { |
| 202 | *p = val & 0xff; |
| 203 | val >>= 8; |
| 204 | } |
| 205 | } |
| 206 | } |
| 207 | |
| 208 | void |
| 209 | store_unsigned_integer (gdb_byte *addr, int len, ULONGEST val) |
| 210 | { |
| 211 | unsigned char *p; |
| 212 | unsigned char *startaddr = (unsigned char *) addr; |
| 213 | unsigned char *endaddr = startaddr + len; |
| 214 | |
| 215 | /* Start at the least significant end of the integer, and work towards |
| 216 | the most significant. */ |
| 217 | if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG) |
| 218 | { |
| 219 | for (p = endaddr - 1; p >= startaddr; --p) |
| 220 | { |
| 221 | *p = val & 0xff; |
| 222 | val >>= 8; |
| 223 | } |
| 224 | } |
| 225 | else |
| 226 | { |
| 227 | for (p = startaddr; p < endaddr; ++p) |
| 228 | { |
| 229 | *p = val & 0xff; |
| 230 | val >>= 8; |
| 231 | } |
| 232 | } |
| 233 | } |
| 234 | |
| 235 | /* Store the address ADDR as a pointer of type TYPE at BUF, in target |
| 236 | form. */ |
| 237 | void |
| 238 | store_typed_address (gdb_byte *buf, struct type *type, CORE_ADDR addr) |
| 239 | { |
| 240 | if (TYPE_CODE (type) != TYPE_CODE_PTR |
| 241 | && TYPE_CODE (type) != TYPE_CODE_REF) |
| 242 | internal_error (__FILE__, __LINE__, |
| 243 | _("store_typed_address: " |
| 244 | "type is not a pointer or reference")); |
| 245 | |
| 246 | ADDRESS_TO_POINTER (type, buf, addr); |
| 247 | } |
| 248 | |
| 249 | |
| 250 | |
| 251 | /* Return a `value' with the contents of (virtual or cooked) register |
| 252 | REGNUM as found in the specified FRAME. The register's type is |
| 253 | determined by register_type(). |
| 254 | |
| 255 | NOTE: returns NULL if register value is not available. Caller will |
| 256 | check return value or die! */ |
| 257 | |
| 258 | struct value * |
| 259 | value_of_register (int regnum, struct frame_info *frame) |
| 260 | { |
| 261 | CORE_ADDR addr; |
| 262 | int optim; |
| 263 | struct value *reg_val; |
| 264 | int realnum; |
| 265 | gdb_byte raw_buffer[MAX_REGISTER_SIZE]; |
| 266 | enum lval_type lval; |
| 267 | |
| 268 | /* User registers lie completely outside of the range of normal |
| 269 | registers. Catch them early so that the target never sees them. */ |
| 270 | if (regnum >= NUM_REGS + NUM_PSEUDO_REGS) |
| 271 | return value_of_user_reg (regnum, frame); |
| 272 | |
| 273 | frame_register (frame, regnum, &optim, &lval, &addr, &realnum, raw_buffer); |
| 274 | |
| 275 | /* FIXME: cagney/2002-05-15: This test is just bogus. |
| 276 | |
| 277 | It indicates that the target failed to supply a value for a |
| 278 | register because it was "not available" at this time. Problem |
| 279 | is, the target still has the register and so get saved_register() |
| 280 | may be returning a value saved on the stack. */ |
| 281 | |
| 282 | if (register_cached (regnum) < 0) |
| 283 | return NULL; /* register value not available */ |
| 284 | |
| 285 | reg_val = allocate_value (register_type (current_gdbarch, regnum)); |
| 286 | |
| 287 | memcpy (value_contents_raw (reg_val), raw_buffer, |
| 288 | register_size (current_gdbarch, regnum)); |
| 289 | VALUE_LVAL (reg_val) = lval; |
| 290 | VALUE_ADDRESS (reg_val) = addr; |
| 291 | VALUE_REGNUM (reg_val) = regnum; |
| 292 | set_value_optimized_out (reg_val, optim); |
| 293 | VALUE_FRAME_ID (reg_val) = get_frame_id (frame); |
| 294 | return reg_val; |
| 295 | } |
| 296 | |
| 297 | /* Given a pointer of type TYPE in target form in BUF, return the |
| 298 | address it represents. */ |
| 299 | CORE_ADDR |
| 300 | unsigned_pointer_to_address (struct type *type, const gdb_byte *buf) |
| 301 | { |
| 302 | return extract_unsigned_integer (buf, TYPE_LENGTH (type)); |
| 303 | } |
| 304 | |
| 305 | CORE_ADDR |
| 306 | signed_pointer_to_address (struct type *type, const gdb_byte *buf) |
| 307 | { |
| 308 | return extract_signed_integer (buf, TYPE_LENGTH (type)); |
| 309 | } |
| 310 | |
| 311 | /* Given an address, store it as a pointer of type TYPE in target |
| 312 | format in BUF. */ |
| 313 | void |
| 314 | unsigned_address_to_pointer (struct type *type, gdb_byte *buf, |
| 315 | CORE_ADDR addr) |
| 316 | { |
| 317 | store_unsigned_integer (buf, TYPE_LENGTH (type), addr); |
| 318 | } |
| 319 | |
| 320 | void |
| 321 | address_to_signed_pointer (struct type *type, gdb_byte *buf, CORE_ADDR addr) |
| 322 | { |
| 323 | store_signed_integer (buf, TYPE_LENGTH (type), addr); |
| 324 | } |
| 325 | \f |
| 326 | /* Will calling read_var_value or locate_var_value on SYM end |
| 327 | up caring what frame it is being evaluated relative to? SYM must |
| 328 | be non-NULL. */ |
| 329 | int |
| 330 | symbol_read_needs_frame (struct symbol *sym) |
| 331 | { |
| 332 | switch (SYMBOL_CLASS (sym)) |
| 333 | { |
| 334 | /* All cases listed explicitly so that gcc -Wall will detect it if |
| 335 | we failed to consider one. */ |
| 336 | case LOC_COMPUTED: |
| 337 | case LOC_COMPUTED_ARG: |
| 338 | /* FIXME: cagney/2004-01-26: It should be possible to |
| 339 | unconditionally call the SYMBOL_OPS method when available. |
| 340 | Unfortunately DWARF 2 stores the frame-base (instead of the |
| 341 | function) location in a function's symbol. Oops! For the |
| 342 | moment enable this when/where applicable. */ |
| 343 | return SYMBOL_OPS (sym)->read_needs_frame (sym); |
| 344 | |
| 345 | case LOC_REGISTER: |
| 346 | case LOC_ARG: |
| 347 | case LOC_REF_ARG: |
| 348 | case LOC_REGPARM: |
| 349 | case LOC_REGPARM_ADDR: |
| 350 | case LOC_LOCAL: |
| 351 | case LOC_LOCAL_ARG: |
| 352 | case LOC_BASEREG: |
| 353 | case LOC_BASEREG_ARG: |
| 354 | case LOC_HP_THREAD_LOCAL_STATIC: |
| 355 | return 1; |
| 356 | |
| 357 | case LOC_UNDEF: |
| 358 | case LOC_CONST: |
| 359 | case LOC_STATIC: |
| 360 | case LOC_INDIRECT: |
| 361 | case LOC_TYPEDEF: |
| 362 | |
| 363 | case LOC_LABEL: |
| 364 | /* Getting the address of a label can be done independently of the block, |
| 365 | even if some *uses* of that address wouldn't work so well without |
| 366 | the right frame. */ |
| 367 | |
| 368 | case LOC_BLOCK: |
| 369 | case LOC_CONST_BYTES: |
| 370 | case LOC_UNRESOLVED: |
| 371 | case LOC_OPTIMIZED_OUT: |
| 372 | return 0; |
| 373 | } |
| 374 | return 1; |
| 375 | } |
| 376 | |
| 377 | /* Given a struct symbol for a variable, |
| 378 | and a stack frame id, read the value of the variable |
| 379 | and return a (pointer to a) struct value containing the value. |
| 380 | If the variable cannot be found, return a zero pointer. |
| 381 | If FRAME is NULL, use the deprecated_selected_frame. */ |
| 382 | |
| 383 | struct value * |
| 384 | read_var_value (struct symbol *var, struct frame_info *frame) |
| 385 | { |
| 386 | struct value *v; |
| 387 | struct type *type = SYMBOL_TYPE (var); |
| 388 | CORE_ADDR addr; |
| 389 | int len; |
| 390 | |
| 391 | if (SYMBOL_CLASS (var) == LOC_COMPUTED |
| 392 | || SYMBOL_CLASS (var) == LOC_COMPUTED_ARG |
| 393 | || SYMBOL_CLASS (var) == LOC_REGISTER |
| 394 | || SYMBOL_CLASS (var) == LOC_REGPARM) |
| 395 | /* These cases do not use V. */ |
| 396 | v = NULL; |
| 397 | else |
| 398 | { |
| 399 | v = allocate_value (type); |
| 400 | VALUE_LVAL (v) = lval_memory; /* The most likely possibility. */ |
| 401 | } |
| 402 | |
| 403 | len = TYPE_LENGTH (type); |
| 404 | |
| 405 | /* FIXME drow/2003-09-06: this call to the selected frame should be |
| 406 | pushed upwards to the callers. */ |
| 407 | if (frame == NULL) |
| 408 | frame = deprecated_safe_get_selected_frame (); |
| 409 | |
| 410 | switch (SYMBOL_CLASS (var)) |
| 411 | { |
| 412 | case LOC_CONST: |
| 413 | /* Put the constant back in target format. */ |
| 414 | store_signed_integer (value_contents_raw (v), len, |
| 415 | (LONGEST) SYMBOL_VALUE (var)); |
| 416 | VALUE_LVAL (v) = not_lval; |
| 417 | return v; |
| 418 | |
| 419 | case LOC_LABEL: |
| 420 | /* Put the constant back in target format. */ |
| 421 | if (overlay_debugging) |
| 422 | { |
| 423 | CORE_ADDR addr |
| 424 | = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var), |
| 425 | SYMBOL_BFD_SECTION (var)); |
| 426 | store_typed_address (value_contents_raw (v), type, addr); |
| 427 | } |
| 428 | else |
| 429 | store_typed_address (value_contents_raw (v), type, |
| 430 | SYMBOL_VALUE_ADDRESS (var)); |
| 431 | VALUE_LVAL (v) = not_lval; |
| 432 | return v; |
| 433 | |
| 434 | case LOC_CONST_BYTES: |
| 435 | { |
| 436 | char *bytes_addr; |
| 437 | bytes_addr = SYMBOL_VALUE_BYTES (var); |
| 438 | memcpy (value_contents_raw (v), bytes_addr, len); |
| 439 | VALUE_LVAL (v) = not_lval; |
| 440 | return v; |
| 441 | } |
| 442 | |
| 443 | case LOC_STATIC: |
| 444 | if (overlay_debugging) |
| 445 | addr = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (var), |
| 446 | SYMBOL_BFD_SECTION (var)); |
| 447 | else |
| 448 | addr = SYMBOL_VALUE_ADDRESS (var); |
| 449 | break; |
| 450 | |
| 451 | case LOC_INDIRECT: |
| 452 | { |
| 453 | /* The import slot does not have a real address in it from the |
| 454 | dynamic loader (dld.sl on HP-UX), if the target hasn't |
| 455 | begun execution yet, so check for that. */ |
| 456 | CORE_ADDR locaddr; |
| 457 | struct value *loc; |
| 458 | if (!target_has_execution) |
| 459 | error (_("\ |
| 460 | Attempt to access variable defined in different shared object or load module when\n\ |
| 461 | addresses have not been bound by the dynamic loader. Try again when executable is running.")); |
| 462 | |
| 463 | locaddr = SYMBOL_VALUE_ADDRESS (var); |
| 464 | loc = value_at (lookup_pointer_type (type), locaddr); |
| 465 | addr = value_as_address (loc); |
| 466 | break; |
| 467 | } |
| 468 | |
| 469 | case LOC_ARG: |
| 470 | if (frame == NULL) |
| 471 | return 0; |
| 472 | addr = get_frame_args_address (frame); |
| 473 | if (!addr) |
| 474 | return 0; |
| 475 | addr += SYMBOL_VALUE (var); |
| 476 | break; |
| 477 | |
| 478 | case LOC_REF_ARG: |
| 479 | { |
| 480 | struct value *ref; |
| 481 | CORE_ADDR argref; |
| 482 | if (frame == NULL) |
| 483 | return 0; |
| 484 | argref = get_frame_args_address (frame); |
| 485 | if (!argref) |
| 486 | return 0; |
| 487 | argref += SYMBOL_VALUE (var); |
| 488 | ref = value_at (lookup_pointer_type (type), argref); |
| 489 | addr = value_as_address (ref); |
| 490 | break; |
| 491 | } |
| 492 | |
| 493 | case LOC_LOCAL: |
| 494 | case LOC_LOCAL_ARG: |
| 495 | if (frame == NULL) |
| 496 | return 0; |
| 497 | addr = get_frame_locals_address (frame); |
| 498 | addr += SYMBOL_VALUE (var); |
| 499 | break; |
| 500 | |
| 501 | case LOC_BASEREG: |
| 502 | case LOC_BASEREG_ARG: |
| 503 | case LOC_HP_THREAD_LOCAL_STATIC: |
| 504 | { |
| 505 | struct value *regval; |
| 506 | |
| 507 | regval = value_from_register (lookup_pointer_type (type), |
| 508 | SYMBOL_BASEREG (var), frame); |
| 509 | if (regval == NULL) |
| 510 | error (_("Value of base register not available.")); |
| 511 | addr = value_as_address (regval); |
| 512 | addr += SYMBOL_VALUE (var); |
| 513 | break; |
| 514 | } |
| 515 | |
| 516 | case LOC_TYPEDEF: |
| 517 | error (_("Cannot look up value of a typedef")); |
| 518 | break; |
| 519 | |
| 520 | case LOC_BLOCK: |
| 521 | if (overlay_debugging) |
| 522 | VALUE_ADDRESS (v) = symbol_overlayed_address |
| 523 | (BLOCK_START (SYMBOL_BLOCK_VALUE (var)), SYMBOL_BFD_SECTION (var)); |
| 524 | else |
| 525 | VALUE_ADDRESS (v) = BLOCK_START (SYMBOL_BLOCK_VALUE (var)); |
| 526 | return v; |
| 527 | |
| 528 | case LOC_REGISTER: |
| 529 | case LOC_REGPARM: |
| 530 | case LOC_REGPARM_ADDR: |
| 531 | { |
| 532 | struct block *b; |
| 533 | int regno = SYMBOL_VALUE (var); |
| 534 | struct value *regval; |
| 535 | |
| 536 | if (frame == NULL) |
| 537 | return 0; |
| 538 | b = get_frame_block (frame, 0); |
| 539 | |
| 540 | if (SYMBOL_CLASS (var) == LOC_REGPARM_ADDR) |
| 541 | { |
| 542 | regval = value_from_register (lookup_pointer_type (type), |
| 543 | regno, |
| 544 | frame); |
| 545 | |
| 546 | if (regval == NULL) |
| 547 | error (_("Value of register variable not available.")); |
| 548 | |
| 549 | addr = value_as_address (regval); |
| 550 | VALUE_LVAL (v) = lval_memory; |
| 551 | } |
| 552 | else |
| 553 | { |
| 554 | regval = value_from_register (type, regno, frame); |
| 555 | |
| 556 | if (regval == NULL) |
| 557 | error (_("Value of register variable not available.")); |
| 558 | return regval; |
| 559 | } |
| 560 | } |
| 561 | break; |
| 562 | |
| 563 | case LOC_COMPUTED: |
| 564 | case LOC_COMPUTED_ARG: |
| 565 | /* FIXME: cagney/2004-01-26: It should be possible to |
| 566 | unconditionally call the SYMBOL_OPS method when available. |
| 567 | Unfortunately DWARF 2 stores the frame-base (instead of the |
| 568 | function) location in a function's symbol. Oops! For the |
| 569 | moment enable this when/where applicable. */ |
| 570 | if (frame == 0 && SYMBOL_OPS (var)->read_needs_frame (var)) |
| 571 | return 0; |
| 572 | return SYMBOL_OPS (var)->read_variable (var, frame); |
| 573 | |
| 574 | case LOC_UNRESOLVED: |
| 575 | { |
| 576 | struct minimal_symbol *msym; |
| 577 | |
| 578 | msym = lookup_minimal_symbol (DEPRECATED_SYMBOL_NAME (var), NULL, NULL); |
| 579 | if (msym == NULL) |
| 580 | return 0; |
| 581 | if (overlay_debugging) |
| 582 | addr = symbol_overlayed_address (SYMBOL_VALUE_ADDRESS (msym), |
| 583 | SYMBOL_BFD_SECTION (msym)); |
| 584 | else |
| 585 | addr = SYMBOL_VALUE_ADDRESS (msym); |
| 586 | } |
| 587 | break; |
| 588 | |
| 589 | case LOC_OPTIMIZED_OUT: |
| 590 | VALUE_LVAL (v) = not_lval; |
| 591 | set_value_optimized_out (v, 1); |
| 592 | return v; |
| 593 | |
| 594 | default: |
| 595 | error (_("Cannot look up value of a botched symbol.")); |
| 596 | break; |
| 597 | } |
| 598 | |
| 599 | VALUE_ADDRESS (v) = addr; |
| 600 | set_value_lazy (v, 1); |
| 601 | return v; |
| 602 | } |
| 603 | |
| 604 | /* Return a value of type TYPE, stored in register REGNUM, in frame |
| 605 | FRAME. |
| 606 | |
| 607 | NOTE: returns NULL if register value is not available. |
| 608 | Caller will check return value or die! */ |
| 609 | |
| 610 | struct value * |
| 611 | value_from_register (struct type *type, int regnum, struct frame_info *frame) |
| 612 | { |
| 613 | struct gdbarch *gdbarch = get_frame_arch (frame); |
| 614 | struct value *v = allocate_value (type); |
| 615 | CHECK_TYPEDEF (type); |
| 616 | |
| 617 | if (TYPE_LENGTH (type) == 0) |
| 618 | { |
| 619 | /* It doesn't matter much what we return for this: since the |
| 620 | length is zero, it could be anything. But if allowed to see |
| 621 | a zero-length type, the register-finding loop below will set |
| 622 | neither mem_stor nor reg_stor, and then report an internal |
| 623 | error. |
| 624 | |
| 625 | Zero-length types can legitimately arise from declarations |
| 626 | like 'struct {}' (a GCC extension, not valid ISO C). GDB may |
| 627 | also create them when it finds bogus debugging information; |
| 628 | for example, in GCC 2.95.4 and binutils 2.11.93.0.2, the |
| 629 | STABS BINCL->EXCL compression process can create bad type |
| 630 | numbers. GDB reads these as TYPE_CODE_UNDEF types, with zero |
| 631 | length. (That bug is actually the only known way to get a |
| 632 | zero-length value allocated to a register --- which is what |
| 633 | it takes to make it here.) |
| 634 | |
| 635 | We'll just attribute the value to the original register. */ |
| 636 | VALUE_LVAL (v) = lval_register; |
| 637 | VALUE_ADDRESS (v) = regnum; |
| 638 | VALUE_REGNUM (v) = regnum; |
| 639 | } |
| 640 | else if (CONVERT_REGISTER_P (regnum, type)) |
| 641 | { |
| 642 | /* The ISA/ABI need to something weird when obtaining the |
| 643 | specified value from this register. It might need to |
| 644 | re-order non-adjacent, starting with REGNUM (see MIPS and |
| 645 | i386). It might need to convert the [float] register into |
| 646 | the corresponding [integer] type (see Alpha). The assumption |
| 647 | is that REGISTER_TO_VALUE populates the entire value |
| 648 | including the location. */ |
| 649 | REGISTER_TO_VALUE (frame, regnum, type, value_contents_raw (v)); |
| 650 | VALUE_LVAL (v) = lval_register; |
| 651 | VALUE_FRAME_ID (v) = get_frame_id (frame); |
| 652 | VALUE_REGNUM (v) = regnum; |
| 653 | } |
| 654 | else |
| 655 | { |
| 656 | int local_regnum; |
| 657 | int mem_stor = 0, reg_stor = 0; |
| 658 | int mem_tracking = 1; |
| 659 | CORE_ADDR last_addr = 0; |
| 660 | CORE_ADDR first_addr = 0; |
| 661 | int first_realnum = regnum; |
| 662 | int len = TYPE_LENGTH (type); |
| 663 | int value_bytes_copied; |
| 664 | int optimized = 0; |
| 665 | gdb_byte *value_bytes = alloca (len + MAX_REGISTER_SIZE); |
| 666 | |
| 667 | /* Copy all of the data out, whereever it may be. */ |
| 668 | for (local_regnum = regnum, value_bytes_copied = 0; |
| 669 | value_bytes_copied < len; |
| 670 | (value_bytes_copied += register_size (current_gdbarch, local_regnum), |
| 671 | ++local_regnum)) |
| 672 | { |
| 673 | int realnum; |
| 674 | int optim; |
| 675 | enum lval_type lval; |
| 676 | CORE_ADDR addr; |
| 677 | frame_register (frame, local_regnum, &optim, &lval, &addr, |
| 678 | &realnum, value_bytes + value_bytes_copied); |
| 679 | optimized += optim; |
| 680 | if (register_cached (local_regnum) == -1) |
| 681 | return NULL; /* register value not available */ |
| 682 | |
| 683 | if (regnum == local_regnum) |
| 684 | { |
| 685 | first_addr = addr; |
| 686 | first_realnum = realnum; |
| 687 | } |
| 688 | if (lval == lval_register) |
| 689 | reg_stor++; |
| 690 | else |
| 691 | { |
| 692 | mem_stor++; |
| 693 | |
| 694 | /* FIXME: cagney/2004-11-12: I think this is trying to |
| 695 | check that the stored registers are adjacent in |
| 696 | memory. It isn't doing a good job? */ |
| 697 | mem_tracking = (mem_tracking |
| 698 | && (regnum == local_regnum |
| 699 | || addr == last_addr)); |
| 700 | } |
| 701 | last_addr = addr; |
| 702 | } |
| 703 | |
| 704 | if (mem_tracking && mem_stor && !reg_stor) |
| 705 | { |
| 706 | VALUE_LVAL (v) = lval_memory; |
| 707 | VALUE_ADDRESS (v) = first_addr; |
| 708 | } |
| 709 | else |
| 710 | { |
| 711 | VALUE_LVAL (v) = lval_register; |
| 712 | VALUE_FRAME_ID (v) = get_frame_id (frame); |
| 713 | VALUE_REGNUM (v) = regnum; |
| 714 | } |
| 715 | |
| 716 | set_value_optimized_out (v, optimized); |
| 717 | |
| 718 | /* Any structure stored in more than one register will always be |
| 719 | an integral number of registers. Otherwise, you need to do |
| 720 | some fiddling with the last register copied here for little |
| 721 | endian machines. */ |
| 722 | if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG |
| 723 | && len < register_size (current_gdbarch, regnum)) |
| 724 | /* Big-endian, and we want less than full size. */ |
| 725 | set_value_offset (v, register_size (current_gdbarch, regnum) - len); |
| 726 | else |
| 727 | set_value_offset (v, 0); |
| 728 | memcpy (value_contents_raw (v), value_bytes + value_offset (v), len); |
| 729 | } |
| 730 | return v; |
| 731 | } |
| 732 | |
| 733 | \f |
| 734 | /* Given a struct symbol for a variable or function, |
| 735 | and a stack frame id, |
| 736 | return a (pointer to a) struct value containing the properly typed |
| 737 | address. */ |
| 738 | |
| 739 | struct value * |
| 740 | locate_var_value (struct symbol *var, struct frame_info *frame) |
| 741 | { |
| 742 | CORE_ADDR addr = 0; |
| 743 | struct type *type = SYMBOL_TYPE (var); |
| 744 | struct value *lazy_value; |
| 745 | |
| 746 | /* Evaluate it first; if the result is a memory address, we're fine. |
| 747 | Lazy evaluation pays off here. */ |
| 748 | |
| 749 | lazy_value = read_var_value (var, frame); |
| 750 | if (lazy_value == 0) |
| 751 | error (_("Address of \"%s\" is unknown."), SYMBOL_PRINT_NAME (var)); |
| 752 | |
| 753 | if (value_lazy (lazy_value) |
| 754 | || TYPE_CODE (type) == TYPE_CODE_FUNC) |
| 755 | { |
| 756 | struct value *val; |
| 757 | |
| 758 | addr = VALUE_ADDRESS (lazy_value); |
| 759 | val = value_from_pointer (lookup_pointer_type (type), addr); |
| 760 | return val; |
| 761 | } |
| 762 | |
| 763 | /* Not a memory address; check what the problem was. */ |
| 764 | switch (VALUE_LVAL (lazy_value)) |
| 765 | { |
| 766 | case lval_register: |
| 767 | gdb_assert (REGISTER_NAME (VALUE_REGNUM (lazy_value)) != NULL |
| 768 | && *REGISTER_NAME (VALUE_REGNUM (lazy_value)) != '\0'); |
| 769 | error (_("Address requested for identifier " |
| 770 | "\"%s\" which is in register $%s"), |
| 771 | SYMBOL_PRINT_NAME (var), |
| 772 | REGISTER_NAME (VALUE_REGNUM (lazy_value))); |
| 773 | break; |
| 774 | |
| 775 | default: |
| 776 | error (_("Can't take address of \"%s\" which isn't an lvalue."), |
| 777 | SYMBOL_PRINT_NAME (var)); |
| 778 | break; |
| 779 | } |
| 780 | return 0; /* For lint -- never reached */ |
| 781 | } |