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;
 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 = (union label *)nasm_malloc(LBLK_SIZE);
 170         lfree = lfree->admin.next;
 171         init_block(lfree);
 172     }
 173
 174     lfree->admin.movingon = BOGUS_VALUE;
 175     lfree->defn.label = perm_copy(label);
 176     lfree->defn.special = NULL;
 177     lfree->defn.is_global = NOT_DEFINED_YET;
 178
 179     hash_add(&ip, lfree->defn.label, lfree);
 180     return lfree++;
 181 }
 182
 183 bool lookup_label(char *label, int32_t *segment, int64_t *offset)
 184 {
 185     union label *lptr;
 186
 187     if (!initialized)
 188         return false;
 189
 190     lptr = find_label(label, 0);
 191     if (lptr && (lptr->defn.is_global & DEFINED_BIT)) {
 192         *segment = lptr->defn.segment;
 193         *offset = lptr->defn.offset;
 194         return true;
 195     }
 196
 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, exi,
 265                                                special ? special : lptr->defn.special);
 266 /**     nasm_free(xsymbol);  ! outobj.c stores the pointer; ouch!!! **/
 267         } else {
 268             if ((lptr->defn.is_global & (GLOBAL_BIT | EXTERN_BIT)) != EXTERN_BIT) {
 269                 ofmt->symdef(lptr->defn.label, segment, offset, exi,
 270                              special ? special : lptr->defn.special);
 271                 ofmt->current_dfmt->debug_deflabel(label, segment, offset, exi,
 272                                                    special ? special : lptr->defn.special);
 273             }
 274         }
 275     }   /* if (pass0 == 1) */
 276 }
 277
 278 void define_label(char *label, int32_t segment, int64_t offset, char *special,
 279                   bool is_norm, bool isextrn)
 280 {
 281     union label *lptr;
 282     int exi;
 283
 284 #ifdef DEBUG
 285 #if DEBUG<3
 286     if (!strncmp(label, "debugdump", 9))
 287 #endif
 288         nasm_error(ERR_DEBUG, "define_label (%s, %"PRIx32", %"PRIx64", %s, %d, %d)",
 289               label, segment, offset, special, is_norm, isextrn);
 290 #endif
 291     lptr = find_label(label, 1);
 292     if (!lptr)
 293         return;
 294     if (lptr->defn.is_global & DEFINED_BIT) {
 295         nasm_error(ERR_NONFATAL, "symbol `%s' redefined", label);
 296         return;
 297     }
 298     lptr->defn.is_global |= DEFINED_BIT;
 299     if (isextrn)
 300         lptr->defn.is_global |= EXTERN_BIT;
 301
 302     if (!islocalchar(label[0]) && is_norm) {
 303         /* not local, but not special either */
 304         prevlabel = lptr->defn.label;
 305     } else if (islocal(label) && !*prevlabel) {
 306         nasm_error(ERR_NONFATAL, "attempt to define a local label before any"
 307               " non-local labels");
 308     }
 309
 310     lptr->defn.segment = segment;
 311     lptr->defn.offset = offset;
 312     lptr->defn.is_norm = (!islocalchar(label[0]) && is_norm);
 313
 314     if (pass0 == 1 || (!is_norm && !isextrn && (segment > 0) && (segment & 1))) {
 315         exi = !!(lptr->defn.is_global & GLOBAL_BIT);
 316         if (exi) {
 317             char *xsymbol;
 318             int slen;
 319             slen = strlen(lprefix);
 320             slen += strlen(lptr->defn.label);
 321             slen += strlen(lpostfix);
 322             slen++;             /* room for that null char */
 323             xsymbol = nasm_malloc(slen);
 324             snprintf(xsymbol, slen, "%s%s%s", lprefix, lptr->defn.label,
 325                      lpostfix);
 326
 327             ofmt->symdef(xsymbol, segment, offset, exi,
 328                          special ? special : lptr->defn.special);
 329             ofmt->current_dfmt->debug_deflabel(xsymbol, segment, offset, exi,
 330                                                special ? special : lptr->defn.special);
 331 /**     nasm_free(xsymbol);  ! outobj.c stores the pointer; ouch!!! **/
 332         } else {
 333             if ((lptr->defn.is_global & (GLOBAL_BIT | EXTERN_BIT)) != EXTERN_BIT) {
 334                 ofmt->symdef(lptr->defn.label, segment, offset, exi,
 335                              special ? special : lptr->defn.special);
 336                 ofmt->current_dfmt->debug_deflabel(label, segment, offset, exi,
 337                                                    special ? special : lptr->defn.special);
 338             }
 339         }
 340     }   /* if (pass0 == 1) */
 341 }
 342
 343 void define_common(char *label, int32_t segment, int32_t size, char *special)
 344 {
 345     union label *lptr;
 346
 347     lptr = find_label(label, 1);
 348     if (!lptr)
 349         return;
 350     if ((lptr->defn.is_global & DEFINED_BIT) &&
 351         (passn == 1 || !(lptr->defn.is_global & COMMON_BIT))) {
 352             nasm_error(ERR_NONFATAL, "symbol `%s' redefined", label);
 353             return;
 354     }
 355     lptr->defn.is_global |= DEFINED_BIT|COMMON_BIT;
 356
 357     if (!islocalchar(label[0])) {
 358         prevlabel = lptr->defn.label;
 359     } else {
 360         nasm_error(ERR_NONFATAL, "attempt to define a local label as a "
 361               "common variable");
 362         return;
 363     }
 364
 365     lptr->defn.segment = segment;
 366     lptr->defn.offset = 0;
 367
 368     if (pass0 == 0)
 369         return;
 370
 371     ofmt->symdef(lptr->defn.label, segment, size, 2,
 372                  special ? special : lptr->defn.special);
 373     ofmt->current_dfmt->debug_deflabel(lptr->defn.label, segment, size, 2,
 374                                        special ? special : lptr->defn.special);
 375 }
 376
 377 void declare_as_global(char *label, char *special)
 378 {
 379     union label *lptr;
 380
 381     if (islocal(label)) {
 382         nasm_error(ERR_NONFATAL, "attempt to declare local symbol `%s' as"
 383               " global", label);
 384         return;
 385     }
 386     lptr = find_label(label, 1);
 387     if (!lptr)
 388         return;
 389     switch (lptr->defn.is_global & TYPE_MASK) {
 390     case NOT_DEFINED_YET:
 391         lptr->defn.is_global = GLOBAL_PLACEHOLDER;
 392         lptr->defn.special = special ? perm_copy(special) : NULL;
 393         break;
 394     case GLOBAL_PLACEHOLDER:   /* already done: silently ignore */
 395     case GLOBAL_SYMBOL:
 396         break;
 397     case LOCAL_SYMBOL:
 398         if (!(lptr->defn.is_global & EXTERN_BIT)) {
 399             nasm_error(ERR_WARNING, "symbol `%s': GLOBAL directive "
 400                   "after symbol definition is an experimental feature", label);
 401             lptr->defn.is_global = GLOBAL_SYMBOL;
 402         }
 403         break;
 404     }
 405 }
 406
 407 int init_labels(void)
 408 {
 409     hash_init(&ltab, HASH_LARGE);
 410
 411     ldata = lfree = (union label *)nasm_malloc(LBLK_SIZE);
 412     init_block(lfree);
 413
 414     perm_head = perm_tail =
 415         (struct permts *)nasm_malloc(sizeof(struct permts));
 416
 417     perm_head->next = NULL;
 418     perm_head->size = PERMTS_SIZE;
 419     perm_head->usage = 0;
 420
 421     prevlabel = "";
 422
 423     initialized = true;
 424
 425     return 0;
 426 }
 427
 428 void cleanup_labels(void)
 429 {
 430     union label *lptr, *lhold;
 431
 432     initialized = false;
 433
 434     hash_free(&ltab);
 435
 436     lptr = lhold = ldata;
 437     while (lptr) {
 438         lptr = &lptr[LABEL_BLOCK-1];
 439         lptr = lptr->admin.next;
 440         nasm_free(lhold);
 441         lhold = lptr;
 442     }
 443
 444     while (perm_head) {
 445         perm_tail = perm_head;
 446         perm_head = perm_head->next;
 447         nasm_free(perm_tail);
 448     }
 449 }
 450
 451 static void init_block(union label *blk)
 452 {
 453     int j;
 454
 455     for (j = 0; j < LABEL_BLOCK - 1; j++)
 456         blk[j].admin.movingon = END_LIST;
 457     blk[LABEL_BLOCK - 1].admin.movingon = END_BLOCK;
 458     blk[LABEL_BLOCK - 1].admin.next = NULL;
 459 }
 460
 461 static char *perm_copy(const char *string)
 462 {
 463     char *p;
 464     int len = strlen(string)+1;
 465
 466     nasm_assert(len <= PERMTS_SIZE);
 467
 468     if (perm_tail->size - perm_tail->usage < len) {
 469         perm_tail->next =
 470             (struct permts *)nasm_malloc(sizeof(struct permts));
 471         perm_tail = perm_tail->next;
 472         perm_tail->next = NULL;
 473         perm_tail->size = PERMTS_SIZE;
 474         perm_tail->usage = 0;
 475     }
 476     p = perm_tail->data + perm_tail->usage;
 477     memcpy(p, string, len);
 478     perm_tail->usage += len;
 479
 480     return p;
 481 }
 482
 483 char *local_scope(char *label)
 484 {
 485    return islocal(label) ? prevlabel : "";
 486 }
 487
 488 /*
 489  * Notes regarding bug involving redefinition of external segments.
 490  *
 491  * Up to and including v0.97, the following code didn't work. From 0.97
 492  * developers release 2 onwards, it will generate an error.
 493  *
 494  * EXTERN extlabel
 495  * newlabel EQU extlabel + 1
 496  *
 497  * The results of allowing this code through are that two import records
 498  * are generated, one for 'extlabel' and one for 'newlabel'.
 499  *
 500  * The reason for this is an inadequacy in the defined interface between
 501  * the label manager and the output formats. The problem lies in how the
 502  * output format driver tells that a label is an external label for which
 503  * a label import record must be produced. Most (all except bin?) produce
 504  * the record if the segment number of the label is not one of the internal
 505  * segments that the output driver is producing.
 506  *
 507  * A simple fix to this would be to make the output formats keep track of
 508  * which symbols they've produced import records for, and make them not
 509  * produce import records for segments that are already defined.
 510  *
 511  * The best way, which is slightly harder but reduces duplication of code
 512  * and should therefore make the entire system smaller and more stable is
 513  * to change the interface between assembler, define_label(), and
 514  * the output module. The changes that are needed are:
 515  *
 516  * The semantics of the 'isextern' flag passed to define_label() need
 517  * examining. This information may or may not tell us what we need to
 518  * know (ie should we be generating an import record at this point for this
 519  * label). If these aren't the semantics, the semantics should be changed
 520  * to this.
 521  *
 522  * The output module interface needs changing, so that the `isextern' flag
 523  * is passed to the module, so that it can be easily tested for.
 524  */