gas/stabs.c

   1 /* Generic stabs parsing for gas.
   2    Copyright (C) 1989-2016 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 s_stab_generic (int, const char *, const char *);
  38 static void generate_asm_file (int, const 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 (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.  */
 174
 175 static void
 176 s_stab_generic (int          what,
 177                 const char * stab_secname,
 178                 const char * stabstr_secname)
 179 {
 180   long longint;
 181   const char *string;
 182   char *saved_string_obstack_end;
 183   int type;
 184   int other;
 185   int desc;
 186
 187   /* The general format is:
 188      .stabs "STRING",TYPE,OTHER,DESC,VALUE
 189      .stabn TYPE,OTHER,DESC,VALUE
 190      .stabd TYPE,OTHER,DESC
 191      At this point input_line_pointer points after the pseudo-op and
 192      any trailing whitespace.  The argument what is one of 's', 'n' or
 193      'd' indicating which type of .stab this is.  */
 194
 195   if (what != 's')
 196     {
 197       string = "";
 198       saved_string_obstack_end = 0;
 199     }
 200   else
 201     {
 202       int length;
 203
 204       string = demand_copy_C_string (&length);
 205       /* FIXME: We should probably find some other temporary storage
 206          for string, rather than leaking memory if someone else
 207          happens to use the notes obstack.  */
 208       saved_string_obstack_end = notes.next_free;
 209       SKIP_WHITESPACE ();
 210       if (*input_line_pointer == ',')
 211         input_line_pointer++;
 212       else
 213         {
 214           as_warn (_(".stab%c: missing comma"), what);
 215           ignore_rest_of_line ();
 216           return;
 217         }
 218     }
 219
 220   if (get_absolute_expression_and_terminator (&longint) != ',')
 221     {
 222       as_warn (_(".stab%c: missing comma"), what);
 223       ignore_rest_of_line ();
 224       return;
 225     }
 226   type = longint;
 227
 228   if (get_absolute_expression_and_terminator (&longint) != ',')
 229     {
 230       as_warn (_(".stab%c: missing comma"), what);
 231       ignore_rest_of_line ();
 232       return;
 233     }
 234   other = longint;
 235
 236   desc = get_absolute_expression ();
 237
 238   if ((desc > 0xffff) || (desc < -0x8000))
 239     /* This could happen for example with a source file with a huge
 240        number of lines.  The only cure is to use a different debug
 241        format, probably DWARF.  */
 242     as_warn (_(".stab%c: description field '%x' too big, try a different debug format"),
 243              what, desc);
 244
 245   if (what == 's' || what == 'n')
 246     {
 247       if (*input_line_pointer != ',')
 248         {
 249           as_warn (_(".stab%c: missing comma"), what);
 250           ignore_rest_of_line ();
 251           return;
 252         }
 253       input_line_pointer++;
 254       SKIP_WHITESPACE ();
 255     }
 256
 257 #ifdef TC_PPC
 258 #ifdef OBJ_ELF
 259   /* Solaris on PowerPC has decided that .stabd can take 4 arguments, so if we were
 260      given 4 arguments, make it a .stabn */
 261   else if (what == 'd')
 262     {
 263       char *save_location = input_line_pointer;
 264
 265       SKIP_WHITESPACE ();
 266       if (*input_line_pointer == ',')
 267         {
 268           input_line_pointer++;
 269           what = 'n';
 270         }
 271       else
 272         input_line_pointer = save_location;
 273     }
 274 #endif /* OBJ_ELF */
 275 #endif /* TC_PPC */
 276
 277 #ifndef NO_LISTING
 278   if (listing)
 279     {
 280       switch (type)
 281         {
 282         case N_SLINE:
 283           listing_source_line ((unsigned int) desc);
 284           break;
 285         case N_SO:
 286         case N_SOL:
 287           listing_source_file (string);
 288           break;
 289         }
 290     }
 291 #endif /* ! NO_LISTING */
 292
 293   /* We have now gathered the type, other, and desc information.  For
 294      .stabs or .stabn, input_line_pointer is now pointing at the
 295      value.  */
 296
 297   if (SEPARATE_STAB_SECTIONS)
 298     /* Output the stab information in a separate section.  This is used
 299        at least for COFF and ELF.  */
 300     {
 301       segT saved_seg = now_seg;
 302       subsegT saved_subseg = now_subseg;
 303       fragS *saved_frag = frag_now;
 304       valueT dot;
 305       segT seg;
 306       unsigned int stroff;
 307       char *p;
 308
 309       static segT cached_sec;
 310       static char *cached_secname;
 311
 312       dot = frag_now_fix ();
 313
 314 #ifdef md_flush_pending_output
 315       md_flush_pending_output ();
 316 #endif
 317
 318       if (cached_secname && !strcmp (cached_secname, stab_secname))
 319         {
 320           seg = cached_sec;
 321           subseg_set (seg, 0);
 322         }
 323       else
 324         {
 325           seg = subseg_new (stab_secname, 0);
 326           if (cached_secname)
 327             free (cached_secname);
 328           cached_secname = xstrdup (stab_secname);
 329           cached_sec = seg;
 330         }
 331
 332       if (! seg_info (seg)->hadone)
 333         {
 334           bfd_set_section_flags (stdoutput, seg,
 335                                  SEC_READONLY | SEC_RELOC | SEC_DEBUGGING);
 336 #ifdef INIT_STAB_SECTION
 337           INIT_STAB_SECTION (seg);
 338 #endif
 339           seg_info (seg)->hadone = 1;
 340         }
 341
 342       stroff = get_stab_string_offset (string, stabstr_secname);
 343       if (what == 's')
 344         {
 345           /* Release the string, if nobody else has used the obstack.  */
 346           if (saved_string_obstack_end == notes.next_free)
 347             obstack_free (&notes, string);
 348         }
 349
 350       /* At least for now, stabs in a special stab section are always
 351          output as 12 byte blocks of information.  */
 352       p = frag_more (8);
 353       md_number_to_chars (p, (valueT) stroff, 4);
 354       md_number_to_chars (p + 4, (valueT) type, 1);
 355       md_number_to_chars (p + 5, (valueT) other, 1);
 356       md_number_to_chars (p + 6, (valueT) desc, 2);
 357
 358       if (what == 's' || what == 'n')
 359         {
 360           /* Pick up the value from the input line.  */
 361           cons (4);
 362           input_line_pointer--;
 363         }
 364       else
 365         {
 366           symbolS *symbol;
 367           expressionS exp;
 368
 369           /* Arrange for a value representing the current location.  */
 370           symbol = symbol_temp_new (saved_seg, dot, saved_frag);
 371
 372           exp.X_op = O_symbol;
 373           exp.X_add_symbol = symbol;
 374           exp.X_add_number = 0;
 375
 376           emit_expr (&exp, 4);
 377         }
 378
 379 #ifdef OBJ_PROCESS_STAB
 380       OBJ_PROCESS_STAB (seg, what, string, type, other, desc);
 381 #endif
 382
 383       subseg_set (saved_seg, saved_subseg);
 384     }
 385   else
 386     {
 387 #ifdef OBJ_PROCESS_STAB
 388       OBJ_PROCESS_STAB (0, what, string, type, other, desc);
 389 #else
 390       abort ();
 391 #endif
 392     }
 393
 394   demand_empty_rest_of_line ();
 395 }
 396
 397 /* Regular stab directive.  */
 398
 399 void
 400 s_stab (int what)
 401 {
 402   s_stab_generic (what, STAB_SECTION_NAME, STAB_STRING_SECTION_NAME);
 403 }
 404
 405 /* "Extended stabs", used in Solaris only now.  */
 406
 407 void
 408 s_xstab (int what)
 409 {
 410   int length;
 411   char *stab_secname, *stabstr_secname;
 412   static char *saved_secname, *saved_strsecname;
 413
 414   /* @@ MEMORY LEAK: This allocates a copy of the string, but in most
 415      cases it will be the same string, so we could release the storage
 416      back to the obstack it came from.  */
 417   stab_secname = demand_copy_C_string (&length);
 418   SKIP_WHITESPACE ();
 419   if (*input_line_pointer == ',')
 420     input_line_pointer++;
 421   else
 422     {
 423       as_bad (_("comma missing in .xstabs"));
 424       ignore_rest_of_line ();
 425       return;
 426     }
 427
 428   /* To get the name of the stab string section, simply add "str" to
 429      the stab section name.  */
 430   if (saved_secname == 0 || strcmp (saved_secname, stab_secname))
 431     {
 432       stabstr_secname = concat (stab_secname, "str", (char *) NULL);
 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 (int ignore ATTRIBUTE_UNUSED)
 450 {
 451   char *name;
 452   char c;
 453   char *p;
 454   symbolS *symbolP;
 455   int temp;
 456
 457   c = get_symbol_name (&name);
 458   p = input_line_pointer;
 459   *p = c;
 460   SKIP_WHITESPACE_AFTER_NAME ();
 461   if (*input_line_pointer != ',')
 462     {
 463       *p = 0;
 464       as_bad (_("expected comma after \"%s\""), name);
 465       *p = c;
 466       ignore_rest_of_line ();
 467     }
 468   else
 469     {
 470       input_line_pointer++;
 471       temp = get_absolute_expression ();
 472       *p = 0;
 473       symbolP = symbol_find_or_make (name);
 474       *p = c;
 475       S_SET_DESC (symbolP, temp);
 476     }
 477   demand_empty_rest_of_line ();
 478 }                               /* s_desc() */
 479
 480 #endif /* defined (S_SET_DESC) */
 481
 482 /* Generate stabs debugging information to denote the main source file.  */
 483
 484 void
 485 stabs_generate_asm_file (void)
 486 {
 487   const char *file;
 488   unsigned int lineno;
 489
 490   file = as_where (&lineno);
 491   if (use_gnu_debug_info_extensions)
 492     {
 493       const char *dir;
 494       char *dir2;
 495
 496       dir = remap_debug_filename (getpwd ());
 497       dir2 = concat (dir, "/", NULL);
 498       generate_asm_file (N_SO, dir2);
 499       free (dir2);
 500       xfree ((char *) dir);
 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, const char *file)
 510 {
 511   static char *last_file;
 512   static int label_count;
 513   char *hold;
 514   char sym[30];
 515   char *buf;
 516   const char *tmp = file;
 517   const char *file_endp = file + strlen (file);
 518   char *bufp;
 519
 520   if (last_file != NULL
 521       && filename_cmp (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 = XNEWVEC (char, 2 * strlen (file) + strlen (sym) + 12);
 537
 538   *bufp++ = '"';
 539
 540   while (tmp < file_endp)
 541     {
 542       const 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   const 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   file = as_where (&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            && filename_cmp (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 (filename_cmp (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 = XNEWVEC (char, 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 = XNEWVEC (char, 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   free (buf);
 648 }
 649
 650 /* Emit a function stab.
 651    All assembler functions are assumed to have return type `void'.  */
 652
 653 void
 654 stabs_generate_asm_func (const char *funcname, const char *startlabname)
 655 {
 656   static int void_emitted_p;
 657   char *hold = input_line_pointer;
 658   char *buf;
 659   unsigned int lineno;
 660
 661   if (! void_emitted_p)
 662     {
 663       input_line_pointer = (char *) "\"void:t1=1\",128,0,0,0";
 664       s_stab ('s');
 665       void_emitted_p = 1;
 666     }
 667
 668   as_where (&lineno);
 669   if (asprintf (&buf, "\"%s:F1\",%d,0,%d,%s",
 670                 funcname, N_FUN, lineno + 1, startlabname) == -1)
 671     as_fatal ("%s", xstrerror (errno));
 672   input_line_pointer = buf;
 673   s_stab ('s');
 674   free (buf);
 675
 676   input_line_pointer = hold;
 677   current_function_label = xstrdup (startlabname);
 678   in_dot_func_p = 1;
 679 }
 680
 681 /* Emit a stab to record the end of a function.  */
 682
 683 void
 684 stabs_generate_asm_endfunc (const char *funcname ATTRIBUTE_UNUSED,
 685                             const char *startlabname)
 686 {
 687   static int label_count;
 688   char *hold = input_line_pointer;
 689   char *buf;
 690   char sym[30];
 691
 692   sprintf (sym, "%sendfunc%d", FAKE_LABEL_NAME, label_count);
 693   ++label_count;
 694   colon (sym);
 695
 696   if (asprintf (&buf, "\"\",%d,0,0,%s-%s", N_FUN, sym, startlabname) == -1)
 697     as_fatal ("%s", xstrerror (errno));
 698   input_line_pointer = buf;
 699   s_stab ('s');
 700   free (buf);
 701
 702   input_line_pointer = hold;
 703   in_dot_func_p = 0;
 704   current_function_label = NULL;
 705 }