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     }
 197
 198     return false;
 199 }
 200
 201 bool is_extern(char *label)
 202 {
 203     union label *lptr;
 204
 205     if (!initialized)
 206         return false;
 207
 208     lptr = find_label(label, 0);
 209     return (lptr && (lptr->defn.is_global & EXTERN_BIT));
 210 }
 211
 212 void redefine_label(char *label, int32_t segment, int64_t offset, char *special,
 213                     bool is_norm, bool isextrn)
 214 {
 215     union label *lptr;
 216     int exi;
 217
 218     /* This routine possibly ought to check for phase errors.  Most assemblers
 219      * check for phase errors at this point.  I don't know whether phase errors
 220      * are even possible, nor whether they are checked somewhere else
 221      */
 222
 223     (void)special;              /* Don't warn that this parameter is unused */
 224     (void)is_norm;              /* Don't warn that this parameter is unused */
 225     (void)isextrn;              /* Don't warn that this parameter is unused */
 226
 227 #ifdef DEBUG
 228 #if DEBUG<3
 229     if (!strncmp(label, "debugdump", 9))
 230 #endif
 231         nasm_error(ERR_DEBUG, "redefine_label (%s, %"PRIx32", %"PRIx64", %s, %d, %d)",
 232               label, segment, offset, special, is_norm, isextrn);
 233 #endif
 234
 235     lptr = find_label(label, 1);
 236     if (!lptr)
 237         nasm_error(ERR_PANIC, "can't find label `%s' on pass two", label);
 238
 239     if (!islocal(label)) {
 240         if (!islocalchar(*label) && lptr->defn.is_norm)
 241             prevlabel = lptr->defn.label;
 242     }
 243
 244     if (lptr->defn.offset != offset)
 245         global_offset_changed++;
 246
 247     lptr->defn.offset = offset;
 248     lptr->defn.segment = segment;
 249
 250     if (pass0 == 1) {
 251         exi = !!(lptr->defn.is_global & GLOBAL_BIT);
 252         if (exi) {
 253             char *xsymbol;
 254             int slen;
 255             slen = strlen(lprefix);
 256             slen += strlen(lptr->defn.label);
 257             slen += strlen(lpostfix);
 258             slen++;             /* room for that null char */
 259             xsymbol = nasm_malloc(slen);
 260             snprintf(xsymbol, slen, "%s%s%s", lprefix, lptr->defn.label,
 261                      lpostfix);
 262
 263             ofmt->symdef(xsymbol, segment, offset, exi,
 264                          special ? special : lptr->defn.special);
 265             ofmt->current_dfmt->debug_deflabel(xsymbol, segment, offset,
 266                                                exi,
 267                                                special ? special : lptr->
 268                                                defn.special);
 269 /**     nasm_free(xsymbol);  ! outobj.c stores the pointer; ouch!!! **/
 270         } else {
 271             if ((lptr->defn.is_global & (GLOBAL_BIT | EXTERN_BIT)) !=
 272                 EXTERN_BIT) {
 273                 ofmt->symdef(lptr->defn.label, segment, offset, exi,
 274                              special ? special : lptr->defn.special);
 275                 ofmt->current_dfmt->debug_deflabel(label, segment, offset,
 276                                                    exi,
 277                                                    special ? special :
 278                                                    lptr->defn.special);
 279             }
 280         }
 281     }
 282     /* if (pass0 == 1) */
 283 }
 284
 285 void define_label(char *label, int32_t segment, int64_t offset, char *special,
 286                   bool is_norm, bool isextrn)
 287 {
 288     union label *lptr;
 289     int exi;
 290
 291 #ifdef DEBUG
 292 #if DEBUG<3
 293     if (!strncmp(label, "debugdump", 9))
 294 #endif
 295         nasm_error(ERR_DEBUG, "define_label (%s, %"PRIx32", %"PRIx64", %s, %d, %d)",
 296               label, segment, offset, special, is_norm, isextrn);
 297 #endif
 298     lptr = find_label(label, 1);
 299     if (!lptr)
 300         return;
 301     if (lptr->defn.is_global & DEFINED_BIT) {
 302         nasm_error(ERR_NONFATAL, "symbol `%s' redefined", label);
 303         return;
 304     }
 305     lptr->defn.is_global |= DEFINED_BIT;
 306     if (isextrn)
 307         lptr->defn.is_global |= EXTERN_BIT;
 308
 309     if (!islocalchar(label[0]) && is_norm) {
 310         /* not local, but not special either */
 311         prevlabel = lptr->defn.label;
 312     } else if (islocal(label) && !*prevlabel) {
 313         nasm_error(ERR_NONFATAL, "attempt to define a local label before any"
 314               " non-local labels");
 315     }
 316
 317     lptr->defn.segment = segment;
 318     lptr->defn.offset = offset;
 319     lptr->defn.is_norm = (!islocalchar(label[0]) && is_norm);
 320
 321     if (pass0 == 1 || (!is_norm && !isextrn && (segment > 0) && (segment & 1))) {
 322         exi = !!(lptr->defn.is_global & GLOBAL_BIT);
 323         if (exi) {
 324             char *xsymbol;
 325             int slen;
 326             slen = strlen(lprefix);
 327             slen += strlen(lptr->defn.label);
 328             slen += strlen(lpostfix);
 329             slen++;             /* room for that null char */
 330             xsymbol = nasm_malloc(slen);
 331             snprintf(xsymbol, slen, "%s%s%s", lprefix, lptr->defn.label,
 332                      lpostfix);
 333
 334             ofmt->symdef(xsymbol, segment, offset, exi,
 335                          special ? special : lptr->defn.special);
 336             ofmt->current_dfmt->debug_deflabel(xsymbol, segment, offset,
 337                                                exi,
 338                                                special ? special : lptr->
 339                                                defn.special);
 340 /**     nasm_free(xsymbol);  ! outobj.c stores the pointer; ouch!!! **/
 341         } else {
 342             if ((lptr->defn.is_global & (GLOBAL_BIT | EXTERN_BIT)) !=
 343                 EXTERN_BIT) {
 344                 ofmt->symdef(lptr->defn.label, segment, offset, exi,
 345                              special ? special : lptr->defn.special);
 346                 ofmt->current_dfmt->debug_deflabel(label, segment, offset,
 347                                                    exi,
 348                                                    special ? special :
 349                                                    lptr->defn.special);
 350             }
 351         }
 352     }                           /* if (pass0 == 1) */
 353 }
 354
 355 void define_common(char *label, int32_t segment, int32_t size, char *special)
 356 {
 357     union label *lptr;
 358
 359     lptr = find_label(label, 1);
 360     if (!lptr)
 361         return;
 362     if ((lptr->defn.is_global & DEFINED_BIT) &&
 363         (passn == 1 || !(lptr->defn.is_global & COMMON_BIT))) {
 364             nasm_error(ERR_NONFATAL, "symbol `%s' redefined", label);
 365             return;
 366     }
 367     lptr->defn.is_global |= DEFINED_BIT|COMMON_BIT;
 368
 369     if (!islocalchar(label[0])) {
 370         prevlabel = lptr->defn.label;
 371     } else {
 372         nasm_error(ERR_NONFATAL, "attempt to define a local label as a "
 373               "common variable");
 374         return;
 375     }
 376
 377     lptr->defn.segment = segment;
 378     lptr->defn.offset = 0;
 379
 380     if (pass0 == 0)
 381         return;
 382
 383     ofmt->symdef(lptr->defn.label, segment, size, 2,
 384                  special ? special : lptr->defn.special);
 385     ofmt->current_dfmt->debug_deflabel(lptr->defn.label, segment, size, 2,
 386                                        special ? special : lptr->defn.
 387                                        special);
 388 }
 389
 390 void declare_as_global(char *label, char *special)
 391 {
 392     union label *lptr;
 393
 394     if (islocal(label)) {
 395         nasm_error(ERR_NONFATAL, "attempt to declare local symbol `%s' as"
 396               " global", label);
 397         return;
 398     }
 399     lptr = find_label(label, 1);
 400     if (!lptr)
 401         return;
 402     switch (lptr->defn.is_global & TYPE_MASK) {
 403     case NOT_DEFINED_YET:
 404         lptr->defn.is_global = GLOBAL_PLACEHOLDER;
 405         lptr->defn.special = special ? perm_copy(special) : NULL;
 406         break;
 407     case GLOBAL_PLACEHOLDER:   /* already done: silently ignore */
 408     case GLOBAL_SYMBOL:
 409         break;
 410     case LOCAL_SYMBOL:
 411         if (!(lptr->defn.is_global & EXTERN_BIT)) {
 412             nasm_error(ERR_WARNING, "symbol `%s': GLOBAL directive "
 413                   "after symbol definition is an experimental feature", label);
 414             lptr->defn.is_global = GLOBAL_SYMBOL;
 415         }
 416         break;
 417     }
 418 }
 419
 420 int init_labels(void)
 421 {
 422     hash_init(&ltab, HASH_LARGE);
 423
 424     ldata = lfree = (union label *)nasm_malloc(LBLK_SIZE);
 425     init_block(lfree);
 426
 427     perm_head =
 428         perm_tail = (struct permts *)nasm_malloc(sizeof(struct permts));
 429
 430     perm_head->next = NULL;
 431     perm_head->size = PERMTS_SIZE;
 432     perm_head->usage = 0;
 433
 434     prevlabel = "";
 435
 436     initialized = true;
 437
 438     return 0;
 439 }
 440
 441 void cleanup_labels(void)
 442 {
 443     union label *lptr, *lhold;
 444
 445     initialized = false;
 446
 447     hash_free(&ltab);
 448
 449     lptr = lhold = ldata;
 450     while (lptr) {
 451         lptr = &lptr[LABEL_BLOCK-1];
 452         lptr = lptr->admin.next;
 453         nasm_free(lhold);
 454         lhold = lptr;
 455     }
 456
 457     while (perm_head) {
 458         perm_tail = perm_head;
 459         perm_head = perm_head->next;
 460         nasm_free(perm_tail);
 461     }
 462 }
 463
 464 static void init_block(union label *blk)
 465 {
 466     int j;
 467
 468     for (j = 0; j < LABEL_BLOCK - 1; j++)
 469         blk[j].admin.movingon = END_LIST;
 470     blk[LABEL_BLOCK - 1].admin.movingon = END_BLOCK;
 471     blk[LABEL_BLOCK - 1].admin.next = NULL;
 472 }
 473
 474 static char *perm_copy(const char *string)
 475 {
 476     char *p;
 477     int len = strlen(string)+1;
 478
 479     nasm_assert(len <= PERMTS_SIZE);
 480
 481     if (perm_tail->size - perm_tail->usage < len) {
 482         perm_tail->next =
 483             (struct permts *)nasm_malloc(sizeof(struct permts));
 484         perm_tail = perm_tail->next;
 485         perm_tail->next = NULL;
 486         perm_tail->size = PERMTS_SIZE;
 487         perm_tail->usage = 0;
 488     }
 489     p = perm_tail->data + perm_tail->usage;
 490     memcpy(p, string, len);
 491     perm_tail->usage += len;
 492
 493     return p;
 494 }
 495
 496 char *local_scope(char *label)
 497 {
 498    return islocal(label) ? prevlabel : "";
 499 }
 500
 501 /*
 502  * Notes regarding bug involving redefinition of external segments.
 503  *
 504  * Up to and including v0.97, the following code didn't work. From 0.97
 505  * developers release 2 onwards, it will generate an error.
 506  *
 507  * EXTERN extlabel
 508  * newlabel EQU extlabel + 1
 509  *
 510  * The results of allowing this code through are that two import records
 511  * are generated, one for 'extlabel' and one for 'newlabel'.
 512  *
 513  * The reason for this is an inadequacy in the defined interface between
 514  * the label manager and the output formats. The problem lies in how the
 515  * output format driver tells that a label is an external label for which
 516  * a label import record must be produced. Most (all except bin?) produce
 517  * the record if the segment number of the label is not one of the internal
 518  * segments that the output driver is producing.
 519  *
 520  * A simple fix to this would be to make the output formats keep track of
 521  * which symbols they've produced import records for, and make them not
 522  * produce import records for segments that are already defined.
 523  *
 524  * The best way, which is slightly harder but reduces duplication of code
 525  * and should therefore make the entire system smaller and more stable is
 526  * to change the interface between assembler, define_label(), and
 527  * the output module. The changes that are needed are:
 528  *
 529  * The semantics of the 'isextern' flag passed to define_label() need
 530  * examining. This information may or may not tell us what we need to
 531  * know (ie should we be generating an import record at this point for this
 532  * label). If these aren't the semantics, the semantics should be changed
 533  * to this.
 534  *
 535  * The output module interface needs changing, so that the `isextern' flag
 536  * is passed to the module, so that it can be easily tested for.
 537  */