gas/cgen.c

   1 /* GAS interface for targets using CGEN: Cpu tools GENerator.
   2    Copyright 1996, 1997, 1998, 1999, 2000, 2001
   3    Free Software Foundation, Inc.
   4
   5 This file is part of GAS, the GNU Assembler.
   6
   7 GAS is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GAS is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GAS; see the file COPYING.  If not, write to the Free Software
  19 Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  20
  21 #include <setjmp.h>
  22 #include "ansidecl.h"
  23 #include "libiberty.h"
  24 #include "bfd.h"
  25 #include "symcat.h"
  26 #include "cgen-desc.h"
  27 #include "as.h"
  28 #include "subsegs.h"
  29 #include "cgen.h"
  30 #include "dwarf2dbg.h"
  31
  32 /* Opcode table descriptor, must be set by md_begin.  */
  33
  34 CGEN_CPU_DESC gas_cgen_cpu_desc;
  35
  36 /* Callback to insert a register into the symbol table.
  37    A target may choose to let GAS parse the registers.
  38    ??? Not currently used.  */
  39
  40 void
  41 cgen_asm_record_register (name, number)
  42      char *name;
  43      int number;
  44 {
  45   /* Use symbol_create here instead of symbol_new so we don't try to
  46      output registers into the object file's symbol table.  */
  47   symbol_table_insert (symbol_create (name, reg_section,
  48                                       number, &zero_address_frag));
  49 }
  50
  51 /* We need to keep a list of fixups.  We can't simply generate them as
  52    we go, because that would require us to first create the frag, and
  53    that would screw up references to ``.''.
  54
  55    This is used by cpu's with simple operands.  It keeps knowledge of what
  56    an `expressionS' is and what a `fixup' is out of CGEN which for the time
  57    being is preferable.
  58
  59    OPINDEX is the index in the operand table.
  60    OPINFO is something the caller chooses to help in reloc determination.  */
  61
  62 struct fixup {
  63   int opindex;
  64   int opinfo;
  65   expressionS exp;
  66 };
  67
  68 static struct fixup fixups[GAS_CGEN_MAX_FIXUPS];
  69 static int num_fixups;
  70
  71 /* Prepare to parse an instruction.
  72    ??? May wish to make this static and delete calls in md_assemble.  */
  73
  74 void
  75 gas_cgen_init_parse ()
  76 {
  77   num_fixups = 0;
  78 }
  79
  80 /* Queue a fixup.  */
  81
  82 static void
  83 queue_fixup (opindex, opinfo, expP)
  84      int           opindex;
  85      int           opinfo;
  86      expressionS * expP;
  87 {
  88   /* We need to generate a fixup for this expression.  */
  89   if (num_fixups >= GAS_CGEN_MAX_FIXUPS)
  90     as_fatal (_("too many fixups"));
  91   fixups[num_fixups].exp     = *expP;
  92   fixups[num_fixups].opindex = opindex;
  93   fixups[num_fixups].opinfo  = opinfo;
  94   ++ num_fixups;
  95 }
  96
  97 /* The following three functions allow a backup of the fixup chain to be made,
  98    and to have this backup be swapped with the current chain.  This allows
  99    certain ports, eg the m32r, to swap two instructions and swap their fixups
 100    at the same time.  */
 101 /* ??? I think with cgen_asm_finish_insn (or something else) there is no
 102    more need for this.  */
 103
 104 static struct fixup saved_fixups[GAS_CGEN_MAX_FIXUPS];
 105 static int saved_num_fixups;
 106
 107 void
 108 gas_cgen_save_fixups ()
 109 {
 110   saved_num_fixups = num_fixups;
 111
 112   memcpy (saved_fixups, fixups, sizeof (fixups[0]) * num_fixups);
 113
 114   num_fixups = 0;
 115 }
 116
 117 void
 118 gas_cgen_restore_fixups ()
 119 {
 120   num_fixups = saved_num_fixups;
 121
 122   memcpy (fixups, saved_fixups, sizeof (fixups[0]) * num_fixups);
 123
 124   saved_num_fixups = 0;
 125 }
 126
 127 void
 128 gas_cgen_swap_fixups ()
 129 {
 130   int tmp;
 131   struct fixup tmp_fixup;
 132
 133   if (num_fixups == 0)
 134     {
 135       gas_cgen_restore_fixups ();
 136     }
 137   else if (saved_num_fixups == 0)
 138     {
 139       gas_cgen_save_fixups ();
 140     }
 141   else
 142     {
 143       tmp = saved_num_fixups;
 144       saved_num_fixups = num_fixups;
 145       num_fixups = tmp;
 146
 147       for (tmp = GAS_CGEN_MAX_FIXUPS; tmp--;)
 148         {
 149           tmp_fixup          = saved_fixups [tmp];
 150           saved_fixups [tmp] = fixups [tmp];
 151           fixups [tmp]       = tmp_fixup;
 152         }
 153     }
 154 }
 155
 156 /* Default routine to record a fixup.
 157    This is a cover function to fix_new.
 158    It exists because we record INSN with the fixup.
 159
 160    FRAG and WHERE are their respective arguments to fix_new_exp.
 161    LENGTH is in bits.
 162    OPINFO is something the caller chooses to help in reloc determination.
 163
 164    At this point we do not use a bfd_reloc_code_real_type for
 165    operands residing in the insn, but instead just use the
 166    operand index.  This lets us easily handle fixups for any
 167    operand type.  We pick a BFD reloc type in md_apply_fix.  */
 168
 169 fixS *
 170 gas_cgen_record_fixup (frag, where, insn, length, operand, opinfo, symbol, offset)
 171      fragS *              frag;
 172      int                  where;
 173      const CGEN_INSN *    insn;
 174      int                  length;
 175      const CGEN_OPERAND * operand;
 176      int                  opinfo;
 177      symbolS *            symbol;
 178      offsetT              offset;
 179 {
 180   fixS *fixP;
 181
 182   /* It may seem strange to use operand->attrs and not insn->attrs here,
 183      but it is the operand that has a pc relative relocation.  */
 184
 185   fixP = fix_new (frag, where, length / 8, symbol, offset,
 186                   CGEN_OPERAND_ATTR_VALUE (operand, CGEN_OPERAND_PCREL_ADDR),
 187                   (bfd_reloc_code_real_type)
 188                     ((int) BFD_RELOC_UNUSED
 189                      + (int) operand->type));
 190   fixP->fx_cgen.insn = insn;
 191   fixP->fx_cgen.opinfo = opinfo;
 192
 193   return fixP;
 194 }
 195
 196 /* Default routine to record a fixup given an expression.
 197    This is a cover function to fix_new_exp.
 198    It exists because we record INSN with the fixup.
 199
 200    FRAG and WHERE are their respective arguments to fix_new_exp.
 201    LENGTH is in bits.
 202    OPINFO is something the caller chooses to help in reloc determination.
 203
 204    At this point we do not use a bfd_reloc_code_real_type for
 205    operands residing in the insn, but instead just use the
 206    operand index.  This lets us easily handle fixups for any
 207    operand type.  We pick a BFD reloc type in md_apply_fix.  */
 208
 209 fixS *
 210 gas_cgen_record_fixup_exp (frag, where, insn, length, operand, opinfo, exp)
 211      fragS *              frag;
 212      int                  where;
 213      const CGEN_INSN *    insn;
 214      int                  length;
 215      const CGEN_OPERAND * operand;
 216      int                  opinfo;
 217      expressionS *        exp;
 218 {
 219   fixS *fixP;
 220
 221   /* It may seem strange to use operand->attrs and not insn->attrs here,
 222      but it is the operand that has a pc relative relocation.  */
 223
 224   fixP = fix_new_exp (frag, where, length / 8, exp,
 225                       CGEN_OPERAND_ATTR_VALUE (operand, CGEN_OPERAND_PCREL_ADDR),
 226                       (bfd_reloc_code_real_type)
 227                         ((int) BFD_RELOC_UNUSED
 228                          + (int) operand->type));
 229   fixP->fx_cgen.insn = insn;
 230   fixP->fx_cgen.opinfo = opinfo;
 231
 232   return fixP;
 233 }
 234
 235 /* Used for communication between the next two procedures.  */
 236 static jmp_buf expr_jmp_buf;
 237 static int expr_jmp_buf_p;
 238
 239 /* Callback for cgen interface.  Parse the expression at *STRP.
 240    The result is an error message or NULL for success (in which case
 241    *STRP is advanced past the parsed text).
 242    WANT is an indication of what the caller is looking for.
 243    If WANT == CGEN_ASM_PARSE_INIT the caller is beginning to try to match
 244    a table entry with the insn, reset the queued fixups counter.
 245    An enum cgen_parse_operand_result is stored in RESULTP.
 246    OPINDEX is the operand's table entry index.
 247    OPINFO is something the caller chooses to help in reloc determination.
 248    The resulting value is stored in VALUEP.  */
 249
 250 const char *
 251 gas_cgen_parse_operand (cd, want, strP, opindex, opinfo, resultP, valueP)
 252      CGEN_CPU_DESC cd ATTRIBUTE_UNUSED;
 253      enum cgen_parse_operand_type want;
 254      const char **strP;
 255      int opindex;
 256      int opinfo;
 257      enum cgen_parse_operand_result *resultP;
 258      bfd_vma *valueP;
 259 {
 260 #ifdef __STDC__
 261   /* These are volatile to survive the setjmp.  */
 262   char * volatile hold;
 263   enum cgen_parse_operand_result * volatile resultP_1;
 264 #else
 265   static char *hold;
 266   static enum cgen_parse_operand_result *resultP_1;
 267 #endif
 268   const char *errmsg = NULL;
 269   expressionS exp;
 270
 271   if (want == CGEN_PARSE_OPERAND_INIT)
 272     {
 273       gas_cgen_init_parse ();
 274       return NULL;
 275     }
 276
 277   resultP_1 = resultP;
 278   hold = input_line_pointer;
 279   input_line_pointer = (char *) *strP;
 280
 281   /* We rely on md_operand to longjmp back to us.
 282      This is done via gas_cgen_md_operand.  */
 283   if (setjmp (expr_jmp_buf) != 0)
 284     {
 285       expr_jmp_buf_p = 0;
 286       input_line_pointer = (char *) hold;
 287       *resultP_1 = CGEN_PARSE_OPERAND_RESULT_ERROR;
 288       return "illegal operand";
 289     }
 290
 291   expr_jmp_buf_p = 1;
 292   expression (&exp);
 293   expr_jmp_buf_p = 0;
 294
 295   *strP = input_line_pointer;
 296   input_line_pointer = hold;
 297
 298   /* FIXME: Need to check `want'.  */
 299
 300   switch (exp.X_op)
 301     {
 302     case O_illegal:
 303       errmsg = _("illegal operand");
 304       *resultP = CGEN_PARSE_OPERAND_RESULT_ERROR;
 305       break;
 306     case O_absent:
 307       errmsg = _("missing operand");
 308       *resultP = CGEN_PARSE_OPERAND_RESULT_ERROR;
 309       break;
 310     case O_constant:
 311       *valueP = exp.X_add_number;
 312       *resultP = CGEN_PARSE_OPERAND_RESULT_NUMBER;
 313       break;
 314     case O_register:
 315       *valueP = exp.X_add_number;
 316       *resultP = CGEN_PARSE_OPERAND_RESULT_REGISTER;
 317       break;
 318     default:
 319       queue_fixup (opindex, opinfo, &exp);
 320       *valueP = 0;
 321       *resultP = CGEN_PARSE_OPERAND_RESULT_QUEUED;
 322       break;
 323     }
 324
 325   return errmsg;
 326 }
 327
 328 /* md_operand handler to catch unrecognized expressions and halt the
 329    parsing process so the next entry can be tried.
 330
 331    ??? This could be done differently by adding code to `expression'.  */
 332
 333 void
 334 gas_cgen_md_operand (expressionP)
 335      expressionS *expressionP ATTRIBUTE_UNUSED;
 336 {
 337   /* Don't longjmp if we're not called from within cgen_parse_operand().  */
 338   if (expr_jmp_buf_p)
 339     longjmp (expr_jmp_buf, 1);
 340 }
 341
 342 /* Finish assembling instruction INSN.
 343    BUF contains what we've built up so far.
 344    LENGTH is the size of the insn in bits.
 345    RELAX_P is non-zero if relaxable insns should be emitted as such.
 346    Otherwise they're emitted in non-relaxable forms.
 347    The "result" is stored in RESULT if non-NULL.  */
 348
 349 void
 350 gas_cgen_finish_insn (insn, buf, length, relax_p, result)
 351      const CGEN_INSN *insn;
 352      CGEN_INSN_BYTES_PTR buf;
 353      unsigned int length;
 354      int relax_p;
 355      finished_insnS *result;
 356 {
 357   int i;
 358   int relax_operand;
 359   char *f;
 360   unsigned int byte_len = length / 8;
 361
 362   /* ??? Target foo issues various warnings here, so one might want to provide
 363      a hook here.  However, our caller is defined in tc-foo.c so there
 364      shouldn't be a need for a hook.  */
 365
 366   /* Write out the instruction.
 367      It is important to fetch enough space in one call to `frag_more'.
 368      We use (f - frag_now->fr_literal) to compute where we are and we
 369      don't want frag_now to change between calls.
 370
 371      Relaxable instructions: We need to ensure we allocate enough
 372      space for the largest insn.  */
 373
 374   if (CGEN_INSN_ATTR_VALUE (insn, CGEN_INSN_RELAX))
 375     /* These currently shouldn't get here.  */
 376     abort ();
 377
 378   /* Is there a relaxable insn with the relaxable operand needing a fixup?  */
 379
 380   relax_operand = -1;
 381   if (relax_p && CGEN_INSN_ATTR_VALUE (insn, CGEN_INSN_RELAXABLE))
 382     {
 383       /* Scan the fixups for the operand affected by relaxing
 384          (i.e. the branch address).  */
 385
 386       for (i = 0; i < num_fixups; ++i)
 387         {
 388           if (CGEN_OPERAND_ATTR_VALUE (cgen_operand_lookup_by_num (gas_cgen_cpu_desc, fixups[i].opindex),
 389                                        CGEN_OPERAND_RELAX))
 390             {
 391               relax_operand = i;
 392               break;
 393             }
 394         }
 395     }
 396
 397   if (relax_operand != -1)
 398     {
 399       int max_len;
 400       fragS *old_frag;
 401
 402 #ifdef TC_CGEN_MAX_RELAX
 403       max_len = TC_CGEN_MAX_RELAX (insn, byte_len);
 404 #else
 405       max_len = CGEN_MAX_INSN_SIZE;
 406 #endif
 407       /* Ensure variable part and fixed part are in same fragment.  */
 408       /* FIXME: Having to do this seems like a hack.  */
 409       frag_grow (max_len);
 410
 411       /* Allocate space for the fixed part.  */
 412       f = frag_more (byte_len);
 413
 414       /* Create a relaxable fragment for this instruction.  */
 415       old_frag = frag_now;
 416
 417       frag_var (rs_machine_dependent,
 418                 max_len - byte_len /* max chars */,
 419                 0 /* variable part already allocated */,
 420                 /* FIXME: When we machine generate the relax table,
 421                    machine generate a macro to compute subtype.  */
 422                 1 /* subtype */,
 423                 fixups[relax_operand].exp.X_add_symbol,
 424                 fixups[relax_operand].exp.X_add_number,
 425                 f);
 426
 427       /* Record the operand number with the fragment so md_convert_frag
 428          can use gas_cgen_md_record_fixup to record the appropriate reloc.  */
 429       old_frag->fr_cgen.insn    = insn;
 430       old_frag->fr_cgen.opindex = fixups[relax_operand].opindex;
 431       old_frag->fr_cgen.opinfo  = fixups[relax_operand].opinfo;
 432       if (result)
 433         result->frag = old_frag;
 434     }
 435   else
 436     {
 437       f = frag_more (byte_len);
 438       if (result)
 439         result->frag = frag_now;
 440     }
 441
 442   /* If we're recording insns as numbers (rather than a string of bytes),
 443      target byte order handling is deferred until now.  */
 444 #if CGEN_INT_INSN_P
 445   cgen_put_insn_value (gas_cgen_cpu_desc, f, length, *buf);
 446 #else
 447   memcpy (f, buf, byte_len);
 448 #endif
 449
 450   /* Emit DWARF2 debugging information.  */
 451   dwarf2_emit_insn (byte_len);
 452
 453   /* Create any fixups.  */
 454   for (i = 0; i < num_fixups; ++i)
 455     {
 456       fixS *fixP;
 457       const CGEN_OPERAND *operand =
 458         cgen_operand_lookup_by_num (gas_cgen_cpu_desc, fixups[i].opindex);
 459
 460       /* Don't create fixups for these.  That's done during relaxation.
 461          We don't need to test for CGEN_INSN_RELAX as they can't get here
 462          (see above).  */
 463       if (relax_p
 464           && CGEN_INSN_ATTR_VALUE (insn, CGEN_INSN_RELAXABLE)
 465           && CGEN_OPERAND_ATTR_VALUE (operand, CGEN_OPERAND_RELAX))
 466         continue;
 467
 468 #ifndef md_cgen_record_fixup_exp
 469 #define md_cgen_record_fixup_exp gas_cgen_record_fixup_exp
 470 #endif
 471
 472       fixP = md_cgen_record_fixup_exp (frag_now, f - frag_now->fr_literal,
 473                                        insn, length, operand,
 474                                        fixups[i].opinfo,
 475                                        &fixups[i].exp);
 476       if (result)
 477         result->fixups[i] = fixP;
 478     }
 479
 480   if (result)
 481     {
 482       result->num_fixups = num_fixups;
 483       result->addr = f;
 484     }
 485 }
 486
 487 /* Apply a fixup to the object code.  This is called for all the
 488    fixups we generated by the call to fix_new_exp, above.  In the call
 489    above we used a reloc code which was the largest legal reloc code
 490    plus the operand index.  Here we undo that to recover the operand
 491    index.  At this point all symbol values should be fully resolved,
 492    and we attempt to completely resolve the reloc.  If we can not do
 493    that, we determine the correct reloc code and put it back in the fixup.  */
 494
 495 /* FIXME: This function handles some of the fixups and bfd_install_relocation
 496    handles the rest.  bfd_install_relocation (or some other bfd function)
 497    should handle them all.  */
 498
 499 int
 500 gas_cgen_md_apply_fix3 (fixP, valueP, seg)
 501      fixS *   fixP;
 502      valueT * valueP;
 503      segT     seg ATTRIBUTE_UNUSED;
 504 {
 505   char *where = fixP->fx_frag->fr_literal + fixP->fx_where;
 506   valueT value;
 507   /* Canonical name, since used a lot.  */
 508   CGEN_CPU_DESC cd = gas_cgen_cpu_desc;
 509
 510   /* FIXME FIXME FIXME: The value we are passed in *valuep includes
 511      the symbol values.  Since we are using BFD_ASSEMBLER, if we are
 512      doing this relocation the code in write.c is going to call
 513      bfd_install_relocation, which is also going to use the symbol
 514      value.  That means that if the reloc is fully resolved we want to
 515      use *valuep since bfd_install_relocation is not being used.
 516      However, if the reloc is not fully resolved we do not want to use
 517      *valuep, and must use fx_offset instead.  However, if the reloc
 518      is PC relative, we do want to use *valuep since it includes the
 519      result of md_pcrel_from.  This is confusing.  */
 520
 521   if (fixP->fx_addsy == (symbolS *) NULL)
 522     {
 523       value = *valueP;
 524       fixP->fx_done = 1;
 525     }
 526   else if (fixP->fx_pcrel)
 527     value = *valueP;
 528   else
 529     {
 530       value = fixP->fx_offset;
 531       if (fixP->fx_subsy != (symbolS *) NULL)
 532         {
 533           if (S_GET_SEGMENT (fixP->fx_subsy) == absolute_section)
 534             value -= S_GET_VALUE (fixP->fx_subsy);
 535           else
 536             {
 537               /* We don't actually support subtracting a symbol.  */
 538               as_bad_where (fixP->fx_file, fixP->fx_line,
 539                             _("expression too complex"));
 540             }
 541         }
 542     }
 543
 544   if ((int) fixP->fx_r_type >= (int) BFD_RELOC_UNUSED)
 545     {
 546       int opindex = (int) fixP->fx_r_type - (int) BFD_RELOC_UNUSED;
 547       const CGEN_OPERAND *operand = cgen_operand_lookup_by_num (cd, opindex);
 548       const char *errmsg;
 549       bfd_reloc_code_real_type reloc_type;
 550       CGEN_FIELDS *fields = alloca (CGEN_CPU_SIZEOF_FIELDS (cd));
 551       const CGEN_INSN *insn = fixP->fx_cgen.insn;
 552
 553       /* If the reloc has been fully resolved finish the operand here.  */
 554       /* FIXME: This duplicates the capabilities of code in BFD.  */
 555       if (fixP->fx_done
 556           /* FIXME: If partial_inplace isn't set bfd_install_relocation won't
 557              finish the job.  Testing for pcrel is a temporary hack.  */
 558           || fixP->fx_pcrel)
 559         {
 560           CGEN_CPU_SET_FIELDS_BITSIZE (cd) (fields, CGEN_INSN_BITSIZE (insn));
 561           CGEN_CPU_SET_VMA_OPERAND (cd) (cd, opindex, fields, (bfd_vma) value);
 562
 563 #if CGEN_INT_INSN_P
 564           {
 565             CGEN_INSN_INT insn_value =
 566               cgen_get_insn_value (cd, where, CGEN_INSN_BITSIZE (insn));
 567
 568             /* ??? 0 is passed for `pc'.  */
 569             errmsg = CGEN_CPU_INSERT_OPERAND (cd) (cd, opindex, fields,
 570                                                    &insn_value, (bfd_vma) 0);
 571             cgen_put_insn_value (cd, where, CGEN_INSN_BITSIZE (insn),
 572                                  insn_value);
 573           }
 574 #else
 575           /* ??? 0 is passed for `pc'.  */
 576           errmsg = CGEN_CPU_INSERT_OPERAND (cd) (cd, opindex, fields, where,
 577                                                  (bfd_vma) 0);
 578 #endif
 579           if (errmsg)
 580             as_bad_where (fixP->fx_file, fixP->fx_line, "%s", errmsg);
 581         }
 582
 583       if (fixP->fx_done)
 584         return 1;
 585
 586       /* The operand isn't fully resolved.  Determine a BFD reloc value
 587          based on the operand information and leave it to
 588          bfd_install_relocation.  Note that this doesn't work when
 589          partial_inplace == false.  */
 590
 591       reloc_type = md_cgen_lookup_reloc (insn, operand, fixP);
 592       if (reloc_type != BFD_RELOC_NONE)
 593         {
 594           fixP->fx_r_type = reloc_type;
 595         }
 596       else
 597         {
 598           as_bad_where (fixP->fx_file, fixP->fx_line,
 599                         _("unresolved expression that must be resolved"));
 600           fixP->fx_done = 1;
 601           return 1;
 602         }
 603     }
 604   else if (fixP->fx_done)
 605     {
 606       /* We're finished with this fixup.  Install it because
 607          bfd_install_relocation won't be called to do it.  */
 608       switch (fixP->fx_r_type)
 609         {
 610         case BFD_RELOC_8:
 611           md_number_to_chars (where, value, 1);
 612           break;
 613         case BFD_RELOC_16:
 614           md_number_to_chars (where, value, 2);
 615           break;
 616         case BFD_RELOC_32:
 617           md_number_to_chars (where, value, 4);
 618           break;
 619         case BFD_RELOC_64:
 620           md_number_to_chars (where, value, 8);
 621           break;
 622         default:
 623           as_bad_where (fixP->fx_file, fixP->fx_line,
 624                         _("internal error: can't install fix for reloc type %d (`%s')"),
 625                         fixP->fx_r_type, bfd_get_reloc_code_name (fixP->fx_r_type));
 626           break;
 627         }
 628     }
 629   else
 630     {
 631       /* bfd_install_relocation will be called to finish things up.  */
 632     }
 633
 634   /* Tuck `value' away for use by tc_gen_reloc.
 635      See the comment describing fx_addnumber in write.h.
 636      This field is misnamed (or misused :-).  */
 637   fixP->fx_addnumber = value;
 638
 639   return 1;
 640 }
 641
 642 /* Translate internal representation of relocation info to BFD target format.
 643
 644    FIXME: To what extent can we get all relevant targets to use this?  */
 645
 646 arelent *
 647 gas_cgen_tc_gen_reloc (section, fixP)
 648      asection * section ATTRIBUTE_UNUSED;
 649      fixS *     fixP;
 650 {
 651   arelent *reloc;
 652
 653   reloc = (arelent *) xmalloc (sizeof (arelent));
 654
 655   reloc->howto = bfd_reloc_type_lookup (stdoutput, fixP->fx_r_type);
 656   if (reloc->howto == (reloc_howto_type *) NULL)
 657     {
 658       as_bad_where (fixP->fx_file, fixP->fx_line,
 659                     _("internal error: can't export reloc type %d (`%s')"),
 660                     fixP->fx_r_type, bfd_get_reloc_code_name (fixP->fx_r_type));
 661       return NULL;
 662     }
 663
 664   assert (!fixP->fx_pcrel == !reloc->howto->pc_relative);
 665
 666   reloc->sym_ptr_ptr = (asymbol **) xmalloc (sizeof (asymbol *));
 667   *reloc->sym_ptr_ptr = symbol_get_bfdsym (fixP->fx_addsy);
 668
 669   /* Use fx_offset for these cases.  */
 670   if (fixP->fx_r_type == BFD_RELOC_VTABLE_ENTRY
 671       || fixP->fx_r_type == BFD_RELOC_VTABLE_INHERIT)
 672     reloc->addend = fixP->fx_offset;
 673   else
 674     reloc->addend = fixP->fx_addnumber;
 675
 676   reloc->address = fixP->fx_frag->fr_address + fixP->fx_where;
 677   return reloc;
 678 }