labels.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 1996-2009 The NASM Authors - All Rights Reserved
   4  *   See the file AUTHORS included with the NASM distribution for
   5  *   the specific copyright holders.
   6  *
   7  *   Redistribution and use in source and binary forms, with or without
   8  *   modification, are permitted provided that the following
   9  *   conditions are met:
  10  *
  11  *   * Redistributions of source code must retain the above copyright
  12  *     notice, this list of conditions and the following disclaimer.
  13  *   * Redistributions in binary form must reproduce the above
  14  *     copyright notice, this list of conditions and the following
  15  *     disclaimer in the documentation and/or other materials provided
  16  *     with the distribution.
  17  *
  18  *     THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  19  *     CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  20  *     INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  21  *     MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  22  *     DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  23  *     CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  *     SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  25  *     NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  26  *     LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  *     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  28  *     CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  29  *     OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  30  *     EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  *
  32  * ----------------------------------------------------------------------- */
  33
  34 /*
  35  * labels.c  label handling for the Netwide Assembler
  36  */
  37
  38 #include "compiler.h"
  39
  40 #include <stdio.h>
  41 #include <string.h>
  42 #include <stdlib.h>
  43 #include <inttypes.h>
  44
  45 #include "nasm.h"
  46 #include "nasmlib.h"
  47 #include "hashtbl.h"
  48
  49 /*
  50  * A local label is one that begins with exactly one period. Things
  51  * that begin with _two_ periods are NASM-specific things.
  52  *
  53  * If TASM compatibility is enabled, a local label can also begin with
  54  * @@, so @@local is a TASM compatible local label. Note that we only
  55  * check for the first @ symbol, although TASM requires both.
  56  */
  57 #define islocal(l)                                              \
  58         (tasm_compatible_mode ?                                 \
  59         (((l)[0] == '.' || (l)[0] == '@') && (l)[1] != '.') :   \
  60         ((l)[0] == '.' && (l)[1] != '.'))
  61 #define islocalchar(c)                                          \
  62         (tasm_compatible_mode ?                                  \
  63         ((c) == '.' || (c) == '@') :                            \
  64         ((c) == '.'))
  65
  66 #define LABEL_BLOCK  128        /* no. of labels/block */
  67 #define LBLK_SIZE    (LABEL_BLOCK*sizeof(union label))
  68
  69 #define END_LIST -3             /* don't clash with NO_SEG! */
  70 #define END_BLOCK -2
  71 #define BOGUS_VALUE -4
  72
  73 #define PERMTS_SIZE  16384      /* size of text blocks */
  74 #if (PERMTS_SIZE < IDLEN_MAX)
  75 #error "IPERMTS_SIZE must be greater than or equal to IDLEN_MAX"
  76 #endif
  77
  78 /* values for label.defn.is_global */
  79 #define DEFINED_BIT     1
  80 #define GLOBAL_BIT      2
  81 #define EXTERN_BIT      4
  82 #define COMMON_BIT      8
  83
  84 #define NOT_DEFINED_YET 0
  85 #define TYPE_MASK 3
  86 #define LOCAL_SYMBOL (DEFINED_BIT)
  87 #define GLOBAL_PLACEHOLDER (GLOBAL_BIT)
  88 #define GLOBAL_SYMBOL (DEFINED_BIT|GLOBAL_BIT)
  89
  90 union label {                   /* actual label structures */
  91     struct {
  92         int32_t segment;
  93         int64_t offset;
  94         char *label, *special;
  95         int is_global, is_norm;
  96     } defn;
  97     struct {
  98         int32_t movingon;
  99         int64_t dummy;
 100         union label *next;
 101     } admin;
 102 };
 103
 104 struct permts {                 /* permanent text storage */
 105     struct permts *next;        /* for the linked list */
 106     int size, usage;            /* size and used space in ... */
 107     char data[PERMTS_SIZE];     /* ... the data block itself */
 108 };
 109
 110 extern int64_t global_offset_changed;       /* defined in nasm.c */
 111
 112 static struct hash_table ltab;          /* labels hash table */
 113 static union label *ldata;              /* all label data blocks */
 114 static union label *lfree;              /* labels free block */
 115 static struct permts *perm_head;        /* start of perm. text storage */
 116 static struct permts *perm_tail;        /* end of perm. text storage */
 117
 118 static void init_block(union label *blk);
 119 static char *perm_copy(const char *string);
 120
 121 static char *prevlabel;
 122
 123 static bool initialized = false;
 124
 125 char lprefix[PREFIX_MAX] = { 0 };
 126 char lpostfix[PREFIX_MAX] = { 0 };
 127
 128 /*
 129  * Internal routine: finds the `union label' corresponding to the
 130  * given label name. Creates a new one, if it isn't found, and if
 131  * `create' is true.
 132  */
 133 static union label *find_label(char *label, int create)
 134 {
 135     char *prev;
 136     int prevlen, len;
 137     union label *lptr, **lpp;
 138     char label_str[IDLEN_MAX];
 139     struct hash_insert ip;
 140
 141     if (islocal(label)) {
 142         prev = prevlabel;
 143         prevlen = strlen(prev);
 144         len = strlen(label);
 145         if (prevlen+len >= IDLEN_MAX) {
 146             nasm_error(ERR_NONFATAL, "identifier length exceed %i bytes",
 147                        IDLEN_MAX);
 148             return NULL;        /* Error... */
 149         }
 150         memcpy(label_str, prev, prevlen);
 151         memcpy(label_str+prevlen, label, len+1);
 152         label = label_str;
 153     } else {
 154         prev = "";
 155         prevlen = 0;
 156     }
 157
 158     lpp = (union label **) hash_find(&ltab, label, &ip);
 159     lptr = lpp ? *lpp : NULL;
 160
 161     if (lptr || !create)
 162         return lptr;
 163
 164     /* Create a new label... */
 165     if (lfree->admin.movingon == END_BLOCK) {
 166         /*
 167          * must allocate a new block
 168          */
 169         lfree->admin.next =
 170             (union label *)nasm_malloc(LBLK_SIZE);
 171         lfree = lfree->admin.next;
 172         init_block(lfree);
 173     }
 174
 175     lfree->admin.movingon = BOGUS_VALUE;
 176     lfree->defn.label = perm_copy(label);
 177     lfree->defn.special = NULL;
 178     lfree->defn.is_global = NOT_DEFINED_YET;
 179
 180     hash_add(&ip, lfree->defn.label, lfree);
 181     return lfree++;
 182 }
 183
 184 bool lookup_label(char *label, int32_t *segment, int64_t *offset)
 185 {
 186     union label *lptr;
 187
 188     if (!initialized)
 189         return false;
 190
 191     lptr = find_label(label, 0);
 192     if (lptr && (lptr->defn.is_global & DEFINED_BIT)) {
 193         *segment = lptr->defn.segment;
 194         *offset = lptr->defn.offset;
 195         return true;
 196     } else
 197         return false;
 198 }
 199
 200 bool is_extern(char *label)
 201 {
 202     union label *lptr;
 203
 204     if (!initialized)
 205         return false;
 206
 207     lptr = find_label(label, 0);
 208     return (lptr && (lptr->defn.is_global & EXTERN_BIT));
 209 }
 210
 211 void redefine_label(char *label, int32_t segment, int64_t offset, char *special,
 212                     bool is_norm, bool isextrn)
 213 {
 214     union label *lptr;
 215     int exi;
 216
 217     /* This routine possibly ought to check for phase errors.  Most assemblers
 218      * check for phase errors at this point.  I don't know whether phase errors
 219      * are even possible, nor whether they are checked somewhere else
 220      */
 221
 222     (void)special;              /* Don't warn that this parameter is unused */
 223     (void)is_norm;              /* Don't warn that this parameter is unused */
 224     (void)isextrn;              /* Don't warn that this parameter is unused */
 225
 226 #ifdef DEBUG
 227 #if DEBUG<3
 228     if (!strncmp(label, "debugdump", 9))
 229 #endif
 230         nasm_error(ERR_DEBUG, "redefine_label (%s, %"PRIx32", %"PRIx64", %s, %d, %d)",
 231               label, segment, offset, special, is_norm, isextrn);
 232 #endif
 233
 234     lptr = find_label(label, 1);
 235     if (!lptr)
 236         nasm_error(ERR_PANIC, "can't find label `%s' on pass two", label);
 237
 238     if (!islocal(label)) {
 239         if (!islocalchar(*label) && lptr->defn.is_norm)
 240             prevlabel = lptr->defn.label;
 241     }
 242
 243     if (lptr->defn.offset != offset)
 244         global_offset_changed++;
 245
 246     lptr->defn.offset = offset;
 247     lptr->defn.segment = segment;
 248
 249     if (pass0 == 1) {
 250         exi = !!(lptr->defn.is_global & GLOBAL_BIT);
 251         if (exi) {
 252             char *xsymbol;
 253             int slen;
 254             slen = strlen(lprefix);
 255             slen += strlen(lptr->defn.label);
 256             slen += strlen(lpostfix);
 257             slen++;             /* room for that null char */
 258             xsymbol = nasm_malloc(slen);
 259             snprintf(xsymbol, slen, "%s%s%s", lprefix, lptr->defn.label,
 260                      lpostfix);
 261
 262             ofmt->symdef(xsymbol, segment, offset, exi,
 263                          special ? special : lptr->defn.special);
 264             ofmt->current_dfmt->debug_deflabel(xsymbol, segment, offset,
 265                                                exi,
 266                                                special ? special : lptr->
 267                                                defn.special);
 268 /**     nasm_free(xsymbol);  ! outobj.c stores the pointer; ouch!!! **/
 269         } else {
 270             if ((lptr->defn.is_global & (GLOBAL_BIT | EXTERN_BIT)) !=
 271                 EXTERN_BIT) {
 272                 ofmt->symdef(lptr->defn.label, segment, offset, exi,
 273                              special ? special : lptr->defn.special);
 274                 ofmt->current_dfmt->debug_deflabel(label, segment, offset,
 275                                                    exi,
 276                                                    special ? special :
 277                                                    lptr->defn.special);
 278             }
 279         }
 280     }
 281     /* if (pass0 == 1) */
 282 }
 283
 284 void define_label(char *label, int32_t segment, int64_t offset, char *special,
 285                   bool is_norm, bool isextrn)
 286 {
 287     union label *lptr;
 288     int exi;
 289
 290 #ifdef DEBUG
 291 #if DEBUG<3
 292     if (!strncmp(label, "debugdump", 9))
 293 #endif
 294         nasm_error(ERR_DEBUG, "define_label (%s, %"PRIx32", %"PRIx64", %s, %d, %d)",
 295               label, segment, offset, special, is_norm, isextrn);
 296 #endif
 297     lptr = find_label(label, 1);
 298     if (!lptr)
 299         return;
 300     if (lptr->defn.is_global & DEFINED_BIT) {
 301         nasm_error(ERR_NONFATAL, "symbol `%s' redefined", label);
 302         return;
 303     }
 304     lptr->defn.is_global |= DEFINED_BIT;
 305     if (isextrn)
 306         lptr->defn.is_global |= EXTERN_BIT;
 307
 308     if (!islocalchar(label[0]) && is_norm) {
 309         /* not local, but not special either */
 310         prevlabel = lptr->defn.label;
 311     } else if (islocal(label) && !*prevlabel) {
 312         nasm_error(ERR_NONFATAL, "attempt to define a local label before any"
 313               " non-local labels");
 314     }
 315
 316     lptr->defn.segment = segment;
 317     lptr->defn.offset = offset;
 318     lptr->defn.is_norm = (!islocalchar(label[0]) && is_norm);
 319
 320     if (pass0 == 1 || (!is_norm && !isextrn && (segment > 0) && (segment & 1))) {
 321         exi = !!(lptr->defn.is_global & GLOBAL_BIT);
 322         if (exi) {
 323             char *xsymbol;
 324             int slen;
 325             slen = strlen(lprefix);
 326             slen += strlen(lptr->defn.label);
 327             slen += strlen(lpostfix);
 328             slen++;             /* room for that null char */
 329             xsymbol = nasm_malloc(slen);
 330             snprintf(xsymbol, slen, "%s%s%s", lprefix, lptr->defn.label,
 331                      lpostfix);
 332
 333             ofmt->symdef(xsymbol, segment, offset, exi,
 334                          special ? special : lptr->defn.special);
 335             ofmt->current_dfmt->debug_deflabel(xsymbol, segment, offset,
 336                                                exi,
 337                                                special ? special : lptr->
 338                                                defn.special);
 339 /**     nasm_free(xsymbol);  ! outobj.c stores the pointer; ouch!!! **/
 340         } else {
 341             if ((lptr->defn.is_global & (GLOBAL_BIT | EXTERN_BIT)) !=
 342                 EXTERN_BIT) {
 343                 ofmt->symdef(lptr->defn.label, segment, offset, exi,
 344                              special ? special : lptr->defn.special);
 345                 ofmt->current_dfmt->debug_deflabel(label, segment, offset,
 346                                                    exi,
 347                                                    special ? special :
 348                                                    lptr->defn.special);
 349             }
 350         }
 351     }                           /* if (pass0 == 1) */
 352 }
 353
 354 void define_common(char *label, int32_t segment, int32_t size, char *special)
 355 {
 356     union label *lptr;
 357
 358     lptr = find_label(label, 1);
 359     if (!lptr)
 360         return;
 361     if ((lptr->defn.is_global & DEFINED_BIT) &&
 362         (passn == 1 || !(lptr->defn.is_global & COMMON_BIT))) {
 363             nasm_error(ERR_NONFATAL, "symbol `%s' redefined", label);
 364             return;
 365     }
 366     lptr->defn.is_global |= DEFINED_BIT|COMMON_BIT;
 367
 368     if (!islocalchar(label[0])) {
 369         prevlabel = lptr->defn.label;
 370     } else {
 371         nasm_error(ERR_NONFATAL, "attempt to define a local label as a "
 372               "common variable");
 373         return;
 374     }
 375
 376     lptr->defn.segment = segment;
 377     lptr->defn.offset = 0;
 378
 379     if (pass0 == 0)
 380         return;
 381
 382     ofmt->symdef(lptr->defn.label, segment, size, 2,
 383                  special ? special : lptr->defn.special);
 384     ofmt->current_dfmt->debug_deflabel(lptr->defn.label, segment, size, 2,
 385                                        special ? special : lptr->defn.
 386                                        special);
 387 }
 388
 389 void declare_as_global(char *label, char *special)
 390 {
 391     union label *lptr;
 392
 393     if (islocal(label)) {
 394         nasm_error(ERR_NONFATAL, "attempt to declare local symbol `%s' as"
 395               " global", label);
 396         return;
 397     }
 398     lptr = find_label(label, 1);
 399     if (!lptr)
 400         return;
 401     switch (lptr->defn.is_global & TYPE_MASK) {
 402     case NOT_DEFINED_YET:
 403         lptr->defn.is_global = GLOBAL_PLACEHOLDER;
 404         lptr->defn.special = special ? perm_copy(special) : NULL;
 405         break;
 406     case GLOBAL_PLACEHOLDER:   /* already done: silently ignore */
 407     case GLOBAL_SYMBOL:
 408         break;
 409     case LOCAL_SYMBOL:
 410         if (!(lptr->defn.is_global & EXTERN_BIT)) {
 411             nasm_error(ERR_WARNING, "symbol `%s': GLOBAL directive "
 412                   "after symbol definition is an experimental feature", label);
 413             lptr->defn.is_global = GLOBAL_SYMBOL;
 414         }
 415         break;
 416     }
 417 }
 418
 419 int init_labels(void)
 420 {
 421     hash_init(&ltab, HASH_LARGE);
 422
 423     ldata = lfree = (union label *)nasm_malloc(LBLK_SIZE);
 424     init_block(lfree);
 425
 426     perm_head =
 427         perm_tail = (struct permts *)nasm_malloc(sizeof(struct permts));
 428
 429     perm_head->next = NULL;
 430     perm_head->size = PERMTS_SIZE;
 431     perm_head->usage = 0;
 432
 433     prevlabel = "";
 434
 435     initialized = true;
 436
 437     return 0;
 438 }
 439
 440 void cleanup_labels(void)
 441 {
 442     union label *lptr, *lhold;
 443
 444     initialized = false;
 445
 446     hash_free(&ltab);
 447
 448     lptr = lhold = ldata;
 449     while (lptr) {
 450         lptr = &lptr[LABEL_BLOCK-1];
 451         lptr = lptr->admin.next;
 452         nasm_free(lhold);
 453         lhold = lptr;
 454     }
 455
 456     while (perm_head) {
 457         perm_tail = perm_head;
 458         perm_head = perm_head->next;
 459         nasm_free(perm_tail);
 460     }
 461 }
 462
 463 static void init_block(union label *blk)
 464 {
 465     int j;
 466
 467     for (j = 0; j < LABEL_BLOCK - 1; j++)
 468         blk[j].admin.movingon = END_LIST;
 469     blk[LABEL_BLOCK - 1].admin.movingon = END_BLOCK;
 470     blk[LABEL_BLOCK - 1].admin.next = NULL;
 471 }
 472
 473 static char *perm_copy(const char *string)
 474 {
 475     char *p;
 476     int len = strlen(string)+1;
 477
 478     nasm_assert(len <= PERMTS_SIZE);
 479
 480     if (perm_tail->size - perm_tail->usage < len) {
 481         perm_tail->next =
 482             (struct permts *)nasm_malloc(sizeof(struct permts));
 483         perm_tail = perm_tail->next;
 484         perm_tail->next = NULL;
 485         perm_tail->size = PERMTS_SIZE;
 486         perm_tail->usage = 0;
 487     }
 488     p = perm_tail->data + perm_tail->usage;
 489     memcpy(p, string, len);
 490     perm_tail->usage += len;
 491
 492     return p;
 493 }
 494
 495 char *local_scope(char *label)
 496 {
 497    return islocal(label) ? prevlabel : "";
 498 }
 499
 500 /*
 501  * Notes regarding bug involving redefinition of external segments.
 502  *
 503  * Up to and including v0.97, the following code didn't work. From 0.97
 504  * developers release 2 onwards, it will generate an error.
 505  *
 506  * EXTERN extlabel
 507  * newlabel EQU extlabel + 1
 508  *
 509  * The results of allowing this code through are that two import records
 510  * are generated, one for 'extlabel' and one for 'newlabel'.
 511  *
 512  * The reason for this is an inadequacy in the defined interface between
 513  * the label manager and the output formats. The problem lies in how the
 514  * output format driver tells that a label is an external label for which
 515  * a label import record must be produced. Most (all except bin?) produce
 516  * the record if the segment number of the label is not one of the internal
 517  * segments that the output driver is producing.
 518  *
 519  * A simple fix to this would be to make the output formats keep track of
 520  * which symbols they've produced import records for, and make them not
 521  * produce import records for segments that are already defined.
 522  *
 523  * The best way, which is slightly harder but reduces duplication of code
 524  * and should therefore make the entire system smaller and more stable is
 525  * to change the interface between assembler, define_label(), and
 526  * the output module. The changes that are needed are:
 527  *
 528  * The semantics of the 'isextern' flag passed to define_label() need
 529  * examining. This information may or may not tell us what we need to
 530  * know (ie should we be generating an import record at this point for this
 531  * label). If these aren't the semantics, the semantics should be changed
 532  * to this.
 533  *
 534  * The output module interface needs changing, so that the `isextern' flag
 535  * is passed to the module, so that it can be easily tested for.
 536  */