| 1 | /* DWARF 2 location expression support for GDB. |
| 2 | |
| 3 | Copyright (C) 2003, 2005, 2007, 2008, 2009 Free Software Foundation, Inc. |
| 4 | |
| 5 | Contributed by Daniel Jacobowitz, MontaVista Software, 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 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 "ui-out.h" |
| 24 | #include "value.h" |
| 25 | #include "frame.h" |
| 26 | #include "gdbcore.h" |
| 27 | #include "target.h" |
| 28 | #include "inferior.h" |
| 29 | #include "ax.h" |
| 30 | #include "ax-gdb.h" |
| 31 | #include "regcache.h" |
| 32 | #include "objfiles.h" |
| 33 | #include "exceptions.h" |
| 34 | #include "block.h" |
| 35 | |
| 36 | #include "dwarf2.h" |
| 37 | #include "dwarf2expr.h" |
| 38 | #include "dwarf2loc.h" |
| 39 | #include "dwarf2-frame.h" |
| 40 | |
| 41 | #include "gdb_string.h" |
| 42 | #include "gdb_assert.h" |
| 43 | |
| 44 | /* A helper function for dealing with location lists. Given a |
| 45 | symbol baton (BATON) and a pc value (PC), find the appropriate |
| 46 | location expression, set *LOCEXPR_LENGTH, and return a pointer |
| 47 | to the beginning of the expression. Returns NULL on failure. |
| 48 | |
| 49 | For now, only return the first matching location expression; there |
| 50 | can be more than one in the list. */ |
| 51 | |
| 52 | static gdb_byte * |
| 53 | find_location_expression (struct dwarf2_loclist_baton *baton, |
| 54 | size_t *locexpr_length, CORE_ADDR pc) |
| 55 | { |
| 56 | CORE_ADDR low, high; |
| 57 | gdb_byte *loc_ptr, *buf_end; |
| 58 | int length; |
| 59 | struct objfile *objfile = dwarf2_per_cu_objfile (baton->per_cu); |
| 60 | struct gdbarch *gdbarch = get_objfile_arch (objfile); |
| 61 | enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); |
| 62 | unsigned int addr_size = dwarf2_per_cu_addr_size (baton->per_cu); |
| 63 | CORE_ADDR base_mask = ~(~(CORE_ADDR)1 << (addr_size * 8 - 1)); |
| 64 | /* Adjust base_address for relocatable objects. */ |
| 65 | CORE_ADDR base_offset = ANOFFSET (objfile->section_offsets, |
| 66 | SECT_OFF_TEXT (objfile)); |
| 67 | CORE_ADDR base_address = baton->base_address + base_offset; |
| 68 | |
| 69 | loc_ptr = baton->data; |
| 70 | buf_end = baton->data + baton->size; |
| 71 | |
| 72 | while (1) |
| 73 | { |
| 74 | if (buf_end - loc_ptr < 2 * addr_size) |
| 75 | error (_("find_location_expression: Corrupted DWARF expression.")); |
| 76 | |
| 77 | low = extract_unsigned_integer (loc_ptr, addr_size, byte_order); |
| 78 | loc_ptr += addr_size; |
| 79 | |
| 80 | /* A base-address-selection entry. */ |
| 81 | if (low == base_mask) |
| 82 | { |
| 83 | base_address = dwarf2_read_address (gdbarch, |
| 84 | loc_ptr, buf_end, addr_size); |
| 85 | loc_ptr += addr_size; |
| 86 | continue; |
| 87 | } |
| 88 | |
| 89 | high = extract_unsigned_integer (loc_ptr, addr_size, byte_order); |
| 90 | loc_ptr += addr_size; |
| 91 | |
| 92 | /* An end-of-list entry. */ |
| 93 | if (low == 0 && high == 0) |
| 94 | return NULL; |
| 95 | |
| 96 | /* Otherwise, a location expression entry. */ |
| 97 | low += base_address; |
| 98 | high += base_address; |
| 99 | |
| 100 | length = extract_unsigned_integer (loc_ptr, 2, byte_order); |
| 101 | loc_ptr += 2; |
| 102 | |
| 103 | if (pc >= low && pc < high) |
| 104 | { |
| 105 | *locexpr_length = length; |
| 106 | return loc_ptr; |
| 107 | } |
| 108 | |
| 109 | loc_ptr += length; |
| 110 | } |
| 111 | } |
| 112 | |
| 113 | /* This is the baton used when performing dwarf2 expression |
| 114 | evaluation. */ |
| 115 | struct dwarf_expr_baton |
| 116 | { |
| 117 | struct frame_info *frame; |
| 118 | struct objfile *objfile; |
| 119 | }; |
| 120 | |
| 121 | /* Helper functions for dwarf2_evaluate_loc_desc. */ |
| 122 | |
| 123 | /* Using the frame specified in BATON, return the value of register |
| 124 | REGNUM, treated as a pointer. */ |
| 125 | static CORE_ADDR |
| 126 | dwarf_expr_read_reg (void *baton, int dwarf_regnum) |
| 127 | { |
| 128 | struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; |
| 129 | struct gdbarch *gdbarch = get_frame_arch (debaton->frame); |
| 130 | CORE_ADDR result; |
| 131 | int regnum; |
| 132 | |
| 133 | regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, dwarf_regnum); |
| 134 | result = address_from_register (builtin_type (gdbarch)->builtin_data_ptr, |
| 135 | regnum, debaton->frame); |
| 136 | return result; |
| 137 | } |
| 138 | |
| 139 | /* Read memory at ADDR (length LEN) into BUF. */ |
| 140 | |
| 141 | static void |
| 142 | dwarf_expr_read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len) |
| 143 | { |
| 144 | read_memory (addr, buf, len); |
| 145 | } |
| 146 | |
| 147 | /* Using the frame specified in BATON, find the location expression |
| 148 | describing the frame base. Return a pointer to it in START and |
| 149 | its length in LENGTH. */ |
| 150 | static void |
| 151 | dwarf_expr_frame_base (void *baton, gdb_byte **start, size_t * length) |
| 152 | { |
| 153 | /* FIXME: cagney/2003-03-26: This code should be using |
| 154 | get_frame_base_address(), and then implement a dwarf2 specific |
| 155 | this_base method. */ |
| 156 | struct symbol *framefunc; |
| 157 | struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; |
| 158 | |
| 159 | /* Use block_linkage_function, which returns a real (not inlined) |
| 160 | function, instead of get_frame_function, which may return an |
| 161 | inlined function. */ |
| 162 | framefunc = block_linkage_function (get_frame_block (debaton->frame, NULL)); |
| 163 | |
| 164 | /* If we found a frame-relative symbol then it was certainly within |
| 165 | some function associated with a frame. If we can't find the frame, |
| 166 | something has gone wrong. */ |
| 167 | gdb_assert (framefunc != NULL); |
| 168 | |
| 169 | if (SYMBOL_LOCATION_BATON (framefunc) == NULL) |
| 170 | *start = NULL; |
| 171 | else if (SYMBOL_COMPUTED_OPS (framefunc) == &dwarf2_loclist_funcs) |
| 172 | { |
| 173 | struct dwarf2_loclist_baton *symbaton; |
| 174 | struct frame_info *frame = debaton->frame; |
| 175 | |
| 176 | symbaton = SYMBOL_LOCATION_BATON (framefunc); |
| 177 | *start = find_location_expression (symbaton, length, |
| 178 | get_frame_address_in_block (frame)); |
| 179 | } |
| 180 | else |
| 181 | { |
| 182 | struct dwarf2_locexpr_baton *symbaton; |
| 183 | symbaton = SYMBOL_LOCATION_BATON (framefunc); |
| 184 | if (symbaton != NULL) |
| 185 | { |
| 186 | *length = symbaton->size; |
| 187 | *start = symbaton->data; |
| 188 | } |
| 189 | else |
| 190 | *start = NULL; |
| 191 | } |
| 192 | |
| 193 | if (*start == NULL) |
| 194 | error (_("Could not find the frame base for \"%s\"."), |
| 195 | SYMBOL_NATURAL_NAME (framefunc)); |
| 196 | } |
| 197 | |
| 198 | /* Helper function for dwarf2_evaluate_loc_desc. Computes the CFA for |
| 199 | the frame in BATON. */ |
| 200 | |
| 201 | static CORE_ADDR |
| 202 | dwarf_expr_frame_cfa (void *baton) |
| 203 | { |
| 204 | struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; |
| 205 | return dwarf2_frame_cfa (debaton->frame); |
| 206 | } |
| 207 | |
| 208 | /* Using the objfile specified in BATON, find the address for the |
| 209 | current thread's thread-local storage with offset OFFSET. */ |
| 210 | static CORE_ADDR |
| 211 | dwarf_expr_tls_address (void *baton, CORE_ADDR offset) |
| 212 | { |
| 213 | struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; |
| 214 | |
| 215 | return target_translate_tls_address (debaton->objfile, offset); |
| 216 | } |
| 217 | |
| 218 | struct piece_closure |
| 219 | { |
| 220 | /* The number of pieces used to describe this variable. */ |
| 221 | int n_pieces; |
| 222 | |
| 223 | /* The architecture, used only for DWARF_VALUE_STACK. */ |
| 224 | struct gdbarch *arch; |
| 225 | |
| 226 | /* The pieces themselves. */ |
| 227 | struct dwarf_expr_piece *pieces; |
| 228 | }; |
| 229 | |
| 230 | /* Allocate a closure for a value formed from separately-described |
| 231 | PIECES. */ |
| 232 | |
| 233 | static struct piece_closure * |
| 234 | allocate_piece_closure (int n_pieces, struct dwarf_expr_piece *pieces, |
| 235 | struct gdbarch *arch) |
| 236 | { |
| 237 | struct piece_closure *c = XZALLOC (struct piece_closure); |
| 238 | |
| 239 | c->n_pieces = n_pieces; |
| 240 | c->arch = arch; |
| 241 | c->pieces = XCALLOC (n_pieces, struct dwarf_expr_piece); |
| 242 | |
| 243 | memcpy (c->pieces, pieces, n_pieces * sizeof (struct dwarf_expr_piece)); |
| 244 | |
| 245 | return c; |
| 246 | } |
| 247 | |
| 248 | static void |
| 249 | read_pieced_value (struct value *v) |
| 250 | { |
| 251 | int i; |
| 252 | long offset = 0; |
| 253 | gdb_byte *contents; |
| 254 | struct piece_closure *c = (struct piece_closure *) value_computed_closure (v); |
| 255 | struct frame_info *frame = frame_find_by_id (VALUE_FRAME_ID (v)); |
| 256 | |
| 257 | contents = value_contents_raw (v); |
| 258 | for (i = 0; i < c->n_pieces; i++) |
| 259 | { |
| 260 | struct dwarf_expr_piece *p = &c->pieces[i]; |
| 261 | switch (p->location) |
| 262 | { |
| 263 | case DWARF_VALUE_REGISTER: |
| 264 | { |
| 265 | struct gdbarch *arch = get_frame_arch (frame); |
| 266 | bfd_byte regval[MAX_REGISTER_SIZE]; |
| 267 | int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, |
| 268 | p->v.expr.value); |
| 269 | get_frame_register (frame, gdb_regnum, regval); |
| 270 | memcpy (contents + offset, regval, p->size); |
| 271 | } |
| 272 | break; |
| 273 | |
| 274 | case DWARF_VALUE_MEMORY: |
| 275 | if (p->v.expr.in_stack_memory) |
| 276 | read_stack (p->v.expr.value, contents + offset, p->size); |
| 277 | else |
| 278 | read_memory (p->v.expr.value, contents + offset, p->size); |
| 279 | break; |
| 280 | |
| 281 | case DWARF_VALUE_STACK: |
| 282 | { |
| 283 | gdb_byte bytes[sizeof (ULONGEST)]; |
| 284 | size_t n; |
| 285 | int addr_size = gdbarch_addr_bit (c->arch) / 8; |
| 286 | store_unsigned_integer (bytes, addr_size, |
| 287 | gdbarch_byte_order (c->arch), |
| 288 | p->v.expr.value); |
| 289 | n = p->size; |
| 290 | if (n > addr_size) |
| 291 | n = addr_size; |
| 292 | memcpy (contents + offset, bytes, n); |
| 293 | } |
| 294 | break; |
| 295 | |
| 296 | case DWARF_VALUE_LITERAL: |
| 297 | { |
| 298 | size_t n = p->size; |
| 299 | if (n > p->v.literal.length) |
| 300 | n = p->v.literal.length; |
| 301 | memcpy (contents + offset, p->v.literal.data, n); |
| 302 | } |
| 303 | break; |
| 304 | |
| 305 | default: |
| 306 | internal_error (__FILE__, __LINE__, _("invalid location type")); |
| 307 | } |
| 308 | offset += p->size; |
| 309 | } |
| 310 | } |
| 311 | |
| 312 | static void |
| 313 | write_pieced_value (struct value *to, struct value *from) |
| 314 | { |
| 315 | int i; |
| 316 | long offset = 0; |
| 317 | gdb_byte *contents; |
| 318 | struct piece_closure *c = (struct piece_closure *) value_computed_closure (to); |
| 319 | struct frame_info *frame = frame_find_by_id (VALUE_FRAME_ID (to)); |
| 320 | |
| 321 | if (frame == NULL) |
| 322 | { |
| 323 | set_value_optimized_out (to, 1); |
| 324 | return; |
| 325 | } |
| 326 | |
| 327 | contents = value_contents_raw (from); |
| 328 | for (i = 0; i < c->n_pieces; i++) |
| 329 | { |
| 330 | struct dwarf_expr_piece *p = &c->pieces[i]; |
| 331 | switch (p->location) |
| 332 | { |
| 333 | case DWARF_VALUE_REGISTER: |
| 334 | { |
| 335 | struct gdbarch *arch = get_frame_arch (frame); |
| 336 | int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, p->v.expr.value); |
| 337 | put_frame_register (frame, gdb_regnum, contents + offset); |
| 338 | } |
| 339 | break; |
| 340 | case DWARF_VALUE_MEMORY: |
| 341 | write_memory (p->v.expr.value, contents + offset, p->size); |
| 342 | break; |
| 343 | default: |
| 344 | set_value_optimized_out (to, 1); |
| 345 | return; |
| 346 | } |
| 347 | offset += p->size; |
| 348 | } |
| 349 | } |
| 350 | |
| 351 | static void * |
| 352 | copy_pieced_value_closure (struct value *v) |
| 353 | { |
| 354 | struct piece_closure *c = (struct piece_closure *) value_computed_closure (v); |
| 355 | |
| 356 | return allocate_piece_closure (c->n_pieces, c->pieces, c->arch); |
| 357 | } |
| 358 | |
| 359 | static void |
| 360 | free_pieced_value_closure (struct value *v) |
| 361 | { |
| 362 | struct piece_closure *c = (struct piece_closure *) value_computed_closure (v); |
| 363 | |
| 364 | xfree (c->pieces); |
| 365 | xfree (c); |
| 366 | } |
| 367 | |
| 368 | /* Functions for accessing a variable described by DW_OP_piece. */ |
| 369 | static struct lval_funcs pieced_value_funcs = { |
| 370 | read_pieced_value, |
| 371 | write_pieced_value, |
| 372 | copy_pieced_value_closure, |
| 373 | free_pieced_value_closure |
| 374 | }; |
| 375 | |
| 376 | /* Evaluate a location description, starting at DATA and with length |
| 377 | SIZE, to find the current location of variable VAR in the context |
| 378 | of FRAME. */ |
| 379 | static struct value * |
| 380 | dwarf2_evaluate_loc_desc (struct symbol *var, struct frame_info *frame, |
| 381 | gdb_byte *data, unsigned short size, |
| 382 | struct dwarf2_per_cu_data *per_cu) |
| 383 | { |
| 384 | struct value *retval; |
| 385 | struct dwarf_expr_baton baton; |
| 386 | struct dwarf_expr_context *ctx; |
| 387 | struct cleanup *old_chain; |
| 388 | |
| 389 | if (size == 0) |
| 390 | { |
| 391 | retval = allocate_value (SYMBOL_TYPE (var)); |
| 392 | VALUE_LVAL (retval) = not_lval; |
| 393 | set_value_optimized_out (retval, 1); |
| 394 | return retval; |
| 395 | } |
| 396 | |
| 397 | baton.frame = frame; |
| 398 | baton.objfile = dwarf2_per_cu_objfile (per_cu); |
| 399 | |
| 400 | ctx = new_dwarf_expr_context (); |
| 401 | old_chain = make_cleanup_free_dwarf_expr_context (ctx); |
| 402 | |
| 403 | ctx->gdbarch = get_objfile_arch (baton.objfile); |
| 404 | ctx->addr_size = dwarf2_per_cu_addr_size (per_cu); |
| 405 | ctx->baton = &baton; |
| 406 | ctx->read_reg = dwarf_expr_read_reg; |
| 407 | ctx->read_mem = dwarf_expr_read_mem; |
| 408 | ctx->get_frame_base = dwarf_expr_frame_base; |
| 409 | ctx->get_frame_cfa = dwarf_expr_frame_cfa; |
| 410 | ctx->get_tls_address = dwarf_expr_tls_address; |
| 411 | |
| 412 | dwarf_expr_eval (ctx, data, size); |
| 413 | if (ctx->num_pieces > 0) |
| 414 | { |
| 415 | struct piece_closure *c; |
| 416 | struct frame_id frame_id = get_frame_id (frame); |
| 417 | |
| 418 | c = allocate_piece_closure (ctx->num_pieces, ctx->pieces, ctx->gdbarch); |
| 419 | retval = allocate_computed_value (SYMBOL_TYPE (var), |
| 420 | &pieced_value_funcs, |
| 421 | c); |
| 422 | VALUE_FRAME_ID (retval) = frame_id; |
| 423 | } |
| 424 | else |
| 425 | { |
| 426 | switch (ctx->location) |
| 427 | { |
| 428 | case DWARF_VALUE_REGISTER: |
| 429 | { |
| 430 | struct gdbarch *arch = get_frame_arch (frame); |
| 431 | CORE_ADDR dwarf_regnum = dwarf_expr_fetch (ctx, 0); |
| 432 | int gdb_regnum = gdbarch_dwarf2_reg_to_regnum (arch, dwarf_regnum); |
| 433 | retval = value_from_register (SYMBOL_TYPE (var), gdb_regnum, frame); |
| 434 | } |
| 435 | break; |
| 436 | |
| 437 | case DWARF_VALUE_MEMORY: |
| 438 | { |
| 439 | CORE_ADDR address = dwarf_expr_fetch (ctx, 0); |
| 440 | int in_stack_memory = dwarf_expr_fetch_in_stack_memory (ctx, 0); |
| 441 | |
| 442 | retval = allocate_value (SYMBOL_TYPE (var)); |
| 443 | VALUE_LVAL (retval) = lval_memory; |
| 444 | set_value_lazy (retval, 1); |
| 445 | if (in_stack_memory) |
| 446 | set_value_stack (retval, 1); |
| 447 | set_value_address (retval, address); |
| 448 | } |
| 449 | break; |
| 450 | |
| 451 | case DWARF_VALUE_STACK: |
| 452 | { |
| 453 | gdb_byte bytes[sizeof (ULONGEST)]; |
| 454 | ULONGEST value = (ULONGEST) dwarf_expr_fetch (ctx, 0); |
| 455 | bfd_byte *contents; |
| 456 | size_t n = ctx->addr_size; |
| 457 | |
| 458 | store_unsigned_integer (bytes, ctx->addr_size, |
| 459 | gdbarch_byte_order (ctx->gdbarch), |
| 460 | value); |
| 461 | retval = allocate_value (SYMBOL_TYPE (var)); |
| 462 | contents = value_contents_raw (retval); |
| 463 | if (n > TYPE_LENGTH (SYMBOL_TYPE (var))) |
| 464 | n = TYPE_LENGTH (SYMBOL_TYPE (var)); |
| 465 | memcpy (contents, bytes, n); |
| 466 | } |
| 467 | break; |
| 468 | |
| 469 | case DWARF_VALUE_LITERAL: |
| 470 | { |
| 471 | bfd_byte *contents; |
| 472 | size_t n = ctx->len; |
| 473 | |
| 474 | retval = allocate_value (SYMBOL_TYPE (var)); |
| 475 | contents = value_contents_raw (retval); |
| 476 | if (n > TYPE_LENGTH (SYMBOL_TYPE (var))) |
| 477 | n = TYPE_LENGTH (SYMBOL_TYPE (var)); |
| 478 | memcpy (contents, ctx->data, n); |
| 479 | } |
| 480 | break; |
| 481 | |
| 482 | default: |
| 483 | internal_error (__FILE__, __LINE__, _("invalid location type")); |
| 484 | } |
| 485 | } |
| 486 | |
| 487 | set_value_initialized (retval, ctx->initialized); |
| 488 | |
| 489 | do_cleanups (old_chain); |
| 490 | |
| 491 | return retval; |
| 492 | } |
| 493 | \f |
| 494 | /* Helper functions and baton for dwarf2_loc_desc_needs_frame. */ |
| 495 | |
| 496 | struct needs_frame_baton |
| 497 | { |
| 498 | int needs_frame; |
| 499 | }; |
| 500 | |
| 501 | /* Reads from registers do require a frame. */ |
| 502 | static CORE_ADDR |
| 503 | needs_frame_read_reg (void *baton, int regnum) |
| 504 | { |
| 505 | struct needs_frame_baton *nf_baton = baton; |
| 506 | nf_baton->needs_frame = 1; |
| 507 | return 1; |
| 508 | } |
| 509 | |
| 510 | /* Reads from memory do not require a frame. */ |
| 511 | static void |
| 512 | needs_frame_read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len) |
| 513 | { |
| 514 | memset (buf, 0, len); |
| 515 | } |
| 516 | |
| 517 | /* Frame-relative accesses do require a frame. */ |
| 518 | static void |
| 519 | needs_frame_frame_base (void *baton, gdb_byte **start, size_t * length) |
| 520 | { |
| 521 | static gdb_byte lit0 = DW_OP_lit0; |
| 522 | struct needs_frame_baton *nf_baton = baton; |
| 523 | |
| 524 | *start = &lit0; |
| 525 | *length = 1; |
| 526 | |
| 527 | nf_baton->needs_frame = 1; |
| 528 | } |
| 529 | |
| 530 | /* CFA accesses require a frame. */ |
| 531 | |
| 532 | static CORE_ADDR |
| 533 | needs_frame_frame_cfa (void *baton) |
| 534 | { |
| 535 | struct needs_frame_baton *nf_baton = baton; |
| 536 | nf_baton->needs_frame = 1; |
| 537 | return 1; |
| 538 | } |
| 539 | |
| 540 | /* Thread-local accesses do require a frame. */ |
| 541 | static CORE_ADDR |
| 542 | needs_frame_tls_address (void *baton, CORE_ADDR offset) |
| 543 | { |
| 544 | struct needs_frame_baton *nf_baton = baton; |
| 545 | nf_baton->needs_frame = 1; |
| 546 | return 1; |
| 547 | } |
| 548 | |
| 549 | /* Return non-zero iff the location expression at DATA (length SIZE) |
| 550 | requires a frame to evaluate. */ |
| 551 | |
| 552 | static int |
| 553 | dwarf2_loc_desc_needs_frame (gdb_byte *data, unsigned short size, |
| 554 | struct dwarf2_per_cu_data *per_cu) |
| 555 | { |
| 556 | struct needs_frame_baton baton; |
| 557 | struct dwarf_expr_context *ctx; |
| 558 | int in_reg; |
| 559 | struct cleanup *old_chain; |
| 560 | |
| 561 | baton.needs_frame = 0; |
| 562 | |
| 563 | ctx = new_dwarf_expr_context (); |
| 564 | old_chain = make_cleanup_free_dwarf_expr_context (ctx); |
| 565 | |
| 566 | ctx->gdbarch = get_objfile_arch (dwarf2_per_cu_objfile (per_cu)); |
| 567 | ctx->addr_size = dwarf2_per_cu_addr_size (per_cu); |
| 568 | ctx->baton = &baton; |
| 569 | ctx->read_reg = needs_frame_read_reg; |
| 570 | ctx->read_mem = needs_frame_read_mem; |
| 571 | ctx->get_frame_base = needs_frame_frame_base; |
| 572 | ctx->get_frame_cfa = needs_frame_frame_cfa; |
| 573 | ctx->get_tls_address = needs_frame_tls_address; |
| 574 | |
| 575 | dwarf_expr_eval (ctx, data, size); |
| 576 | |
| 577 | in_reg = ctx->location == DWARF_VALUE_REGISTER; |
| 578 | |
| 579 | if (ctx->num_pieces > 0) |
| 580 | { |
| 581 | int i; |
| 582 | |
| 583 | /* If the location has several pieces, and any of them are in |
| 584 | registers, then we will need a frame to fetch them from. */ |
| 585 | for (i = 0; i < ctx->num_pieces; i++) |
| 586 | if (ctx->pieces[i].location == DWARF_VALUE_REGISTER) |
| 587 | in_reg = 1; |
| 588 | } |
| 589 | |
| 590 | do_cleanups (old_chain); |
| 591 | |
| 592 | return baton.needs_frame || in_reg; |
| 593 | } |
| 594 | |
| 595 | static void |
| 596 | dwarf2_tracepoint_var_ref (struct symbol *symbol, struct gdbarch *gdbarch, |
| 597 | struct agent_expr *ax, struct axs_value *value, |
| 598 | gdb_byte *data, int size) |
| 599 | { |
| 600 | if (size == 0) |
| 601 | error (_("Symbol \"%s\" has been optimized out."), |
| 602 | SYMBOL_PRINT_NAME (symbol)); |
| 603 | |
| 604 | if (size == 1 |
| 605 | && data[0] >= DW_OP_reg0 |
| 606 | && data[0] <= DW_OP_reg31) |
| 607 | { |
| 608 | value->kind = axs_lvalue_register; |
| 609 | value->u.reg = data[0] - DW_OP_reg0; |
| 610 | } |
| 611 | else if (data[0] == DW_OP_regx) |
| 612 | { |
| 613 | ULONGEST reg; |
| 614 | read_uleb128 (data + 1, data + size, ®); |
| 615 | value->kind = axs_lvalue_register; |
| 616 | value->u.reg = reg; |
| 617 | } |
| 618 | else if (data[0] == DW_OP_fbreg) |
| 619 | { |
| 620 | /* And this is worse than just minimal; we should honor the frame base |
| 621 | as above. */ |
| 622 | int frame_reg; |
| 623 | LONGEST frame_offset; |
| 624 | gdb_byte *buf_end; |
| 625 | |
| 626 | buf_end = read_sleb128 (data + 1, data + size, &frame_offset); |
| 627 | if (buf_end != data + size) |
| 628 | error (_("Unexpected opcode after DW_OP_fbreg for symbol \"%s\"."), |
| 629 | SYMBOL_PRINT_NAME (symbol)); |
| 630 | |
| 631 | gdbarch_virtual_frame_pointer (gdbarch, |
| 632 | ax->scope, &frame_reg, &frame_offset); |
| 633 | ax_reg (ax, frame_reg); |
| 634 | ax_const_l (ax, frame_offset); |
| 635 | ax_simple (ax, aop_add); |
| 636 | |
| 637 | value->kind = axs_lvalue_memory; |
| 638 | } |
| 639 | else if (data[0] >= DW_OP_breg0 |
| 640 | && data[0] <= DW_OP_breg31) |
| 641 | { |
| 642 | unsigned int reg; |
| 643 | LONGEST offset; |
| 644 | gdb_byte *buf_end; |
| 645 | |
| 646 | reg = data[0] - DW_OP_breg0; |
| 647 | buf_end = read_sleb128 (data + 1, data + size, &offset); |
| 648 | if (buf_end != data + size) |
| 649 | error (_("Unexpected opcode after DW_OP_breg%u for symbol \"%s\"."), |
| 650 | reg, SYMBOL_PRINT_NAME (symbol)); |
| 651 | |
| 652 | ax_reg (ax, reg); |
| 653 | ax_const_l (ax, offset); |
| 654 | ax_simple (ax, aop_add); |
| 655 | |
| 656 | value->kind = axs_lvalue_memory; |
| 657 | } |
| 658 | else |
| 659 | error (_("Unsupported DWARF opcode 0x%x in the location of \"%s\"."), |
| 660 | data[0], SYMBOL_PRINT_NAME (symbol)); |
| 661 | } |
| 662 | \f |
| 663 | /* Return the value of SYMBOL in FRAME using the DWARF-2 expression |
| 664 | evaluator to calculate the location. */ |
| 665 | static struct value * |
| 666 | locexpr_read_variable (struct symbol *symbol, struct frame_info *frame) |
| 667 | { |
| 668 | struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); |
| 669 | struct value *val; |
| 670 | val = dwarf2_evaluate_loc_desc (symbol, frame, dlbaton->data, dlbaton->size, |
| 671 | dlbaton->per_cu); |
| 672 | |
| 673 | return val; |
| 674 | } |
| 675 | |
| 676 | /* Return non-zero iff we need a frame to evaluate SYMBOL. */ |
| 677 | static int |
| 678 | locexpr_read_needs_frame (struct symbol *symbol) |
| 679 | { |
| 680 | struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); |
| 681 | return dwarf2_loc_desc_needs_frame (dlbaton->data, dlbaton->size, |
| 682 | dlbaton->per_cu); |
| 683 | } |
| 684 | |
| 685 | /* Print a natural-language description of SYMBOL to STREAM. */ |
| 686 | static int |
| 687 | locexpr_describe_location (struct symbol *symbol, struct ui_file *stream) |
| 688 | { |
| 689 | /* FIXME: be more extensive. */ |
| 690 | struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); |
| 691 | int addr_size = dwarf2_per_cu_addr_size (dlbaton->per_cu); |
| 692 | |
| 693 | if (dlbaton->size == 1 |
| 694 | && dlbaton->data[0] >= DW_OP_reg0 |
| 695 | && dlbaton->data[0] <= DW_OP_reg31) |
| 696 | { |
| 697 | struct objfile *objfile = dwarf2_per_cu_objfile (dlbaton->per_cu); |
| 698 | struct gdbarch *gdbarch = get_objfile_arch (objfile); |
| 699 | int regno = gdbarch_dwarf2_reg_to_regnum (gdbarch, |
| 700 | dlbaton->data[0] - DW_OP_reg0); |
| 701 | fprintf_filtered (stream, |
| 702 | "a variable in register %s", |
| 703 | gdbarch_register_name (gdbarch, regno)); |
| 704 | return 1; |
| 705 | } |
| 706 | |
| 707 | /* The location expression for a TLS variable looks like this (on a |
| 708 | 64-bit LE machine): |
| 709 | |
| 710 | DW_AT_location : 10 byte block: 3 4 0 0 0 0 0 0 0 e0 |
| 711 | (DW_OP_addr: 4; DW_OP_GNU_push_tls_address) |
| 712 | |
| 713 | 0x3 is the encoding for DW_OP_addr, which has an operand as long |
| 714 | as the size of an address on the target machine (here is 8 |
| 715 | bytes). 0xe0 is the encoding for DW_OP_GNU_push_tls_address. |
| 716 | The operand represents the offset at which the variable is within |
| 717 | the thread local storage. */ |
| 718 | |
| 719 | if (dlbaton->size > 1 |
| 720 | && dlbaton->data[dlbaton->size - 1] == DW_OP_GNU_push_tls_address) |
| 721 | if (dlbaton->data[0] == DW_OP_addr) |
| 722 | { |
| 723 | struct objfile *objfile = dwarf2_per_cu_objfile (dlbaton->per_cu); |
| 724 | struct gdbarch *gdbarch = get_objfile_arch (objfile); |
| 725 | CORE_ADDR offset = dwarf2_read_address (gdbarch, |
| 726 | &dlbaton->data[1], |
| 727 | &dlbaton->data[dlbaton->size - 1], |
| 728 | addr_size); |
| 729 | fprintf_filtered (stream, |
| 730 | "a thread-local variable at offset %s in the " |
| 731 | "thread-local storage for `%s'", |
| 732 | paddress (gdbarch, offset), objfile->name); |
| 733 | return 1; |
| 734 | } |
| 735 | |
| 736 | |
| 737 | fprintf_filtered (stream, |
| 738 | "a variable with complex or multiple locations (DWARF2)"); |
| 739 | return 1; |
| 740 | } |
| 741 | |
| 742 | |
| 743 | /* Describe the location of SYMBOL as an agent value in VALUE, generating |
| 744 | any necessary bytecode in AX. |
| 745 | |
| 746 | NOTE drow/2003-02-26: This function is extremely minimal, because |
| 747 | doing it correctly is extremely complicated and there is no |
| 748 | publicly available stub with tracepoint support for me to test |
| 749 | against. When there is one this function should be revisited. */ |
| 750 | |
| 751 | static void |
| 752 | locexpr_tracepoint_var_ref (struct symbol *symbol, struct gdbarch *gdbarch, |
| 753 | struct agent_expr *ax, struct axs_value *value) |
| 754 | { |
| 755 | struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); |
| 756 | |
| 757 | dwarf2_tracepoint_var_ref (symbol, gdbarch, ax, value, |
| 758 | dlbaton->data, dlbaton->size); |
| 759 | } |
| 760 | |
| 761 | /* The set of location functions used with the DWARF-2 expression |
| 762 | evaluator. */ |
| 763 | const struct symbol_computed_ops dwarf2_locexpr_funcs = { |
| 764 | locexpr_read_variable, |
| 765 | locexpr_read_needs_frame, |
| 766 | locexpr_describe_location, |
| 767 | locexpr_tracepoint_var_ref |
| 768 | }; |
| 769 | |
| 770 | |
| 771 | /* Wrapper functions for location lists. These generally find |
| 772 | the appropriate location expression and call something above. */ |
| 773 | |
| 774 | /* Return the value of SYMBOL in FRAME using the DWARF-2 expression |
| 775 | evaluator to calculate the location. */ |
| 776 | static struct value * |
| 777 | loclist_read_variable (struct symbol *symbol, struct frame_info *frame) |
| 778 | { |
| 779 | struct dwarf2_loclist_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); |
| 780 | struct value *val; |
| 781 | gdb_byte *data; |
| 782 | size_t size; |
| 783 | |
| 784 | data = find_location_expression (dlbaton, &size, |
| 785 | frame ? get_frame_address_in_block (frame) |
| 786 | : 0); |
| 787 | if (data == NULL) |
| 788 | { |
| 789 | val = allocate_value (SYMBOL_TYPE (symbol)); |
| 790 | VALUE_LVAL (val) = not_lval; |
| 791 | set_value_optimized_out (val, 1); |
| 792 | } |
| 793 | else |
| 794 | val = dwarf2_evaluate_loc_desc (symbol, frame, data, size, |
| 795 | dlbaton->per_cu); |
| 796 | |
| 797 | return val; |
| 798 | } |
| 799 | |
| 800 | /* Return non-zero iff we need a frame to evaluate SYMBOL. */ |
| 801 | static int |
| 802 | loclist_read_needs_frame (struct symbol *symbol) |
| 803 | { |
| 804 | /* If there's a location list, then assume we need to have a frame |
| 805 | to choose the appropriate location expression. With tracking of |
| 806 | global variables this is not necessarily true, but such tracking |
| 807 | is disabled in GCC at the moment until we figure out how to |
| 808 | represent it. */ |
| 809 | |
| 810 | return 1; |
| 811 | } |
| 812 | |
| 813 | /* Print a natural-language description of SYMBOL to STREAM. */ |
| 814 | static int |
| 815 | loclist_describe_location (struct symbol *symbol, struct ui_file *stream) |
| 816 | { |
| 817 | /* FIXME: Could print the entire list of locations. */ |
| 818 | fprintf_filtered (stream, "a variable with multiple locations"); |
| 819 | return 1; |
| 820 | } |
| 821 | |
| 822 | /* Describe the location of SYMBOL as an agent value in VALUE, generating |
| 823 | any necessary bytecode in AX. */ |
| 824 | static void |
| 825 | loclist_tracepoint_var_ref (struct symbol *symbol, struct gdbarch *gdbarch, |
| 826 | struct agent_expr *ax, struct axs_value *value) |
| 827 | { |
| 828 | struct dwarf2_loclist_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); |
| 829 | gdb_byte *data; |
| 830 | size_t size; |
| 831 | |
| 832 | data = find_location_expression (dlbaton, &size, ax->scope); |
| 833 | if (data == NULL) |
| 834 | error (_("Variable \"%s\" is not available."), SYMBOL_NATURAL_NAME (symbol)); |
| 835 | |
| 836 | dwarf2_tracepoint_var_ref (symbol, gdbarch, ax, value, data, size); |
| 837 | } |
| 838 | |
| 839 | /* The set of location functions used with the DWARF-2 expression |
| 840 | evaluator and location lists. */ |
| 841 | const struct symbol_computed_ops dwarf2_loclist_funcs = { |
| 842 | loclist_read_variable, |
| 843 | loclist_read_needs_frame, |
| 844 | loclist_describe_location, |
| 845 | loclist_tracepoint_var_ref |
| 846 | }; |