gdb/block.c

   1 /* Block-related functions for the GNU debugger, GDB.
   2
   3    Copyright (C) 2003-2014 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 "block.h"
  22 #include "symtab.h"
  23 #include "symfile.h"
  24 #include "gdb_obstack.h"
  25 #include "cp-support.h"
  26 #include "addrmap.h"
  27 #include "gdbtypes.h"
  28
  29 /* This is used by struct block to store namespace-related info for
  30    C++ files, namely using declarations and the current namespace in
  31    scope.  */
  32
  33 struct block_namespace_info
  34 {
  35   const char *scope;
  36   struct using_direct *using;
  37 };
  38
  39 static void block_initialize_namespace (struct block *block,
  40                                         struct obstack *obstack);
  41
  42 /* Return Nonzero if block a is lexically nested within block b,
  43    or if a and b have the same pc range.
  44    Return zero otherwise.  */
  45
  46 int
  47 contained_in (const struct block *a, const struct block *b)
  48 {
  49   if (!a || !b)
  50     return 0;
  51
  52   do
  53     {
  54       if (a == b)
  55         return 1;
  56       /* If A is a function block, then A cannot be contained in B,
  57          except if A was inlined.  */
  58       if (BLOCK_FUNCTION (a) != NULL && !block_inlined_p (a))
  59         return 0;
  60       a = BLOCK_SUPERBLOCK (a);
  61     }
  62   while (a != NULL);
  63
  64   return 0;
  65 }
  66
  67
  68 /* Return the symbol for the function which contains a specified
  69    lexical block, described by a struct block BL.  The return value
  70    will not be an inlined function; the containing function will be
  71    returned instead.  */
  72
  73 struct symbol *
  74 block_linkage_function (const struct block *bl)
  75 {
  76   while ((BLOCK_FUNCTION (bl) == NULL || block_inlined_p (bl))
  77          && BLOCK_SUPERBLOCK (bl) != NULL)
  78     bl = BLOCK_SUPERBLOCK (bl);
  79
  80   return BLOCK_FUNCTION (bl);
  81 }
  82
  83 /* Return the symbol for the function which contains a specified
  84    block, described by a struct block BL.  The return value will be
  85    the closest enclosing function, which might be an inline
  86    function.  */
  87
  88 struct symbol *
  89 block_containing_function (const struct block *bl)
  90 {
  91   while (BLOCK_FUNCTION (bl) == NULL && BLOCK_SUPERBLOCK (bl) != NULL)
  92     bl = BLOCK_SUPERBLOCK (bl);
  93
  94   return BLOCK_FUNCTION (bl);
  95 }
  96
  97 /* Return one if BL represents an inlined function.  */
  98
  99 int
 100 block_inlined_p (const struct block *bl)
 101 {
 102   return BLOCK_FUNCTION (bl) != NULL && SYMBOL_INLINED (BLOCK_FUNCTION (bl));
 103 }
 104
 105 /* A helper function that checks whether PC is in the blockvector BL.
 106    It returns the containing block if there is one, or else NULL.  */
 107
 108 static struct block *
 109 find_block_in_blockvector (const struct blockvector *bl, CORE_ADDR pc)
 110 {
 111   struct block *b;
 112   int bot, top, half;
 113
 114   /* If we have an addrmap mapping code addresses to blocks, then use
 115      that.  */
 116   if (BLOCKVECTOR_MAP (bl))
 117     return addrmap_find (BLOCKVECTOR_MAP (bl), pc);
 118
 119   /* Otherwise, use binary search to find the last block that starts
 120      before PC.
 121      Note: GLOBAL_BLOCK is block 0, STATIC_BLOCK is block 1.
 122      They both have the same START,END values.
 123      Historically this code would choose STATIC_BLOCK over GLOBAL_BLOCK but the
 124      fact that this choice was made was subtle, now we make it explicit.  */
 125   gdb_assert (BLOCKVECTOR_NBLOCKS (bl) >= 2);
 126   bot = STATIC_BLOCK;
 127   top = BLOCKVECTOR_NBLOCKS (bl);
 128
 129   while (top - bot > 1)
 130     {
 131       half = (top - bot + 1) >> 1;
 132       b = BLOCKVECTOR_BLOCK (bl, bot + half);
 133       if (BLOCK_START (b) <= pc)
 134         bot += half;
 135       else
 136         top = bot + half;
 137     }
 138
 139   /* Now search backward for a block that ends after PC.  */
 140
 141   while (bot >= STATIC_BLOCK)
 142     {
 143       b = BLOCKVECTOR_BLOCK (bl, bot);
 144       if (BLOCK_END (b) > pc)
 145         return b;
 146       bot--;
 147     }
 148
 149   return NULL;
 150 }
 151
 152 /* Return the blockvector immediately containing the innermost lexical
 153    block containing the specified pc value and section, or 0 if there
 154    is none.  PBLOCK is a pointer to the block.  If PBLOCK is NULL, we
 155    don't pass this information back to the caller.  */
 156
 157 const struct blockvector *
 158 blockvector_for_pc_sect (CORE_ADDR pc, struct obj_section *section,
 159                          const struct block **pblock,
 160                          struct compunit_symtab *cust)
 161 {
 162   const struct blockvector *bl;
 163   struct block *b;
 164
 165   if (cust == NULL)
 166     {
 167       /* First search all symtabs for one whose file contains our pc */
 168       cust = find_pc_sect_compunit_symtab (pc, section);
 169       if (cust == NULL)
 170         return 0;
 171     }
 172
 173   bl = COMPUNIT_BLOCKVECTOR (cust);
 174
 175   /* Then search that symtab for the smallest block that wins.  */
 176   b = find_block_in_blockvector (bl, pc);
 177   if (b == NULL)
 178     return NULL;
 179
 180   if (pblock)
 181     *pblock = b;
 182   return bl;
 183 }
 184
 185 /* Return true if the blockvector BV contains PC, false otherwise.  */
 186
 187 int
 188 blockvector_contains_pc (const struct blockvector *bv, CORE_ADDR pc)
 189 {
 190   return find_block_in_blockvector (bv, pc) != NULL;
 191 }
 192
 193 /* Return call_site for specified PC in GDBARCH.  PC must match exactly, it
 194    must be the next instruction after call (or after tail call jump).  Throw
 195    NO_ENTRY_VALUE_ERROR otherwise.  This function never returns NULL.  */
 196
 197 struct call_site *
 198 call_site_for_pc (struct gdbarch *gdbarch, CORE_ADDR pc)
 199 {
 200   struct compunit_symtab *cust;
 201   void **slot = NULL;
 202
 203   /* -1 as tail call PC can be already after the compilation unit range.  */
 204   cust = find_pc_compunit_symtab (pc - 1);
 205
 206   if (cust != NULL && COMPUNIT_CALL_SITE_HTAB (cust) != NULL)
 207     slot = htab_find_slot (COMPUNIT_CALL_SITE_HTAB (cust), &pc, NO_INSERT);
 208
 209   if (slot == NULL)
 210     {
 211       struct bound_minimal_symbol msym = lookup_minimal_symbol_by_pc (pc);
 212
 213       /* DW_TAG_gnu_call_site will be missing just if GCC could not determine
 214          the call target.  */
 215       throw_error (NO_ENTRY_VALUE_ERROR,
 216                    _("DW_OP_GNU_entry_value resolving cannot find "
 217                      "DW_TAG_GNU_call_site %s in %s"),
 218                    paddress (gdbarch, pc),
 219                    (msym.minsym == NULL ? "???"
 220                     : MSYMBOL_PRINT_NAME (msym.minsym)));
 221     }
 222
 223   return *slot;
 224 }
 225
 226 /* Return the blockvector immediately containing the innermost lexical block
 227    containing the specified pc value, or 0 if there is none.
 228    Backward compatibility, no section.  */
 229
 230 const struct blockvector *
 231 blockvector_for_pc (CORE_ADDR pc, const struct block **pblock)
 232 {
 233   return blockvector_for_pc_sect (pc, find_pc_mapped_section (pc),
 234                                   pblock, NULL);
 235 }
 236
 237 /* Return the innermost lexical block containing the specified pc value
 238    in the specified section, or 0 if there is none.  */
 239
 240 const struct block *
 241 block_for_pc_sect (CORE_ADDR pc, struct obj_section *section)
 242 {
 243   const struct blockvector *bl;
 244   const struct block *b;
 245
 246   bl = blockvector_for_pc_sect (pc, section, &b, NULL);
 247   if (bl)
 248     return b;
 249   return 0;
 250 }
 251
 252 /* Return the innermost lexical block containing the specified pc value,
 253    or 0 if there is none.  Backward compatibility, no section.  */
 254
 255 const struct block *
 256 block_for_pc (CORE_ADDR pc)
 257 {
 258   return block_for_pc_sect (pc, find_pc_mapped_section (pc));
 259 }
 260
 261 /* Now come some functions designed to deal with C++ namespace issues.
 262    The accessors are safe to use even in the non-C++ case.  */
 263
 264 /* This returns the namespace that BLOCK is enclosed in, or "" if it
 265    isn't enclosed in a namespace at all.  This travels the chain of
 266    superblocks looking for a scope, if necessary.  */
 267
 268 const char *
 269 block_scope (const struct block *block)
 270 {
 271   for (; block != NULL; block = BLOCK_SUPERBLOCK (block))
 272     {
 273       if (BLOCK_NAMESPACE (block) != NULL
 274           && BLOCK_NAMESPACE (block)->scope != NULL)
 275         return BLOCK_NAMESPACE (block)->scope;
 276     }
 277
 278   return "";
 279 }
 280
 281 /* Set BLOCK's scope member to SCOPE; if needed, allocate memory via
 282    OBSTACK.  (It won't make a copy of SCOPE, however, so that already
 283    has to be allocated correctly.)  */
 284
 285 void
 286 block_set_scope (struct block *block, const char *scope,
 287                  struct obstack *obstack)
 288 {
 289   block_initialize_namespace (block, obstack);
 290
 291   BLOCK_NAMESPACE (block)->scope = scope;
 292 }
 293
 294 /* This returns the using directives list associated with BLOCK, if
 295    any.  */
 296
 297 struct using_direct *
 298 block_using (const struct block *block)
 299 {
 300   if (block == NULL || BLOCK_NAMESPACE (block) == NULL)
 301     return NULL;
 302   else
 303     return BLOCK_NAMESPACE (block)->using;
 304 }
 305
 306 /* Set BLOCK's using member to USING; if needed, allocate memory via
 307    OBSTACK.  (It won't make a copy of USING, however, so that already
 308    has to be allocated correctly.)  */
 309
 310 void
 311 block_set_using (struct block *block,
 312                  struct using_direct *using,
 313                  struct obstack *obstack)
 314 {
 315   block_initialize_namespace (block, obstack);
 316
 317   BLOCK_NAMESPACE (block)->using = using;
 318 }
 319
 320 /* If BLOCK_NAMESPACE (block) is NULL, allocate it via OBSTACK and
 321    ititialize its members to zero.  */
 322
 323 static void
 324 block_initialize_namespace (struct block *block, struct obstack *obstack)
 325 {
 326   if (BLOCK_NAMESPACE (block) == NULL)
 327     {
 328       BLOCK_NAMESPACE (block)
 329         = obstack_alloc (obstack, sizeof (struct block_namespace_info));
 330       BLOCK_NAMESPACE (block)->scope = NULL;
 331       BLOCK_NAMESPACE (block)->using = NULL;
 332     }
 333 }
 334
 335 /* Return the static block associated to BLOCK.  Return NULL if block
 336    is NULL or if block is a global block.  */
 337
 338 const struct block *
 339 block_static_block (const struct block *block)
 340 {
 341   if (block == NULL || BLOCK_SUPERBLOCK (block) == NULL)
 342     return NULL;
 343
 344   while (BLOCK_SUPERBLOCK (BLOCK_SUPERBLOCK (block)) != NULL)
 345     block = BLOCK_SUPERBLOCK (block);
 346
 347   return block;
 348 }
 349
 350 /* Return the static block associated to BLOCK.  Return NULL if block
 351    is NULL.  */
 352
 353 const struct block *
 354 block_global_block (const struct block *block)
 355 {
 356   if (block == NULL)
 357     return NULL;
 358
 359   while (BLOCK_SUPERBLOCK (block) != NULL)
 360     block = BLOCK_SUPERBLOCK (block);
 361
 362   return block;
 363 }
 364
 365 /* Allocate a block on OBSTACK, and initialize its elements to
 366    zero/NULL.  This is useful for creating "dummy" blocks that don't
 367    correspond to actual source files.
 368
 369    Warning: it sets the block's BLOCK_DICT to NULL, which isn't a
 370    valid value.  If you really don't want the block to have a
 371    dictionary, then you should subsequently set its BLOCK_DICT to
 372    dict_create_linear (obstack, NULL).  */
 373
 374 struct block *
 375 allocate_block (struct obstack *obstack)
 376 {
 377   struct block *bl = OBSTACK_ZALLOC (obstack, struct block);
 378
 379   return bl;
 380 }
 381
 382 /* Allocate a global block.  */
 383
 384 struct block *
 385 allocate_global_block (struct obstack *obstack)
 386 {
 387   struct global_block *bl = OBSTACK_ZALLOC (obstack, struct global_block);
 388
 389   return &bl->block;
 390 }
 391
 392 /* Set the compunit of the global block.  */
 393
 394 void
 395 set_block_compunit_symtab (struct block *block, struct compunit_symtab *cu)
 396 {
 397   struct global_block *gb;
 398
 399   gdb_assert (BLOCK_SUPERBLOCK (block) == NULL);
 400   gb = (struct global_block *) block;
 401   gdb_assert (gb->compunit_symtab == NULL);
 402   gb->compunit_symtab = cu;
 403 }
 404
 405 /* Return the compunit of the global block.  */
 406
 407 static struct compunit_symtab *
 408 get_block_compunit_symtab (const struct block *block)
 409 {
 410   struct global_block *gb;
 411
 412   gdb_assert (BLOCK_SUPERBLOCK (block) == NULL);
 413   gb = (struct global_block *) block;
 414   gdb_assert (gb->compunit_symtab != NULL);
 415   return gb->compunit_symtab;
 416 }
 417
 418 \f
 419
 420 /* Initialize a block iterator, either to iterate over a single block,
 421    or, for static and global blocks, all the included symtabs as
 422    well.  */
 423
 424 static void
 425 initialize_block_iterator (const struct block *block,
 426                            struct block_iterator *iter)
 427 {
 428   enum block_enum which;
 429   struct compunit_symtab *cu;
 430
 431   iter->idx = -1;
 432
 433   if (BLOCK_SUPERBLOCK (block) == NULL)
 434     {
 435       which = GLOBAL_BLOCK;
 436       cu = get_block_compunit_symtab (block);
 437     }
 438   else if (BLOCK_SUPERBLOCK (BLOCK_SUPERBLOCK (block)) == NULL)
 439     {
 440       which = STATIC_BLOCK;
 441       cu = get_block_compunit_symtab (BLOCK_SUPERBLOCK (block));
 442     }
 443   else
 444     {
 445       iter->d.block = block;
 446       /* A signal value meaning that we're iterating over a single
 447          block.  */
 448       iter->which = FIRST_LOCAL_BLOCK;
 449       return;
 450     }
 451
 452   /* If this is an included symtab, find the canonical includer and
 453      use it instead.  */
 454   while (cu->user != NULL)
 455     cu = cu->user;
 456
 457   /* Putting this check here simplifies the logic of the iterator
 458      functions.  If there are no included symtabs, we only need to
 459      search a single block, so we might as well just do that
 460      directly.  */
 461   if (cu->includes == NULL)
 462     {
 463       iter->d.block = block;
 464       /* A signal value meaning that we're iterating over a single
 465          block.  */
 466       iter->which = FIRST_LOCAL_BLOCK;
 467     }
 468   else
 469     {
 470       iter->d.compunit_symtab = cu;
 471       iter->which = which;
 472     }
 473 }
 474
 475 /* A helper function that finds the current compunit over whose static
 476    or global block we should iterate.  */
 477
 478 static struct compunit_symtab *
 479 find_iterator_compunit_symtab (struct block_iterator *iterator)
 480 {
 481   if (iterator->idx == -1)
 482     return iterator->d.compunit_symtab;
 483   return iterator->d.compunit_symtab->includes[iterator->idx];
 484 }
 485
 486 /* Perform a single step for a plain block iterator, iterating across
 487    symbol tables as needed.  Returns the next symbol, or NULL when
 488    iteration is complete.  */
 489
 490 static struct symbol *
 491 block_iterator_step (struct block_iterator *iterator, int first)
 492 {
 493   struct symbol *sym;
 494
 495   gdb_assert (iterator->which != FIRST_LOCAL_BLOCK);
 496
 497   while (1)
 498     {
 499       if (first)
 500         {
 501           struct compunit_symtab *cust
 502             = find_iterator_compunit_symtab (iterator);
 503           const struct block *block;
 504
 505           /* Iteration is complete.  */
 506           if (cust == NULL)
 507             return  NULL;
 508
 509           block = BLOCKVECTOR_BLOCK (COMPUNIT_BLOCKVECTOR (cust),
 510                                      iterator->which);
 511           sym = dict_iterator_first (BLOCK_DICT (block), &iterator->dict_iter);
 512         }
 513       else
 514         sym = dict_iterator_next (&iterator->dict_iter);
 515
 516       if (sym != NULL)
 517         return sym;
 518
 519       /* We have finished iterating the appropriate block of one
 520          symtab.  Now advance to the next symtab and begin iteration
 521          there.  */
 522       ++iterator->idx;
 523       first = 1;
 524     }
 525 }
 526
 527 /* See block.h.  */
 528
 529 struct symbol *
 530 block_iterator_first (const struct block *block,
 531                       struct block_iterator *iterator)
 532 {
 533   initialize_block_iterator (block, iterator);
 534
 535   if (iterator->which == FIRST_LOCAL_BLOCK)
 536     return dict_iterator_first (block->dict, &iterator->dict_iter);
 537
 538   return block_iterator_step (iterator, 1);
 539 }
 540
 541 /* See block.h.  */
 542
 543 struct symbol *
 544 block_iterator_next (struct block_iterator *iterator)
 545 {
 546   if (iterator->which == FIRST_LOCAL_BLOCK)
 547     return dict_iterator_next (&iterator->dict_iter);
 548
 549   return block_iterator_step (iterator, 0);
 550 }
 551
 552 /* Perform a single step for a "name" block iterator, iterating across
 553    symbol tables as needed.  Returns the next symbol, or NULL when
 554    iteration is complete.  */
 555
 556 static struct symbol *
 557 block_iter_name_step (struct block_iterator *iterator, const char *name,
 558                       int first)
 559 {
 560   struct symbol *sym;
 561
 562   gdb_assert (iterator->which != FIRST_LOCAL_BLOCK);
 563
 564   while (1)
 565     {
 566       if (first)
 567         {
 568           struct compunit_symtab *cust
 569             = find_iterator_compunit_symtab (iterator);
 570           const struct block *block;
 571
 572           /* Iteration is complete.  */
 573           if (cust == NULL)
 574             return  NULL;
 575
 576           block = BLOCKVECTOR_BLOCK (COMPUNIT_BLOCKVECTOR (cust),
 577                                      iterator->which);
 578           sym = dict_iter_name_first (BLOCK_DICT (block), name,
 579                                       &iterator->dict_iter);
 580         }
 581       else
 582         sym = dict_iter_name_next (name, &iterator->dict_iter);
 583
 584       if (sym != NULL)
 585         return sym;
 586
 587       /* We have finished iterating the appropriate block of one
 588          symtab.  Now advance to the next symtab and begin iteration
 589          there.  */
 590       ++iterator->idx;
 591       first = 1;
 592     }
 593 }
 594
 595 /* See block.h.  */
 596
 597 struct symbol *
 598 block_iter_name_first (const struct block *block,
 599                        const char *name,
 600                        struct block_iterator *iterator)
 601 {
 602   initialize_block_iterator (block, iterator);
 603
 604   if (iterator->which == FIRST_LOCAL_BLOCK)
 605     return dict_iter_name_first (block->dict, name, &iterator->dict_iter);
 606
 607   return block_iter_name_step (iterator, name, 1);
 608 }
 609
 610 /* See block.h.  */
 611
 612 struct symbol *
 613 block_iter_name_next (const char *name, struct block_iterator *iterator)
 614 {
 615   if (iterator->which == FIRST_LOCAL_BLOCK)
 616     return dict_iter_name_next (name, &iterator->dict_iter);
 617
 618   return block_iter_name_step (iterator, name, 0);
 619 }
 620
 621 /* Perform a single step for a "match" block iterator, iterating
 622    across symbol tables as needed.  Returns the next symbol, or NULL
 623    when iteration is complete.  */
 624
 625 static struct symbol *
 626 block_iter_match_step (struct block_iterator *iterator,
 627                        const char *name,
 628                        symbol_compare_ftype *compare,
 629                        int first)
 630 {
 631   struct symbol *sym;
 632
 633   gdb_assert (iterator->which != FIRST_LOCAL_BLOCK);
 634
 635   while (1)
 636     {
 637       if (first)
 638         {
 639           struct compunit_symtab *cust
 640             = find_iterator_compunit_symtab (iterator);
 641           const struct block *block;
 642
 643           /* Iteration is complete.  */
 644           if (cust == NULL)
 645             return  NULL;
 646
 647           block = BLOCKVECTOR_BLOCK (COMPUNIT_BLOCKVECTOR (cust),
 648                                      iterator->which);
 649           sym = dict_iter_match_first (BLOCK_DICT (block), name,
 650                                        compare, &iterator->dict_iter);
 651         }
 652       else
 653         sym = dict_iter_match_next (name, compare, &iterator->dict_iter);
 654
 655       if (sym != NULL)
 656         return sym;
 657
 658       /* We have finished iterating the appropriate block of one
 659          symtab.  Now advance to the next symtab and begin iteration
 660          there.  */
 661       ++iterator->idx;
 662       first = 1;
 663     }
 664 }
 665
 666 /* See block.h.  */
 667
 668 struct symbol *
 669 block_iter_match_first (const struct block *block,
 670                         const char *name,
 671                         symbol_compare_ftype *compare,
 672                         struct block_iterator *iterator)
 673 {
 674   initialize_block_iterator (block, iterator);
 675
 676   if (iterator->which == FIRST_LOCAL_BLOCK)
 677     return dict_iter_match_first (block->dict, name, compare,
 678                                   &iterator->dict_iter);
 679
 680   return block_iter_match_step (iterator, name, compare, 1);
 681 }
 682
 683 /* See block.h.  */
 684
 685 struct symbol *
 686 block_iter_match_next (const char *name,
 687                        symbol_compare_ftype *compare,
 688                        struct block_iterator *iterator)
 689 {
 690   if (iterator->which == FIRST_LOCAL_BLOCK)
 691     return dict_iter_match_next (name, compare, &iterator->dict_iter);
 692
 693   return block_iter_match_step (iterator, name, compare, 0);
 694 }
 695
 696 /* See block.h.
 697
 698    Note that if NAME is the demangled form of a C++ symbol, we will fail
 699    to find a match during the binary search of the non-encoded names, but
 700    for now we don't worry about the slight inefficiency of looking for
 701    a match we'll never find, since it will go pretty quick.  Once the
 702    binary search terminates, we drop through and do a straight linear
 703    search on the symbols.  Each symbol which is marked as being a ObjC/C++
 704    symbol (language_cplus or language_objc set) has both the encoded and
 705    non-encoded names tested for a match.  */
 706
 707 struct symbol *
 708 block_lookup_symbol (const struct block *block, const char *name,
 709                      const domain_enum domain)
 710 {
 711   struct block_iterator iter;
 712   struct symbol *sym;
 713
 714   if (!BLOCK_FUNCTION (block))
 715     {
 716       ALL_BLOCK_SYMBOLS_WITH_NAME (block, name, iter, sym)
 717         {
 718           if (symbol_matches_domain (SYMBOL_LANGUAGE (sym),
 719                                      SYMBOL_DOMAIN (sym), domain))
 720             return sym;
 721         }
 722       return NULL;
 723     }
 724   else
 725     {
 726       /* Note that parameter symbols do not always show up last in the
 727          list; this loop makes sure to take anything else other than
 728          parameter symbols first; it only uses parameter symbols as a
 729          last resort.  Note that this only takes up extra computation
 730          time on a match.  */
 731
 732       struct symbol *sym_found = NULL;
 733
 734       ALL_BLOCK_SYMBOLS_WITH_NAME (block, name, iter, sym)
 735         {
 736           if (symbol_matches_domain (SYMBOL_LANGUAGE (sym),
 737                                      SYMBOL_DOMAIN (sym), domain))
 738             {
 739               sym_found = sym;
 740               if (!SYMBOL_IS_ARGUMENT (sym))
 741                 {
 742                   break;
 743                 }
 744             }
 745         }
 746       return (sym_found);       /* Will be NULL if not found.  */
 747     }
 748 }