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 = (char *) xmalloc (strlen (stab_secname) + 4);
 433       strcpy (stabstr_secname, stab_secname);
 434       strcat (stabstr_secname, "str");
 435       if (saved_secname)
 436         {
 437           free (saved_secname);
 438           free (saved_strsecname);
 439         }
 440       saved_secname = stab_secname;
 441       saved_strsecname = stabstr_secname;
 442     }
 443   s_stab_generic (what, saved_secname, saved_strsecname);
 444 }
 445
 446 #ifdef S_SET_DESC
 447
 448 /* Frob invented at RMS' request. Set the n_desc of a symbol.  */
 449
 450 void
 451 s_desc (int ignore ATTRIBUTE_UNUSED)
 452 {
 453   char *name;
 454   char c;
 455   char *p;
 456   symbolS *symbolP;
 457   int temp;
 458
 459   c = get_symbol_name (&name);
 460   p = input_line_pointer;
 461   *p = c;
 462   SKIP_WHITESPACE_AFTER_NAME ();
 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   const char *file;
 490   unsigned int lineno;
 491
 492   file = as_where (&lineno);
 493   if (use_gnu_debug_info_extensions)
 494     {
 495       const char *dir;
 496       char *dir2;
 497
 498       dir = remap_debug_filename (getpwd ());
 499       dir2 = concat (dir, "/", NULL);
 500       generate_asm_file (N_SO, dir2);
 501       free (dir2);
 502       xfree ((char *) dir);
 503     }
 504   generate_asm_file (N_SO, file);
 505 }
 506
 507 /* Generate stabs debugging information to denote the source file.
 508    TYPE is one of N_SO, N_SOL.  */
 509
 510 static void
 511 generate_asm_file (int type, const char *file)
 512 {
 513   static char *last_file;
 514   static int label_count;
 515   char *hold;
 516   char sym[30];
 517   char *buf;
 518   const char *tmp = file;
 519   const char *file_endp = file + strlen (file);
 520   char *bufp;
 521
 522   if (last_file != NULL
 523       && filename_cmp (last_file, file) == 0)
 524     return;
 525
 526   /* Rather than try to do this in some efficient fashion, we just
 527      generate a string and then parse it again.  That lets us use the
 528      existing stabs hook, which expect to see a string, rather than
 529      inventing new ones.  */
 530   hold = input_line_pointer;
 531
 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 = (char *) xmalloc (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) ? (size_t) (bslash - tmp + 1) : strlen (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       strncpy (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   input_line_pointer = buf;
 562   s_stab ('s');
 563   colon (sym);
 564
 565   if (last_file != NULL)
 566     free (last_file);
 567   last_file = xstrdup (file);
 568
 569   free (buf);
 570
 571   input_line_pointer = hold;
 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   char *hold;
 582   const char *file;
 583   unsigned int lineno;
 584   char *buf;
 585   char sym[30];
 586   /* Remember the last file/line and avoid duplicates.  */
 587   static unsigned int prev_lineno = -1;
 588   static char *prev_file = NULL;
 589
 590   /* Rather than try to do this in some efficient fashion, we just
 591      generate a string and then parse it again.  That lets us use the
 592      existing stabs hook, which expect to see a string, rather than
 593      inventing new ones.  */
 594
 595   hold = input_line_pointer;
 596
 597   file = as_where (&lineno);
 598
 599   /* Don't emit sequences of stabs for the same line.  */
 600   if (prev_file == NULL)
 601     {
 602       /* First time thru.  */
 603       prev_file = xstrdup (file);
 604       prev_lineno = lineno;
 605     }
 606   else if (lineno == prev_lineno
 607            && filename_cmp (file, prev_file) == 0)
 608     {
 609       /* Same file/line as last time.  */
 610       return;
 611     }
 612   else
 613     {
 614       /* Remember file/line for next time.  */
 615       prev_lineno = lineno;
 616       if (filename_cmp (file, prev_file) != 0)
 617         {
 618           free (prev_file);
 619           prev_file = xstrdup (file);
 620         }
 621     }
 622
 623   /* Let the world know that we are in the middle of generating a
 624      piece of stabs line debugging information.  */
 625   outputting_stabs_line_debug = 1;
 626
 627   generate_asm_file (N_SOL, file);
 628
 629   sprintf (sym, "%sL%d", FAKE_LABEL_NAME, label_count);
 630   ++label_count;
 631
 632   if (in_dot_func_p)
 633     {
 634       buf = (char *) xmalloc (100 + strlen (current_function_label));
 635       sprintf (buf, "%d,0,%d,%s-%s\n", N_SLINE, lineno,
 636                sym, current_function_label);
 637     }
 638   else
 639     {
 640       buf = (char *) xmalloc (100);
 641       sprintf (buf, "%d,0,%d,%s\n", N_SLINE, lineno, sym);
 642     }
 643   input_line_pointer = buf;
 644   s_stab ('n');
 645   colon (sym);
 646
 647   input_line_pointer = hold;
 648   outputting_stabs_line_debug = 0;
 649   free (buf);
 650 }
 651
 652 /* Emit a function stab.
 653    All assembler functions are assumed to have return type `void'.  */
 654
 655 void
 656 stabs_generate_asm_func (const char *funcname, const char *startlabname)
 657 {
 658   static int void_emitted_p;
 659   char *hold = input_line_pointer;
 660   char *buf;
 661   unsigned int lineno;
 662
 663   if (! void_emitted_p)
 664     {
 665       input_line_pointer = (char *) "\"void:t1=1\",128,0,0,0";
 666       s_stab ('s');
 667       void_emitted_p = 1;
 668     }
 669
 670   as_where (&lineno);
 671   if (asprintf (&buf, "\"%s:F1\",%d,0,%d,%s",
 672                 funcname, N_FUN, lineno + 1, startlabname) == -1)
 673     as_fatal ("%s", xstrerror (errno));
 674   input_line_pointer = buf;
 675   s_stab ('s');
 676   free (buf);
 677
 678   input_line_pointer = hold;
 679   current_function_label = xstrdup (startlabname);
 680   in_dot_func_p = 1;
 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 *hold = input_line_pointer;
 691   char *buf;
 692   char sym[30];
 693
 694   sprintf (sym, "%sendfunc%d", FAKE_LABEL_NAME, label_count);
 695   ++label_count;
 696   colon (sym);
 697
 698   if (asprintf (&buf, "\"\",%d,0,0,%s-%s", N_FUN, sym, startlabname) == -1)
 699     as_fatal ("%s", xstrerror (errno));
 700   input_line_pointer = buf;
 701   s_stab ('s');
 702   free (buf);
 703
 704   input_line_pointer = hold;
 705   in_dot_func_p = 0;
 706   current_function_label = NULL;
 707 }