gas/stabs.c

   1 /* Generic stabs parsing for gas.
   2    Copyright (C) 1989-2019 Free Software Foundation, Inc.
   3
   4    This file is part of GAS, the GNU Assembler.
   5
   6    GAS is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as
   8    published by the Free Software Foundation; either version 3,
   9    or (at your option) any later version.
  10
  11    GAS is distributed in the hope that it will be useful, but
  12    WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  14    the GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with GAS; see the file COPYING.  If not, write to the Free
  18    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
  19    02110-1301, USA.  */
  20
  21 #include "as.h"
  22 #include "filenames.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 generate_asm_file (int, const char *);
  38
  39 /* Allow backends to override the names used for the stab sections.  */
  40 #ifndef STAB_SECTION_NAME
  41 #define STAB_SECTION_NAME ".stab"
  42 #endif
  43
  44 #ifndef STAB_STRING_SECTION_NAME
  45 #define STAB_STRING_SECTION_NAME ".stabstr"
  46 #endif
  47
  48 /* True if we're in the middle of a .func function, in which case
  49    stabs_generate_asm_lineno emits function relative line number stabs.
  50    Otherwise it emits line number stabs with absolute addresses.  Note that
  51    both cases only apply to assembler code assembled with -gstabs.  */
  52 static bfd_boolean in_dot_func_p = FALSE;
  53
  54 /* Label at start of current function if in_dot_func_p != FALSE.  */
  55 static const char *current_function_label;
  56
  57 /*
  58  * Handle .stabX directives, which used to be open-coded.
  59  * So much creeping featurism overloaded the semantics that we decided
  60  * to put all .stabX thinking in one place. Here.
  61  *
  62  * We try to make any .stabX directive legal. Other people's AS will often
  63  * do assembly-time consistency checks: eg assigning meaning to n_type bits
  64  * and "protecting" you from setting them to certain values. (They also zero
  65  * certain bits before emitting symbols. Tut tut.)
  66  *
  67  * If an expression is not absolute we either gripe or use the relocation
  68  * information. Other people's assemblers silently forget information they
  69  * don't need and invent information they need that you didn't supply.
  70  */
  71
  72 /*
  73  * Build a string dictionary entry for a .stabX symbol.
  74  * The symbol is added to the .<secname>str section.
  75  */
  76
  77 #ifndef SEPARATE_STAB_SECTIONS
  78 #define SEPARATE_STAB_SECTIONS 0
  79 #endif
  80
  81 unsigned int
  82 get_stab_string_offset (const char *string, const char *stabstr_secname,
  83                         bfd_boolean free_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, if it doesn't already exist.  */
 101   seg = subseg_new (stabstr_secname, 0);
 102   if (free_stabstr_secname && seg->name != stabstr_secname)
 103     free ((char *) stabstr_secname);
 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       bfd_set_section_flags (seg, SEC_READONLY | SEC_DEBUGGING);
 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 (int what, const char *string, int type, int other, int desc)
 138 {
 139   /* Put the stab information in the symbol table.  */
 140   symbolS *symbol;
 141
 142   /* Create the symbol now, but only insert it into the symbol chain
 143      after any symbols mentioned in the value expression get into the
 144      symbol chain.  This is to avoid "continuation symbols" (where one
 145      ends in "\" and the debug info is continued in the next .stabs
 146      directive) from being separated by other random symbols.  */
 147   symbol = symbol_create (string, undefined_section, 0,
 148                           &zero_address_frag);
 149   if (what == 's' || what == 'n')
 150     {
 151       /* Pick up the value from the input line.  */
 152       pseudo_set (symbol);
 153     }
 154   else
 155     {
 156       /* .stabd sets the name to NULL.  Why?  */
 157       S_SET_NAME (symbol, NULL);
 158       symbol_set_frag (symbol, frag_now);
 159       S_SET_VALUE (symbol, (valueT) frag_now_fix ());
 160     }
 161
 162   symbol_append (symbol, symbol_lastP, &symbol_rootP, &symbol_lastP);
 163
 164   symbol_get_bfdsym (symbol)->flags |= BSF_DEBUGGING;
 165
 166   S_SET_TYPE (symbol, type);
 167   S_SET_OTHER (symbol, other);
 168   S_SET_DESC (symbol, desc);
 169 }
 170 #endif
 171
 172 /* This can handle different kinds of stabs (s,n,d) and different
 173    kinds of stab sections.  If STAB_SECNAME_OBSTACK_END is non-NULL,
 174    then STAB_SECNAME and STABSTR_SECNAME will be freed if possible
 175    before this function returns (the former by obstack_free).  */
 176
 177 static void
 178 s_stab_generic (int what,
 179                 const char *stab_secname,
 180                 const char *stabstr_secname,
 181                 const char *stab_secname_obstack_end)
 182 {
 183   long longint;
 184   const char *string;
 185   char *saved_string_obstack_end;
 186   int type;
 187   int other;
 188   int desc;
 189
 190   /* The general format is:
 191      .stabs "STRING",TYPE,OTHER,DESC,VALUE
 192      .stabn TYPE,OTHER,DESC,VALUE
 193      .stabd TYPE,OTHER,DESC
 194      At this point input_line_pointer points after the pseudo-op and
 195      any trailing whitespace.  The argument what is one of 's', 'n' or
 196      'd' indicating which type of .stab this is.  */
 197
 198   if (what != 's')
 199     {
 200       string = "";
 201       saved_string_obstack_end = 0;
 202     }
 203   else
 204     {
 205       int length;
 206
 207       string = demand_copy_C_string (&length);
 208       if (string == NULL)
 209         {
 210           as_warn (_(".stab%c: missing string"), what);
 211           ignore_rest_of_line ();
 212           return;
 213         }
 214       /* FIXME: We should probably find some other temporary storage
 215          for string, rather than leaking memory if someone else
 216          happens to use the notes obstack.  */
 217       saved_string_obstack_end = obstack_next_free (&notes);
 218       SKIP_WHITESPACE ();
 219       if (*input_line_pointer == ',')
 220         input_line_pointer++;
 221       else
 222         {
 223           as_warn (_(".stab%c: missing comma"), what);
 224           ignore_rest_of_line ();
 225           return;
 226         }
 227     }
 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   type = longint;
 236
 237   if (get_absolute_expression_and_terminator (&longint) != ',')
 238     {
 239       as_warn (_(".stab%c: missing comma"), what);
 240       ignore_rest_of_line ();
 241       return;
 242     }
 243   other = longint;
 244
 245   desc = get_absolute_expression ();
 246
 247   if ((desc > 0xffff) || (desc < -0x8000))
 248     /* This could happen for example with a source file with a huge
 249        number of lines.  The only cure is to use a different debug
 250        format, probably DWARF.  */
 251     as_warn (_(".stab%c: description field '%x' too big, try a different debug format"),
 252              what, desc);
 253
 254   if (what == 's' || what == 'n')
 255     {
 256       if (*input_line_pointer != ',')
 257         {
 258           as_warn (_(".stab%c: missing comma"), what);
 259           ignore_rest_of_line ();
 260           return;
 261         }
 262       input_line_pointer++;
 263       SKIP_WHITESPACE ();
 264     }
 265
 266 #ifdef TC_PPC
 267 #ifdef OBJ_ELF
 268   /* Solaris on PowerPC has decided that .stabd can take 4 arguments, so if we were
 269      given 4 arguments, make it a .stabn */
 270   else if (what == 'd')
 271     {
 272       char *save_location = input_line_pointer;
 273
 274       SKIP_WHITESPACE ();
 275       if (*input_line_pointer == ',')
 276         {
 277           input_line_pointer++;
 278           what = 'n';
 279         }
 280       else
 281         input_line_pointer = save_location;
 282     }
 283 #endif /* OBJ_ELF */
 284 #endif /* TC_PPC */
 285
 286 #ifndef NO_LISTING
 287   if (listing)
 288     {
 289       switch (type)
 290         {
 291         case N_SLINE:
 292           listing_source_line ((unsigned int) desc);
 293           break;
 294         case N_SO:
 295         case N_SOL:
 296           listing_source_file (string);
 297           break;
 298         }
 299     }
 300 #endif /* ! NO_LISTING */
 301
 302   /* We have now gathered the type, other, and desc information.  For
 303      .stabs or .stabn, input_line_pointer is now pointing at the
 304      value.  */
 305
 306   if (SEPARATE_STAB_SECTIONS)
 307     /* Output the stab information in a separate section.  This is used
 308        at least for COFF and ELF.  */
 309     {
 310       segT saved_seg = now_seg;
 311       subsegT saved_subseg = now_subseg;
 312       fragS *saved_frag = frag_now;
 313       valueT dot;
 314       segT seg;
 315       unsigned int stroff;
 316       char *p;
 317
 318       static segT cached_sec;
 319
 320       dot = frag_now_fix ();
 321
 322 #ifdef md_flush_pending_output
 323       md_flush_pending_output ();
 324 #endif
 325
 326       if (cached_sec && strcmp (cached_sec->name, stab_secname) == 0)
 327         {
 328           seg = cached_sec;
 329           subseg_set (seg, 0);
 330         }
 331       else
 332         {
 333           seg = subseg_new (stab_secname, 0);
 334           cached_sec = seg;
 335         }
 336
 337       if (! seg_info (seg)->hadone)
 338         {
 339           bfd_set_section_flags (seg,
 340                                  SEC_READONLY | SEC_RELOC | SEC_DEBUGGING);
 341 #ifdef INIT_STAB_SECTION
 342           INIT_STAB_SECTION (seg);
 343 #endif
 344           seg_info (seg)->hadone = 1;
 345         }
 346
 347       stroff = get_stab_string_offset (string, stabstr_secname,
 348                                        stab_secname_obstack_end != NULL);
 349
 350       /* Release the string, if nobody else has used the obstack.  */
 351       if (saved_string_obstack_end != NULL
 352           && saved_string_obstack_end == obstack_next_free (&notes))
 353         obstack_free (&notes, string);
 354       /* Similarly for the section name.  This must be done before
 355          creating symbols below, which uses the notes obstack.  */
 356       if (seg->name != stab_secname
 357           && stab_secname_obstack_end != NULL
 358           && stab_secname_obstack_end == obstack_next_free (&notes))
 359         obstack_free (&notes, stab_secname);
 360
 361       /* At least for now, stabs in a special stab section are always
 362          output as 12 byte blocks of information.  */
 363       p = frag_more (8);
 364       md_number_to_chars (p, (valueT) stroff, 4);
 365       md_number_to_chars (p + 4, (valueT) type, 1);
 366       md_number_to_chars (p + 5, (valueT) other, 1);
 367       md_number_to_chars (p + 6, (valueT) desc, 2);
 368
 369       if (what == 's' || what == 'n')
 370         {
 371           /* Pick up the value from the input line.  */
 372           cons (4);
 373           input_line_pointer--;
 374         }
 375       else
 376         {
 377           symbolS *symbol;
 378           expressionS exp;
 379
 380           /* Arrange for a value representing the current location.  */
 381           symbol = symbol_temp_new (saved_seg, dot, saved_frag);
 382
 383           exp.X_op = O_symbol;
 384           exp.X_add_symbol = symbol;
 385           exp.X_add_number = 0;
 386
 387           emit_expr (&exp, 4);
 388         }
 389
 390 #ifdef OBJ_PROCESS_STAB
 391       OBJ_PROCESS_STAB (seg, what, string, type, other, desc);
 392 #endif
 393
 394       subseg_set (saved_seg, saved_subseg);
 395     }
 396   else
 397     {
 398       if (stab_secname_obstack_end != NULL)
 399         {
 400           free ((char *) stabstr_secname);
 401           if (stab_secname_obstack_end == obstack_next_free (&notes))
 402             obstack_free (&notes, stab_secname);
 403         }
 404 #ifdef OBJ_PROCESS_STAB
 405       OBJ_PROCESS_STAB (0, what, string, type, other, desc);
 406 #else
 407       abort ();
 408 #endif
 409     }
 410
 411   demand_empty_rest_of_line ();
 412 }
 413
 414 /* Regular stab directive.  */
 415
 416 void
 417 s_stab (int what)
 418 {
 419   s_stab_generic (what, STAB_SECTION_NAME, STAB_STRING_SECTION_NAME, NULL);
 420 }
 421
 422 /* "Extended stabs", used in Solaris only now.  */
 423
 424 void
 425 s_xstab (int what)
 426 {
 427   int length;
 428   char *stab_secname, *stabstr_secname, *stab_secname_obstack_end;
 429
 430   stab_secname = demand_copy_C_string (&length);
 431   stab_secname_obstack_end = obstack_next_free (&notes);
 432   SKIP_WHITESPACE ();
 433   if (*input_line_pointer == ',')
 434     input_line_pointer++;
 435   else
 436     {
 437       as_bad (_("comma missing in .xstabs"));
 438       ignore_rest_of_line ();
 439       return;
 440     }
 441
 442   /* To get the name of the stab string section, simply add "str" to
 443      the stab section name.  */
 444   stabstr_secname = concat (stab_secname, "str", (char *) NULL);
 445   s_stab_generic (what, stab_secname, stabstr_secname,
 446                   stab_secname_obstack_end);
 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 (int ignore ATTRIBUTE_UNUSED)
 455 {
 456   char *name;
 457   char c;
 458   char *p;
 459   symbolS *symbolP;
 460   int temp;
 461
 462   c = get_symbol_name (&name);
 463   p = input_line_pointer;
 464   *p = c;
 465   SKIP_WHITESPACE_AFTER_NAME ();
 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   const char *file;
 493   unsigned int lineno;
 494
 495   file = as_where (&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 = concat (dir, "/", NULL);
 503       generate_asm_file (N_SO, dir2);
 504       free (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, const char *file)
 515 {
 516   static char *last_file;
 517   static int label_count;
 518   char sym[30];
 519   char *buf;
 520   const char *tmp = file;
 521   const char *file_endp = file + strlen (file);
 522   char *bufp;
 523
 524   if (last_file != NULL
 525       && filename_cmp (last_file, file) == 0)
 526     return;
 527
 528   /* Rather than try to do this in some efficient fashion, we just
 529      generate a string and then parse it again.  That lets us use the
 530      existing stabs hook, which expect to see a string, rather than
 531      inventing new ones.  */
 532   sprintf (sym, "%sF%d", FAKE_LABEL_NAME, label_count);
 533   ++label_count;
 534
 535   /* Allocate enough space for the file name (possibly extended with
 536      doubled up backslashes), the symbol name, and the other characters
 537      that make up a stabs file directive.  */
 538   bufp = buf = XNEWVEC (char, 2 * strlen (file) + strlen (sym) + 12);
 539
 540   *bufp++ = '"';
 541
 542   while (tmp < file_endp)
 543     {
 544       const char *bslash = strchr (tmp, '\\');
 545       size_t len = bslash != NULL ? bslash - tmp + 1 : file_endp - tmp;
 546
 547       /* Double all backslashes, since demand_copy_C_string (used by
 548          s_stab to extract the part in quotes) will try to replace them as
 549          escape sequences.  backslash may appear in a filespec.  */
 550       memcpy (bufp, tmp, len);
 551
 552       tmp += len;
 553       bufp += len;
 554
 555       if (bslash != NULL)
 556         *bufp++ = '\\';
 557     }
 558
 559   sprintf (bufp, "\",%d,0,0,%s\n", type, sym);
 560
 561   temp_ilp (buf);
 562   s_stab ('s');
 563   restore_ilp ();
 564
 565   colon (sym);
 566
 567   if (last_file != NULL)
 568     free (last_file);
 569   last_file = xstrdup (file);
 570
 571   free (buf);
 572 }
 573
 574 /* Generate stabs debugging information for the current line.  This is
 575    used to produce debugging information for an assembler file.  */
 576
 577 void
 578 stabs_generate_asm_lineno (void)
 579 {
 580   static int label_count;
 581   const char *file;
 582   unsigned int lineno;
 583   char *buf;
 584   char sym[30];
 585   /* Remember the last file/line and avoid duplicates.  */
 586   static unsigned int prev_lineno = -1;
 587   static char *prev_file = NULL;
 588
 589   /* Rather than try to do this in some efficient fashion, we just
 590      generate a string and then parse it again.  That lets us use the
 591      existing stabs hook, which expect to see a string, rather than
 592      inventing new ones.  */
 593
 594   file = as_where (&lineno);
 595
 596   /* Don't emit sequences of stabs for the same line.  */
 597   if (prev_file == NULL)
 598     {
 599       /* First time through.  */
 600       prev_file = xstrdup (file);
 601       prev_lineno = lineno;
 602     }
 603   else if (lineno == prev_lineno
 604            && filename_cmp (file, prev_file) == 0)
 605     {
 606       /* Same file/line as last time.  */
 607       return;
 608     }
 609   else
 610     {
 611       /* Remember file/line for next time.  */
 612       prev_lineno = lineno;
 613       if (filename_cmp (file, prev_file) != 0)
 614         {
 615           free (prev_file);
 616           prev_file = xstrdup (file);
 617         }
 618     }
 619
 620   /* Let the world know that we are in the middle of generating a
 621      piece of stabs line debugging information.  */
 622   outputting_stabs_line_debug = 1;
 623
 624   generate_asm_file (N_SOL, file);
 625
 626   sprintf (sym, "%sL%d", FAKE_LABEL_NAME, label_count);
 627   ++label_count;
 628
 629   if (in_dot_func_p)
 630     {
 631       buf = XNEWVEC (char, 100 + strlen (current_function_label));
 632       sprintf (buf, "%d,0,%d,%s-%s\n", N_SLINE, lineno,
 633                sym, current_function_label);
 634     }
 635   else
 636     {
 637       buf = XNEWVEC (char, 100);
 638       sprintf (buf, "%d,0,%d,%s\n", N_SLINE, lineno, sym);
 639     }
 640
 641   temp_ilp (buf);
 642   s_stab ('n');
 643   restore_ilp ();
 644
 645   colon (sym);
 646
 647   outputting_stabs_line_debug = 0;
 648   free (buf);
 649 }
 650
 651 /* Emit a function stab.
 652    All assembler functions are assumed to have return type `void'.  */
 653
 654 void
 655 stabs_generate_asm_func (const char *funcname, const char *startlabname)
 656 {
 657   static bfd_boolean void_emitted_p = FALSE;
 658   char *buf;
 659   unsigned int lineno;
 660
 661   if (! void_emitted_p)
 662     {
 663       temp_ilp ((char *) "\"void:t1=1\",128,0,0,0");
 664       s_stab ('s');
 665       restore_ilp ();
 666       void_emitted_p = TRUE;
 667     }
 668
 669   as_where (&lineno);
 670   if (asprintf (&buf, "\"%s:F1\",%d,0,%d,%s",
 671                 funcname, N_FUN, lineno + 1, startlabname) == -1)
 672     as_fatal ("%s", xstrerror (errno));
 673
 674   temp_ilp (buf);
 675   s_stab ('s');
 676   restore_ilp ();
 677   free (buf);
 678
 679   current_function_label = xstrdup (startlabname);
 680   in_dot_func_p = TRUE;
 681 }
 682
 683 /* Emit a stab to record the end of a function.  */
 684
 685 void
 686 stabs_generate_asm_endfunc (const char *funcname ATTRIBUTE_UNUSED,
 687                             const char *startlabname)
 688 {
 689   static int label_count;
 690   char *buf;
 691   char sym[30];
 692
 693   sprintf (sym, "%sendfunc%d", FAKE_LABEL_NAME, label_count);
 694   ++label_count;
 695   colon (sym);
 696
 697   if (asprintf (&buf, "\"\",%d,0,0,%s-%s", N_FUN, sym, startlabname) == -1)
 698     as_fatal ("%s", xstrerror (errno));
 699
 700   temp_ilp (buf);
 701   s_stab ('s');
 702   restore_ilp ();
 703   free (buf);
 704
 705   in_dot_func_p = FALSE;
 706   current_function_label = NULL;
 707 }