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 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  /* symbol must be born in some fixed state.  This seems as good as any. */
 180         memset(symbolP, 0, sizeof(symbolS));
 181
 182 #ifdef STRIP_UNDERSCORE
 183         S_SET_NAME(symbolP, (*preserved_copy_of_name == '_'
 184                                             ? preserved_copy_of_name + 1
 185                                             : preserved_copy_of_name));
 186 #else /* STRIP_UNDERSCORE */
 187         S_SET_NAME(symbolP, preserved_copy_of_name);
 188 #endif /* STRIP_UNDERSCORE */
 189
 190         S_SET_SEGMENT(symbolP, segment);
 191         S_SET_VALUE(symbolP, value);
 192 /*      symbol_clear_list_pointers(symbolP); uneeded if symbol is born zeroed. */
 193
 194         symbolP->sy_frag = frag;
 195         /* krm: uneeded if symbol is born zeroed.
 196            symbolP->sy_forward = NULL; */ /* JF */
 197         symbolP->sy_number = ~0;
 198         symbolP->sy_name_offset = ~0;
 199
 200         /*
 201          * Link to end of symbol chain.
 202          */
 203         symbol_append(symbolP, symbol_lastP, &symbol_rootP, &symbol_lastP);
 204
 205         obj_symbol_new_hook(symbolP);
 206
 207 #ifdef DEBUG
 208         verify_symbol_chain(symbol_rootP, symbol_lastP);
 209 #endif /* DEBUG */
 210
 211         return(symbolP);
 212 } /* symbol_new() */
 213
 214 \f
 215 /*
 216  *                      colon()
 217  *
 218  * We have just seen "<name>:".
 219  * Creates a struct symbol unless it already exists.
 220  *
 221  * Gripes if we are redefining a symbol incompatibly (and ignores it).
 222  *
 223  */
 224 void colon(sym_name)            /* just seen "x:" - rattle symbols & frags */
 225      register char *  sym_name; /* symbol name, as a cannonical string */
 226                                 /* We copy this string: OK to alter later. */
 227 {
 228   register symbolS * symbolP; /* symbol we are working with */
 229
 230 #ifdef LOCAL_LABELS_DOLLAR
 231   /* Sun local labels go out of scope whenever a non-local symbol is defined.  */
 232
 233   if(*sym_name !='L')
 234     bzero((void *) local_label_defined, sizeof(local_label_defined));
 235 #endif
 236
 237 #ifndef WORKING_DOT_WORD
 238   if(new_broken_words) {
 239     struct broken_word *a;
 240     int possible_bytes;
 241     fragS *frag_tmp;
 242     char *frag_opcode;
 243
 244     extern md_short_jump_size;
 245     extern md_long_jump_size;
 246     possible_bytes=md_short_jump_size + new_broken_words * md_long_jump_size;
 247
 248     frag_tmp=frag_now;
 249     frag_opcode=frag_var(rs_broken_word,
 250                          possible_bytes,
 251                          possible_bytes,
 252                          (relax_substateT) 0,
 253                          (symbolS *) broken_words,
 254                          0L,
 255                          NULL);
 256
 257     /* We want to store the pointer to where to insert the jump table in the
 258        fr_opcode of the rs_broken_word frag.  This requires a little hackery */
 259     while(frag_tmp && (frag_tmp->fr_type!=rs_broken_word || frag_tmp->fr_opcode))
 260       frag_tmp=frag_tmp->fr_next;
 261     know(frag_tmp);
 262     frag_tmp->fr_opcode=frag_opcode;
 263     new_broken_words = 0;
 264
 265     for(a=broken_words;a && a->dispfrag==0;a=a->next_broken_word)
 266       a->dispfrag=frag_tmp;
 267   }
 268 #endif
 269   if ((symbolP = symbol_find(sym_name)) != 0) {
 270 #ifdef  VMS
 271           /*
 272            *    If the new symbol is .comm AND it has a size of zero,
 273            *    we ignore it (i.e. the old symbol overrides it)
 274            */
 275           if ((SEGMENT_TO_SYMBOL_TYPE((int) now_seg) == (N_UNDF | N_EXT)) &&
 276               ((obstack_next_free(& frags) - frag_now->fr_literal) == 0))
 277               return;
 278           /*
 279            *    If the old symbol is .comm and it has a size of zero,
 280            *    we override it with the new symbol value.
 281            */
 282           if ((symbolP->sy_type == (N_UNDF | N_EXT))
 283               && (S_GET_VALUE(symbolP) == 0)) {
 284                   symbolP->sy_frag  = frag_now;
 285                   symbolP->sy_other = const_flag;
 286                   S_SET_VALUE(symbolP, obstack_next_free(& frags) - frag_now->fr_literal);
 287                   symbolP->sy_type |= SEGMENT_TO_SYMBOL_TYPE((int) now_seg); /* keep N_EXT bit */
 288                   return;
 289           }
 290 #endif  /* VMS */
 291           /*
 292            *    Now check for undefined symbols
 293            */
 294           if (!S_IS_DEFINED(symbolP)) {
 295                   if (S_GET_VALUE(symbolP) == 0) {
 296                           symbolP->sy_frag  = frag_now;
 297 #ifdef VMS
 298                           symbolP->sy_other = const_flag;
 299 #endif
 300                           S_SET_VALUE(symbolP, obstack_next_free(&frags) - frag_now->fr_literal);
 301                           S_SET_SEGMENT(symbolP, now_seg);
 302 #ifdef N_UNDF
 303                           know(N_UNDF == 0);
 304 #endif /* if we have one, it better be zero. */
 305
 306                   } else {
 307                           /*
 308                            *    There are still several cases to check:
 309                            *            A .comm/.lcomm symbol being redefined as
 310                            *                    initialized data is OK
 311                            *            A .comm/.lcomm symbol being redefined with
 312                            *                    a larger size is also OK
 313                            *
 314                            * This only used to be allowed on VMS gas, but Sun cc
 315                            * on the sparc also depends on it.
 316                            */
 317 /*                        char New_Type = SEGMENT_TO_SYMBOL_TYPE((int) now_seg); */
 318 #ifdef MANY_SEGMENTS
 319 #define SEG_BSS SEG_E2
 320 #define SEG_DATA SEG_E1
 321 #endif
 322
 323                           if (((!S_IS_DEBUG(symbolP) && !S_IS_DEFINED(symbolP) && S_IS_EXTERNAL(symbolP))
 324                                || (S_GET_SEGMENT(symbolP) == SEG_BSS))
 325                               && ((now_seg == SEG_DATA)
 326                                   || (now_seg == S_GET_SEGMENT(symbolP)))) {
 327                                   /*
 328                                    *    Select which of the 2 cases this is
 329                                    */
 330                                   if (now_seg != SEG_DATA) {
 331                                           /*
 332                                            *   New .comm for prev .comm symbol.
 333                                            *    If the new size is larger we just
 334                                            *    change its value.  If the new size
 335                                            *    is smaller, we ignore this symbol
 336                                            */
 337                                           if (S_GET_VALUE(symbolP)
 338                                               < ((unsigned) (obstack_next_free(& frags) - frag_now->fr_literal))) {
 339                                                   S_SET_VALUE(symbolP,
 340                                                               obstack_next_free(& frags) -
 341                                                               frag_now->fr_literal);
 342                                           }
 343                                   } else {
 344                                           /*
 345                                            *    It is a .comm/.lcomm being converted
 346                                            *    to initialized data.
 347                                            */
 348                                           symbolP->sy_frag  = frag_now;
 349 #ifdef VMS
 350                                           symbolP->sy_other = const_flag;
 351 #endif /* VMS */
 352                                           S_SET_VALUE(symbolP, obstack_next_free(& frags) - frag_now->fr_literal);
 353                                           S_SET_SEGMENT(symbolP, now_seg); /* keep N_EXT bit */
 354                                   }
 355                           } else {
 356 #ifdef OBJ_COFF
 357                                   as_fatal("Symbol \"%s\" is already defined as \"%s\"/%d.",
 358                                            sym_name,
 359                                            segment_name(S_GET_SEGMENT(symbolP)),
 360                                            S_GET_VALUE(symbolP));
 361 #else /* OBJ_COFF */
 362                                   as_fatal("Symbol \"%s\" is already defined as \"%s\"/%d.%d.%d.",
 363                                            sym_name,
 364                                            segment_name(S_GET_SEGMENT(symbolP)),
 365                                            S_GET_OTHER(symbolP), S_GET_DESC(symbolP),
 366                                            S_GET_VALUE(symbolP));
 367 #endif /* OBJ_COFF */
 368                           }
 369                   } /* if the undefined symbol has no value */
 370           } else {
 371                   as_fatal("Symbol %s already defined.", sym_name);
 372           } /* if this symbol is not yet defined */
 373
 374   } else {
 375           symbolP = symbol_new(sym_name,
 376                                 now_seg,
 377                                 (valueT)(obstack_next_free(&frags)-frag_now->fr_literal),
 378                                 frag_now);
 379 #ifdef VMS
 380           S_SET_OTHER(symbolP, const_flag);
 381 #endif /* VMS */
 382
 383           symbol_table_insert(symbolP);
 384   } /* if we have seen this symbol before */
 385
 386   return;
 387 } /* colon() */
 388
 389 \f
 390 /*
 391  *                      symbol_table_insert()
 392  *
 393  * Die if we can't insert the symbol.
 394  *
 395  */
 396
 397 void symbol_table_insert(symbolP)
 398 symbolS *symbolP;
 399 {
 400         register char *error_string;
 401
 402         know(symbolP);
 403         know(S_GET_NAME(symbolP));
 404
 405         if (*(error_string = hash_jam(sy_hash, S_GET_NAME(symbolP), (char *)symbolP))) {
 406                 as_fatal("Inserting \"%s\" into symbol table failed: %s",
 407                          S_GET_NAME(symbolP), error_string);
 408         } /* on error */
 409 } /* symbol_table_insert() */
 410 \f
 411 /*
 412  *                      symbol_find_or_make()
 413  *
 414  * If a symbol name does not exist, create it as undefined, and insert
 415  * it into the symbol table. Return a pointer to it.
 416  */
 417 symbolS *symbol_find_or_make(name)
 418 char *name;
 419 {
 420         register symbolS *symbolP;
 421
 422         symbolP = symbol_find(name);
 423
 424         if (symbolP == NULL) {
 425                 symbolP = symbol_make(name);
 426
 427                 symbol_table_insert(symbolP);
 428         } /* if symbol wasn't found */
 429
 430         return(symbolP);
 431 } /* symbol_find_or_make() */
 432
 433 symbolS *symbol_make(name)
 434 char *name;
 435 {
 436         symbolS *symbolP;
 437
 438         /* Let the machine description default it, e.g. for register names. */
 439         symbolP = md_undefined_symbol(name);
 440
 441         if (!symbolP) {
 442                 symbolP = symbol_new(name,
 443                                      SEG_UNKNOWN,
 444                                      0,
 445                                      &zero_address_frag);
 446         } /* if md didn't build us a symbol */
 447
 448         return(symbolP);
 449 } /* symbol_make() */
 450
 451 /*
 452  *                      symbol_find()
 453  *
 454  * Implement symbol table lookup.
 455  * In:  A symbol's name as a string: '\0' can't be part of a symbol name.
 456  * Out: NULL if the name was not in the symbol table, else the address
 457  *      of a struct symbol associated with that name.
 458  */
 459
 460 symbolS *symbol_find(name)
 461 char *name;
 462 {
 463 #ifdef STRIP_UNDERSCORE
 464         return(symbol_find_base(name, 1));
 465 #else /* STRIP_UNDERSCORE */
 466         return(symbol_find_base(name, 0));
 467 #endif /* STRIP_UNDERSCORE */
 468 } /* symbol_find() */
 469
 470 symbolS *symbol_find_base(name, strip_underscore)
 471 char *name;
 472 int strip_underscore;
 473 {
 474     if(strip_underscore && *name == '_') name++;
 475     return ( (symbolS *) hash_find( sy_hash, name ));
 476 }
 477
 478 /*
 479  * Once upon a time, symbols were kept in a singly linked list.  At
 480  * least coff needs to be able to rearrange them from time to time, for
 481  * which a doubly linked list is much more convenient.  Loic did these
 482  * as macros which seemed dangerous to me so they're now functions.
 483  * xoxorich.
 484  */
 485
 486 /* Link symbol ADDME after symbol TARGET in the chain. */
 487 void symbol_append(addme, target, rootPP, lastPP)
 488 symbolS *addme;
 489 symbolS *target;
 490 symbolS **rootPP;
 491 symbolS **lastPP;
 492 {
 493         if (target == NULL) {
 494                 know(*rootPP == NULL);
 495                 know(*lastPP == NULL);
 496                 *rootPP = addme;
 497                 *lastPP = addme;
 498                 return;
 499         } /* if the list is empty */
 500
 501         if (target->sy_next != NULL) {
 502 #ifdef SYMBOLS_NEED_BACKPOINTERS
 503                 target->sy_next->sy_previous = addme;
 504 #endif /* SYMBOLS_NEED_BACKPOINTERS */
 505         } else {
 506                 know(*lastPP == target);
 507                 *lastPP = addme;
 508         } /* if we have a next */
 509
 510         addme->sy_next = target->sy_next;
 511         target->sy_next = addme;
 512
 513 #ifdef SYMBOLS_NEED_BACKPOINTERS
 514         addme->sy_previous = target;
 515 #endif /* SYMBOLS_NEED_BACKPOINTERS */
 516
 517 #ifdef DEBUG
 518         verify_symbol_chain(*rootPP, *lastPP);
 519 #endif /* DEBUG */
 520
 521         return;
 522 } /* symbol_append() */
 523
 524 #ifdef SYMBOLS_NEED_BACKPOINTERS
 525 /* Remove SYMBOLP from the list. */
 526 void symbol_remove(symbolP, rootPP, lastPP)
 527 symbolS *symbolP;
 528 symbolS **rootPP;
 529 symbolS **lastPP;
 530 {
 531         if (symbolP == *rootPP) {
 532                 *rootPP = symbolP->sy_next;
 533         } /* if it was the root */
 534
 535         if (symbolP == *lastPP) {
 536                 *lastPP = symbolP->sy_previous;
 537         } /* if it was the tail */
 538
 539         if (symbolP->sy_next != NULL) {
 540                 symbolP->sy_next->sy_previous = symbolP->sy_previous;
 541         } /* if not last */
 542
 543         if (symbolP->sy_previous != NULL) {
 544                 symbolP->sy_previous->sy_next = symbolP->sy_next;
 545         } /* if not first */
 546
 547 #ifdef DEBUG
 548         verify_symbol_chain(*rootPP, *lastPP);
 549 #endif /* DEBUG */
 550
 551         return;
 552 } /* symbol_remove() */
 553
 554 /* Set the chain pointers of SYMBOL to null. */
 555 void symbol_clear_list_pointers(symbolP)
 556 symbolS *symbolP;
 557 {
 558     symbolP->sy_next = NULL;
 559     symbolP->sy_previous = NULL;
 560 } /* symbol_clear_list_pointers() */
 561
 562 /* Link symbol ADDME before symbol TARGET in the chain. */
 563 void symbol_insert(addme, target, rootPP, lastPP)
 564 symbolS *addme;
 565 symbolS *target;
 566 symbolS **rootPP;
 567 symbolS **lastPP;
 568 {
 569     if (target->sy_previous != NULL) {
 570             target->sy_previous->sy_next = addme;
 571     } else {
 572             know(*rootPP == target);
 573             *rootPP = addme;
 574     } /* if not first */
 575
 576     addme->sy_previous = target->sy_previous;
 577     target->sy_previous = addme;
 578     addme->sy_next = target;
 579
 580 #ifdef DEBUG
 581     verify_symbol_chain(*rootPP, *lastPP);
 582 #endif /* DEBUG */
 583
 584     return;
 585 } /* symbol_insert() */
 586 #endif /* SYMBOLS_NEED_BACKPOINTERS */
 587
 588 void verify_symbol_chain(rootP, lastP)
 589 symbolS *rootP;
 590 symbolS *lastP;
 591 {
 592         symbolS *symbolP = rootP;
 593
 594         if (symbolP == NULL) {
 595                 return;
 596         } /* empty chain */
 597
 598         for ( ; symbol_next(symbolP) != NULL; symbolP = symbol_next(symbolP)) {
 599 #ifdef SYMBOLS_NEED_BACKPOINTERS
 600                 /*$if (symbolP->sy_previous) {
 601                         know(symbolP->sy_previous->sy_next == symbolP);
 602                 } else {
 603                         know(symbolP == rootP);
 604                 }$*/ /* both directions */
 605                 know(symbolP->sy_next->sy_previous == symbolP);
 606 #else /* SYMBOLS_NEED_BACKPOINTERS */
 607                 ;
 608 #endif /* SYMBOLS_NEED_BACKPOINTERS */
 609         } /* verify pointers */
 610
 611         know(lastP == symbolP);
 612
 613         return;
 614 } /* verify_symbol_chain() */
 615
 616
 617 /*
 618  * decode name that may have been generated by local_label_name() above.  If
 619  * the name wasn't generated by local_label_name(), then return it unaltered.
 620  * This is used for error messages.
 621  */
 622
 623 char *decode_local_label_name(s)
 624 char *s;
 625 {
 626         char *symbol_decode;
 627         int label_number;
 628  /*     int label_version; */
 629         char *message_format = "\"%d\" (instance number %s of a local label)";
 630
 631         if (s[0] != 'L'
 632             || s[2] != 1) {
 633                 return(s);
 634         } /* not a local_label_name() generated name. */
 635
 636         label_number = s[1] - '0';
 637
 638         (void) sprintf(symbol_decode = obstack_alloc(&notes, strlen(s + 3) + strlen(message_format) + 10),
 639                 message_format, label_number, s + 3);
 640
 641         return(symbol_decode);
 642 } /* decode_local_label_name() */
 643
 644
 645 /*
 646  * Local Variables:
 647  * comment-column: 0
 648  * fill-column: 131
 649  * End:
 650  */
 651
 652 /* end: symbols.c */