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, 2009  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 "filenames.h"
  24 #include "obstack.h"
  25 #include "subsegs.h"
  26 #include "ecoff.h"
  27
  28 /* We need this, despite the apparent object format dependency, since
  29    it defines stab types, which all object formats can use now.  */
  30
  31 #include "aout/stab_gnu.h"
  32
  33 /* Holds whether the assembler is generating stabs line debugging
  34    information or not.  Potentially used by md_cleanup function.  */
  35
  36 int outputting_stabs_line_debug = 0;
  37
  38 static void s_stab_generic (int, char *, char *);
  39 static void generate_asm_file (int, char *);
  40
  41 /* Allow backends to override the names used for the stab sections.  */
  42 #ifndef STAB_SECTION_NAME
  43 #define STAB_SECTION_NAME ".stab"
  44 #endif
  45
  46 #ifndef STAB_STRING_SECTION_NAME
  47 #define STAB_STRING_SECTION_NAME ".stabstr"
  48 #endif
  49
  50 /* Non-zero if we're in the middle of a .func function, in which case
  51    stabs_generate_asm_lineno emits function relative line number stabs.
  52    Otherwise it emits line number stabs with absolute addresses.  Note that
  53    both cases only apply to assembler code assembled with -gstabs.  */
  54 static int in_dot_func_p;
  55
  56 /* Label at start of current function if in_dot_func_p != 0.  */
  57 static const char *current_function_label;
  58
  59 /*
  60  * Handle .stabX directives, which used to be open-coded.
  61  * So much creeping featurism overloaded the semantics that we decided
  62  * to put all .stabX thinking in one place. Here.
  63  *
  64  * We try to make any .stabX directive legal. Other people's AS will often
  65  * do assembly-time consistency checks: eg assigning meaning to n_type bits
  66  * and "protecting" you from setting them to certain values. (They also zero
  67  * certain bits before emitting symbols. Tut tut.)
  68  *
  69  * If an expression is not absolute we either gripe or use the relocation
  70  * information. Other people's assemblers silently forget information they
  71  * don't need and invent information they need that you didn't supply.
  72  */
  73
  74 /*
  75  * Build a string dictionary entry for a .stabX symbol.
  76  * The symbol is added to the .<secname>str section.
  77  */
  78
  79 #ifndef SEPARATE_STAB_SECTIONS
  80 #define SEPARATE_STAB_SECTIONS 0
  81 #endif
  82
  83 unsigned int
  84 get_stab_string_offset (const char *string, const char *stabstr_secname)
  85 {
  86   unsigned int length;
  87   unsigned int retval;
  88   segT save_seg;
  89   subsegT save_subseg;
  90   segT seg;
  91   char *p;
  92
  93   if (! SEPARATE_STAB_SECTIONS)
  94     abort ();
  95
  96   length = strlen (string);
  97
  98   save_seg = now_seg;
  99   save_subseg = now_subseg;
 100
 101   /* Create the stab string section.  */
 102   seg = subseg_new (stabstr_secname, 0);
 103
 104   retval = seg_info (seg)->stabu.stab_string_size;
 105   if (retval <= 0)
 106     {
 107       /* Make sure the first string is empty.  */
 108       p = frag_more (1);
 109       *p = 0;
 110       retval = seg_info (seg)->stabu.stab_string_size = 1;
 111       bfd_set_section_flags (stdoutput, seg, SEC_READONLY | SEC_DEBUGGING);
 112       if (seg->name == stabstr_secname)
 113         seg->name = xstrdup (stabstr_secname);
 114     }
 115
 116   if (length > 0)
 117     {                           /* Ordinary case.  */
 118       p = frag_more (length + 1);
 119       strcpy (p, string);
 120
 121       seg_info (seg)->stabu.stab_string_size += length + 1;
 122     }
 123   else
 124     retval = 0;
 125
 126   subseg_set (save_seg, save_subseg);
 127
 128   return retval;
 129 }
 130
 131 #ifdef AOUT_STABS
 132 #ifndef OBJ_PROCESS_STAB
 133 #define OBJ_PROCESS_STAB(SEG,W,S,T,O,D) aout_process_stab(W,S,T,O,D)
 134 #endif
 135
 136 /* Here instead of obj-aout.c because other formats use it too.  */
 137 void
 138 aout_process_stab (what, string, type, other, desc)
 139      int what;
 140      const char *string;
 141      int type, other, desc;
 142 {
 143   /* Put the stab information in the symbol table.  */
 144   symbolS *symbol;
 145
 146   /* Create the symbol now, but only insert it into the symbol chain
 147      after any symbols mentioned in the value expression get into the
 148      symbol chain.  This is to avoid "continuation symbols" (where one
 149      ends in "\" and the debug info is continued in the next .stabs
 150      directive) from being separated by other random symbols.  */
 151   symbol = symbol_create (string, undefined_section, 0,
 152                           &zero_address_frag);
 153   if (what == 's' || what == 'n')
 154     {
 155       /* Pick up the value from the input line.  */
 156       pseudo_set (symbol);
 157     }
 158   else
 159     {
 160       /* .stabd sets the name to NULL.  Why?  */
 161       S_SET_NAME (symbol, NULL);
 162       symbol_set_frag (symbol, frag_now);
 163       S_SET_VALUE (symbol, (valueT) frag_now_fix ());
 164     }
 165
 166   symbol_append (symbol, symbol_lastP, &symbol_rootP, &symbol_lastP);
 167
 168   symbol_get_bfdsym (symbol)->flags |= BSF_DEBUGGING;
 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           bfd_set_section_flags (stdoutput, seg,
 336                                  SEC_READONLY | SEC_RELOC | SEC_DEBUGGING);
 337 #ifdef INIT_STAB_SECTION
 338           INIT_STAB_SECTION (seg);
 339 #endif
 340           seg_info (seg)->hadone = 1;
 341         }
 342
 343       stroff = get_stab_string_offset (string, stabstr_secname);
 344       if (what == 's')
 345         {
 346           /* Release the string, if nobody else has used the obstack.  */
 347           if (saved_string_obstack_end == notes.next_free)
 348             obstack_free (&notes, string);
 349         }
 350
 351       /* At least for now, stabs in a special stab section are always
 352          output as 12 byte blocks of information.  */
 353       p = frag_more (8);
 354       md_number_to_chars (p, (valueT) stroff, 4);
 355       md_number_to_chars (p + 4, (valueT) type, 1);
 356       md_number_to_chars (p + 5, (valueT) other, 1);
 357       md_number_to_chars (p + 6, (valueT) desc, 2);
 358
 359       if (what == 's' || what == 'n')
 360         {
 361           /* Pick up the value from the input line.  */
 362           cons (4);
 363           input_line_pointer--;
 364         }
 365       else
 366         {
 367           symbolS *symbol;
 368           expressionS exp;
 369
 370           /* Arrange for a value representing the current location.  */
 371           symbol = symbol_temp_new (saved_seg, dot, saved_frag);
 372
 373           exp.X_op = O_symbol;
 374           exp.X_add_symbol = symbol;
 375           exp.X_add_number = 0;
 376
 377           emit_expr (&exp, 4);
 378         }
 379
 380 #ifdef OBJ_PROCESS_STAB
 381       OBJ_PROCESS_STAB (seg, what, string, type, other, desc);
 382 #endif
 383
 384       subseg_set (saved_seg, saved_subseg);
 385     }
 386   else
 387     {
 388 #ifdef OBJ_PROCESS_STAB
 389       OBJ_PROCESS_STAB (0, what, string, type, other, desc);
 390 #else
 391       abort ();
 392 #endif
 393     }
 394
 395   demand_empty_rest_of_line ();
 396 }
 397
 398 /* Regular stab directive.  */
 399
 400 void
 401 s_stab (int what)
 402 {
 403   s_stab_generic (what, STAB_SECTION_NAME, STAB_STRING_SECTION_NAME);
 404 }
 405
 406 /* "Extended stabs", used in Solaris only now.  */
 407
 408 void
 409 s_xstab (int what)
 410 {
 411   int length;
 412   char *stab_secname, *stabstr_secname;
 413   static char *saved_secname, *saved_strsecname;
 414
 415   /* @@ MEMORY LEAK: This allocates a copy of the string, but in most
 416      cases it will be the same string, so we could release the storage
 417      back to the obstack it came from.  */
 418   stab_secname = demand_copy_C_string (&length);
 419   SKIP_WHITESPACE ();
 420   if (*input_line_pointer == ',')
 421     input_line_pointer++;
 422   else
 423     {
 424       as_bad (_("comma missing in .xstabs"));
 425       ignore_rest_of_line ();
 426       return;
 427     }
 428
 429   /* To get the name of the stab string section, simply add "str" to
 430      the stab section name.  */
 431   if (saved_secname == 0 || strcmp (saved_secname, stab_secname))
 432     {
 433       stabstr_secname = (char *) xmalloc (strlen (stab_secname) + 4);
 434       strcpy (stabstr_secname, stab_secname);
 435       strcat (stabstr_secname, "str");
 436       if (saved_secname)
 437         {
 438           free (saved_secname);
 439           free (saved_strsecname);
 440         }
 441       saved_secname = stab_secname;
 442       saved_strsecname = stabstr_secname;
 443     }
 444   s_stab_generic (what, saved_secname, saved_strsecname);
 445 }
 446
 447 #ifdef S_SET_DESC
 448
 449 /* Frob invented at RMS' request. Set the n_desc of a symbol.  */
 450
 451 void
 452 s_desc (ignore)
 453      int ignore ATTRIBUTE_UNUSED;
 454 {
 455   char *name;
 456   char c;
 457   char *p;
 458   symbolS *symbolP;
 459   int temp;
 460
 461   name = input_line_pointer;
 462   c = get_symbol_end ();
 463   p = input_line_pointer;
 464   *p = c;
 465   SKIP_WHITESPACE ();
 466   if (*input_line_pointer != ',')
 467     {
 468       *p = 0;
 469       as_bad (_("expected comma after \"%s\""), name);
 470       *p = c;
 471       ignore_rest_of_line ();
 472     }
 473   else
 474     {
 475       input_line_pointer++;
 476       temp = get_absolute_expression ();
 477       *p = 0;
 478       symbolP = symbol_find_or_make (name);
 479       *p = c;
 480       S_SET_DESC (symbolP, temp);
 481     }
 482   demand_empty_rest_of_line ();
 483 }                               /* s_desc() */
 484
 485 #endif /* defined (S_SET_DESC) */
 486
 487 /* Generate stabs debugging information to denote the main source file.  */
 488
 489 void
 490 stabs_generate_asm_file (void)
 491 {
 492   char *file;
 493   unsigned int lineno;
 494
 495   as_where (&file, &lineno);
 496   if (use_gnu_debug_info_extensions)
 497     {
 498       const char *dir;
 499       char *dir2;
 500
 501       dir = remap_debug_filename (getpwd ());
 502       dir2 = (char *) alloca (strlen (dir) + 2);
 503       sprintf (dir2, "%s%s", dir, "/");
 504       generate_asm_file (N_SO, dir2);
 505       xfree ((char *) dir);
 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 *file_endp = file + strlen (file);
 523   char *bufp;
 524
 525   if (last_file != NULL
 526       && filename_cmp (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 = (char *) xmalloc (2 * strlen (file) + strlen (sym) + 12);
 542
 543   *bufp++ = '"';
 544
 545   while (tmp < file_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            && filename_cmp (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 (filename_cmp (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   if (asprintf (&buf, "\"%s:F1\",%d,0,%d,%s",
 675                 funcname, N_FUN, lineno + 1, startlabname) == -1)
 676     as_fatal ("%s", xstrerror (errno));
 677   input_line_pointer = buf;
 678   s_stab ('s');
 679   free (buf);
 680
 681   input_line_pointer = hold;
 682   current_function_label = xstrdup (startlabname);
 683   in_dot_func_p = 1;
 684 }
 685
 686 /* Emit a stab to record the end of a function.  */
 687
 688 void
 689 stabs_generate_asm_endfunc (const char *funcname ATTRIBUTE_UNUSED,
 690                             const char *startlabname)
 691 {
 692   static int label_count;
 693   char *hold = input_line_pointer;
 694   char *buf;
 695   char sym[30];
 696
 697   sprintf (sym, "%sendfunc%d", FAKE_LABEL_NAME, label_count);
 698   ++label_count;
 699   colon (sym);
 700
 701   if (asprintf (&buf, "\"\",%d,0,0,%s-%s", N_FUN, sym, startlabname) == -1)
 702     as_fatal ("%s", xstrerror (errno));
 703   input_line_pointer = buf;
 704   s_stab ('s');
 705   free (buf);
 706
 707   input_line_pointer = hold;
 708   in_dot_func_p = 0;
 709   current_function_label = NULL;
 710 }