gas/config/obj-evax.c

   1 /* obj-evax.c - EVAX (openVMS/Alpha) object file format.
   2    Copyright 1996, 1997, 2007, 2008 Free Software Foundation, Inc.
   3    Contributed by Klaus Kämpf (kkaempf@progis.de) of
   4      proGIS Software, Aachen, Germany.
   5    Extensively enhanced by Douglas Rupp of AdaCore.
   6
   7    This file is part of GAS, the GNU Assembler
   8
   9    GAS is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 3, or (at your option)
  12    any later version.
  13
  14    GAS is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with GAS; see the file COPYING.  If not, write to
  21    the Free Software Foundation, 51 Franklin Street - Fifth Floor, Boston,
  22    MA 02110-1301, USA.  */
  23
  24 #define OBJ_HEADER "obj-evax.h"
  25
  26 #include "bfd.h"
  27 #include "vms.h"
  28 #include "as.h"
  29 #include "subsegs.h"
  30 #include "struc-symbol.h"
  31 #include "safe-ctype.h"
  32
  33 static void s_evax_weak (int);
  34 static unsigned int crc32 (unsigned char *, int);
  35 static char *encode_32 (unsigned int);
  36 static char *encode_16 (unsigned int);
  37 static int decode_16 (const char *);
  38
  39 const pseudo_typeS obj_pseudo_table[] =
  40 {
  41   { "weak", s_evax_weak, 0},
  42   {0, 0, 0},
  43 };                              /* obj_pseudo_table */
  44
  45 void obj_read_begin_hook () {}
  46
  47 /* Handle the weak specific pseudo-op.  */
  48
  49 static void
  50 s_evax_weak (int ignore ATTRIBUTE_UNUSED)
  51 {
  52   char *name;
  53   int c;
  54   symbolS *symbolP;
  55   char *stop = NULL;
  56   char stopc;
  57
  58   if (flag_mri)
  59     stop = mri_comment_field (&stopc);
  60
  61   do
  62     {
  63       name = input_line_pointer;
  64       c = get_symbol_end ();
  65       symbolP = symbol_find_or_make (name);
  66       *input_line_pointer = c;
  67       SKIP_WHITESPACE ();
  68       S_SET_WEAK (symbolP);
  69       if (c == ',')
  70         {
  71           input_line_pointer++;
  72           SKIP_WHITESPACE ();
  73           if (*input_line_pointer == '\n')
  74             c = '\n';
  75         }
  76     }
  77   while (c == ',');
  78
  79   if (flag_mri)
  80     mri_comment_end (stop, stopc);
  81
  82   demand_empty_rest_of_line ();
  83 }
  84
  85 void
  86 evax_symbol_new_hook (symbolS *sym)
  87 {
  88   struct evax_private_udata_struct *udata;
  89
  90   udata = (struct evax_private_udata_struct *)
  91     xmalloc (sizeof (struct evax_private_udata_struct));
  92
  93   udata->bsym = symbol_get_bfdsym (sym);
  94   udata->enbsym = NULL;
  95   udata->origname = xstrdup (S_GET_NAME (sym));
  96   udata->lkindex = 0;
  97   symbol_get_bfdsym(sym)->udata.p = (PTR) udata;
  98 }
  99
 100 void
 101 evax_frob_symbol (symbolS *sym, int *punt)
 102 {
 103   const char *symname = S_GET_NAME (sym);
 104   int symlen = strlen (symname);
 105   asymbol *symbol = symbol_get_bfdsym (sym);
 106
 107   if (symlen > 4
 108       && strcmp (symname + symlen - 4, "..en") == 0
 109       && S_GET_SEGMENT (sym) == undefined_section)
 110     {
 111       symbol_clear_used_in_reloc (sym);
 112       *punt = 1;
 113     }
 114
 115   else if ((symbol->flags & BSF_GLOBAL) && (symbol->flags & BSF_FUNCTION))
 116     {
 117       struct evax_private_udata_struct *udata
 118         = (struct evax_private_udata_struct *)symbol->udata.p;
 119
 120       /* Fix up equates of function definitions.  */
 121       while (udata->enbsym == NULL)
 122         {
 123           /* ??? Equates have been resolved at this point so their
 124              expression is O_constant; but they previously were
 125              O_symbol and we hope the equated symbol is still there.  */
 126           sym = symbol_get_value_expression (sym)->X_add_symbol;
 127           if (sym == NULL)
 128             abort ();
 129           symbol = symbol_get_bfdsym (sym);
 130           udata->enbsym
 131             = ((struct evax_private_udata_struct *)symbol->udata.p)->enbsym;
 132         }
 133     }
 134 }
 135
 136 void
 137 evax_frob_file_before_adjust (void)
 138 {
 139   struct alpha_linkage_fixups *l;
 140   segT current_section = now_seg;
 141   int current_subsec = now_subseg;
 142   segment_info_type *seginfo;
 143   int linkage_index = 1;
 144
 145   subseg_set (alpha_link_section, 0);
 146   seginfo = seg_info (alpha_link_section);
 147
 148   for (l = alpha_linkage_fixup_root; l != NULL; l = l->next)
 149     {
 150       if (S_GET_SEGMENT (l->fixp->fx_addsy) == alpha_link_section)
 151         {
 152           symbolS * entry_sym;
 153           fixS *fixpentry, *fixppdesc, *fixtail;
 154
 155           fixtail = seginfo->fix_tail;
 156
 157           /* Replace the linkage with the local symbols */
 158           entry_sym = symbol_find
 159             (((struct evax_private_udata_struct *)symbol_get_bfdsym (l->fixp->fx_addsy)->udata.p)->enbsym->name);
 160           if (!entry_sym)
 161             abort ();
 162           fixpentry = fix_new (l->fixp->fx_frag, l->fixp->fx_where, 8,
 163                                entry_sym, l->fixp->fx_offset, 0,
 164                                BFD_RELOC_64);
 165           fixppdesc = fix_new (l->fixp->fx_frag, l->fixp->fx_where+8, 8,
 166                                l->fixp->fx_addsy, l->fixp->fx_offset, 0,
 167                                BFD_RELOC_64);
 168           l->fixp->fx_size = 0;
 169           l->fixp->fx_done = 1;
 170
 171           /* If not already at the tail, splice the new fixups into
 172              the chain right after the one we are nulling out */
 173           if (fixtail != l->fixp)
 174             {
 175               fixppdesc->fx_next = l->fixp->fx_next;
 176               l->fixp->fx_next = fixpentry;
 177               fixtail->fx_next = 0;
 178               seginfo->fix_tail = fixtail;
 179             }
 180         }
 181       else
 182         {
 183           ((struct evax_private_udata_struct *)
 184            symbol_get_bfdsym (l->label)->udata.p)->lkindex = linkage_index;
 185
 186           l->fixp->fx_addnumber = linkage_index;
 187
 188           linkage_index += 2;
 189         }
 190     }
 191
 192   subseg_set (current_section, current_subsec);
 193 }
 194
 195 void
 196 evax_frob_file_before_fix (void)
 197 {
 198   /* Now that the fixups are done earlier, we need to transfer the values
 199      into the BFD symbols before calling fix_segment (ideally should not
 200      be done also later).  */
 201   if (symbol_rootP)
 202     {
 203       symbolS *symp;
 204
 205       /* Set the value into the BFD symbol.  Up til now the value
 206          has only been kept in the gas symbolS struct.  */
 207       for (symp = symbol_rootP; symp; symp = symbol_next (symp))
 208         symbol_get_bfdsym (symp)->value = S_GET_VALUE (symp);
 209     }
 210 }
 211
 212 /* The length is computed from the maximum allowable length of 64 less the
 213    4 character ..xx extension that must be preserved (removed before
 214    krunching and appended back on afterwards).  The $<nnn>.. prefix is
 215    also removed and prepened back on, but doesn't enter into the length
 216    computation because symbols with that prefix are always resolved
 217    by the assembler and will never appear in the symbol table. At least
 218    I hope that's true, TBD.  */
 219 #define MAX_LABEL_LENGTH 60
 220
 221 static char *shorten_identifier (char *);
 222 static int is_truncated_identifier (char *);
 223
 224 char *
 225 evax_shorten_name (char *id)
 226 {
 227   int prefix_dotdot = 0;
 228   char prefix [64];
 229   int len = strlen (id);
 230   int suffix_dotdot = len;
 231   char suffix [64];
 232   char *base_id;
 233
 234   /* This test may be too conservative.  */
 235   if (len <= MAX_LABEL_LENGTH)
 236     return id;
 237
 238   suffix [0] = 0;
 239   prefix [0] = 0;
 240
 241   /* Check for ..xx suffix and save it.  */
 242   if (strncmp (&id[len-4], "..", 2) == 0)
 243     {
 244       suffix_dotdot = len - 4;
 245       strncpy (suffix, &id[len-4], 4);
 246       suffix [4] = 0;
 247     }
 248
 249   /* Check for $<nnn>.. prefix and save it.  */
 250   if ((id[0] == '$') && ISDIGIT (id[1]))
 251     {
 252       int i;
 253
 254       for (i=2; i < len; i++)
 255         {
 256           if (!ISDIGIT (id[i]))
 257             {
 258               if (id[i] == '.' && id [i+1] == '.')
 259                  {
 260                    prefix_dotdot = i+2;
 261                    strncpy (prefix, id, prefix_dotdot);
 262                    prefix [prefix_dotdot] = 0;
 263                  }
 264                break;
 265             }
 266         }
 267     }
 268
 269   /* We only need worry about krunching the base symbol.  */
 270   base_id = xmalloc (suffix_dotdot - prefix_dotdot + 1);
 271   strncpy (base_id, &id[prefix_dotdot], suffix_dotdot - prefix_dotdot);
 272   base_id [suffix_dotdot - prefix_dotdot] = 0;
 273
 274   if (strlen (base_id) > MAX_LABEL_LENGTH)
 275     {
 276       char new_id [4096];
 277       char *return_id;
 278
 279       strcpy (new_id, base_id);
 280
 281       /* Shorten it.  */
 282       strcpy (new_id, shorten_identifier (new_id));
 283
 284       /* Prepend back the prefix if there was one.  */
 285       if (prefix_dotdot)
 286         {
 287           memmove (&new_id [prefix_dotdot], new_id, strlen (new_id) + 1);
 288           strncpy (new_id, prefix, prefix_dotdot);
 289         }
 290
 291       /* Append back the suffix if there was one.  */
 292       if (strlen (suffix))
 293         strcat (new_id, suffix);
 294
 295       /* Save it on the heap and return.  */
 296       return_id = xmalloc (strlen (new_id) + 1);
 297       strcpy (return_id, new_id);
 298
 299       return return_id;
 300     }
 301   else
 302     return id;
 303 }
 304
 305 /* The code below implements a mechanism for truncating long
 306    identifiers to an arbitrary length (set by MAX_LABEL_LENGTH).
 307
 308    It attempts to make each truncated identifier unique by replacing
 309    part of the identifier with an encoded 32-bit CRC and an associated
 310    checksum (the checksum is used as a way to determine that the name
 311    was truncated).
 312
 313    Note that both a portion of the start and of the end of the
 314    identifier may be kept.  The macro ID_SUFFIX_LENGTH will return the
 315    number of characters in the suffix of the identifier that should be
 316    kept.
 317
 318    The portion of the identifier that is going to be removed is
 319    checksummed.  The checksum is then encoded as a 5-character string,
 320    the characters of which are then summed.  This sum is then encoded
 321    as a 3-character string.  Finally, the original length of the
 322    identifier is encoded as a 3-character string.
 323
 324    These three strings are then concatenated together (along with an _h
 325    which further designates that the name was truncated):
 326
 327    "original_identifier"_haaaaabbbccc
 328
 329    aaaaa = 32-bit CRC
 330    bbb = length of original identifier
 331    ccc = sum of 32-bit CRC characters
 332
 333    The resulting identifier will be MAX_LABEL_LENGTH characters long.
 334
 335    */
 336
 337
 338 /* Table used to convert an integer into a string.  */
 339
 340 static const char codings[] = {
 341   'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
 342   'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
 343   'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
 344   'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
 345   '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '_'};
 346
 347 /* The number of codings in the above table.  */
 348 static const int number_of_codings = sizeof (codings) / sizeof (char);
 349
 350 /* Table used by decode_16 () to convert an encoded string back into
 351    an integer.  */
 352 static char decodings[256];
 353
 354 /* Table used by the crc32 function to calcuate the checksum.  */
 355 static unsigned int crc32_table[256] = {0, 0};
 356
 357 /* Given a string in BUF, calculate a 32-bit CRC for it.
 358
 359    This is used as a reasonably unique hash for the given string.  */
 360
 361 static unsigned int
 362 crc32 (unsigned char *buf, int len)
 363 {
 364   unsigned int crc = 0xffffffff;
 365
 366   if (! crc32_table[1])
 367     {
 368       /* Initialize the CRC table and the decoding table. */
 369       int i, j;
 370       unsigned int c;
 371
 372       for (i = 0; i < 256; i++)
 373         {
 374           for (c = i << 24, j = 8; j > 0; --j)
 375             c = c & 0x80000000 ? (c << 1) ^ 0x04c11db7 : (c << 1);
 376           crc32_table[i] = c;
 377           decodings[i] = 0;
 378         }
 379       for (i = 0; i < number_of_codings; i++)
 380         decodings[codings[i] & 255] = i;
 381     }
 382
 383   while (len--)
 384     {
 385       crc = (crc << 8) ^ crc32_table[(crc >> 24) ^ *buf];
 386       buf++;
 387     }
 388   return crc;
 389 }
 390
 391 /* Encode the lower 32 bits of VALUE as a 5-character string.  */
 392
 393 static char *
 394 encode_32 (unsigned int value)
 395 {
 396   static char res[6];
 397   int x;
 398
 399   res[5] = 0;
 400   for(x = 0; x < 5; x++)
 401     {
 402       res[x] = codings[value % number_of_codings];
 403       value = value / number_of_codings;
 404     }
 405   return res;
 406 }
 407
 408 /* Encode the lower 16 bits of VALUE as a 3-character string.  */
 409
 410 static char *
 411 encode_16 (unsigned int value)
 412 {
 413   static char res[4];
 414   int x;
 415
 416   res[3] = 0;
 417   for(x = 0; x < 3; x++)
 418     {
 419       res[x] = codings[value % number_of_codings];
 420       value = value / number_of_codings;
 421     }
 422   return res;
 423 }
 424
 425 /* Convert the encoded string obtained from encode_16 () back into a
 426    16-bit integer.  */
 427
 428 static int
 429 decode_16 (const char *string)
 430 {
 431   return decodings[(int) string[2]] * number_of_codings * number_of_codings
 432     + decodings[(int) string[1]] * number_of_codings
 433     + decodings[(int) string[0]];
 434 }
 435
 436 /* ID_SUFFIX_LENGTH is used to determine how many characters in the
 437    suffix of the identifier are to be preserved, if any.  */
 438
 439 #ifndef ID_SUFFIX_LENGTH
 440 #define ID_SUFFIX_LENGTH(ID) (0)
 441 #endif
 442
 443 /* Return a reasonably-unique version of NAME that is less than or
 444    equal to MAX_LABEL_LENGTH characters long.  The string returned from
 445    this function may be a copy of NAME; the function will never
 446    actually modify the contents of NAME.  */
 447
 448 static char newname[MAX_LABEL_LENGTH + 1];
 449
 450 static char *
 451 shorten_identifier (char *name)
 452 {
 453   int crc, len, sum, x, final_len;
 454   char *crc_chars;
 455   int suffix_length = ID_SUFFIX_LENGTH (name);
 456
 457   if ((len = strlen (name)) <= MAX_LABEL_LENGTH)
 458     return name;
 459
 460   final_len = MAX_LABEL_LENGTH - 2 - 5 - 3 - 3 - suffix_length;
 461   crc = crc32 ((unsigned char *)name + final_len,
 462                len - final_len - suffix_length);
 463   crc_chars = encode_32 (crc);
 464   sum = 0;
 465   for (x = 0; x < 5; x++)
 466     sum += crc_chars [x];
 467   strncpy (newname, name, final_len);
 468   newname [MAX_LABEL_LENGTH] = 0;
 469   /* Now append the suffix of the original identifier, if any.  */
 470   if (suffix_length)
 471   strncpy (newname + MAX_LABEL_LENGTH - suffix_length,
 472            name + len - suffix_length,
 473            suffix_length);
 474   strncpy (newname + final_len, "_h", 2);
 475   strncpy (newname + final_len + 2 , crc_chars, 5);
 476   strncpy (newname + final_len + 2 + 5, encode_16 (len), 3);
 477   strncpy (newname + final_len + 2 + 5 + 3, encode_16 (sum), 3);
 478   if (!is_truncated_identifier (newname))
 479     abort ();
 480   return newname;
 481 }
 482
 483 /* Determine whether or not ID is a truncated identifier, and return a
 484    non-zero value if it is.  */
 485
 486 static int
 487 is_truncated_identifier (char *id)
 488 {
 489   char *ptr;
 490   int len = strlen (id);
 491   /* If it's not exactly MAX_LABEL_LENGTH characters long, it can't be
 492      a truncated identifier.  */
 493   if (len != MAX_LABEL_LENGTH)
 494     return 0;
 495
 496   /* Start scanning backwards for a _h.  */
 497   len = len - 3 - 3 - 5 - 2;
 498   ptr = id + len;
 499   while (ptr >= id)
 500     {
 501       if (ptr[0] == '_' && ptr[1] == 'h')
 502         {
 503           /* Now see if the sum encoded in the identifer matches.  */
 504           int x, sum;
 505           sum = 0;
 506           for (x = 0; x < 5; x++)
 507             sum += ptr[x + 2];
 508           /* If it matches, this is probably a truncated identifier.  */
 509           if (sum == decode_16 (ptr + 5 + 2 + 3))
 510             return 1;
 511         }
 512       ptr--;
 513     }
 514   return 0;
 515 }
 516
 517 /* end of obj-evax.c */