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, 2005, 2007 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 3,
  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, 51 Franklin Street - Fifth Floor, Boston, MA
  20    02110-1301, 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       bfd_set_section_flags (stdoutput, seg, SEC_READONLY | SEC_DEBUGGING);
 111       if (seg->name == stabstr_secname)
 112         seg->name = xstrdup (stabstr_secname);
 113     }
 114
 115   if (length > 0)
 116     {                           /* Ordinary case.  */
 117       p = frag_more (length + 1);
 118       strcpy (p, string);
 119
 120       seg_info (seg)->stabu.stab_string_size += length + 1;
 121     }
 122   else
 123     retval = 0;
 124
 125   subseg_set (save_seg, save_subseg);
 126
 127   return retval;
 128 }
 129
 130 #ifdef AOUT_STABS
 131 #ifndef OBJ_PROCESS_STAB
 132 #define OBJ_PROCESS_STAB(SEG,W,S,T,O,D) aout_process_stab(W,S,T,O,D)
 133 #endif
 134
 135 /* Here instead of obj-aout.c because other formats use it too.  */
 136 void
 137 aout_process_stab (what, string, type, other, desc)
 138      int what;
 139      const char *string;
 140      int type, other, desc;
 141 {
 142   /* Put the stab information in the symbol table.  */
 143   symbolS *symbol;
 144
 145   /* Create the symbol now, but only insert it into the symbol chain
 146      after any symbols mentioned in the value expression get into the
 147      symbol chain.  This is to avoid "continuation symbols" (where one
 148      ends in "\" and the debug info is continued in the next .stabs
 149      directive) from being separated by other random symbols.  */
 150   symbol = symbol_create (string, undefined_section, 0,
 151                           &zero_address_frag);
 152   if (what == 's' || what == 'n')
 153     {
 154       /* Pick up the value from the input line.  */
 155       pseudo_set (symbol);
 156     }
 157   else
 158     {
 159       /* .stabd sets the name to NULL.  Why?  */
 160       S_SET_NAME (symbol, NULL);
 161       symbol_set_frag (symbol, frag_now);
 162       S_SET_VALUE (symbol, (valueT) frag_now_fix ());
 163     }
 164
 165   symbol_append (symbol, symbol_lastP, &symbol_rootP, &symbol_lastP);
 166
 167   S_SET_TYPE (symbol, type);
 168   S_SET_OTHER (symbol, other);
 169   S_SET_DESC (symbol, desc);
 170 }
 171 #endif
 172
 173 /* This can handle different kinds of stabs (s,n,d) and different
 174    kinds of stab sections.  */
 175
 176 static void
 177 s_stab_generic (int what, char *stab_secname, char *stabstr_secname)
 178 {
 179   long longint;
 180   char *string, *saved_string_obstack_end;
 181   int type;
 182   int other;
 183   int desc;
 184
 185   /* The general format is:
 186      .stabs "STRING",TYPE,OTHER,DESC,VALUE
 187      .stabn TYPE,OTHER,DESC,VALUE
 188      .stabd TYPE,OTHER,DESC
 189      At this point input_line_pointer points after the pseudo-op and
 190      any trailing whitespace.  The argument what is one of 's', 'n' or
 191      'd' indicating which type of .stab this is.  */
 192
 193   if (what != 's')
 194     {
 195       string = "";
 196       saved_string_obstack_end = 0;
 197     }
 198   else
 199     {
 200       int length;
 201
 202       string = demand_copy_C_string (&length);
 203       /* FIXME: We should probably find some other temporary storage
 204          for string, rather than leaking memory if someone else
 205          happens to use the notes obstack.  */
 206       saved_string_obstack_end = notes.next_free;
 207       SKIP_WHITESPACE ();
 208       if (*input_line_pointer == ',')
 209         input_line_pointer++;
 210       else
 211         {
 212           as_warn (_(".stab%c: missing comma"), what);
 213           ignore_rest_of_line ();
 214           return;
 215         }
 216     }
 217
 218   if (get_absolute_expression_and_terminator (&longint) != ',')
 219     {
 220       as_warn (_(".stab%c: missing comma"), what);
 221       ignore_rest_of_line ();
 222       return;
 223     }
 224   type = longint;
 225
 226   if (get_absolute_expression_and_terminator (&longint) != ',')
 227     {
 228       as_warn (_(".stab%c: missing comma"), what);
 229       ignore_rest_of_line ();
 230       return;
 231     }
 232   other = longint;
 233
 234   desc = get_absolute_expression ();
 235
 236   if ((desc > 0xffff) || (desc < -0x8000))
 237     /* This could happen for example with a source file with a huge
 238        number of lines.  The only cure is to use a different debug
 239        format, probably DWARF.  */
 240     as_warn (_(".stab%c: description field '%x' too big, try a different debug format"),
 241              what, desc);
 242
 243   if (what == 's' || what == 'n')
 244     {
 245       if (*input_line_pointer != ',')
 246         {
 247           as_warn (_(".stab%c: missing comma"), what);
 248           ignore_rest_of_line ();
 249           return;
 250         }
 251       input_line_pointer++;
 252       SKIP_WHITESPACE ();
 253     }
 254
 255 #ifdef TC_PPC
 256 #ifdef OBJ_ELF
 257   /* Solaris on PowerPC has decided that .stabd can take 4 arguments, so if we were
 258      given 4 arguments, make it a .stabn */
 259   else if (what == 'd')
 260     {
 261       char *save_location = input_line_pointer;
 262
 263       SKIP_WHITESPACE ();
 264       if (*input_line_pointer == ',')
 265         {
 266           input_line_pointer++;
 267           what = 'n';
 268         }
 269       else
 270         input_line_pointer = save_location;
 271     }
 272 #endif /* OBJ_ELF */
 273 #endif /* TC_PPC */
 274
 275 #ifndef NO_LISTING
 276   if (listing)
 277     {
 278       switch (type)
 279         {
 280         case N_SLINE:
 281           listing_source_line ((unsigned int) desc);
 282           break;
 283         case N_SO:
 284         case N_SOL:
 285           listing_source_file (string);
 286           break;
 287         }
 288     }
 289 #endif /* ! NO_LISTING */
 290
 291   /* We have now gathered the type, other, and desc information.  For
 292      .stabs or .stabn, input_line_pointer is now pointing at the
 293      value.  */
 294
 295   if (SEPARATE_STAB_SECTIONS)
 296     /* Output the stab information in a separate section.  This is used
 297        at least for COFF and ELF.  */
 298     {
 299       segT saved_seg = now_seg;
 300       subsegT saved_subseg = now_subseg;
 301       fragS *saved_frag = frag_now;
 302       valueT dot;
 303       segT seg;
 304       unsigned int stroff;
 305       char *p;
 306
 307       static segT cached_sec;
 308       static char *cached_secname;
 309
 310       dot = frag_now_fix ();
 311
 312 #ifdef md_flush_pending_output
 313       md_flush_pending_output ();
 314 #endif
 315
 316       if (cached_secname && !strcmp (cached_secname, stab_secname))
 317         {
 318           seg = cached_sec;
 319           subseg_set (seg, 0);
 320         }
 321       else
 322         {
 323           seg = subseg_new (stab_secname, 0);
 324           if (cached_secname)
 325             free (cached_secname);
 326           cached_secname = xstrdup (stab_secname);
 327           cached_sec = seg;
 328         }
 329
 330       if (! seg_info (seg)->hadone)
 331         {
 332           bfd_set_section_flags (stdoutput, seg,
 333                                  SEC_READONLY | SEC_RELOC | SEC_DEBUGGING);
 334 #ifdef INIT_STAB_SECTION
 335           INIT_STAB_SECTION (seg);
 336 #endif
 337           seg_info (seg)->hadone = 1;
 338         }
 339
 340       stroff = get_stab_string_offset (string, stabstr_secname);
 341       if (what == 's')
 342         {
 343           /* Release the string, if nobody else has used the obstack.  */
 344           if (saved_string_obstack_end == notes.next_free)
 345             obstack_free (&notes, string);
 346         }
 347
 348       /* At least for now, stabs in a special stab section are always
 349          output as 12 byte blocks of information.  */
 350       p = frag_more (8);
 351       md_number_to_chars (p, (valueT) stroff, 4);
 352       md_number_to_chars (p + 4, (valueT) type, 1);
 353       md_number_to_chars (p + 5, (valueT) other, 1);
 354       md_number_to_chars (p + 6, (valueT) desc, 2);
 355
 356       if (what == 's' || what == 'n')
 357         {
 358           /* Pick up the value from the input line.  */
 359           cons (4);
 360           input_line_pointer--;
 361         }
 362       else
 363         {
 364           symbolS *symbol;
 365           expressionS exp;
 366
 367           /* Arrange for a value representing the current location.  */
 368           symbol = symbol_temp_new (saved_seg, dot, saved_frag);
 369
 370           exp.X_op = O_symbol;
 371           exp.X_add_symbol = symbol;
 372           exp.X_add_number = 0;
 373
 374           emit_expr (&exp, 4);
 375         }
 376
 377 #ifdef OBJ_PROCESS_STAB
 378       OBJ_PROCESS_STAB (seg, what, string, type, other, desc);
 379 #endif
 380
 381       subseg_set (saved_seg, saved_subseg);
 382     }
 383   else
 384     {
 385 #ifdef OBJ_PROCESS_STAB
 386       OBJ_PROCESS_STAB (0, what, string, type, other, desc);
 387 #else
 388       abort ();
 389 #endif
 390     }
 391
 392   demand_empty_rest_of_line ();
 393 }
 394
 395 /* Regular stab directive.  */
 396
 397 void
 398 s_stab (int what)
 399 {
 400   s_stab_generic (what, STAB_SECTION_NAME, STAB_STRING_SECTION_NAME);
 401 }
 402
 403 /* "Extended stabs", used in Solaris only now.  */
 404
 405 void
 406 s_xstab (int what)
 407 {
 408   int length;
 409   char *stab_secname, *stabstr_secname;
 410   static char *saved_secname, *saved_strsecname;
 411
 412   /* @@ MEMORY LEAK: This allocates a copy of the string, but in most
 413      cases it will be the same string, so we could release the storage
 414      back to the obstack it came from.  */
 415   stab_secname = demand_copy_C_string (&length);
 416   SKIP_WHITESPACE ();
 417   if (*input_line_pointer == ',')
 418     input_line_pointer++;
 419   else
 420     {
 421       as_bad (_("comma missing in .xstabs"));
 422       ignore_rest_of_line ();
 423       return;
 424     }
 425
 426   /* To get the name of the stab string section, simply add "str" to
 427      the stab section name.  */
 428   if (saved_secname == 0 || strcmp (saved_secname, stab_secname))
 429     {
 430       stabstr_secname = (char *) xmalloc (strlen (stab_secname) + 4);
 431       strcpy (stabstr_secname, stab_secname);
 432       strcat (stabstr_secname, "str");
 433       if (saved_secname)
 434         {
 435           free (saved_secname);
 436           free (saved_strsecname);
 437         }
 438       saved_secname = stab_secname;
 439       saved_strsecname = stabstr_secname;
 440     }
 441   s_stab_generic (what, saved_secname, saved_strsecname);
 442 }
 443
 444 #ifdef S_SET_DESC
 445
 446 /* Frob invented at RMS' request. Set the n_desc of a symbol.  */
 447
 448 void
 449 s_desc (ignore)
 450      int ignore ATTRIBUTE_UNUSED;
 451 {
 452   char *name;
 453   char c;
 454   char *p;
 455   symbolS *symbolP;
 456   int temp;
 457
 458   name = input_line_pointer;
 459   c = get_symbol_end ();
 460   p = input_line_pointer;
 461   *p = c;
 462   SKIP_WHITESPACE ();
 463   if (*input_line_pointer != ',')
 464     {
 465       *p = 0;
 466       as_bad (_("expected comma after \"%s\""), name);
 467       *p = c;
 468       ignore_rest_of_line ();
 469     }
 470   else
 471     {
 472       input_line_pointer++;
 473       temp = get_absolute_expression ();
 474       *p = 0;
 475       symbolP = symbol_find_or_make (name);
 476       *p = c;
 477       S_SET_DESC (symbolP, temp);
 478     }
 479   demand_empty_rest_of_line ();
 480 }                               /* s_desc() */
 481
 482 #endif /* defined (S_SET_DESC) */
 483
 484 /* Generate stabs debugging information to denote the main source file.  */
 485
 486 void
 487 stabs_generate_asm_file (void)
 488 {
 489   char *file;
 490   unsigned int lineno;
 491
 492   as_where (&file, &lineno);
 493   if (use_gnu_debug_info_extensions)
 494     {
 495       char *dir, *dir2;
 496
 497       dir = getpwd ();
 498       dir2 = alloca (strlen (dir) + 2);
 499       sprintf (dir2, "%s%s", dir, "/");
 500       generate_asm_file (N_SO, dir2);
 501     }
 502   generate_asm_file (N_SO, file);
 503 }
 504
 505 /* Generate stabs debugging information to denote the source file.
 506    TYPE is one of N_SO, N_SOL.  */
 507
 508 static void
 509 generate_asm_file (int type, char *file)
 510 {
 511   static char *last_file;
 512   static int label_count;
 513   char *hold;
 514   char sym[30];
 515   char *buf;
 516   char *tmp = file;
 517   char *endp = file + strlen (file);
 518   char *bufp;
 519
 520   if (last_file != NULL
 521       && strcmp (last_file, file) == 0)
 522     return;
 523
 524   /* Rather than try to do this in some efficient fashion, we just
 525      generate a string and then parse it again.  That lets us use the
 526      existing stabs hook, which expect to see a string, rather than
 527      inventing new ones.  */
 528   hold = input_line_pointer;
 529
 530   sprintf (sym, "%sF%d", FAKE_LABEL_NAME, label_count);
 531   ++label_count;
 532
 533   /* Allocate enough space for the file name (possibly extended with
 534      doubled up backslashes), the symbol name, and the other characters
 535      that make up a stabs file directive.  */
 536   bufp = buf = xmalloc (2 * strlen (file) + strlen (sym) + 12);
 537
 538   *bufp++ = '"';
 539
 540   while (tmp < endp)
 541     {
 542       char *bslash = strchr (tmp, '\\');
 543       size_t len = (bslash) ? (size_t) (bslash - tmp + 1) : strlen (tmp);
 544
 545       /* Double all backslashes, since demand_copy_C_string (used by
 546          s_stab to extract the part in quotes) will try to replace them as
 547          escape sequences.  backslash may appear in a filespec.  */
 548       strncpy (bufp, tmp, len);
 549
 550       tmp += len;
 551       bufp += len;
 552
 553       if (bslash != NULL)
 554         *bufp++ = '\\';
 555     }
 556
 557   sprintf (bufp, "\",%d,0,0,%s\n", type, sym);
 558
 559   input_line_pointer = buf;
 560   s_stab ('s');
 561   colon (sym);
 562
 563   if (last_file != NULL)
 564     free (last_file);
 565   last_file = xstrdup (file);
 566
 567   free (buf);
 568
 569   input_line_pointer = hold;
 570 }
 571
 572 /* Generate stabs debugging information for the current line.  This is
 573    used to produce debugging information for an assembler file.  */
 574
 575 void
 576 stabs_generate_asm_lineno (void)
 577 {
 578   static int label_count;
 579   char *hold;
 580   char *file;
 581   unsigned int lineno;
 582   char *buf;
 583   char sym[30];
 584   /* Remember the last file/line and avoid duplicates.  */
 585   static unsigned int prev_lineno = -1;
 586   static char *prev_file = NULL;
 587
 588   /* Rather than try to do this in some efficient fashion, we just
 589      generate a string and then parse it again.  That lets us use the
 590      existing stabs hook, which expect to see a string, rather than
 591      inventing new ones.  */
 592
 593   hold = input_line_pointer;
 594
 595   as_where (&file, &lineno);
 596
 597   /* Don't emit sequences of stabs for the same line.  */
 598   if (prev_file == NULL)
 599     {
 600       /* First time thru.  */
 601       prev_file = xstrdup (file);
 602       prev_lineno = lineno;
 603     }
 604   else if (lineno == prev_lineno
 605            && strcmp (file, prev_file) == 0)
 606     {
 607       /* Same file/line as last time.  */
 608       return;
 609     }
 610   else
 611     {
 612       /* Remember file/line for next time.  */
 613       prev_lineno = lineno;
 614       if (strcmp (file, prev_file) != 0)
 615         {
 616           free (prev_file);
 617           prev_file = xstrdup (file);
 618         }
 619     }
 620
 621   /* Let the world know that we are in the middle of generating a
 622      piece of stabs line debugging information.  */
 623   outputting_stabs_line_debug = 1;
 624
 625   generate_asm_file (N_SOL, file);
 626
 627   sprintf (sym, "%sL%d", FAKE_LABEL_NAME, label_count);
 628   ++label_count;
 629
 630   if (in_dot_func_p)
 631     {
 632       buf = (char *) alloca (100 + strlen (current_function_label));
 633       sprintf (buf, "%d,0,%d,%s-%s\n", N_SLINE, lineno,
 634                sym, current_function_label);
 635     }
 636   else
 637     {
 638       buf = (char *) alloca (100);
 639       sprintf (buf, "%d,0,%d,%s\n", N_SLINE, lineno, sym);
 640     }
 641   input_line_pointer = buf;
 642   s_stab ('n');
 643   colon (sym);
 644
 645   input_line_pointer = hold;
 646   outputting_stabs_line_debug = 0;
 647 }
 648
 649 /* Emit a function stab.
 650    All assembler functions are assumed to have return type `void'.  */
 651
 652 void
 653 stabs_generate_asm_func (const char *funcname, const char *startlabname)
 654 {
 655   static int void_emitted_p;
 656   char *hold = input_line_pointer;
 657   char *buf;
 658   char *file;
 659   unsigned int lineno;
 660
 661   if (! void_emitted_p)
 662     {
 663       input_line_pointer = "\"void:t1=1\",128,0,0,0";
 664       s_stab ('s');
 665       void_emitted_p = 1;
 666     }
 667
 668   as_where (&file, &lineno);
 669   asprintf (&buf, "\"%s:F1\",%d,0,%d,%s",
 670             funcname, N_FUN, lineno + 1, startlabname);
 671   input_line_pointer = buf;
 672   s_stab ('s');
 673   free (buf);
 674
 675   input_line_pointer = hold;
 676   current_function_label = xstrdup (startlabname);
 677   in_dot_func_p = 1;
 678 }
 679
 680 /* Emit a stab to record the end of a function.  */
 681
 682 void
 683 stabs_generate_asm_endfunc (const char *funcname ATTRIBUTE_UNUSED,
 684                             const char *startlabname)
 685 {
 686   static int label_count;
 687   char *hold = input_line_pointer;
 688   char *buf;
 689   char sym[30];
 690
 691   sprintf (sym, "%sendfunc%d", FAKE_LABEL_NAME, label_count);
 692   ++label_count;
 693   colon (sym);
 694
 695   asprintf (&buf, "\"\",%d,0,0,%s-%s", N_FUN, sym, startlabname);
 696   input_line_pointer = buf;
 697   s_stab ('s');
 698   free (buf);
 699
 700   input_line_pointer = hold;
 701   in_dot_func_p = 0;
 702   current_function_label = NULL;
 703 }