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 2, 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  * decode name that may have been generated by local_label_name() above.  If
 138  * the name wasn't generated by local_label_name(), then return it unaltered.
 139  * This is used for error messages.
 140  */
 141
 142 char *decode_local_label_name(s)
 143 char *s;
 144 {
 145         char *symbol_decode;
 146         int label_number;
 147         int label_version;
 148         char *message_format = "\"%d\" (instance number %s of a local label)";
 149
 150         if (s[0] != 'L'
 151             || s[2] != 1) {
 152                 return(s);
 153         } /* not a local_label_name() generated name. */
 154
 155         label_number = s[1] - '0';
 156
 157         (void) sprintf(symbol_decode = obstack_alloc(&notes, strlen(s + 3) + strlen(message_format) + 10),
 158                 message_format, label_number, s + 3);
 159
 160         return(symbol_decode);
 161 } /* decode_local_label_name() */
 162
 163 void local_colon (n)
 164 int n;  /* just saw "n:" */
 165 {
 166   local_label_counter [n] ++;
 167 #ifdef LOCAL_LABELS_DOLLAR
 168   local_label_defined[n]=1;
 169 #endif
 170   colon (local_label_name (n, 0));
 171 }
 172 \f
 173 /*
 174  *                      symbol_new()
 175  *
 176  * Return a pointer to a new symbol.
 177  * Die if we can't make a new symbol.
 178  * Fill in the symbol's values.
 179  * Add symbol to end of symbol chain.
 180  *
 181  *
 182  * Please always call this to create a new symbol.
 183  *
 184  * Changes since 1985: Symbol names may not contain '\0'. Sigh.
 185  * 2nd argument is now a SEG rather than a TYPE.  The mapping between
 186  * segments and types is mostly encapsulated herein (actually, we inherit it
 187  * from macros in struc-symbol.h).
 188  */
 189
 190 symbolS *symbol_new(name, segment, value, frag)
 191 char *name;                     /* It is copied, the caller can destroy/modify */
 192 segT segment;                   /* Segment identifier (SEG_<something>) */
 193 long value;                     /* Symbol value */
 194 fragS *frag;                    /* Associated fragment */
 195 {
 196         unsigned int name_length;
 197         char *preserved_copy_of_name;
 198         symbolS *symbolP;
 199
 200         name_length = strlen(name) + 1; /* +1 for \0 */
 201         obstack_grow(&notes, name, name_length);
 202         preserved_copy_of_name = obstack_finish(&notes);
 203         symbolP = (symbolS *)obstack_alloc(&notes, sizeof(symbolS));
 204
 205  /* symbol must be born in some fixed state.  This seems as good as any. */
 206         memset(symbolP, 0, sizeof(symbolS));
 207
 208 #if STRIP_UNDERSCORE
 209         S_SET_NAME(symbolP, (*preserved_copy_of_name == '_'
 210                                             ? preserved_copy_of_name + 1
 211                                             : preserved_copy_of_name));
 212 #else /* STRIP_UNDERSCORE */
 213         S_SET_NAME(symbolP, preserved_copy_of_name);
 214 #endif /* STRIP_UNDERSCORE */
 215
 216         S_SET_SEGMENT(symbolP, segment);
 217         S_SET_VALUE(symbolP, value);
 218 /*      symbol_clear_list_pointers(symbolP); uneeded if symbol is born zeroed. */
 219
 220         symbolP->sy_frag = frag;
 221         /* krm: uneeded if symbol is born zeroed.
 222            symbolP->sy_forward = NULL; */ /* JF */
 223         symbolP->sy_number = ~0;
 224         symbolP->sy_name_offset = ~0;
 225
 226         /*
 227          * Link to end of symbol chain.
 228          */
 229         symbol_append(symbolP, symbol_lastP, &symbol_rootP, &symbol_lastP);
 230
 231         obj_symbol_new_hook(symbolP);
 232
 233 #ifdef DEBUG
 234         verify_symbol_chain(symbol_rootP, symbol_lastP);
 235 #endif /* DEBUG */
 236
 237         return(symbolP);
 238 } /* symbol_new() */
 239
 240 \f
 241 /*
 242  *                      colon()
 243  *
 244  * We have just seen "<name>:".
 245  * Creates a struct symbol unless it already exists.
 246  *
 247  * Gripes if we are redefining a symbol incompatibly (and ignores it).
 248  *
 249  */
 250 void colon(sym_name)            /* just seen "x:" - rattle symbols & frags */
 251      register char *  sym_name; /* symbol name, as a cannonical string */
 252                                 /* We copy this string: OK to alter later. */
 253 {
 254   register symbolS * symbolP; /* symbol we are working with */
 255
 256 #ifdef LOCAL_LABELS_DOLLAR
 257   /* Sun local labels go out of scope whenever a non-local symbol is defined.  */
 258
 259   if(*sym_name !='L')
 260     bzero((void *) local_label_defined, sizeof(local_label_defined));
 261 #endif
 262
 263 #ifndef WORKING_DOT_WORD
 264   if(new_broken_words) {
 265     struct broken_word *a;
 266     int possible_bytes;
 267     fragS *frag_tmp;
 268     char *frag_opcode;
 269     extern md_short_jump_size;
 270     extern md_long_jump_size;
 271
 272     possible_bytes=md_short_jump_size + new_broken_words * md_long_jump_size;
 273     frag_tmp=frag_now;
 274     frag_opcode=frag_var(rs_broken_word,
 275                          possible_bytes,
 276                          possible_bytes,
 277                          (relax_substateT) 0,
 278                          (symbolS *) broken_words,
 279                          0L,
 280                          NULL);
 281
 282     /* We want to store the pointer to where to insert the jump table in the
 283        fr_opcode of the rs_broken_word frag.  This requires a little hackery */
 284     while(frag_tmp && (frag_tmp->fr_type!=rs_broken_word || frag_tmp->fr_opcode))
 285       frag_tmp=frag_tmp->fr_next;
 286     know(frag_tmp);
 287     frag_tmp->fr_opcode=frag_opcode;
 288     new_broken_words = 0;
 289
 290     for(a=broken_words;a && a->dispfrag==0;a=a->next_broken_word)
 291       a->dispfrag=frag_tmp;
 292   }
 293 #endif
 294   if ((symbolP = symbol_find(sym_name)) != 0) {
 295 #ifdef  VMS
 296           /*
 297            *    If the new symbol is .comm AND it has a size of zero,
 298            *    we ignore it (i.e. the old symbol overrides it)
 299            */
 300           if ((SEGMENT_TO_SYMBOL_TYPE((int) now_seg) == (N_UNDF | N_EXT)) &&
 301               ((obstack_next_free(& frags) - frag_now->fr_literal) == 0))
 302               return;
 303           /*
 304            *    If the old symbol is .comm and it has a size of zero,
 305            *    we override it with the new symbol value.
 306            */
 307           if ((symbolP->sy_type == (N_UNDF | N_EXT))
 308               && (S_GET_VALUE(symbolP) == 0)) {
 309                   symbolP->sy_frag  = frag_now;
 310                   symbolP->sy_other = const_flag;
 311                   S_SET_VALUE(symbolP, obstack_next_free(& frags) - frag_now->fr_literal);
 312                   symbolP->sy_type |= SEGMENT_TO_SYMBOL_TYPE((int) now_seg); /* keep N_EXT bit */
 313                   return;
 314           }
 315 #endif  /* VMS */
 316           /*
 317            *    Now check for undefined symbols
 318            */
 319           if (!S_IS_DEFINED(symbolP)) {
 320                   if (S_GET_VALUE(symbolP) == 0) {
 321                           symbolP->sy_frag  = frag_now;
 322 #ifdef VMS
 323                           symbolP->sy_other = const_flag;
 324 #endif
 325                           S_SET_VALUE(symbolP, obstack_next_free(&frags) - frag_now->fr_literal);
 326                           S_SET_SEGMENT(symbolP, now_seg);
 327 #ifdef N_UNDF
 328                           know(N_UNDF == 0);
 329 #endif /* if we have one, it better be zero. */
 330
 331                   } else {
 332                           /*
 333                            *    There are still several cases to check:
 334                            *            A .comm/.lcomm symbol being redefined as
 335                            *                    initialized data is OK
 336                            *            A .comm/.lcomm symbol being redefined with
 337                            *                    a larger size is also OK
 338                            *
 339                            * This only used to be allowed on VMS gas, but Sun cc
 340                            * on the sparc also depends on it.
 341                            */
 342 /*                        char New_Type = SEGMENT_TO_SYMBOL_TYPE((int) now_seg); */
 343
 344                           if (((!S_IS_DEBUG(symbolP) && !S_IS_DEFINED(symbolP) && S_IS_EXTERNAL(symbolP))
 345                                || (S_GET_SEGMENT(symbolP) == SEG_BSS))
 346                               && ((now_seg == SEG_DATA)
 347                                   || (now_seg == S_GET_SEGMENT(symbolP)))) {
 348                                   /*
 349                                    *    Select which of the 2 cases this is
 350                                    */
 351                                   if (now_seg != SEG_DATA) {
 352                                           /*
 353                                            *   New .comm for prev .comm symbol.
 354                                            *    If the new size is larger we just
 355                                            *    change its value.  If the new size
 356                                            *    is smaller, we ignore this symbol
 357                                            */
 358                                           if (S_GET_VALUE(symbolP)
 359                                               < ((unsigned) (obstack_next_free(& frags) - frag_now->fr_literal))) {
 360                                                   S_SET_VALUE(symbolP,
 361                                                               obstack_next_free(& frags) -
 362                                                               frag_now->fr_literal);
 363                                           }
 364                                   } else {
 365                                           /*
 366                                            *    It is a .comm/.lcomm being converted
 367                                            *    to initialized data.
 368                                            */
 369                                           symbolP->sy_frag  = frag_now;
 370 #ifdef VMS
 371                                           symbolP->sy_other = const_flag;
 372 #endif /* VMS */
 373                                           S_SET_VALUE(symbolP, obstack_next_free(& frags) - frag_now->fr_literal);
 374                                           S_SET_SEGMENT(symbolP, now_seg); /* keep N_EXT bit */
 375                                   }
 376                           } else {
 377 #ifdef OBJ_COFF
 378                                   as_fatal("Symbol \"%s\" is already defined as \"%s\"/%d.",
 379                                            sym_name,
 380                                            segment_name(S_GET_SEGMENT(symbolP)),
 381                                            S_GET_VALUE(symbolP));
 382 #else /* OBJ_COFF */
 383                                   as_fatal("Symbol \"%s\" is already defined as \"%s\"/%d.%d.%d.",
 384                                            sym_name,
 385                                            segment_name(S_GET_SEGMENT(symbolP)),
 386                                            S_GET_OTHER(symbolP), S_GET_DESC(symbolP),
 387                                            S_GET_VALUE(symbolP));
 388 #endif /* OBJ_COFF */
 389                           }
 390                   } /* if the undefined symbol has no value */
 391           } else {
 392                   as_fatal("Symbol %s already defined.", sym_name);
 393           } /* if this symbol is not yet defined */
 394
 395   } else {
 396           symbolP = symbol_new(sym_name,
 397                                 now_seg,
 398                                 (valueT)(obstack_next_free(&frags)-frag_now->fr_literal),
 399                                 frag_now);
 400 #ifdef VMS
 401           S_SET_OTHER(symbolP, const_flag);
 402 #endif /* VMS */
 403
 404           symbol_table_insert(symbolP);
 405   } /* if we have seen this symbol before */
 406
 407   return;
 408 } /* colon() */
 409
 410 \f
 411 /*
 412  *                      symbol_table_insert()
 413  *
 414  * Die if we can't insert the symbol.
 415  *
 416  */
 417
 418 void symbol_table_insert(symbolP)
 419 symbolS *symbolP;
 420 {
 421         register char *error_string;
 422
 423         know(symbolP);
 424         know(S_GET_NAME(symbolP));
 425
 426         if (*(error_string = hash_jam(sy_hash, S_GET_NAME(symbolP), (char *)symbolP))) {
 427                 as_fatal("Inserting \"%s\" into symbol table failed: %s",
 428                          S_GET_NAME(symbolP), error_string);
 429         } /* on error */
 430 } /* symbol_table_insert() */
 431 \f
 432 /*
 433  *                      symbol_find_or_make()
 434  *
 435  * If a symbol name does not exist, create it as undefined, and insert
 436  * it into the symbol table. Return a pointer to it.
 437  */
 438 symbolS *symbol_find_or_make(name)
 439 char *name;
 440 {
 441         register symbolS *symbolP;
 442
 443         symbolP = symbol_find(name);
 444
 445         if (symbolP == NULL) {
 446                 symbolP = symbol_make(name);
 447
 448                 symbol_table_insert(symbolP);
 449         } /* if symbol wasn't found */
 450
 451         return(symbolP);
 452 } /* symbol_find_or_make() */
 453
 454 symbolS *symbol_make(name)
 455 char *name;
 456 {
 457         symbolS *symbolP;
 458
 459         /* Let the machine description default it, e.g. for register names. */
 460         symbolP = md_undefined_symbol(name);
 461
 462         if (!symbolP) {
 463                 symbolP = symbol_new(name,
 464                                      SEG_UNKNOWN,
 465                                      0,
 466                                      &zero_address_frag);
 467         } /* if md didn't build us a symbol */
 468
 469         return(symbolP);
 470 } /* symbol_make() */
 471
 472 /*
 473  *                      symbol_find()
 474  *
 475  * Implement symbol table lookup.
 476  * In:  A symbol's name as a string: '\0' can't be part of a symbol name.
 477  * Out: NULL if the name was not in the symbol table, else the address
 478  *      of a struct symbol associated with that name.
 479  */
 480
 481 symbolS *symbol_find(name)
 482 char *name;
 483 {
 484 #ifndef STRIP_UNDERSCORE
 485 #define STRIP_UNDERSCORE 0
 486 #endif /* STRIP_UNDERSCORE */
 487     return symbol_find_base(name, STRIP_UNDERSCORE);
 488 }
 489
 490 symbolS *symbol_find_base(name, strip_underscore)
 491 char *name;
 492 int strip_underscore;
 493 {
 494     if(strip_underscore && *name == '_') name++;
 495     return ( (symbolS *) hash_find( sy_hash, name ));
 496 }
 497
 498 /*
 499  * Once upon a time, symbols were kept in a singly linked list.  At
 500  * least coff needs to be able to rearrange them from time to time, for
 501  * which a doubly linked list is much more convenient.  Loic did these
 502  * as macros which seemed dangerous to me so they're now functions.
 503  * xoxorich.
 504  */
 505
 506 /* Link symbol ADDME after symbol TARGET in the chain. */
 507 void symbol_append(addme, target, rootPP, lastPP)
 508 symbolS *addme;
 509 symbolS *target;
 510 symbolS **rootPP;
 511 symbolS **lastPP;
 512 {
 513         if (target == NULL) {
 514                 know(*rootPP == NULL);
 515                 know(*lastPP == NULL);
 516                 *rootPP = addme;
 517                 *lastPP = addme;
 518                 return;
 519         } /* if the list is empty */
 520
 521         if (target->sy_next != NULL) {
 522 #ifdef SYMBOLS_NEED_BACKPOINTERS
 523                 target->sy_next->sy_previous = addme;
 524 #endif /* SYMBOLS_NEED_BACKPOINTERS */
 525         } else {
 526                 know(*lastPP == target);
 527                 *lastPP = addme;
 528         } /* if we have a next */
 529
 530         addme->sy_next = target->sy_next;
 531         target->sy_next = addme;
 532
 533 #ifdef SYMBOLS_NEED_BACKPOINTERS
 534         addme->sy_previous = target;
 535 #endif /* SYMBOLS_NEED_BACKPOINTERS */
 536
 537 #ifdef DEBUG
 538         verify_symbol_chain(*rootPP, *lastPP);
 539 #endif /* DEBUG */
 540
 541         return;
 542 } /* symbol_append() */
 543
 544 #ifdef SYMBOLS_NEED_BACKPOINTERS
 545 /* Remove SYMBOLP from the list. */
 546 void symbol_remove(symbolP, rootPP, lastPP)
 547 symbolS *symbolP;
 548 symbolS **rootPP;
 549 symbolS **lastPP;
 550 {
 551         if (symbolP == *rootPP) {
 552                 *rootPP = symbolP->sy_next;
 553         } /* if it was the root */
 554
 555         if (symbolP == *lastPP) {
 556                 *lastPP = symbolP->sy_previous;
 557         } /* if it was the tail */
 558
 559         if (symbolP->sy_next != NULL) {
 560                 symbolP->sy_next->sy_previous = symbolP->sy_previous;
 561         } /* if not last */
 562
 563         if (symbolP->sy_previous != NULL) {
 564                 symbolP->sy_previous->sy_next = symbolP->sy_next;
 565         } /* if not first */
 566
 567 #ifdef DEBUG
 568         verify_symbol_chain(*rootPP, *lastPP);
 569 #endif /* DEBUG */
 570
 571         return;
 572 } /* symbol_remove() */
 573
 574 /* Set the chain pointers of SYMBOL to null. */
 575 void symbol_clear_list_pointers(symbolP)
 576 symbolS *symbolP;
 577 {
 578     symbolP->sy_next = NULL;
 579     symbolP->sy_previous = NULL;
 580 } /* symbol_clear_list_pointers() */
 581
 582 /* Link symbol ADDME before symbol TARGET in the chain. */
 583 void symbol_insert(addme, target, rootPP, lastPP)
 584 symbolS *addme;
 585 symbolS *target;
 586 symbolS **rootPP;
 587 symbolS **lastPP;
 588 {
 589     if (target->sy_previous != NULL) {
 590             target->sy_previous->sy_next = addme;
 591     } else {
 592             know(*rootPP == target);
 593             *rootPP = addme;
 594     } /* if not first */
 595
 596     addme->sy_previous = target->sy_previous;
 597     target->sy_previous = addme;
 598     addme->sy_next = target;
 599
 600 #ifdef DEBUG
 601     verify_symbol_chain(*rootPP, *lastPP);
 602 #endif /* DEBUG */
 603
 604     return;
 605 } /* symbol_insert() */
 606 #endif /* SYMBOLS_NEED_BACKPOINTERS */
 607
 608 void verify_symbol_chain(rootP, lastP)
 609 symbolS *rootP;
 610 symbolS *lastP;
 611 {
 612         symbolS *symbolP = rootP;
 613
 614         if (symbolP == NULL) {
 615                 return;
 616         } /* empty chain */
 617
 618         for ( ; symbol_next(symbolP) != NULL; symbolP = symbol_next(symbolP)) {
 619 #ifdef SYMBOLS_NEED_BACKPOINTERS
 620                 /*$if (symbolP->sy_previous) {
 621                         know(symbolP->sy_previous->sy_next == symbolP);
 622                 } else {
 623                         know(symbolP == rootP);
 624                 }$*/ /* both directions */
 625                 know(symbolP->sy_next->sy_previous == symbolP);
 626 #else /* SYMBOLS_NEED_BACKPOINTERS */
 627                 ;
 628 #endif /* SYMBOLS_NEED_BACKPOINTERS */
 629         } /* verify pointers */
 630
 631         know(lastP == symbolP);
 632
 633         return;
 634 } /* verify_symbol_chain() */
 635
 636
 637 /*
 638  * Local Variables:
 639  * comment-column: 0
 640  * fill-column: 131
 641  * End:
 642  */
 643
 644 /* end: symbols.c */