gas/symbols.c

   1 /* symbols.c -symbol table-
   2    Copyright (C) 1987, 1990, 1991 Free Software Foundation, Inc.
   3
   4 This file is part of GAS, the GNU Assembler.
   5
   6 GAS is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 1, or (at your option)
   9 any later version.
  10
  11 GAS is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GAS; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  19
  20 /* static const char rcsid[] = "$Id$"; */
  21
  22 #include "as.h"
  23
  24 #include "obstack.h"            /* For "symbols.h" */
  25 #include "subsegs.h"
  26
  27 #ifndef WORKING_DOT_WORD
  28 extern int new_broken_words;
  29 #endif
  30 #ifdef VMS
  31 extern char const_flag;
  32 #endif
  33
  34 static
  35 struct hash_control *
  36 sy_hash;                        /* symbol-name => struct symbol pointer */
  37
  38                                 /* Below are commented in "symbols.h". */
  39 unsigned int local_bss_counter;
  40 symbolS * symbol_rootP;
  41 symbolS * symbol_lastP;
  42 symbolS abs_symbol;
  43
  44 symbolS*                dot_text_symbol;
  45 symbolS*                dot_data_symbol;
  46 symbolS*                dot_bss_symbol;
  47
  48 struct obstack  notes;
  49
  50 /*
  51  * Un*x idea of local labels. They are made by "n:" where n
  52  * is any decimal digit. Refer to them with
  53  *  "nb" for previous (backward) n:
  54  *  or "nf" for next (forward) n:.
  55  *
  56  * Like Un*x AS, we have one set of local label counters for entire assembly,
  57  * not one set per (sub)segment like in most assemblers. This implies that
  58  * one can refer to a label in another segment, and indeed some crufty
  59  * compilers have done just that.
  60  *
  61  * I document the symbol names here to save duplicating words elsewhere.
  62  * The mth occurence of label n: is turned into the symbol "Ln^Am" where
  63  * n is a digit and m is a decimal number. "L" makes it a label discarded
  64  * unless debugging and "^A"('\1') ensures no ordinary symbol SHOULD get the
  65  * same name as a local label symbol. The first "4:" is "L4^A1" - the m
  66  * numbers begin at 1.
  67  */
  68
  69 typedef short unsigned int
  70 local_label_countT;
  71
  72 static local_label_countT
  73 local_label_counter[10];
  74
  75 static                          /* Returned to caller, then copied. */
  76   char symbol_name_build[12];   /* used for created names ("4f") */
  77
  78 #ifdef LOCAL_LABELS_DOLLAR
  79 int local_label_defined[10];
  80 #endif
  81
  82 \f
  83 void
  84 symbol_begin()
  85 {
  86   symbol_lastP = NULL;
  87   symbol_rootP = NULL;          /* In case we have 0 symbols (!!) */
  88   sy_hash = hash_new();
  89   bzero ((char *)(& abs_symbol), sizeof(abs_symbol));
  90   S_SET_SEGMENT(&abs_symbol, SEG_ABSOLUTE);     /* Can't initialise a union. Sigh. */
  91   bzero ((char *)(local_label_counter), sizeof(local_label_counter) );
  92   local_bss_counter = 0;
  93 }
  94 \f
  95 /*
  96  *                      local_label_name()
  97  *
  98  * Caller must copy returned name: we re-use the area for the next name.
  99  */
 100
 101 char *                          /* Return local label name. */
 102 local_label_name(n, augend)
 103      register int n;    /* we just saw "n:", "nf" or "nb" : n a digit */
 104      register int augend; /* 0 for nb, 1 for n:, nf */
 105 {
 106   register char *       p;
 107   register char *       q;
 108   char symbol_name_temporary[10]; /* build up a number, BACKWARDS */
 109
 110   know( n >= 0 );
 111   know( augend == 0 || augend == 1 );
 112   p = symbol_name_build;
 113   * p ++ = 'L';
 114   * p ++ = n + '0';             /* Make into ASCII */
 115   * p ++ = 1;                   /* ^A */
 116   n = local_label_counter [ n ] + augend;
 117                                 /* version number of this local label */
 118   /*
 119    * Next code just does sprintf( {}, "%d", n);
 120    * It is more elegant to do the next part recursively, but a procedure
 121    * call for each digit emitted is considered too costly.
 122    */
 123   q = symbol_name_temporary;
 124   for (*q++=0; n; q++)          /* emits NOTHING if n starts as 0 */
 125     {
 126       know(n>0);                /* We expect n > 0 always */
 127       *q = n % 10 + '0';
 128       n /= 10;
 129     }
 130   while (( * p ++ = * -- q ) != '\0') ;;
 131
 132   /* The label, as a '\0' ended string, starts at symbol_name_build. */
 133   return(symbol_name_build);
 134 } /* local_label_name() */
 135
 136
 137 void local_colon (n)
 138 int n;  /* just saw "n:" */
 139 {
 140   local_label_counter [n] ++;
 141 #ifdef LOCAL_LABELS_DOLLAR
 142   local_label_defined[n]=1;
 143 #endif
 144   colon (local_label_name (n, 0));
 145 }
 146 \f
 147 /*
 148  *                      symbol_new()
 149  *
 150  * Return a pointer to a new symbol.
 151  * Die if we can't make a new symbol.
 152  * Fill in the symbol's values.
 153  * Add symbol to end of symbol chain.
 154  *
 155  *
 156  * Please always call this to create a new symbol.
 157  *
 158  * Changes since 1985: Symbol names may not contain '\0'. Sigh.
 159  * 2nd argument is now a SEG rather than a TYPE.  The mapping between
 160  * segments and types is mostly encapsulated herein (actually, we inherit it
 161  * from macros in struc-symbol.h).
 162  */
 163
 164 symbolS *symbol_new(name, segment, value, frag)
 165 char *name;                     /* It is copied, the caller can destroy/modify */
 166 segT segment;                   /* Segment identifier (SEG_<something>) */
 167 long value;                     /* Symbol value */
 168 fragS *frag;                    /* Associated fragment */
 169 {
 170         unsigned int name_length;
 171         char *preserved_copy_of_name;
 172         symbolS *symbolP;
 173
 174         name_length = strlen(name) + 1; /* +1 for \0 */
 175         obstack_grow(&notes, name, name_length);
 176         preserved_copy_of_name = obstack_finish(&notes);
 177         symbolP = (symbolS *)obstack_alloc(&notes, sizeof(symbolS));
 178
 179 #if STRIP_UNDERSCORE
 180         S_SET_NAME(symbolP, (*preserved_copy_of_name == '_'
 181                                             ? preserved_copy_of_name + 1
 182                                             : preserved_copy_of_name));
 183 #else /* STRIP_UNDERSCORE */
 184         S_SET_NAME(symbolP, preserved_copy_of_name);
 185 #endif /* STRIP_UNDERSCORE */
 186
 187         S_SET_SEGMENT(symbolP, segment);
 188         S_SET_VALUE(symbolP, value);
 189         symbol_clear_list_pointers(symbolP);
 190
 191         symbolP->sy_frag = frag;
 192         symbolP->sy_forward = NULL; /* JF */
 193         symbolP->sy_number = ~0;
 194         symbolP->sy_name_offset = ~0;
 195
 196         /*
 197          * Link to end of symbol chain.
 198          */
 199         symbol_append(symbolP, symbol_lastP, &symbol_rootP, &symbol_lastP);
 200
 201         obj_symbol_new_hook(symbolP);
 202
 203 #ifdef DEBUG
 204         verify_symbol_chain(symbol_rootP, symbol_lastP);
 205 #endif /* DEBUG */
 206
 207         return(symbolP);
 208 } /* symbol_new() */
 209
 210 \f
 211 /*
 212  *                      colon()
 213  *
 214  * We have just seen "<name>:".
 215  * Creates a struct symbol unless it already exists.
 216  *
 217  * Gripes if we are redefining a symbol incompatibly (and ignores it).
 218  *
 219  */
 220 void colon(sym_name)            /* just seen "x:" - rattle symbols & frags */
 221      register char *  sym_name; /* symbol name, as a cannonical string */
 222                                 /* We copy this string: OK to alter later. */
 223 {
 224   register symbolS * symbolP; /* symbol we are working with */
 225
 226 #ifdef LOCAL_LABELS_DOLLAR
 227   /* Sun local labels go out of scope whenever a non-local symbol is defined.  */
 228
 229   if(*sym_name !='L')
 230     bzero((void *) local_label_defined, sizeof(local_label_defined));
 231 #endif
 232
 233 #ifndef WORKING_DOT_WORD
 234   if(new_broken_words) {
 235     struct broken_word *a;
 236     int possible_bytes;
 237     fragS *frag_tmp;
 238     char *frag_opcode;
 239     extern md_short_jump_size;
 240     extern md_long_jump_size;
 241
 242     possible_bytes=md_short_jump_size + new_broken_words * md_long_jump_size;
 243     frag_tmp=frag_now;
 244     frag_opcode=frag_var(rs_broken_word,
 245                          possible_bytes,
 246                          possible_bytes,
 247                          (relax_substateT) 0,
 248                          (symbolS *) broken_words,
 249                          0L,
 250                          NULL);
 251
 252     /* We want to store the pointer to where to insert the jump table in the
 253        fr_opcode of the rs_broken_word frag.  This requires a little hackery */
 254     while(frag_tmp && (frag_tmp->fr_type!=rs_broken_word || frag_tmp->fr_opcode))
 255       frag_tmp=frag_tmp->fr_next;
 256     know(frag_tmp);
 257     frag_tmp->fr_opcode=frag_opcode;
 258     new_broken_words = 0;
 259
 260     for(a=broken_words;a && a->dispfrag==0;a=a->next_broken_word)
 261       a->dispfrag=frag_tmp;
 262   }
 263 #endif
 264   if ((symbolP = symbol_find(sym_name)) != 0) {
 265 #ifdef  VMS
 266           /*
 267            *    If the new symbol is .comm AND it has a size of zero,
 268            *    we ignore it (i.e. the old symbol overrides it)
 269            */
 270           if ((SEGMENT_TO_SYMBOL_TYPE((int) now_seg) == (N_UNDF | N_EXT)) &&
 271               ((obstack_next_free(& frags) - frag_now->fr_literal) == 0))
 272               return;
 273           /*
 274            *    If the old symbol is .comm and it has a size of zero,
 275            *    we override it with the new symbol value.
 276            */
 277           if ((symbolP->sy_type == (N_UNDF | N_EXT))
 278               && (S_GET_VALUE(symbolP) == 0)) {
 279                   symbolP->sy_frag  = frag_now;
 280                   symbolP->sy_other = const_flag;
 281                   S_SET_VALUE(symbolP, obstack_next_free(& frags) - frag_now->fr_literal);
 282                   symbolP->sy_type |= SEGMENT_TO_SYMBOL_TYPE((int) now_seg); /* keep N_EXT bit */
 283                   return;
 284           }
 285 #endif  /* VMS */
 286           /*
 287            *    Now check for undefined symbols
 288            */
 289           if (!S_IS_DEFINED(symbolP)) {
 290                   if (S_GET_VALUE(symbolP) == 0) {
 291                           symbolP->sy_frag  = frag_now;
 292 #ifdef VMS
 293                           symbolP->sy_other = const_flag;
 294 #endif
 295                           S_SET_VALUE(symbolP, obstack_next_free(&frags) - frag_now->fr_literal);
 296                           S_SET_SEGMENT(symbolP, now_seg);
 297 #ifdef N_UNDF
 298                           know(N_UNDF == 0);
 299 #endif /* if we have one, it better be zero. */
 300
 301                   } else {
 302                           /*
 303                            *    There are still several cases to check:
 304                            *            A .comm/.lcomm symbol being redefined as
 305                            *                    initialized data is OK
 306                            *            A .comm/.lcomm symbol being redefined with
 307                            *                    a larger size is also OK
 308                            *
 309                            * This only used to be allowed on VMS gas, but Sun cc
 310                            * on the sparc also depends on it.
 311                            */
 312                           char New_Type = SEGMENT_TO_SYMBOL_TYPE((int) now_seg);
 313
 314                           if (((!S_IS_DEBUG(symbolP) && !S_IS_DEFINED(symbolP) && S_IS_EXTERNAL(symbolP))
 315                                || (S_GET_SEGMENT(symbolP) == SEG_BSS))
 316                               && ((now_seg == SEG_DATA)
 317                                   || (now_seg == S_GET_SEGMENT(symbolP)))) {
 318                                   /*
 319                                    *    Select which of the 2 cases this is
 320                                    */
 321                                   if (now_seg != SEG_DATA) {
 322                                           /*
 323                                            *   New .comm for prev .comm symbol.
 324                                            *    If the new size is larger we just
 325                                            *    change its value.  If the new size
 326                                            *    is smaller, we ignore this symbol
 327                                            */
 328                                           if (S_GET_VALUE(symbolP)
 329                                               < ((unsigned) (obstack_next_free(& frags) - frag_now->fr_literal))) {
 330                                                   S_SET_VALUE(symbolP,
 331                                                               obstack_next_free(& frags) -
 332                                                               frag_now->fr_literal);
 333                                           }
 334                                   } else {
 335                                           /*
 336                                            *    It is a .comm/.lcomm being converted
 337                                            *    to initialized data.
 338                                            */
 339                                           symbolP->sy_frag  = frag_now;
 340 #ifdef VMS
 341                                           symbolP->sy_other = const_flag;
 342 #endif /* VMS */
 343                                           S_SET_VALUE(symbolP, obstack_next_free(& frags) - frag_now->fr_literal);
 344                                           S_SET_SEGMENT(symbolP, now_seg); /* keep N_EXT bit */
 345                                   }
 346                           } else {
 347 #ifdef OBJ_COFF
 348                                   as_fatal("Symbol \"%s\" is already defined as \"%s\"/%d.",
 349                                            sym_name,
 350                                            segment_name(S_GET_SEGMENT(symbolP)),
 351                                            S_GET_VALUE(symbolP));
 352 #else /* OBJ_COFF */
 353                                   as_fatal("Symbol \"%s\" is already defined as \"%s\"/%d.%d.%d.",
 354                                            sym_name,
 355                                            segment_name(S_GET_SEGMENT(symbolP)),
 356                                            S_GET_OTHER(symbolP), S_GET_DESC(symbolP),
 357                                            S_GET_VALUE(symbolP));
 358 #endif /* OBJ_COFF */
 359                           }
 360                   } /* if the undefined symbol has no value */
 361           } else {
 362                   as_fatal("Symbol %s already defined.", sym_name);
 363           } /* if this symbol is not yet defined */
 364
 365   } else {
 366           symbolP = symbol_new(sym_name,
 367                                 now_seg,
 368                                 (valueT)(obstack_next_free(&frags)-frag_now->fr_literal),
 369                                 frag_now);
 370 #ifdef VMS
 371           S_SET_OTHER(symbolP, const_flag);
 372 #endif /* VMS */
 373
 374           symbol_table_insert(symbolP);
 375   } /* if we have seen this symbol before */
 376
 377   return;
 378 } /* colon() */
 379
 380 \f
 381 /*
 382  *                      symbol_table_insert()
 383  *
 384  * Die if we can't insert the symbol.
 385  *
 386  */
 387
 388 void symbol_table_insert(symbolP)
 389 symbolS *symbolP;
 390 {
 391         register char *error_string;
 392
 393         know(symbolP);
 394         know(S_GET_NAME(symbolP));
 395
 396         if (*(error_string = hash_jam(sy_hash, S_GET_NAME(symbolP), (char *)symbolP))) {
 397                 as_fatal("Inserting \"%s\" into symbol table failed: %s",
 398                          S_GET_NAME(symbolP), error_string);
 399         } /* on error */
 400 } /* symbol_table_insert() */
 401 \f
 402 /*
 403  *                      symbol_find_or_make()
 404  *
 405  * If a symbol name does not exist, create it as undefined, and insert
 406  * it into the symbol table. Return a pointer to it.
 407  */
 408 symbolS *symbol_find_or_make(name)
 409 char *name;
 410 {
 411         register symbolS *symbolP;
 412
 413         symbolP = symbol_find(name);
 414
 415         if (symbolP == NULL) {
 416                 symbolP = symbol_make(name);
 417
 418                 symbol_table_insert(symbolP);
 419         } /* if symbol wasn't found */
 420
 421         return(symbolP);
 422 } /* symbol_find_or_make() */
 423
 424 symbolS *symbol_make(name)
 425 char *name;
 426 {
 427         symbolS *symbolP;
 428
 429         /* Let the machine description default it, e.g. for register names. */
 430         symbolP = md_undefined_symbol(name);
 431
 432         if (!symbolP) {
 433                 symbolP = symbol_new(name,
 434                                      SEG_UNKNOWN,
 435                                      0,
 436                                      &zero_address_frag);
 437         } /* if md didn't build us a symbol */
 438
 439         return(symbolP);
 440 } /* symbol_make() */
 441
 442 /*
 443  *                      symbol_find()
 444  *
 445  * Implement symbol table lookup.
 446  * In:  A symbol's name as a string: '\0' can't be part of a symbol name.
 447  * Out: NULL if the name was not in the symbol table, else the address
 448  *      of a struct symbol associated with that name.
 449  */
 450
 451 symbolS *symbol_find(name)
 452 char *name;
 453 {
 454 #ifndef STRIP_UNDERSCORE
 455 #define STRIP_UNDERSCORE 0
 456 #endif /* STRIP_UNDERSCORE */
 457     return symbol_find_base(name, STRIP_UNDERSCORE);
 458 }
 459
 460 symbolS *symbol_find_base(name, strip_underscore)
 461 char *name;
 462 int strip_underscore;
 463 {
 464     if(strip_underscore && *name == '_') name++;
 465     return ( (symbolS *) hash_find( sy_hash, name ));
 466 }
 467
 468 /*
 469  * Once upon a time, symbols were kept in a singly linked list.  At
 470  * least coff needs to be able to rearrange them from time to time, for
 471  * which a doubly linked list is much more convenient.  Loic did these
 472  * as macros which seemed dangerous to me so they're now functions.
 473  * xoxorich.
 474  */
 475
 476 /* Link symbol ADDME after symbol TARGET in the chain. */
 477 void symbol_append(addme, target, rootPP, lastPP)
 478 symbolS *addme;
 479 symbolS *target;
 480 symbolS **rootPP;
 481 symbolS **lastPP;
 482 {
 483         if (target == NULL) {
 484                 know(*rootPP == NULL);
 485                 know(*lastPP == NULL);
 486                 *rootPP = addme;
 487                 *lastPP = addme;
 488                 return;
 489         } /* if the list is empty */
 490
 491         if (target->sy_next != NULL) {
 492 #ifdef SYMBOLS_NEED_BACKPOINTERS
 493                 target->sy_next->sy_previous = addme;
 494 #endif /* SYMBOLS_NEED_BACKPOINTERS */
 495         } else {
 496                 know(*lastPP == target);
 497                 *lastPP = addme;
 498         } /* if we have a next */
 499
 500         addme->sy_next = target->sy_next;
 501         target->sy_next = addme;
 502
 503 #ifdef SYMBOLS_NEED_BACKPOINTERS
 504         addme->sy_previous = target;
 505 #endif /* SYMBOLS_NEED_BACKPOINTERS */
 506
 507 #ifdef DEBUG
 508         verify_symbol_chain(*rootPP, *lastPP);
 509 #endif /* DEBUG */
 510
 511         return;
 512 } /* symbol_append() */
 513
 514 #ifdef SYMBOLS_NEED_BACKPOINTERS
 515 /* Remove SYMBOLP from the list. */
 516 void symbol_remove(symbolP, rootPP, lastPP)
 517 symbolS *symbolP;
 518 symbolS **rootPP;
 519 symbolS **lastPP;
 520 {
 521         if (symbolP == *rootPP) {
 522                 *rootPP = symbolP->sy_next;
 523         } /* if it was the root */
 524
 525         if (symbolP == *lastPP) {
 526                 *lastPP = symbolP->sy_previous;
 527         } /* if it was the tail */
 528
 529         if (symbolP->sy_next != NULL) {
 530                 symbolP->sy_next->sy_previous = symbolP->sy_previous;
 531         } /* if not last */
 532
 533         if (symbolP->sy_previous != NULL) {
 534                 symbolP->sy_previous->sy_next = symbolP->sy_next;
 535         } /* if not first */
 536
 537 #ifdef DEBUG
 538         verify_symbol_chain(*rootPP, *lastPP);
 539 #endif /* DEBUG */
 540
 541         return;
 542 } /* symbol_remove() */
 543
 544 /* Set the chain pointers of SYMBOL to null. */
 545 void symbol_clear_list_pointers(symbolP)
 546 symbolS *symbolP;
 547 {
 548     symbolP->sy_next = NULL;
 549     symbolP->sy_previous = NULL;
 550 } /* symbol_clear_list_pointers() */
 551
 552 /* Link symbol ADDME before symbol TARGET in the chain. */
 553 void symbol_insert(addme, target, rootPP, lastPP)
 554 symbolS *addme;
 555 symbolS *target;
 556 symbolS **rootPP;
 557 symbolS **lastPP;
 558 {
 559     if (target->sy_previous != NULL) {
 560             target->sy_previous->sy_next = addme;
 561     } else {
 562             know(*rootPP == target);
 563             *rootPP = addme;
 564     } /* if not first */
 565
 566     addme->sy_previous = target->sy_previous;
 567     target->sy_previous = addme;
 568     addme->sy_next = target;
 569
 570 #ifdef DEBUG
 571     verify_symbol_chain(*rootPP, *lastPP);
 572 #endif /* DEBUG */
 573
 574     return;
 575 } /* symbol_insert() */
 576 #endif /* SYMBOLS_NEED_BACKPOINTERS */
 577
 578 void verify_symbol_chain(rootP, lastP)
 579 symbolS *rootP;
 580 symbolS *lastP;
 581 {
 582         symbolS *symbolP = rootP;
 583
 584         if (symbolP == NULL) {
 585                 return;
 586         } /* empty chain */
 587
 588         for ( ; symbol_next(symbolP) != NULL; symbolP = symbol_next(symbolP)) {
 589 #ifdef SYMBOLS_NEED_BACKPOINTERS
 590                 /*$if (symbolP->sy_previous) {
 591                         know(symbolP->sy_previous->sy_next == symbolP);
 592                 } else {
 593                         know(symbolP == rootP);
 594                 }$*/ /* both directions */
 595                 know(symbolP->sy_next->sy_previous == symbolP);
 596 #else /* SYMBOLS_NEED_BACKPOINTERS */
 597                 ;
 598 #endif /* SYMBOLS_NEED_BACKPOINTERS */
 599         } /* verify pointers */
 600
 601         know(lastP == symbolP);
 602
 603         return;
 604 } /* verify_symbol_chain() */
 605
 606
 607 /*
 608  * Local Variables:
 609  * comment-column: 0
 610  * fill-column: 131
 611  * End:
 612  */
 613
 614 /* end: symbols.c */