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             return NULL;        /* Error... */
 147         memcpy(label_str, prev, prevlen);
 148         memcpy(label_str+prevlen, label, len+1);
 149         label = label_str;
 150     } else {
 151         prev = "";
 152         prevlen = 0;
 153     }
 154
 155     lpp = (union label **) hash_find(&ltab, label, &ip);
 156     lptr = lpp ? *lpp : NULL;
 157
 158     if (lptr || !create)
 159         return lptr;
 160
 161     /* Create a new label... */
 162     if (lfree->admin.movingon == END_BLOCK) {
 163         /*
 164          * must allocate a new block
 165          */
 166         lfree->admin.next =
 167             (union label *)nasm_malloc(LBLK_SIZE);
 168         lfree = lfree->admin.next;
 169         init_block(lfree);
 170     }
 171
 172     lfree->admin.movingon = BOGUS_VALUE;
 173     lfree->defn.label = perm_copy(label);
 174     lfree->defn.special = NULL;
 175     lfree->defn.is_global = NOT_DEFINED_YET;
 176
 177     hash_add(&ip, lfree->defn.label, lfree);
 178     return lfree++;
 179 }
 180
 181 bool lookup_label(char *label, int32_t *segment, int64_t *offset)
 182 {
 183     union label *lptr;
 184
 185     if (!initialized)
 186         return false;
 187
 188     lptr = find_label(label, 0);
 189     if (lptr && (lptr->defn.is_global & DEFINED_BIT)) {
 190         *segment = lptr->defn.segment;
 191         *offset = lptr->defn.offset;
 192         return true;
 193     } else
 194         return false;
 195 }
 196
 197 bool is_extern(char *label)
 198 {
 199     union label *lptr;
 200
 201     if (!initialized)
 202         return false;
 203
 204     lptr = find_label(label, 0);
 205     return (lptr && (lptr->defn.is_global & EXTERN_BIT));
 206 }
 207
 208 void redefine_label(char *label, int32_t segment, int64_t offset, char *special,
 209                     bool is_norm, bool isextrn)
 210 {
 211     union label *lptr;
 212     int exi;
 213
 214     /* This routine possibly ought to check for phase errors.  Most assemblers
 215      * check for phase errors at this point.  I don't know whether phase errors
 216      * are even possible, nor whether they are checked somewhere else
 217      */
 218
 219     (void)special;              /* Don't warn that this parameter is unused */
 220     (void)is_norm;              /* Don't warn that this parameter is unused */
 221     (void)isextrn;              /* Don't warn that this parameter is unused */
 222
 223 #ifdef DEBUG
 224 #if DEBUG<3
 225     if (!strncmp(label, "debugdump", 9))
 226 #endif
 227         nasm_error(ERR_DEBUG, "redefine_label (%s, %"PRIx32", %"PRIx64", %s, %d, %d)",
 228               label, segment, offset, special, is_norm, isextrn);
 229 #endif
 230
 231     lptr = find_label(label, 1);
 232     if (!lptr)
 233         nasm_error(ERR_PANIC, "can't find label `%s' on pass two", label);
 234
 235     if (!islocal(label)) {
 236         if (!islocalchar(*label) && lptr->defn.is_norm)
 237             prevlabel = lptr->defn.label;
 238     }
 239
 240     if (lptr->defn.offset != offset)
 241         global_offset_changed++;
 242
 243     lptr->defn.offset = offset;
 244     lptr->defn.segment = segment;
 245
 246     if (pass0 == 1) {
 247         exi = !!(lptr->defn.is_global & GLOBAL_BIT);
 248         if (exi) {
 249             char *xsymbol;
 250             int slen;
 251             slen = strlen(lprefix);
 252             slen += strlen(lptr->defn.label);
 253             slen += strlen(lpostfix);
 254             slen++;             /* room for that null char */
 255             xsymbol = nasm_malloc(slen);
 256             snprintf(xsymbol, slen, "%s%s%s", lprefix, lptr->defn.label,
 257                      lpostfix);
 258
 259             ofmt->symdef(xsymbol, segment, offset, exi,
 260                          special ? special : lptr->defn.special);
 261             ofmt->current_dfmt->debug_deflabel(xsymbol, segment, offset,
 262                                                exi,
 263                                                special ? special : lptr->
 264                                                defn.special);
 265 /**     nasm_free(xsymbol);  ! outobj.c stores the pointer; ouch!!! **/
 266         } else {
 267             if ((lptr->defn.is_global & (GLOBAL_BIT | EXTERN_BIT)) !=
 268                 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,
 272                                                    exi,
 273                                                    special ? special :
 274                                                    lptr->defn.special);
 275             }
 276         }
 277     }
 278     /* if (pass0 == 1) */
 279 }
 280
 281 void define_label(char *label, int32_t segment, int64_t offset, char *special,
 282                   bool is_norm, bool isextrn)
 283 {
 284     union label *lptr;
 285     int exi;
 286
 287 #ifdef DEBUG
 288 #if DEBUG<3
 289     if (!strncmp(label, "debugdump", 9))
 290 #endif
 291         nasm_error(ERR_DEBUG, "define_label (%s, %"PRIx32", %"PRIx64", %s, %d, %d)",
 292               label, segment, offset, special, is_norm, isextrn);
 293 #endif
 294     lptr = find_label(label, 1);
 295     if (lptr->defn.is_global & DEFINED_BIT) {
 296         nasm_error(ERR_NONFATAL, "symbol `%s' redefined", label);
 297         return;
 298     }
 299     lptr->defn.is_global |= DEFINED_BIT;
 300     if (isextrn)
 301         lptr->defn.is_global |= EXTERN_BIT;
 302
 303     if (!islocalchar(label[0]) && is_norm) {
 304         /* not local, but not special either */
 305         prevlabel = lptr->defn.label;
 306     } else if (islocal(label) && !*prevlabel) {
 307         nasm_error(ERR_NONFATAL, "attempt to define a local label before any"
 308               " non-local labels");
 309     }
 310
 311     lptr->defn.segment = segment;
 312     lptr->defn.offset = offset;
 313     lptr->defn.is_norm = (!islocalchar(label[0]) && is_norm);
 314
 315     if (pass0 == 1 || (!is_norm && !isextrn && (segment > 0) && (segment & 1))) {
 316         exi = !!(lptr->defn.is_global & GLOBAL_BIT);
 317         if (exi) {
 318             char *xsymbol;
 319             int slen;
 320             slen = strlen(lprefix);
 321             slen += strlen(lptr->defn.label);
 322             slen += strlen(lpostfix);
 323             slen++;             /* room for that null char */
 324             xsymbol = nasm_malloc(slen);
 325             snprintf(xsymbol, slen, "%s%s%s", lprefix, lptr->defn.label,
 326                      lpostfix);
 327
 328             ofmt->symdef(xsymbol, segment, offset, exi,
 329                          special ? special : lptr->defn.special);
 330             ofmt->current_dfmt->debug_deflabel(xsymbol, segment, offset,
 331                                                exi,
 332                                                special ? special : lptr->
 333                                                defn.special);
 334 /**     nasm_free(xsymbol);  ! outobj.c stores the pointer; ouch!!! **/
 335         } else {
 336             if ((lptr->defn.is_global & (GLOBAL_BIT | EXTERN_BIT)) !=
 337                 EXTERN_BIT) {
 338                 ofmt->symdef(lptr->defn.label, segment, offset, exi,
 339                              special ? special : lptr->defn.special);
 340                 ofmt->current_dfmt->debug_deflabel(label, segment, offset,
 341                                                    exi,
 342                                                    special ? special :
 343                                                    lptr->defn.special);
 344             }
 345         }
 346     }                           /* if (pass0 == 1) */
 347 }
 348
 349 void define_common(char *label, int32_t segment, int32_t size, char *special)
 350 {
 351     union label *lptr;
 352
 353     lptr = find_label(label, 1);
 354     if ((lptr->defn.is_global & DEFINED_BIT) &&
 355         (passn == 1 || !(lptr->defn.is_global & COMMON_BIT))) {
 356             nasm_error(ERR_NONFATAL, "symbol `%s' redefined", label);
 357             return;
 358     }
 359     lptr->defn.is_global |= DEFINED_BIT|COMMON_BIT;
 360
 361     if (!islocalchar(label[0])) {
 362         prevlabel = lptr->defn.label;
 363     } else {
 364         nasm_error(ERR_NONFATAL, "attempt to define a local label as a "
 365               "common variable");
 366         return;
 367     }
 368
 369     lptr->defn.segment = segment;
 370     lptr->defn.offset = 0;
 371
 372     if (pass0 == 0)
 373         return;
 374
 375     ofmt->symdef(lptr->defn.label, segment, size, 2,
 376                  special ? special : lptr->defn.special);
 377     ofmt->current_dfmt->debug_deflabel(lptr->defn.label, segment, size, 2,
 378                                        special ? special : lptr->defn.
 379                                        special);
 380 }
 381
 382 void declare_as_global(char *label, char *special)
 383 {
 384     union label *lptr;
 385
 386     if (islocal(label)) {
 387         nasm_error(ERR_NONFATAL, "attempt to declare local symbol `%s' as"
 388               " global", label);
 389         return;
 390     }
 391     lptr = find_label(label, 1);
 392     switch (lptr->defn.is_global & TYPE_MASK) {
 393     case NOT_DEFINED_YET:
 394         lptr->defn.is_global = GLOBAL_PLACEHOLDER;
 395         lptr->defn.special = special ? perm_copy(special) : NULL;
 396         break;
 397     case GLOBAL_PLACEHOLDER:   /* already done: silently ignore */
 398     case GLOBAL_SYMBOL:
 399         break;
 400     case LOCAL_SYMBOL:
 401         if (!(lptr->defn.is_global & EXTERN_BIT)) {
 402             nasm_error(ERR_WARNING, "symbol `%s': GLOBAL directive "
 403                   "after symbol definition is an experimental feature", label);
 404             lptr->defn.is_global = GLOBAL_SYMBOL;
 405         }
 406         break;
 407     }
 408 }
 409
 410 int init_labels(void)
 411 {
 412     hash_init(&ltab, HASH_LARGE);
 413
 414     ldata = lfree = (union label *)nasm_malloc(LBLK_SIZE);
 415     init_block(lfree);
 416
 417     perm_head =
 418         perm_tail = (struct permts *)nasm_malloc(sizeof(struct permts));
 419
 420     perm_head->next = NULL;
 421     perm_head->size = PERMTS_SIZE;
 422     perm_head->usage = 0;
 423
 424     prevlabel = "";
 425
 426     initialized = true;
 427
 428     return 0;
 429 }
 430
 431 void cleanup_labels(void)
 432 {
 433     union label *lptr, *lhold;
 434
 435     initialized = false;
 436
 437     hash_free(&ltab);
 438
 439     lptr = lhold = ldata;
 440     while (lptr) {
 441         lptr = &lptr[LABEL_BLOCK-1];
 442         lptr = lptr->admin.next;
 443         nasm_free(lhold);
 444         lhold = lptr;
 445     }
 446
 447     while (perm_head) {
 448         perm_tail = perm_head;
 449         perm_head = perm_head->next;
 450         nasm_free(perm_tail);
 451     }
 452 }
 453
 454 static void init_block(union label *blk)
 455 {
 456     int j;
 457
 458     for (j = 0; j < LABEL_BLOCK - 1; j++)
 459         blk[j].admin.movingon = END_LIST;
 460     blk[LABEL_BLOCK - 1].admin.movingon = END_BLOCK;
 461     blk[LABEL_BLOCK - 1].admin.next = NULL;
 462 }
 463
 464 static char *perm_copy(const char *string)
 465 {
 466     char *p;
 467     int len = strlen(string)+1;
 468
 469     nasm_assert(len <= PERMTS_SIZE);
 470
 471     if (perm_tail->size - perm_tail->usage < len) {
 472         perm_tail->next =
 473             (struct permts *)nasm_malloc(sizeof(struct permts));
 474         perm_tail = perm_tail->next;
 475         perm_tail->next = NULL;
 476         perm_tail->size = PERMTS_SIZE;
 477         perm_tail->usage = 0;
 478     }
 479     p = perm_tail->data + perm_tail->usage;
 480     memcpy(p, string, len);
 481     perm_tail->usage += len;
 482
 483     return p;
 484 }
 485
 486 char *local_scope(char *label)
 487 {
 488    return islocal(label) ? prevlabel : "";
 489 }
 490
 491 /*
 492  * Notes regarding bug involving redefinition of external segments.
 493  *
 494  * Up to and including v0.97, the following code didn't work. From 0.97
 495  * developers release 2 onwards, it will generate an error.
 496  *
 497  * EXTERN extlabel
 498  * newlabel EQU extlabel + 1
 499  *
 500  * The results of allowing this code through are that two import records
 501  * are generated, one for 'extlabel' and one for 'newlabel'.
 502  *
 503  * The reason for this is an inadequacy in the defined interface between
 504  * the label manager and the output formats. The problem lies in how the
 505  * output format driver tells that a label is an external label for which
 506  * a label import record must be produced. Most (all except bin?) produce
 507  * the record if the segment number of the label is not one of the internal
 508  * segments that the output driver is producing.
 509  *
 510  * A simple fix to this would be to make the output formats keep track of
 511  * which symbols they've produced import records for, and make them not
 512  * produce import records for segments that are already defined.
 513  *
 514  * The best way, which is slightly harder but reduces duplication of code
 515  * and should therefore make the entire system smaller and more stable is
 516  * to change the interface between assembler, define_label(), and
 517  * the output module. The changes that are needed are:
 518  *
 519  * The semantics of the 'isextern' flag passed to define_label() need
 520  * examining. This information may or may not tell us what we need to
 521  * know (ie should we be generating an import record at this point for this
 522  * label). If these aren't the semantics, the semantics should be changed
 523  * to this.
 524  *
 525  * The output module interface needs changing, so that the `isextern' flag
 526  * is passed to the module, so that it can be easily tested for.
 527  */