gas/subsegs.c

   1 /* subsegs.c - subsegments -
   2    Copyright (C) 1987, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 2000
   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
  19    Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20    02111-1307, USA.  */
  21
  22 /*
  23  * Segments & sub-segments.
  24  */
  25
  26 #include "as.h"
  27
  28 #include "subsegs.h"
  29 #include "obstack.h"
  30
  31 frchainS *frchain_root, *frchain_now;
  32
  33 static struct obstack frchains;
  34
  35 #ifndef BFD_ASSEMBLER
  36 #ifdef MANY_SEGMENTS
  37 segment_info_type segment_info[SEG_MAXIMUM_ORDINAL];
  38
  39 #else
  40 /* Commented in "subsegs.h".  */
  41 frchainS *data0_frchainP, *bss0_frchainP;
  42
  43 #endif /* MANY_SEGMENTS */
  44 char const *const seg_name[] =
  45 {
  46   "absolute",
  47 #ifdef MANY_SEGMENTS
  48   "e0", "e1", "e2", "e3", "e4", "e5", "e6", "e7", "e8", "e9",
  49   "e10", "e11", "e12", "e13", "e14", "e15", "e16", "e17", "e18", "e19",
  50   "e20", "e21", "e22", "e23", "e24", "e25", "e26", "e27", "e28", "e29",
  51   "e30", "e31", "e32", "e33", "e34", "e35", "e36", "e37", "e38", "e39",
  52 #else
  53   "text",
  54   "data",
  55   "bss",
  56 #endif /* MANY_SEGMENTS */
  57   "unknown",
  58   "ASSEMBLER-INTERNAL-LOGIC-ERROR!",
  59   "expr",
  60   "debug",
  61   "transfert vector preload",
  62   "transfert vector postload",
  63   "register",
  64   "",
  65 };                              /* Used by error reporters, dumpers etc.  */
  66 #else /* BFD_ASSEMBLER */
  67
  68 /* Gas segment information for bfd_abs_section_ptr and
  69    bfd_und_section_ptr.  */
  70 static segment_info_type *abs_seg_info;
  71 static segment_info_type *und_seg_info;
  72
  73 #endif /* BFD_ASSEMBLER */
  74
  75 static void subseg_set_rest PARAMS ((segT, subsegT));
  76
  77 static fragS dummy_frag;
  78
  79 static frchainS absolute_frchain;
  80 \f
  81 void
  82 subsegs_begin ()
  83 {
  84   /* Check table(s) seg_name[], seg_N_TYPE[] is in correct order */
  85 #if !defined (MANY_SEGMENTS) && !defined (BFD_ASSEMBLER)
  86   know (SEG_ABSOLUTE == 0);
  87   know (SEG_TEXT == 1);
  88   know (SEG_DATA == 2);
  89   know (SEG_BSS == 3);
  90   know (SEG_UNKNOWN == 4);
  91   know (SEG_GOOF == 5);
  92   know (SEG_EXPR == 6);
  93   know (SEG_DEBUG == 7);
  94   know (SEG_NTV == 8);
  95   know (SEG_PTV == 9);
  96   know (SEG_REGISTER == 10);
  97   know (SEG_MAXIMUM_ORDINAL == SEG_REGISTER);
  98 #endif
  99
 100   obstack_begin (&frchains, chunksize);
 101 #if __GNUC__ >= 2
 102   obstack_alignment_mask (&frchains) = __alignof__ (frchainS) - 1;
 103 #endif
 104
 105   frchain_root = NULL;
 106   frchain_now = NULL;           /* Warn new_subseg() that we are booting.  */
 107
 108   frag_now = &dummy_frag;
 109
 110 #ifndef BFD_ASSEMBLER
 111   now_subseg = 42;              /* Lie for 1st call to subseg_new.  */
 112 #ifdef MANY_SEGMENTS
 113   {
 114     int i;
 115     for (i = SEG_E0; i < SEG_UNKNOWN; i++)
 116       {
 117         subseg_set (i, 0);
 118         segment_info[i].frchainP = frchain_now;
 119       }
 120   }
 121 #else
 122   subseg_set (SEG_DATA, 0);     /* .data 0 */
 123   data0_frchainP = frchain_now;
 124
 125   subseg_set (SEG_BSS, 0);
 126   bss0_frchainP = frchain_now;
 127
 128 #endif /* ! MANY_SEGMENTS */
 129 #endif /* ! BFD_ASSEMBLER */
 130
 131   absolute_frchain.frch_seg = absolute_section;
 132   absolute_frchain.frch_subseg = 0;
 133 #ifdef BFD_ASSEMBLER
 134   absolute_frchain.fix_root = absolute_frchain.fix_tail = 0;
 135 #endif
 136   absolute_frchain.frch_frag_now = &zero_address_frag;
 137   absolute_frchain.frch_root = absolute_frchain.frch_last = &zero_address_frag;
 138 }
 139 \f
 140 /*
 141  *                      subseg_change()
 142  *
 143  * Change the subsegment we are in, BUT DO NOT MAKE A NEW FRAG for the
 144  * subsegment. If we are already in the correct subsegment, change nothing.
 145  * This is used eg as a worker for subseg_set [which does make a new frag_now]
 146  * and for changing segments after we have read the source. We construct eg
 147  * fixSs even after the source file is read, so we do have to keep the
 148  * segment context correct.
 149  */
 150 void
 151 subseg_change (seg, subseg)
 152      register segT seg;
 153      register int subseg;
 154 {
 155   now_seg = seg;
 156   now_subseg = subseg;
 157
 158   if (now_seg == absolute_section)
 159     return;
 160
 161 #ifdef BFD_ASSEMBLER
 162   {
 163     segment_info_type *seginfo;
 164     seginfo = (segment_info_type *) bfd_get_section_userdata (stdoutput, seg);
 165     if (! seginfo)
 166       {
 167         seginfo = (segment_info_type *) xmalloc (sizeof (*seginfo));
 168         memset ((PTR) seginfo, 0, sizeof (*seginfo));
 169         seginfo->fix_root = NULL;
 170         seginfo->fix_tail = NULL;
 171         seginfo->bfd_section = seg;
 172         seginfo->sym = 0;
 173         if (seg == bfd_abs_section_ptr)
 174           abs_seg_info = seginfo;
 175         else if (seg == bfd_und_section_ptr)
 176           und_seg_info = seginfo;
 177         else
 178           bfd_set_section_userdata (stdoutput, seg, (PTR) seginfo);
 179       }
 180   }
 181 #else
 182 #ifdef MANY_SEGMENTS
 183   seg_fix_rootP = &segment_info[seg].fix_root;
 184   seg_fix_tailP = &segment_info[seg].fix_tail;
 185 #else
 186   if (seg == SEG_DATA)
 187     {
 188       seg_fix_rootP = &data_fix_root;
 189       seg_fix_tailP = &data_fix_tail;
 190     }
 191   else if (seg == SEG_TEXT)
 192     {
 193       seg_fix_rootP = &text_fix_root;
 194       seg_fix_tailP = &text_fix_tail;
 195     }
 196   else
 197     {
 198       know (seg == SEG_BSS);
 199       seg_fix_rootP = &bss_fix_root;
 200       seg_fix_tailP = &bss_fix_tail;
 201     }
 202
 203 #endif
 204 #endif
 205 }
 206 \f
 207 static void
 208 subseg_set_rest (seg, subseg)
 209      segT seg;
 210      subsegT subseg;
 211 {
 212   register frchainS *frcP;      /* crawl frchain chain */
 213   register frchainS **lastPP;   /* address of last pointer */
 214   frchainS *newP;               /* address of new frchain */
 215
 216   mri_common_symbol = NULL;
 217
 218   if (frag_now && frchain_now)
 219     frchain_now->frch_frag_now = frag_now;
 220
 221   assert (frchain_now == 0
 222           || now_seg == undefined_section
 223           || now_seg == absolute_section
 224           || frchain_now->frch_last == frag_now);
 225
 226   subseg_change (seg, (int) subseg);
 227
 228   if (seg == absolute_section)
 229     {
 230       frchain_now = &absolute_frchain;
 231       frag_now = &zero_address_frag;
 232       return;
 233     }
 234
 235   assert (frchain_now == 0
 236           || now_seg == undefined_section
 237           || frchain_now->frch_last == frag_now);
 238
 239   /*
 240    * Attempt to find or make a frchain for that sub seg.
 241    * Crawl along chain of frchainSs, begins @ frchain_root.
 242    * If we need to make a frchainS, link it into correct
 243    * position of chain rooted in frchain_root.
 244    */
 245   for (frcP = *(lastPP = &frchain_root);
 246        frcP && frcP->frch_seg <= seg;
 247        frcP = *(lastPP = &frcP->frch_next))
 248     {
 249       if (frcP->frch_seg == seg
 250           && frcP->frch_subseg >= subseg)
 251         {
 252           break;
 253         }
 254     }
 255   /*
 256    * frcP:              Address of the 1st frchainS in correct segment with
 257    *            frch_subseg >= subseg.
 258    *            We want to either use this frchainS, or we want
 259    *            to insert a new frchainS just before it.
 260    *
 261    *            If frcP==NULL, then we are at the end of the chain
 262    *            of frchainS-s. A NULL frcP means we fell off the end
 263    *            of the chain looking for a
 264    *            frch_subseg >= subseg, so we
 265    *            must make a new frchainS.
 266    *
 267    *            If we ever maintain a pointer to
 268    *            the last frchainS in the chain, we change that pointer
 269    *            ONLY when frcP==NULL.
 270    *
 271    * lastPP:    Address of the pointer with value frcP;
 272    *            Never NULL.
 273    *            May point to frchain_root.
 274    *
 275    */
 276   if (!frcP
 277       || (frcP->frch_seg > seg
 278           || frcP->frch_subseg > subseg))       /* Kinky logic only works with 2 segments.  */
 279     {
 280       /*
 281        * This should be the only code that creates a frchainS.
 282        */
 283       newP = (frchainS *) obstack_alloc (&frchains, sizeof (frchainS));
 284       newP->frch_subseg = subseg;
 285       newP->frch_seg = seg;
 286 #ifdef BFD_ASSEMBLER
 287       newP->fix_root = NULL;
 288       newP->fix_tail = NULL;
 289 #endif
 290       obstack_begin (&newP->frch_obstack, chunksize);
 291 #if __GNUC__ >= 2
 292       obstack_alignment_mask (&newP->frch_obstack) = __alignof__ (fragS) - 1;
 293 #endif
 294       newP->frch_frag_now = frag_alloc (&newP->frch_obstack);
 295       newP->frch_frag_now->fr_type = rs_fill;
 296
 297       newP->frch_root = newP->frch_last = newP->frch_frag_now;
 298
 299       *lastPP = newP;
 300       newP->frch_next = frcP;   /* perhaps NULL */
 301
 302 #ifdef BFD_ASSEMBLER
 303       {
 304         segment_info_type *seginfo;
 305         seginfo = seg_info (seg);
 306         if (seginfo && seginfo->frchainP == frcP)
 307           seginfo->frchainP = newP;
 308       }
 309 #endif
 310
 311       frcP = newP;
 312     }
 313   /*
 314    * Here with frcP pointing to the frchainS for subseg.
 315    */
 316   frchain_now = frcP;
 317   frag_now = frcP->frch_frag_now;
 318
 319   assert (frchain_now->frch_last == frag_now);
 320 }
 321
 322 /*
 323  *                      subseg_set(segT, subsegT)
 324  *
 325  * If you attempt to change to the current subsegment, nothing happens.
 326  *
 327  * In:  segT, subsegT code for new subsegment.
 328  *      frag_now -> incomplete frag for current subsegment.
 329  *      If frag_now==NULL, then there is no old, incomplete frag, so
 330  *      the old frag is not closed off.
 331  *
 332  * Out: now_subseg, now_seg updated.
 333  *      Frchain_now points to the (possibly new) struct frchain for this
 334  *      sub-segment.
 335  *      Frchain_root updated if needed.
 336  */
 337
 338 #ifndef BFD_ASSEMBLER
 339
 340 segT
 341 subseg_new (segname, subseg)
 342      const char *segname;
 343      subsegT subseg;
 344 {
 345   int i;
 346
 347   for (i = 0; i < (int) SEG_MAXIMUM_ORDINAL; i++)
 348     {
 349       const char *s;
 350
 351       s = segment_name ((segT) i);
 352       if (strcmp (segname, s) == 0
 353           || (segname[0] == '.'
 354               && strcmp (segname + 1, s) == 0))
 355         {
 356           subseg_set ((segT) i, subseg);
 357           return (segT) i;
 358         }
 359 #ifdef obj_segment_name
 360       s = obj_segment_name ((segT) i);
 361       if (strcmp (segname, s) == 0
 362           || (segname[0] == '.'
 363               && strcmp (segname + 1, s) == 0))
 364         {
 365           subseg_set ((segT) i, subseg);
 366           return (segT) i;
 367         }
 368 #endif
 369     }
 370
 371 #ifdef obj_add_segment
 372   {
 373     segT new_seg;
 374     new_seg = obj_add_segment (segname);
 375     subseg_set (new_seg, subseg);
 376     return new_seg;
 377   }
 378 #else
 379   as_bad (_("Attempt to switch to nonexistent segment \"%s\""), segname);
 380   return now_seg;
 381 #endif
 382 }
 383
 384 void
 385 subseg_set (seg, subseg)        /* begin assembly for a new sub-segment */
 386      register segT seg;         /* SEG_DATA or SEG_TEXT */
 387      register subsegT subseg;
 388 {
 389 #ifndef MANY_SEGMENTS
 390   know (seg == SEG_DATA
 391         || seg == SEG_TEXT
 392         || seg == SEG_BSS
 393         || seg == SEG_ABSOLUTE);
 394 #endif
 395
 396   if (seg != now_seg || subseg != now_subseg)
 397     {                           /* we just changed sub-segments */
 398       subseg_set_rest (seg, subseg);
 399     }
 400   mri_common_symbol = NULL;
 401 }
 402
 403 #else /* BFD_ASSEMBLER */
 404
 405 segT
 406 subseg_get (segname, force_new)
 407      const char *segname;
 408      int force_new;
 409 {
 410   segT secptr;
 411   segment_info_type *seginfo;
 412   const char *now_seg_name = (now_seg
 413                               ? bfd_get_section_name (stdoutput, now_seg)
 414                               : 0);
 415
 416   if (!force_new
 417       && now_seg_name
 418       && (now_seg_name == segname
 419           || !strcmp (now_seg_name, segname)))
 420     return now_seg;
 421
 422   if (!force_new)
 423     secptr = bfd_make_section_old_way (stdoutput, segname);
 424   else
 425     secptr = bfd_make_section_anyway (stdoutput, segname);
 426
 427   seginfo = seg_info (secptr);
 428   if (! seginfo)
 429     {
 430       /* Check whether output_section is set first because secptr may
 431          be bfd_abs_section_ptr.  */
 432       if (secptr->output_section != secptr)
 433         secptr->output_section = secptr;
 434       seginfo = (segment_info_type *) xmalloc (sizeof (*seginfo));
 435       memset ((PTR) seginfo, 0, sizeof (*seginfo));
 436       seginfo->fix_root = NULL;
 437       seginfo->fix_tail = NULL;
 438       seginfo->bfd_section = secptr;
 439       if (secptr == bfd_abs_section_ptr)
 440         abs_seg_info = seginfo;
 441       else if (secptr == bfd_und_section_ptr)
 442         und_seg_info = seginfo;
 443       else
 444         bfd_set_section_userdata (stdoutput, secptr, (PTR) seginfo);
 445       seginfo->frchainP = NULL;
 446       seginfo->lineno_list_head = seginfo->lineno_list_tail = NULL;
 447       seginfo->sym = NULL;
 448       seginfo->dot = NULL;
 449     }
 450   return secptr;
 451 }
 452
 453 segT
 454 subseg_new (segname, subseg)
 455      const char *segname;
 456      subsegT subseg;
 457 {
 458   segT secptr;
 459   segment_info_type *seginfo;
 460
 461   secptr = subseg_get (segname, 0);
 462   subseg_set_rest (secptr, subseg);
 463   seginfo = seg_info (secptr);
 464   if (! seginfo->frchainP)
 465     seginfo->frchainP = frchain_now;
 466   return secptr;
 467 }
 468
 469 /* Like subseg_new, except a new section is always created, even if
 470    a section with that name already exists.  */
 471 segT
 472 subseg_force_new (segname, subseg)
 473      const char *segname;
 474      subsegT subseg;
 475 {
 476   segT secptr;
 477   segment_info_type *seginfo;
 478
 479   secptr = subseg_get (segname, 1);
 480   subseg_set_rest (secptr, subseg);
 481   seginfo = seg_info (secptr);
 482   if (! seginfo->frchainP)
 483     seginfo->frchainP = frchain_now;
 484   return secptr;
 485 }
 486
 487 void
 488 subseg_set (secptr, subseg)
 489      segT secptr;
 490      subsegT subseg;
 491 {
 492   if (! (secptr == now_seg && subseg == now_subseg))
 493     subseg_set_rest (secptr, subseg);
 494   mri_common_symbol = NULL;
 495 }
 496
 497 #ifndef obj_sec_sym_ok_for_reloc
 498 #define obj_sec_sym_ok_for_reloc(SEC)   0
 499 #endif
 500
 501 /* Get the gas information we are storing for a section.  */
 502
 503 segment_info_type *
 504 seg_info (sec)
 505      segT sec;
 506 {
 507   if (sec == bfd_abs_section_ptr)
 508     return abs_seg_info;
 509   else if (sec == bfd_und_section_ptr)
 510     return und_seg_info;
 511   else
 512     return (segment_info_type *) bfd_get_section_userdata (stdoutput, sec);
 513 }
 514
 515 symbolS *
 516 section_symbol (sec)
 517      segT sec;
 518 {
 519   segment_info_type *seginfo = seg_info (sec);
 520   symbolS *s;
 521
 522   if (seginfo == 0)
 523     abort ();
 524   if (seginfo->sym)
 525     return seginfo->sym;
 526
 527 #ifndef EMIT_SECTION_SYMBOLS
 528 #define EMIT_SECTION_SYMBOLS 1
 529 #endif
 530
 531   if (! EMIT_SECTION_SYMBOLS
 532 #ifdef BFD_ASSEMBLER
 533       || symbol_table_frozen
 534 #endif
 535       )
 536     {
 537       /* Here we know it won't be going into the symbol table.  */
 538       s = symbol_create (sec->name, sec, 0, &zero_address_frag);
 539     }
 540   else
 541     {
 542       s = symbol_find_base (sec->name, 0);
 543       if (s == NULL)
 544         s = symbol_new (sec->name, sec, 0, &zero_address_frag);
 545       else
 546         {
 547           if (S_GET_SEGMENT (s) == undefined_section)
 548             {
 549               S_SET_SEGMENT (s, sec);
 550               symbol_set_frag (s, &zero_address_frag);
 551             }
 552         }
 553     }
 554
 555   S_CLEAR_EXTERNAL (s);
 556
 557   /* Use the BFD section symbol, if possible.  */
 558   if (obj_sec_sym_ok_for_reloc (sec))
 559     symbol_set_bfdsym (s, sec->symbol);
 560
 561   seginfo->sym = s;
 562   return s;
 563 }
 564
 565 #endif /* BFD_ASSEMBLER */
 566
 567 /* Return whether the specified segment is thought to hold text.  */
 568
 569 #ifndef BFD_ASSEMBLER
 570 const char * const nontext_section_names[] =
 571 {
 572   ".eh_frame",
 573   ".gcc_except_table",
 574 #ifdef OBJ_COFF
 575 #ifndef COFF_LONG_SECTION_NAMES
 576   ".eh_fram",
 577   ".gcc_exc",
 578 #endif
 579 #endif
 580   NULL
 581 };
 582 #endif /* ! BFD_ASSEMBLER */
 583
 584 int
 585 subseg_text_p (sec)
 586      segT sec;
 587 {
 588 #ifdef BFD_ASSEMBLER
 589   return (bfd_get_section_flags (stdoutput, sec) & SEC_CODE) != 0;
 590 #else /* ! BFD_ASSEMBLER */
 591   const char * const *p;
 592
 593   if (sec == data_section || sec == bss_section)
 594     return 0;
 595
 596   for (p = nontext_section_names; *p != NULL; ++p)
 597     {
 598       if (strcmp (segment_name (sec), *p) == 0)
 599         return 0;
 600
 601 #ifdef obj_segment_name
 602       if (strcmp (obj_segment_name (sec), *p) == 0)
 603         return 0;
 604 #endif
 605     }
 606
 607   return 1;
 608
 609 #endif /* ! BFD_ASSEMBLER */
 610 }
 611
 612 void
 613 subsegs_print_statistics (file)
 614      FILE *file;
 615 {
 616   frchainS *frchp;
 617   fprintf (file, "frag chains:\n");
 618   for (frchp = frchain_root; frchp; frchp = frchp->frch_next)
 619     {
 620       int count = 0;
 621       fragS *fragp;
 622
 623       /* If frch_subseg is non-zero, it's probably been chained onto
 624          the end of a previous subsection.  Don't count it again.  */
 625       if (frchp->frch_subseg != 0)
 626         continue;
 627
 628       /* Skip gas-internal sections.  */
 629       if (segment_name (frchp->frch_seg)[0] == '*')
 630         continue;
 631
 632       for (fragp = frchp->frch_root; fragp; fragp = fragp->fr_next)
 633         {
 634 #if 0
 635           switch (fragp->fr_type)
 636             {
 637             case rs_fill:
 638               fprintf (file, "f"); break;
 639             case rs_align:
 640               fprintf (file, "a"); break;
 641             case rs_align_code:
 642               fprintf (file, "c"); break;
 643             case rs_org:
 644               fprintf (file, "o"); break;
 645             case rs_machine_dependent:
 646               fprintf (file, "m"); break;
 647             case rs_space:
 648               fprintf (file, "s"); break;
 649             case 0:
 650               fprintf (file, "0"); break;
 651             default:
 652               fprintf (file, "?"); break;
 653             }
 654 #endif
 655           count++;
 656         }
 657       fprintf (file, "\n");
 658       fprintf (file, "\t%p %-10s\t%10d frags\n", frchp,
 659                segment_name (frchp->frch_seg), count);
 660     }
 661 }
 662
 663 /* end of subsegs.c */