gas/stabs.c

   1 /* Generic stabs parsing for gas.
   2    Copyright 1989, 1990, 1991, 1993, 1995, 1996, 1997, 1998, 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
   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 PARAMS ((int, char *, char *));
  38 static void generate_asm_file PARAMS ((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 (string, stabstr_secname)
  84      const char *string;
  85      const char *stabstr_secname;
  86 {
  87   unsigned int length;
  88   unsigned int retval;
  89   segT save_seg;
  90   subsegT save_subseg;
  91   segT seg;
  92   char *p;
  93
  94   if (! SEPARATE_STAB_SECTIONS)
  95     abort ();
  96
  97   length = strlen (string);
  98
  99   save_seg = now_seg;
 100   save_subseg = now_subseg;
 101
 102   /* Create the stab string section.  */
 103   seg = subseg_new (stabstr_secname, 0);
 104
 105   retval = seg_info (seg)->stabu.stab_string_size;
 106   if (retval <= 0)
 107     {
 108       /* Make sure the first string is empty.  */
 109       p = frag_more (1);
 110       *p = 0;
 111       retval = seg_info (seg)->stabu.stab_string_size = 1;
 112 #ifdef BFD_ASSEMBLER
 113       bfd_set_section_flags (stdoutput, seg, SEC_READONLY | SEC_DEBUGGING);
 114       if (seg->name == stabstr_secname)
 115         seg->name = xstrdup (stabstr_secname);
 116 #endif
 117     }
 118
 119   if (length > 0)
 120     {                           /* Ordinary case.  */
 121       p = frag_more (length + 1);
 122       strcpy (p, string);
 123
 124       seg_info (seg)->stabu.stab_string_size += length + 1;
 125     }
 126   else
 127     retval = 0;
 128
 129   subseg_set (save_seg, save_subseg);
 130
 131   return retval;
 132 }
 133
 134 #ifdef AOUT_STABS
 135 #ifndef OBJ_PROCESS_STAB
 136 #define OBJ_PROCESS_STAB(SEG,W,S,T,O,D) aout_process_stab(W,S,T,O,D)
 137 #endif
 138
 139 /* Here instead of obj-aout.c because other formats use it too.  */
 140 void
 141 aout_process_stab (what, string, type, other, desc)
 142      int what;
 143      const char *string;
 144      int type, other, desc;
 145 {
 146   /* Put the stab information in the symbol table.  */
 147   symbolS *symbol;
 148
 149   /* Create the symbol now, but only insert it into the symbol chain
 150      after any symbols mentioned in the value expression get into the
 151      symbol chain.  This is to avoid "continuation symbols" (where one
 152      ends in "\" and the debug info is continued in the next .stabs
 153      directive) from being separated by other random symbols.  */
 154   symbol = symbol_create (string, undefined_section, 0,
 155                           (struct frag *) NULL);
 156   if (what == 's' || what == 'n')
 157     {
 158       /* Pick up the value from the input line.  */
 159       symbol_set_frag (symbol, &zero_address_frag);
 160       pseudo_set (symbol);
 161     }
 162   else
 163     {
 164       /* .stabd sets the name to NULL.  Why?  */
 165       S_SET_NAME (symbol, NULL);
 166       symbol_set_frag (symbol, frag_now);
 167       S_SET_VALUE (symbol, (valueT) frag_now_fix ());
 168     }
 169
 170   symbol_append (symbol, symbol_lastP, &symbol_rootP, &symbol_lastP);
 171
 172   S_SET_TYPE (symbol, type);
 173   S_SET_OTHER (symbol, other);
 174   S_SET_DESC (symbol, desc);
 175 }
 176 #endif
 177
 178 /* This can handle different kinds of stabs (s,n,d) and different
 179    kinds of stab sections.  */
 180
 181 static void
 182 s_stab_generic (what, stab_secname, stabstr_secname)
 183      int what;
 184      char *stab_secname;
 185      char *stabstr_secname;
 186 {
 187   long longint;
 188   char *string, *saved_string_obstack_end;
 189   int type;
 190   int other;
 191   int desc;
 192
 193   /* The general format is:
 194      .stabs "STRING",TYPE,OTHER,DESC,VALUE
 195      .stabn TYPE,OTHER,DESC,VALUE
 196      .stabd TYPE,OTHER,DESC
 197      At this point input_line_pointer points after the pseudo-op and
 198      any trailing whitespace.  The argument what is one of 's', 'n' or
 199      'd' indicating which type of .stab this is.  */
 200
 201   if (what != 's')
 202     {
 203       string = "";
 204       saved_string_obstack_end = 0;
 205     }
 206   else
 207     {
 208       int length;
 209
 210       string = demand_copy_C_string (&length);
 211       /* FIXME: We should probably find some other temporary storage
 212          for string, rather than leaking memory if someone else
 213          happens to use the notes obstack.  */
 214       saved_string_obstack_end = notes.next_free;
 215       SKIP_WHITESPACE ();
 216       if (*input_line_pointer == ',')
 217         input_line_pointer++;
 218       else
 219         {
 220           as_warn (_(".stab%c: missing comma"), what);
 221           ignore_rest_of_line ();
 222           return;
 223         }
 224     }
 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   type = longint;
 233
 234   if (get_absolute_expression_and_terminator (&longint) != ',')
 235     {
 236       as_warn (_(".stab%c: missing comma"), what);
 237       ignore_rest_of_line ();
 238       return;
 239     }
 240   other = longint;
 241
 242   desc = get_absolute_expression ();
 243
 244   if ((desc > 0xffff) || (desc < -0x8000))
 245     /* This could happen for example with a source file with a huge
 246        number of lines.  The only cure is to use a different debug
 247        format, probably DWARF.  */
 248     as_warn (_(".stab%c: description field '%x' too big, try a different debug format"),
 249              what, desc);
 250
 251   if (what == 's' || what == 'n')
 252     {
 253       if (*input_line_pointer != ',')
 254         {
 255           as_warn (_(".stab%c: missing comma"), what);
 256           ignore_rest_of_line ();
 257           return;
 258         }
 259       input_line_pointer++;
 260       SKIP_WHITESPACE ();
 261     }
 262
 263 #ifdef TC_PPC
 264 #ifdef OBJ_ELF
 265   /* Solaris on PowerPC has decided that .stabd can take 4 arguments, so if we were
 266      given 4 arguments, make it a .stabn */
 267   else if (what == 'd')
 268     {
 269       char *save_location = input_line_pointer;
 270
 271       SKIP_WHITESPACE ();
 272       if (*input_line_pointer == ',')
 273         {
 274           input_line_pointer++;
 275           what = 'n';
 276         }
 277       else
 278         input_line_pointer = save_location;
 279     }
 280 #endif /* OBJ_ELF */
 281 #endif /* TC_PPC */
 282
 283 #ifndef NO_LISTING
 284   if (listing)
 285     {
 286       switch (type)
 287         {
 288         case N_SLINE:
 289           listing_source_line ((unsigned int) desc);
 290           break;
 291         case N_SO:
 292         case N_SOL:
 293           listing_source_file (string);
 294           break;
 295         }
 296     }
 297 #endif /* ! NO_LISTING */
 298
 299   /* We have now gathered the type, other, and desc information.  For
 300      .stabs or .stabn, input_line_pointer is now pointing at the
 301      value.  */
 302
 303   if (SEPARATE_STAB_SECTIONS)
 304     /* Output the stab information in a separate section.  This is used
 305        at least for COFF and ELF.  */
 306     {
 307       segT saved_seg = now_seg;
 308       subsegT saved_subseg = now_subseg;
 309       fragS *saved_frag = frag_now;
 310       valueT dot;
 311       segT seg;
 312       unsigned int stroff;
 313       char *p;
 314
 315       static segT cached_sec;
 316       static char *cached_secname;
 317
 318       dot = frag_now_fix ();
 319
 320 #ifdef md_flush_pending_output
 321       md_flush_pending_output ();
 322 #endif
 323
 324       if (cached_secname && !strcmp (cached_secname, stab_secname))
 325         {
 326           seg = cached_sec;
 327           subseg_set (seg, 0);
 328         }
 329       else
 330         {
 331           seg = subseg_new (stab_secname, 0);
 332           if (cached_secname)
 333             free (cached_secname);
 334           cached_secname = xstrdup (stab_secname);
 335           cached_sec = seg;
 336         }
 337
 338       if (! seg_info (seg)->hadone)
 339         {
 340 #ifdef BFD_ASSEMBLER
 341           bfd_set_section_flags (stdoutput, seg,
 342                                  SEC_READONLY | SEC_RELOC | SEC_DEBUGGING);
 343 #endif
 344 #ifdef INIT_STAB_SECTION
 345           INIT_STAB_SECTION (seg);
 346 #endif
 347           seg_info (seg)->hadone = 1;
 348         }
 349
 350       stroff = get_stab_string_offset (string, stabstr_secname);
 351       if (what == 's')
 352         {
 353           /* Release the string, if nobody else has used the obstack.  */
 354           if (saved_string_obstack_end == notes.next_free)
 355             obstack_free (&notes, string);
 356         }
 357
 358       /* At least for now, stabs in a special stab section are always
 359          output as 12 byte blocks of information.  */
 360       p = frag_more (8);
 361       md_number_to_chars (p, (valueT) stroff, 4);
 362       md_number_to_chars (p + 4, (valueT) type, 1);
 363       md_number_to_chars (p + 5, (valueT) other, 1);
 364       md_number_to_chars (p + 6, (valueT) desc, 2);
 365
 366       if (what == 's' || what == 'n')
 367         {
 368           /* Pick up the value from the input line.  */
 369           cons (4);
 370           input_line_pointer--;
 371         }
 372       else
 373         {
 374           symbolS *symbol;
 375           expressionS exp;
 376
 377           /* Arrange for a value representing the current location.  */
 378           symbol = symbol_temp_new (saved_seg, dot, saved_frag);
 379
 380           exp.X_op = O_symbol;
 381           exp.X_add_symbol = symbol;
 382           exp.X_add_number = 0;
 383
 384           emit_expr (&exp, 4);
 385         }
 386
 387 #ifdef OBJ_PROCESS_STAB
 388       OBJ_PROCESS_STAB (seg, what, string, type, other, desc);
 389 #endif
 390
 391       subseg_set (saved_seg, saved_subseg);
 392     }
 393   else
 394     {
 395 #ifdef OBJ_PROCESS_STAB
 396       OBJ_PROCESS_STAB (0, what, string, type, other, desc);
 397 #else
 398       abort ();
 399 #endif
 400     }
 401
 402   demand_empty_rest_of_line ();
 403 }
 404
 405 /* Regular stab directive.  */
 406
 407 void
 408 s_stab (what)
 409      int what;
 410 {
 411   s_stab_generic (what, STAB_SECTION_NAME, STAB_STRING_SECTION_NAME);
 412 }
 413
 414 /* "Extended stabs", used in Solaris only now.  */
 415
 416 void
 417 s_xstab (what)
 418      int what;
 419 {
 420   int length;
 421   char *stab_secname, *stabstr_secname;
 422   static char *saved_secname, *saved_strsecname;
 423
 424   /* @@ MEMORY LEAK: This allocates a copy of the string, but in most
 425      cases it will be the same string, so we could release the storage
 426      back to the obstack it came from.  */
 427   stab_secname = demand_copy_C_string (&length);
 428   SKIP_WHITESPACE ();
 429   if (*input_line_pointer == ',')
 430     input_line_pointer++;
 431   else
 432     {
 433       as_bad (_("comma missing in .xstabs"));
 434       ignore_rest_of_line ();
 435       return;
 436     }
 437
 438   /* To get the name of the stab string section, simply add "str" to
 439      the stab section name.  */
 440   if (saved_secname == 0 || strcmp (saved_secname, stab_secname))
 441     {
 442       stabstr_secname = (char *) xmalloc (strlen (stab_secname) + 4);
 443       strcpy (stabstr_secname, stab_secname);
 444       strcat (stabstr_secname, "str");
 445       if (saved_secname)
 446         {
 447           free (saved_secname);
 448           free (saved_strsecname);
 449         }
 450       saved_secname = stab_secname;
 451       saved_strsecname = stabstr_secname;
 452     }
 453   s_stab_generic (what, saved_secname, saved_strsecname);
 454 }
 455
 456 #ifdef S_SET_DESC
 457
 458 /* Frob invented at RMS' request. Set the n_desc of a symbol.  */
 459
 460 void
 461 s_desc (ignore)
 462      int ignore ATTRIBUTE_UNUSED;
 463 {
 464   char *name;
 465   char c;
 466   char *p;
 467   symbolS *symbolP;
 468   int temp;
 469
 470   name = input_line_pointer;
 471   c = get_symbol_end ();
 472   p = input_line_pointer;
 473   *p = c;
 474   SKIP_WHITESPACE ();
 475   if (*input_line_pointer != ',')
 476     {
 477       *p = 0;
 478       as_bad (_("expected comma after \"%s\""), name);
 479       *p = c;
 480       ignore_rest_of_line ();
 481     }
 482   else
 483     {
 484       input_line_pointer++;
 485       temp = get_absolute_expression ();
 486       *p = 0;
 487       symbolP = symbol_find_or_make (name);
 488       *p = c;
 489       S_SET_DESC (symbolP, temp);
 490     }
 491   demand_empty_rest_of_line ();
 492 }                               /* s_desc() */
 493
 494 #endif /* defined (S_SET_DESC) */
 495
 496 /* Generate stabs debugging information to denote the main source file.  */
 497
 498 void
 499 stabs_generate_asm_file ()
 500 {
 501   char *file;
 502   unsigned int lineno;
 503
 504   as_where (&file, &lineno);
 505   if (use_gnu_debug_info_extensions)
 506     {
 507       char *dir, *dir2;
 508
 509       dir = getpwd ();
 510       dir2 = alloca (strlen (dir) + 2);
 511       sprintf (dir2, "%s%s", dir, "/");
 512       generate_asm_file (N_SO, dir2);
 513     }
 514   generate_asm_file (N_SO, file);
 515 }
 516
 517 /* Generate stabs debugging information to denote the source file.
 518    TYPE is one of N_SO, N_SOL.  */
 519
 520 static void
 521 generate_asm_file (type, file)
 522      int type;
 523      char *file;
 524 {
 525   static char *last_file;
 526   static int label_count;
 527   char *hold;
 528   char sym[30];
 529   char *buf;
 530   char *tmp = file;
 531   char *endp = file + strlen (file);
 532   char *bufp = buf;
 533
 534   if (last_file != NULL
 535       && strcmp (last_file, file) == 0)
 536     return;
 537
 538   /* Rather than try to do this in some efficient fashion, we just
 539      generate a string and then parse it again.  That lets us use the
 540      existing stabs hook, which expect to see a string, rather than
 541      inventing new ones.  */
 542   hold = input_line_pointer;
 543
 544   sprintf (sym, "%sF%d", FAKE_LABEL_NAME, label_count);
 545   ++label_count;
 546
 547   /* Allocate enough space for the file name (possibly extended with
 548      doubled up backslashes), the symbol name, and the other characters
 549      that make up a stabs file directive.  */
 550   bufp = buf = xmalloc (2 * strlen (file) + strlen (sym) + 12);
 551
 552   *bufp++ = '"';
 553
 554   while (tmp < endp)
 555     {
 556       char *bslash = strchr (tmp, '\\');
 557       size_t len = (bslash) ? (size_t) (bslash - tmp + 1) : strlen (tmp);
 558
 559       /* Double all backslashes, since demand_copy_C_string (used by
 560          s_stab to extract the part in quotes) will try to replace them as
 561          escape sequences.  backslash may appear in a filespec.  */
 562       strncpy (bufp, tmp, len);
 563
 564       tmp += len;
 565       bufp += len;
 566
 567       if (bslash != NULL)
 568         *bufp++ = '\\';
 569     }
 570
 571   sprintf (bufp, "\",%d,0,0,%s\n", type, sym);
 572
 573   input_line_pointer = buf;
 574   s_stab ('s');
 575   colon (sym);
 576
 577   if (last_file != NULL)
 578     free (last_file);
 579   last_file = xstrdup (file);
 580
 581   free (buf);
 582
 583   input_line_pointer = hold;
 584 }
 585
 586 /* Generate stabs debugging information for the current line.  This is
 587    used to produce debugging information for an assembler file.  */
 588
 589 void
 590 stabs_generate_asm_lineno ()
 591 {
 592   static int label_count;
 593   char *hold;
 594   char *file;
 595   unsigned int lineno;
 596   char *buf;
 597   char sym[30];
 598   /* Remember the last file/line and avoid duplicates.  */
 599   static unsigned int prev_lineno = -1;
 600   static char *prev_file = NULL;
 601
 602   /* Rather than try to do this in some efficient fashion, we just
 603      generate a string and then parse it again.  That lets us use the
 604      existing stabs hook, which expect to see a string, rather than
 605      inventing new ones.  */
 606
 607   hold = input_line_pointer;
 608
 609   as_where (&file, &lineno);
 610
 611   /* Don't emit sequences of stabs for the same line.  */
 612   if (prev_file == NULL)
 613     {
 614       /* First time thru.  */
 615       prev_file = xstrdup (file);
 616       prev_lineno = lineno;
 617     }
 618   else if (lineno == prev_lineno
 619            && strcmp (file, prev_file) == 0)
 620     {
 621       /* Same file/line as last time.  */
 622       return;
 623     }
 624   else
 625     {
 626       /* Remember file/line for next time.  */
 627       prev_lineno = lineno;
 628       if (strcmp (file, prev_file) != 0)
 629         {
 630           free (prev_file);
 631           prev_file = xstrdup (file);
 632         }
 633     }
 634
 635   /* Let the world know that we are in the middle of generating a
 636      piece of stabs line debugging information.  */
 637   outputting_stabs_line_debug = 1;
 638
 639   generate_asm_file (N_SOL, file);
 640
 641   sprintf (sym, "%sL%d", FAKE_LABEL_NAME, label_count);
 642   ++label_count;
 643
 644   if (in_dot_func_p)
 645     {
 646       buf = (char *) alloca (100 + strlen (current_function_label));
 647       sprintf (buf, "%d,0,%d,%s-%s\n", N_SLINE, lineno,
 648                sym, current_function_label);
 649     }
 650   else
 651     {
 652       buf = (char *) alloca (100);
 653       sprintf (buf, "%d,0,%d,%s\n", N_SLINE, lineno, sym);
 654     }
 655   input_line_pointer = buf;
 656   s_stab ('n');
 657   colon (sym);
 658
 659   input_line_pointer = hold;
 660   outputting_stabs_line_debug = 0;
 661 }
 662
 663 /* Emit a function stab.
 664    All assembler functions are assumed to have return type `void'.  */
 665
 666 void
 667 stabs_generate_asm_func (funcname, startlabname)
 668      const char *funcname;
 669      const char *startlabname;
 670 {
 671   static int void_emitted_p;
 672   char *hold = input_line_pointer;
 673   char *buf;
 674   char *file;
 675   unsigned int lineno;
 676
 677   if (! void_emitted_p)
 678     {
 679       input_line_pointer = "\"void:t1=1\",128,0,0,0";
 680       s_stab ('s');
 681       void_emitted_p = 1;
 682     }
 683
 684   as_where (&file, &lineno);
 685   asprintf (&buf, "\"%s:F1\",%d,0,%d,%s",
 686             funcname, N_FUN, lineno + 1, startlabname);
 687   input_line_pointer = buf;
 688   s_stab ('s');
 689   free (buf);
 690
 691   input_line_pointer = hold;
 692   current_function_label = xstrdup (startlabname);
 693   in_dot_func_p = 1;
 694 }
 695
 696 /* Emit a stab to record the end of a function.  */
 697
 698 void
 699 stabs_generate_asm_endfunc (funcname, startlabname)
 700      const char *funcname ATTRIBUTE_UNUSED;
 701      const char *startlabname;
 702 {
 703   static int label_count;
 704   char *hold = input_line_pointer;
 705   char *buf;
 706   char sym[30];
 707
 708   sprintf (sym, "%sendfunc%d", FAKE_LABEL_NAME, label_count);
 709   ++label_count;
 710   colon (sym);
 711
 712   asprintf (&buf, "\"\",%d,0,0,%s-%s", N_FUN, sym, startlabname);
 713   input_line_pointer = buf;
 714   s_stab ('s');
 715   free (buf);
 716
 717   input_line_pointer = hold;
 718   in_dot_func_p = 0;
 719   current_function_label = NULL;
 720 }