gas/stabs.c

   1 /* Generic stabs parsing for gas.
   2    Copyright 1989, 1990, 1991, 1993, 1995, 1996, 1997, 1998, 2000, 2001
   3    2002, 2003, 2004 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
   9 published by the Free Software Foundation; either version 2,
  10 or (at your option) any later version.
  11
  12 GAS is distributed in the hope that it will be useful, but
  13 WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  15 the 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 #include "as.h"
  23 #include "obstack.h"
  24 #include "subsegs.h"
  25 #include "ecoff.h"
  26
  27 /* We need this, despite the apparent object format dependency, since
  28    it defines stab types, which all object formats can use now.  */
  29
  30 #include "aout/stab_gnu.h"
  31
  32 /* Holds whether the assembler is generating stabs line debugging
  33    information or not.  Potentially used by md_cleanup function.  */
  34
  35 int outputting_stabs_line_debug = 0;
  36
  37 static void s_stab_generic (int, char *, char *);
  38 static void generate_asm_file (int, char *);
  39
  40 /* Allow backends to override the names used for the stab sections.  */
  41 #ifndef STAB_SECTION_NAME
  42 #define STAB_SECTION_NAME ".stab"
  43 #endif
  44
  45 #ifndef STAB_STRING_SECTION_NAME
  46 #define STAB_STRING_SECTION_NAME ".stabstr"
  47 #endif
  48
  49 /* Non-zero if we're in the middle of a .func function, in which case
  50    stabs_generate_asm_lineno emits function relative line number stabs.
  51    Otherwise it emits line number stabs with absolute addresses.  Note that
  52    both cases only apply to assembler code assembled with -gstabs.  */
  53 static int in_dot_func_p;
  54
  55 /* Label at start of current function if in_dot_func_p != 0.  */
  56 static const char *current_function_label;
  57
  58 /*
  59  * Handle .stabX directives, which used to be open-coded.
  60  * So much creeping featurism overloaded the semantics that we decided
  61  * to put all .stabX thinking in one place. Here.
  62  *
  63  * We try to make any .stabX directive legal. Other people's AS will often
  64  * do assembly-time consistency checks: eg assigning meaning to n_type bits
  65  * and "protecting" you from setting them to certain values. (They also zero
  66  * certain bits before emitting symbols. Tut tut.)
  67  *
  68  * If an expression is not absolute we either gripe or use the relocation
  69  * information. Other people's assemblers silently forget information they
  70  * don't need and invent information they need that you didn't supply.
  71  */
  72
  73 /*
  74  * Build a string dictionary entry for a .stabX symbol.
  75  * The symbol is added to the .<secname>str section.
  76  */
  77
  78 #ifndef SEPARATE_STAB_SECTIONS
  79 #define SEPARATE_STAB_SECTIONS 0
  80 #endif
  81
  82 unsigned int
  83 get_stab_string_offset (const char *string, const char *stabstr_secname)
  84 {
  85   unsigned int length;
  86   unsigned int retval;
  87   segT save_seg;
  88   subsegT save_subseg;
  89   segT seg;
  90   char *p;
  91
  92   if (! SEPARATE_STAB_SECTIONS)
  93     abort ();
  94
  95   length = strlen (string);
  96
  97   save_seg = now_seg;
  98   save_subseg = now_subseg;
  99
 100   /* Create the stab string section.  */
 101   seg = subseg_new (stabstr_secname, 0);
 102
 103   retval = seg_info (seg)->stabu.stab_string_size;
 104   if (retval <= 0)
 105     {
 106       /* Make sure the first string is empty.  */
 107       p = frag_more (1);
 108       *p = 0;
 109       retval = seg_info (seg)->stabu.stab_string_size = 1;
 110 #ifdef BFD_ASSEMBLER
 111       bfd_set_section_flags (stdoutput, seg, SEC_READONLY | SEC_DEBUGGING);
 112       if (seg->name == stabstr_secname)
 113         seg->name = xstrdup (stabstr_secname);
 114 #endif
 115     }
 116
 117   if (length > 0)
 118     {                           /* Ordinary case.  */
 119       p = frag_more (length + 1);
 120       strcpy (p, string);
 121
 122       seg_info (seg)->stabu.stab_string_size += length + 1;
 123     }
 124   else
 125     retval = 0;
 126
 127   subseg_set (save_seg, save_subseg);
 128
 129   return retval;
 130 }
 131
 132 #ifdef AOUT_STABS
 133 #ifndef OBJ_PROCESS_STAB
 134 #define OBJ_PROCESS_STAB(SEG,W,S,T,O,D) aout_process_stab(W,S,T,O,D)
 135 #endif
 136
 137 /* Here instead of obj-aout.c because other formats use it too.  */
 138 void
 139 aout_process_stab (what, string, type, other, desc)
 140      int what;
 141      const char *string;
 142      int type, other, desc;
 143 {
 144   /* Put the stab information in the symbol table.  */
 145   symbolS *symbol;
 146
 147   /* Create the symbol now, but only insert it into the symbol chain
 148      after any symbols mentioned in the value expression get into the
 149      symbol chain.  This is to avoid "continuation symbols" (where one
 150      ends in "\" and the debug info is continued in the next .stabs
 151      directive) from being separated by other random symbols.  */
 152   symbol = symbol_create (string, undefined_section, 0,
 153                           (struct frag *) NULL);
 154   if (what == 's' || what == 'n')
 155     {
 156       /* Pick up the value from the input line.  */
 157       symbol_set_frag (symbol, &zero_address_frag);
 158       pseudo_set (symbol);
 159     }
 160   else
 161     {
 162       /* .stabd sets the name to NULL.  Why?  */
 163       S_SET_NAME (symbol, NULL);
 164       symbol_set_frag (symbol, frag_now);
 165       S_SET_VALUE (symbol, (valueT) frag_now_fix ());
 166     }
 167
 168   symbol_append (symbol, symbol_lastP, &symbol_rootP, &symbol_lastP);
 169
 170   S_SET_TYPE (symbol, type);
 171   S_SET_OTHER (symbol, other);
 172   S_SET_DESC (symbol, desc);
 173 }
 174 #endif
 175
 176 /* This can handle different kinds of stabs (s,n,d) and different
 177    kinds of stab sections.  */
 178
 179 static void
 180 s_stab_generic (int what, char *stab_secname, char *stabstr_secname)
 181 {
 182   long longint;
 183   char *string, *saved_string_obstack_end;
 184   int type;
 185   int other;
 186   int desc;
 187
 188   /* The general format is:
 189      .stabs "STRING",TYPE,OTHER,DESC,VALUE
 190      .stabn TYPE,OTHER,DESC,VALUE
 191      .stabd TYPE,OTHER,DESC
 192      At this point input_line_pointer points after the pseudo-op and
 193      any trailing whitespace.  The argument what is one of 's', 'n' or
 194      'd' indicating which type of .stab this is.  */
 195
 196   if (what != 's')
 197     {
 198       string = "";
 199       saved_string_obstack_end = 0;
 200     }
 201   else
 202     {
 203       int length;
 204
 205       string = demand_copy_C_string (&length);
 206       /* FIXME: We should probably find some other temporary storage
 207          for string, rather than leaking memory if someone else
 208          happens to use the notes obstack.  */
 209       saved_string_obstack_end = notes.next_free;
 210       SKIP_WHITESPACE ();
 211       if (*input_line_pointer == ',')
 212         input_line_pointer++;
 213       else
 214         {
 215           as_warn (_(".stab%c: missing comma"), what);
 216           ignore_rest_of_line ();
 217           return;
 218         }
 219     }
 220
 221   if (get_absolute_expression_and_terminator (&longint) != ',')
 222     {
 223       as_warn (_(".stab%c: missing comma"), what);
 224       ignore_rest_of_line ();
 225       return;
 226     }
 227   type = longint;
 228
 229   if (get_absolute_expression_and_terminator (&longint) != ',')
 230     {
 231       as_warn (_(".stab%c: missing comma"), what);
 232       ignore_rest_of_line ();
 233       return;
 234     }
 235   other = longint;
 236
 237   desc = get_absolute_expression ();
 238
 239   if ((desc > 0xffff) || (desc < -0x8000))
 240     /* This could happen for example with a source file with a huge
 241        number of lines.  The only cure is to use a different debug
 242        format, probably DWARF.  */
 243     as_warn (_(".stab%c: description field '%x' too big, try a different debug format"),
 244              what, desc);
 245
 246   if (what == 's' || what == 'n')
 247     {
 248       if (*input_line_pointer != ',')
 249         {
 250           as_warn (_(".stab%c: missing comma"), what);
 251           ignore_rest_of_line ();
 252           return;
 253         }
 254       input_line_pointer++;
 255       SKIP_WHITESPACE ();
 256     }
 257
 258 #ifdef TC_PPC
 259 #ifdef OBJ_ELF
 260   /* Solaris on PowerPC has decided that .stabd can take 4 arguments, so if we were
 261      given 4 arguments, make it a .stabn */
 262   else if (what == 'd')
 263     {
 264       char *save_location = input_line_pointer;
 265
 266       SKIP_WHITESPACE ();
 267       if (*input_line_pointer == ',')
 268         {
 269           input_line_pointer++;
 270           what = 'n';
 271         }
 272       else
 273         input_line_pointer = save_location;
 274     }
 275 #endif /* OBJ_ELF */
 276 #endif /* TC_PPC */
 277
 278 #ifndef NO_LISTING
 279   if (listing)
 280     {
 281       switch (type)
 282         {
 283         case N_SLINE:
 284           listing_source_line ((unsigned int) desc);
 285           break;
 286         case N_SO:
 287         case N_SOL:
 288           listing_source_file (string);
 289           break;
 290         }
 291     }
 292 #endif /* ! NO_LISTING */
 293
 294   /* We have now gathered the type, other, and desc information.  For
 295      .stabs or .stabn, input_line_pointer is now pointing at the
 296      value.  */
 297
 298   if (SEPARATE_STAB_SECTIONS)
 299     /* Output the stab information in a separate section.  This is used
 300        at least for COFF and ELF.  */
 301     {
 302       segT saved_seg = now_seg;
 303       subsegT saved_subseg = now_subseg;
 304       fragS *saved_frag = frag_now;
 305       valueT dot;
 306       segT seg;
 307       unsigned int stroff;
 308       char *p;
 309
 310       static segT cached_sec;
 311       static char *cached_secname;
 312
 313       dot = frag_now_fix ();
 314
 315 #ifdef md_flush_pending_output
 316       md_flush_pending_output ();
 317 #endif
 318
 319       if (cached_secname && !strcmp (cached_secname, stab_secname))
 320         {
 321           seg = cached_sec;
 322           subseg_set (seg, 0);
 323         }
 324       else
 325         {
 326           seg = subseg_new (stab_secname, 0);
 327           if (cached_secname)
 328             free (cached_secname);
 329           cached_secname = xstrdup (stab_secname);
 330           cached_sec = seg;
 331         }
 332
 333       if (! seg_info (seg)->hadone)
 334         {
 335 #ifdef BFD_ASSEMBLER
 336           bfd_set_section_flags (stdoutput, seg,
 337                                  SEC_READONLY | SEC_RELOC | SEC_DEBUGGING);
 338 #endif
 339 #ifdef INIT_STAB_SECTION
 340           INIT_STAB_SECTION (seg);
 341 #endif
 342           seg_info (seg)->hadone = 1;
 343         }
 344
 345       stroff = get_stab_string_offset (string, stabstr_secname);
 346       if (what == 's')
 347         {
 348           /* Release the string, if nobody else has used the obstack.  */
 349           if (saved_string_obstack_end == notes.next_free)
 350             obstack_free (&notes, string);
 351         }
 352
 353       /* At least for now, stabs in a special stab section are always
 354          output as 12 byte blocks of information.  */
 355       p = frag_more (8);
 356       md_number_to_chars (p, (valueT) stroff, 4);
 357       md_number_to_chars (p + 4, (valueT) type, 1);
 358       md_number_to_chars (p + 5, (valueT) other, 1);
 359       md_number_to_chars (p + 6, (valueT) desc, 2);
 360
 361       if (what == 's' || what == 'n')
 362         {
 363           /* Pick up the value from the input line.  */
 364           cons (4);
 365           input_line_pointer--;
 366         }
 367       else
 368         {
 369           symbolS *symbol;
 370           expressionS exp;
 371
 372           /* Arrange for a value representing the current location.  */
 373           symbol = symbol_temp_new (saved_seg, dot, saved_frag);
 374
 375           exp.X_op = O_symbol;
 376           exp.X_add_symbol = symbol;
 377           exp.X_add_number = 0;
 378
 379           emit_expr (&exp, 4);
 380         }
 381
 382 #ifdef OBJ_PROCESS_STAB
 383       OBJ_PROCESS_STAB (seg, what, string, type, other, desc);
 384 #endif
 385
 386       subseg_set (saved_seg, saved_subseg);
 387     }
 388   else
 389     {
 390 #ifdef OBJ_PROCESS_STAB
 391       OBJ_PROCESS_STAB (0, what, string, type, other, desc);
 392 #else
 393       abort ();
 394 #endif
 395     }
 396
 397   demand_empty_rest_of_line ();
 398 }
 399
 400 /* Regular stab directive.  */
 401
 402 void
 403 s_stab (int what)
 404 {
 405   s_stab_generic (what, STAB_SECTION_NAME, STAB_STRING_SECTION_NAME);
 406 }
 407
 408 /* "Extended stabs", used in Solaris only now.  */
 409
 410 void
 411 s_xstab (int what)
 412 {
 413   int length;
 414   char *stab_secname, *stabstr_secname;
 415   static char *saved_secname, *saved_strsecname;
 416
 417   /* @@ MEMORY LEAK: This allocates a copy of the string, but in most
 418      cases it will be the same string, so we could release the storage
 419      back to the obstack it came from.  */
 420   stab_secname = demand_copy_C_string (&length);
 421   SKIP_WHITESPACE ();
 422   if (*input_line_pointer == ',')
 423     input_line_pointer++;
 424   else
 425     {
 426       as_bad (_("comma missing in .xstabs"));
 427       ignore_rest_of_line ();
 428       return;
 429     }
 430
 431   /* To get the name of the stab string section, simply add "str" to
 432      the stab section name.  */
 433   if (saved_secname == 0 || strcmp (saved_secname, stab_secname))
 434     {
 435       stabstr_secname = (char *) xmalloc (strlen (stab_secname) + 4);
 436       strcpy (stabstr_secname, stab_secname);
 437       strcat (stabstr_secname, "str");
 438       if (saved_secname)
 439         {
 440           free (saved_secname);
 441           free (saved_strsecname);
 442         }
 443       saved_secname = stab_secname;
 444       saved_strsecname = stabstr_secname;
 445     }
 446   s_stab_generic (what, saved_secname, saved_strsecname);
 447 }
 448
 449 #ifdef S_SET_DESC
 450
 451 /* Frob invented at RMS' request. Set the n_desc of a symbol.  */
 452
 453 void
 454 s_desc (ignore)
 455      int ignore ATTRIBUTE_UNUSED;
 456 {
 457   char *name;
 458   char c;
 459   char *p;
 460   symbolS *symbolP;
 461   int temp;
 462
 463   name = input_line_pointer;
 464   c = get_symbol_end ();
 465   p = input_line_pointer;
 466   *p = c;
 467   SKIP_WHITESPACE ();
 468   if (*input_line_pointer != ',')
 469     {
 470       *p = 0;
 471       as_bad (_("expected comma after \"%s\""), name);
 472       *p = c;
 473       ignore_rest_of_line ();
 474     }
 475   else
 476     {
 477       input_line_pointer++;
 478       temp = get_absolute_expression ();
 479       *p = 0;
 480       symbolP = symbol_find_or_make (name);
 481       *p = c;
 482       S_SET_DESC (symbolP, temp);
 483     }
 484   demand_empty_rest_of_line ();
 485 }                               /* s_desc() */
 486
 487 #endif /* defined (S_SET_DESC) */
 488
 489 /* Generate stabs debugging information to denote the main source file.  */
 490
 491 void
 492 stabs_generate_asm_file (void)
 493 {
 494   char *file;
 495   unsigned int lineno;
 496
 497   as_where (&file, &lineno);
 498   if (use_gnu_debug_info_extensions)
 499     {
 500       char *dir, *dir2;
 501
 502       dir = getpwd ();
 503       dir2 = alloca (strlen (dir) + 2);
 504       sprintf (dir2, "%s%s", dir, "/");
 505       generate_asm_file (N_SO, dir2);
 506     }
 507   generate_asm_file (N_SO, file);
 508 }
 509
 510 /* Generate stabs debugging information to denote the source file.
 511    TYPE is one of N_SO, N_SOL.  */
 512
 513 static void
 514 generate_asm_file (int type, char *file)
 515 {
 516   static char *last_file;
 517   static int label_count;
 518   char *hold;
 519   char sym[30];
 520   char *buf;
 521   char *tmp = file;
 522   char *endp = file + strlen (file);
 523   char *bufp;
 524
 525   if (last_file != NULL
 526       && strcmp (last_file, file) == 0)
 527     return;
 528
 529   /* Rather than try to do this in some efficient fashion, we just
 530      generate a string and then parse it again.  That lets us use the
 531      existing stabs hook, which expect to see a string, rather than
 532      inventing new ones.  */
 533   hold = input_line_pointer;
 534
 535   sprintf (sym, "%sF%d", FAKE_LABEL_NAME, label_count);
 536   ++label_count;
 537
 538   /* Allocate enough space for the file name (possibly extended with
 539      doubled up backslashes), the symbol name, and the other characters
 540      that make up a stabs file directive.  */
 541   bufp = buf = xmalloc (2 * strlen (file) + strlen (sym) + 12);
 542
 543   *bufp++ = '"';
 544
 545   while (tmp < endp)
 546     {
 547       char *bslash = strchr (tmp, '\\');
 548       size_t len = (bslash) ? (size_t) (bslash - tmp + 1) : strlen (tmp);
 549
 550       /* Double all backslashes, since demand_copy_C_string (used by
 551          s_stab to extract the part in quotes) will try to replace them as
 552          escape sequences.  backslash may appear in a filespec.  */
 553       strncpy (bufp, tmp, len);
 554
 555       tmp += len;
 556       bufp += len;
 557
 558       if (bslash != NULL)
 559         *bufp++ = '\\';
 560     }
 561
 562   sprintf (bufp, "\",%d,0,0,%s\n", type, sym);
 563
 564   input_line_pointer = buf;
 565   s_stab ('s');
 566   colon (sym);
 567
 568   if (last_file != NULL)
 569     free (last_file);
 570   last_file = xstrdup (file);
 571
 572   free (buf);
 573
 574   input_line_pointer = hold;
 575 }
 576
 577 /* Generate stabs debugging information for the current line.  This is
 578    used to produce debugging information for an assembler file.  */
 579
 580 void
 581 stabs_generate_asm_lineno (void)
 582 {
 583   static int label_count;
 584   char *hold;
 585   char *file;
 586   unsigned int lineno;
 587   char *buf;
 588   char sym[30];
 589   /* Remember the last file/line and avoid duplicates.  */
 590   static unsigned int prev_lineno = -1;
 591   static char *prev_file = NULL;
 592
 593   /* Rather than try to do this in some efficient fashion, we just
 594      generate a string and then parse it again.  That lets us use the
 595      existing stabs hook, which expect to see a string, rather than
 596      inventing new ones.  */
 597
 598   hold = input_line_pointer;
 599
 600   as_where (&file, &lineno);
 601
 602   /* Don't emit sequences of stabs for the same line.  */
 603   if (prev_file == NULL)
 604     {
 605       /* First time thru.  */
 606       prev_file = xstrdup (file);
 607       prev_lineno = lineno;
 608     }
 609   else if (lineno == prev_lineno
 610            && strcmp (file, prev_file) == 0)
 611     {
 612       /* Same file/line as last time.  */
 613       return;
 614     }
 615   else
 616     {
 617       /* Remember file/line for next time.  */
 618       prev_lineno = lineno;
 619       if (strcmp (file, prev_file) != 0)
 620         {
 621           free (prev_file);
 622           prev_file = xstrdup (file);
 623         }
 624     }
 625
 626   /* Let the world know that we are in the middle of generating a
 627      piece of stabs line debugging information.  */
 628   outputting_stabs_line_debug = 1;
 629
 630   generate_asm_file (N_SOL, file);
 631
 632   sprintf (sym, "%sL%d", FAKE_LABEL_NAME, label_count);
 633   ++label_count;
 634
 635   if (in_dot_func_p)
 636     {
 637       buf = (char *) alloca (100 + strlen (current_function_label));
 638       sprintf (buf, "%d,0,%d,%s-%s\n", N_SLINE, lineno,
 639                sym, current_function_label);
 640     }
 641   else
 642     {
 643       buf = (char *) alloca (100);
 644       sprintf (buf, "%d,0,%d,%s\n", N_SLINE, lineno, sym);
 645     }
 646   input_line_pointer = buf;
 647   s_stab ('n');
 648   colon (sym);
 649
 650   input_line_pointer = hold;
 651   outputting_stabs_line_debug = 0;
 652 }
 653
 654 /* Emit a function stab.
 655    All assembler functions are assumed to have return type `void'.  */
 656
 657 void
 658 stabs_generate_asm_func (const char *funcname, const char *startlabname)
 659 {
 660   static int void_emitted_p;
 661   char *hold = input_line_pointer;
 662   char *buf;
 663   char *file;
 664   unsigned int lineno;
 665
 666   if (! void_emitted_p)
 667     {
 668       input_line_pointer = "\"void:t1=1\",128,0,0,0";
 669       s_stab ('s');
 670       void_emitted_p = 1;
 671     }
 672
 673   as_where (&file, &lineno);
 674   asprintf (&buf, "\"%s:F1\",%d,0,%d,%s",
 675             funcname, N_FUN, lineno + 1, startlabname);
 676   input_line_pointer = buf;
 677   s_stab ('s');
 678   free (buf);
 679
 680   input_line_pointer = hold;
 681   current_function_label = xstrdup (startlabname);
 682   in_dot_func_p = 1;
 683 }
 684
 685 /* Emit a stab to record the end of a function.  */
 686
 687 void
 688 stabs_generate_asm_endfunc (const char *funcname ATTRIBUTE_UNUSED,
 689                             const char *startlabname)
 690 {
 691   static int label_count;
 692   char *hold = input_line_pointer;
 693   char *buf;
 694   char sym[30];
 695
 696   sprintf (sym, "%sendfunc%d", FAKE_LABEL_NAME, label_count);
 697   ++label_count;
 698   colon (sym);
 699
 700   asprintf (&buf, "\"\",%d,0,0,%s-%s", N_FUN, sym, startlabname);
 701   input_line_pointer = buf;
 702   s_stab ('s');
 703   free (buf);
 704
 705   input_line_pointer = hold;
 706   in_dot_func_p = 0;
 707   current_function_label = NULL;
 708 }