gas/dw2gencfi.c

   1 /* dw2gencfi.c - Support for generating Dwarf2 CFI information.
   2    Copyright 2003 Free Software Foundation, Inc.
   3    Contributed by Michal Ludvig <mludvig@suse.cz>
   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 published by
   9    the Free Software Foundation; either version 2, or (at your option)
  10    any later version.
  11
  12    GAS is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    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 "dw2gencfi.h"
  24
  25
  26 /* We re-use DWARF2_LINE_MIN_INSN_LENGTH for the code alignment field
  27    of the CIE.  Default to 1 if not otherwise specified.  */
  28 #ifndef DWARF2_LINE_MIN_INSN_LENGTH
  29 # define DWARF2_LINE_MIN_INSN_LENGTH 1
  30 #endif
  31
  32 /* If TARGET_USE_CFIPOP is defined, it is required that the target
  33    provide the following definitions.  Otherwise provide them to
  34    allow compilation to continue.  */
  35 #ifndef TARGET_USE_CFIPOP
  36 # ifndef DWARF2_DEFAULT_RETURN_COLUMN
  37 #  define DWARF2_DEFAULT_RETURN_COLUMN 0
  38 # endif
  39 # ifndef DWARF2_CIE_DATA_ALIGNMENT
  40 #  define DWARF2_CIE_DATA_ALIGNMENT 1
  41 # endif
  42 #endif
  43
  44 #ifndef EH_FRAME_ALIGNMENT
  45 # ifdef BFD_ASSEMBLER
  46 #  define EH_FRAME_ALIGNMENT (bfd_get_arch_size (stdoutput) == 64 ? 3 : 2)
  47 # else
  48 #  define EH_FRAME_ALIGNMENT 2
  49 # endif
  50 #endif
  51
  52 #ifndef tc_cfi_frame_initial_instructions
  53 # define tc_cfi_frame_initial_instructions() ((void)0)
  54 #endif
  55
  56
  57 struct cfi_insn_data
  58 {
  59   struct cfi_insn_data *next;
  60   int insn;
  61   union {
  62     struct {
  63       unsigned reg;
  64       offsetT offset;
  65     } ri;
  66
  67     struct {
  68       unsigned reg1;
  69       unsigned reg2;
  70     } rr;
  71
  72     unsigned r;
  73     offsetT i;
  74
  75     struct {
  76       symbolS *lab1;
  77       symbolS *lab2;
  78     } ll;
  79
  80     struct cfi_escape_data {
  81       struct cfi_escape_data *next;
  82       expressionS exp;
  83     } *esc;
  84   } u;
  85 };
  86
  87 struct fde_entry
  88 {
  89   struct fde_entry *next;
  90   symbolS *start_address;
  91   symbolS *end_address;
  92   struct cfi_insn_data *data;
  93   struct cfi_insn_data **last;
  94   unsigned int return_column;
  95 };
  96
  97 struct cie_entry
  98 {
  99   struct cie_entry *next;
 100   symbolS *start_address;
 101   unsigned int return_column;
 102   struct cfi_insn_data *first, *last;
 103 };
 104
 105
 106 /* Current open FDE entry.  */
 107 static struct fde_entry *cur_fde_data;
 108 static symbolS *last_address;
 109 static offsetT cur_cfa_offset;
 110
 111 /* List of FDE entries.  */
 112 static struct fde_entry *all_fde_data;
 113 static struct fde_entry **last_fde_data = &all_fde_data;
 114
 115 /* List of CIEs so that they could be reused.  */
 116 static struct cie_entry *cie_root;
 117
 118 /* Stack of old CFI data, for save/restore.  */
 119 struct cfa_save_data
 120 {
 121   struct cfa_save_data *next;
 122   offsetT cfa_offset;
 123 };
 124
 125 static struct cfa_save_data *cfa_save_stack;
 126 \f
 127 /* Construct a new FDE structure and add it to the end of the fde list.  */
 128
 129 static struct fde_entry *
 130 alloc_fde_entry (void)
 131 {
 132   struct fde_entry *fde = xcalloc (1, sizeof (struct fde_entry));
 133
 134   cur_fde_data = fde;
 135   *last_fde_data = fde;
 136   last_fde_data = &fde->next;
 137
 138   fde->last = &fde->data;
 139   fde->return_column = DWARF2_DEFAULT_RETURN_COLUMN;
 140
 141   return fde;
 142 }
 143
 144 /* The following functions are available for a backend to construct its
 145    own unwind information, usually from legacy unwind directives.  */
 146
 147 /* Construct a new INSN structure and add it to the end of the insn list
 148    for the currently active FDE.  */
 149
 150 static struct cfi_insn_data *
 151 alloc_cfi_insn_data (void)
 152 {
 153   struct cfi_insn_data *insn = xcalloc (1, sizeof (struct cfi_insn_data));
 154
 155   *cur_fde_data->last = insn;
 156   cur_fde_data->last = &insn->next;
 157
 158   return insn;
 159 }
 160
 161 /* Construct a new FDE structure that begins at LABEL.  */
 162
 163 void
 164 cfi_new_fde (symbolS *label)
 165 {
 166   struct fde_entry *fde = alloc_fde_entry ();
 167   fde->start_address = label;
 168   last_address = label;
 169 }
 170
 171 /* End the currently open FDE.  */
 172
 173 void
 174 cfi_end_fde (symbolS *label)
 175 {
 176   cur_fde_data->end_address = label;
 177   cur_fde_data = NULL;
 178 }
 179
 180 /* Set the return column for the current FDE.  */
 181
 182 void
 183 cfi_set_return_column (unsigned regno)
 184 {
 185   cur_fde_data->return_column = regno;
 186 }
 187
 188 /* Universal functions to store new instructions.  */
 189
 190 static void
 191 cfi_add_CFA_insn(int insn)
 192 {
 193   struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
 194
 195   insn_ptr->insn = insn;
 196 }
 197
 198 static void
 199 cfi_add_CFA_insn_reg (int insn, unsigned regno)
 200 {
 201   struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
 202
 203   insn_ptr->insn = insn;
 204   insn_ptr->u.r = regno;
 205 }
 206
 207 static void
 208 cfi_add_CFA_insn_offset (int insn, offsetT offset)
 209 {
 210   struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
 211
 212   insn_ptr->insn = insn;
 213   insn_ptr->u.i = offset;
 214 }
 215
 216 static void
 217 cfi_add_CFA_insn_reg_reg (int insn, unsigned reg1, unsigned reg2)
 218 {
 219   struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
 220
 221   insn_ptr->insn = insn;
 222   insn_ptr->u.rr.reg1 = reg1;
 223   insn_ptr->u.rr.reg2 = reg2;
 224 }
 225
 226 static void
 227 cfi_add_CFA_insn_reg_offset (int insn, unsigned regno, offsetT offset)
 228 {
 229   struct cfi_insn_data *insn_ptr = alloc_cfi_insn_data ();
 230
 231   insn_ptr->insn = insn;
 232   insn_ptr->u.ri.reg = regno;
 233   insn_ptr->u.ri.offset = offset;
 234 }
 235
 236 /* Add a CFI insn to advance the PC from the last address to LABEL.  */
 237
 238 void
 239 cfi_add_advance_loc (symbolS *label)
 240 {
 241   struct cfi_insn_data *insn = alloc_cfi_insn_data ();
 242
 243   insn->insn = DW_CFA_advance_loc;
 244   insn->u.ll.lab1 = last_address;
 245   insn->u.ll.lab2 = label;
 246
 247   last_address = label;
 248 }
 249
 250 /* Add a DW_CFA_offset record to the CFI data.  */
 251
 252 void
 253 cfi_add_CFA_offset (unsigned regno, offsetT offset)
 254 {
 255   unsigned int abs_data_align;
 256
 257   cfi_add_CFA_insn_reg_offset (DW_CFA_offset, regno, offset);
 258
 259   abs_data_align = (DWARF2_CIE_DATA_ALIGNMENT < 0
 260                     ? -DWARF2_CIE_DATA_ALIGNMENT : DWARF2_CIE_DATA_ALIGNMENT);
 261   if (offset % abs_data_align)
 262     as_bad (_("register save offset not a multiple of %u"), abs_data_align);
 263 }
 264
 265 /* Add a DW_CFA_def_cfa record to the CFI data.  */
 266
 267 void
 268 cfi_add_CFA_def_cfa (unsigned regno, offsetT offset)
 269 {
 270   cfi_add_CFA_insn_reg_offset (DW_CFA_def_cfa, regno, offset);
 271   cur_cfa_offset = offset;
 272 }
 273
 274 /* Add a DW_CFA_register record to the CFI data.  */
 275
 276 void
 277 cfi_add_CFA_register (unsigned reg1, unsigned reg2)
 278 {
 279   cfi_add_CFA_insn_reg_reg (DW_CFA_register, reg1, reg2);
 280 }
 281
 282 /* Add a DW_CFA_def_cfa_register record to the CFI data.  */
 283
 284 void
 285 cfi_add_CFA_def_cfa_register (unsigned regno)
 286 {
 287   cfi_add_CFA_insn_reg (DW_CFA_def_cfa_register, regno);
 288 }
 289
 290 /* Add a DW_CFA_def_cfa_offset record to the CFI data.  */
 291
 292 void
 293 cfi_add_CFA_def_cfa_offset (offsetT offset)
 294 {
 295   cfi_add_CFA_insn_offset (DW_CFA_def_cfa_offset, offset);
 296   cur_cfa_offset = offset;
 297 }
 298
 299 void
 300 cfi_add_CFA_restore (unsigned regno)
 301 {
 302   cfi_add_CFA_insn_reg (DW_CFA_restore, regno);
 303 }
 304
 305 void
 306 cfi_add_CFA_undefined (unsigned regno)
 307 {
 308   cfi_add_CFA_insn_reg (DW_CFA_undefined, regno);
 309 }
 310
 311 void
 312 cfi_add_CFA_same_value (unsigned regno)
 313 {
 314   cfi_add_CFA_insn_reg (DW_CFA_same_value, regno);
 315 }
 316
 317 void
 318 cfi_add_CFA_remember_state (void)
 319 {
 320   struct cfa_save_data *p;
 321
 322   cfi_add_CFA_insn (DW_CFA_remember_state);
 323
 324   p = xmalloc (sizeof (*p));
 325   p->cfa_offset = cur_cfa_offset;
 326   p->next = cfa_save_stack;
 327   cfa_save_stack = p;
 328 }
 329
 330 void
 331 cfi_add_CFA_restore_state (void)
 332 {
 333   struct cfa_save_data *p;
 334
 335   cfi_add_CFA_insn (DW_CFA_restore_state);
 336
 337   p = cfa_save_stack;
 338   if (p)
 339     {
 340       cur_cfa_offset = p->cfa_offset;
 341       cfa_save_stack = p->next;
 342       free (p);
 343     }
 344 }
 345
 346 \f
 347 /* Parse CFI assembler directives.  */
 348
 349 static void dot_cfi (int);
 350 static void dot_cfi_escape (int);
 351 static void dot_cfi_startproc (int);
 352 static void dot_cfi_endproc (int);
 353
 354 /* Fake CFI type; outside the byte range of any real CFI insn.  */
 355 #define CFI_adjust_cfa_offset   0x100
 356 #define CFI_return_column       0x101
 357 #define CFI_rel_offset          0x102
 358 #define CFI_escape              0x103
 359
 360 const pseudo_typeS cfi_pseudo_table[] =
 361   {
 362     { "cfi_startproc", dot_cfi_startproc, 0 },
 363     { "cfi_endproc", dot_cfi_endproc, 0 },
 364     { "cfi_def_cfa", dot_cfi, DW_CFA_def_cfa },
 365     { "cfi_def_cfa_register", dot_cfi, DW_CFA_def_cfa_register },
 366     { "cfi_def_cfa_offset", dot_cfi, DW_CFA_def_cfa_offset },
 367     { "cfi_adjust_cfa_offset", dot_cfi, CFI_adjust_cfa_offset },
 368     { "cfi_offset", dot_cfi, DW_CFA_offset },
 369     { "cfi_rel_offset", dot_cfi, CFI_rel_offset },
 370     { "cfi_register", dot_cfi, DW_CFA_register },
 371     { "cfi_return_column", dot_cfi, CFI_return_column },
 372     { "cfi_restore", dot_cfi, DW_CFA_restore },
 373     { "cfi_undefined", dot_cfi, DW_CFA_undefined },
 374     { "cfi_same_value", dot_cfi, DW_CFA_same_value },
 375     { "cfi_remember_state", dot_cfi, DW_CFA_remember_state },
 376     { "cfi_restore_state", dot_cfi, DW_CFA_restore_state },
 377     { "cfi_window_save", dot_cfi, DW_CFA_GNU_window_save },
 378     { "cfi_escape", dot_cfi_escape, 0 },
 379     { NULL, NULL, 0 }
 380   };
 381
 382 static void
 383 cfi_parse_separator (void)
 384 {
 385   SKIP_WHITESPACE ();
 386   if (*input_line_pointer == ',')
 387     input_line_pointer++;
 388   else
 389     as_bad (_("missing separator"));
 390 }
 391
 392 static unsigned
 393 cfi_parse_reg (void)
 394 {
 395   int regno;
 396   expressionS exp;
 397
 398 #ifdef tc_regname_to_dw2regnum
 399   SKIP_WHITESPACE ();
 400   if (is_name_beginner (*input_line_pointer)
 401       || (*input_line_pointer == '%'
 402           && is_name_beginner (*++input_line_pointer)))
 403     {
 404       char *name, c;
 405
 406       name = input_line_pointer;
 407       c = get_symbol_end ();
 408
 409       if ((regno = tc_regname_to_dw2regnum (name)) < 0)
 410         {
 411           as_bad (_("bad register expression"));
 412           regno = 0;
 413         }
 414
 415       *input_line_pointer = c;
 416       return regno;
 417     }
 418 #endif
 419
 420   expression (&exp);
 421   switch (exp.X_op)
 422     {
 423     case O_register:
 424     case O_constant:
 425       regno = exp.X_add_number;
 426       break;
 427
 428     default:
 429       as_bad (_("bad register expression"));
 430       regno = 0;
 431       break;
 432     }
 433
 434   return regno;
 435 }
 436
 437 static offsetT
 438 cfi_parse_const (void)
 439 {
 440   return get_absolute_expression ();
 441 }
 442
 443 static void
 444 dot_cfi (int arg)
 445 {
 446   offsetT offset;
 447   unsigned reg1, reg2;
 448
 449   if (!cur_fde_data)
 450     {
 451       as_bad (_("CFI instruction used without previous .cfi_startproc"));
 452       return;
 453     }
 454
 455   /* If the last address was not at the current PC, advance to current.  */
 456   if (symbol_get_frag (last_address) != frag_now
 457       || S_GET_VALUE (last_address) != frag_now_fix ())
 458     cfi_add_advance_loc (symbol_temp_new_now ());
 459
 460   switch (arg)
 461     {
 462     case DW_CFA_offset:
 463       reg1 = cfi_parse_reg ();
 464       cfi_parse_separator ();
 465       offset = cfi_parse_const ();
 466       cfi_add_CFA_offset (reg1, offset);
 467       break;
 468
 469     case CFI_rel_offset:
 470       reg1 = cfi_parse_reg ();
 471       cfi_parse_separator ();
 472       offset = cfi_parse_const ();
 473       cfi_add_CFA_offset (reg1, offset - cur_cfa_offset);
 474       break;
 475
 476     case DW_CFA_def_cfa:
 477       reg1 = cfi_parse_reg ();
 478       cfi_parse_separator ();
 479       offset = cfi_parse_const ();
 480       cfi_add_CFA_def_cfa (reg1, offset);
 481       break;
 482
 483     case DW_CFA_register:
 484       reg1 = cfi_parse_reg ();
 485       cfi_parse_separator ();
 486       reg2 = cfi_parse_reg ();
 487       cfi_add_CFA_register (reg1, reg2);
 488       break;
 489
 490     case DW_CFA_def_cfa_register:
 491       reg1 = cfi_parse_reg ();
 492       cfi_add_CFA_def_cfa_register (reg1);
 493       break;
 494
 495     case DW_CFA_def_cfa_offset:
 496       offset = cfi_parse_const ();
 497       cfi_add_CFA_def_cfa_offset (offset);
 498       break;
 499
 500     case CFI_adjust_cfa_offset:
 501       offset = cfi_parse_const ();
 502       cfi_add_CFA_def_cfa_offset (cur_cfa_offset + offset);
 503       break;
 504
 505     case DW_CFA_restore:
 506       reg1 = cfi_parse_reg ();
 507       cfi_add_CFA_restore (reg1);
 508       break;
 509
 510     case DW_CFA_undefined:
 511       reg1 = cfi_parse_reg ();
 512       cfi_add_CFA_undefined (reg1);
 513       break;
 514
 515     case DW_CFA_same_value:
 516       reg1 = cfi_parse_reg ();
 517       cfi_add_CFA_same_value (reg1);
 518       break;
 519
 520     case CFI_return_column:
 521       reg1 = cfi_parse_reg ();
 522       cfi_set_return_column (reg1);
 523       break;
 524
 525     case DW_CFA_remember_state:
 526       cfi_add_CFA_remember_state ();
 527       break;
 528
 529     case DW_CFA_restore_state:
 530       cfi_add_CFA_restore_state ();
 531       break;
 532
 533     case DW_CFA_GNU_window_save:
 534       cfi_add_CFA_insn (DW_CFA_GNU_window_save);
 535       break;
 536
 537     default:
 538       abort ();
 539     }
 540
 541   demand_empty_rest_of_line ();
 542 }
 543
 544 static void
 545 dot_cfi_escape (int ignored ATTRIBUTE_UNUSED)
 546 {
 547   struct cfi_escape_data *head, **tail, *e;
 548   struct cfi_insn_data *insn;
 549
 550   if (!cur_fde_data)
 551     {
 552       as_bad (_("CFI instruction used without previous .cfi_startproc"));
 553       return;
 554     }
 555
 556   /* If the last address was not at the current PC, advance to current.  */
 557   if (symbol_get_frag (last_address) != frag_now
 558       || S_GET_VALUE (last_address) != frag_now_fix ())
 559     cfi_add_advance_loc (symbol_temp_new_now ());
 560
 561   tail = &head;
 562   do
 563     {
 564       e = xmalloc (sizeof (*e));
 565       do_parse_cons_expression (&e->exp, 1);
 566       *tail = e;
 567       tail = &e->next;
 568     }
 569   while (*input_line_pointer++ == ',');
 570   *tail = NULL;
 571
 572   insn = alloc_cfi_insn_data ();
 573   insn->insn = CFI_escape;
 574   insn->u.esc = head;
 575 }
 576
 577 static void
 578 dot_cfi_startproc (int ignored ATTRIBUTE_UNUSED)
 579 {
 580   int simple = 0;
 581
 582   if (cur_fde_data)
 583     {
 584       as_bad (_("previous CFI entry not closed (missing .cfi_endproc)"));
 585       return;
 586     }
 587
 588   cfi_new_fde (symbol_temp_new_now ());
 589
 590   SKIP_WHITESPACE ();
 591   if (is_name_beginner (*input_line_pointer))
 592     {
 593       char *name, c;
 594
 595       name = input_line_pointer;
 596       c = get_symbol_end ();
 597
 598       if (strcmp (name, "simple") == 0)
 599         {
 600           simple = 1;
 601           *input_line_pointer = c;
 602         }
 603       else
 604         input_line_pointer = name;
 605     }
 606   demand_empty_rest_of_line ();
 607
 608   if (!simple)
 609     tc_cfi_frame_initial_instructions ();
 610 }
 611
 612 static void
 613 dot_cfi_endproc (int ignored ATTRIBUTE_UNUSED)
 614 {
 615   if (! cur_fde_data)
 616     {
 617       as_bad (_(".cfi_endproc without corresponding .cfi_startproc"));
 618       return;
 619     }
 620
 621   cfi_end_fde (symbol_temp_new_now ());
 622 }
 623
 624 \f
 625 /* Emit a single byte into the current segment.  */
 626
 627 static inline void
 628 out_one (int byte)
 629 {
 630   FRAG_APPEND_1_CHAR (byte);
 631 }
 632
 633 /* Emit a two-byte word into the current segment.  */
 634
 635 static inline void
 636 out_two (int data)
 637 {
 638   md_number_to_chars (frag_more (2), data, 2);
 639 }
 640
 641 /* Emit a four byte word into the current segment.  */
 642
 643 static inline void
 644 out_four (int data)
 645 {
 646   md_number_to_chars (frag_more (4), data, 4);
 647 }
 648
 649 /* Emit an unsigned "little-endian base 128" number.  */
 650
 651 static void
 652 out_uleb128 (addressT value)
 653 {
 654   output_leb128 (frag_more (sizeof_leb128 (value, 0)), value, 0);
 655 }
 656
 657 /* Emit an unsigned "little-endian base 128" number.  */
 658
 659 static void
 660 out_sleb128 (offsetT value)
 661 {
 662   output_leb128 (frag_more (sizeof_leb128 (value, 1)), value, 1);
 663 }
 664
 665 static void
 666 output_cfi_insn (struct cfi_insn_data *insn)
 667 {
 668   offsetT offset;
 669   unsigned int regno;
 670
 671   switch (insn->insn)
 672     {
 673     case DW_CFA_advance_loc:
 674       {
 675         symbolS *from = insn->u.ll.lab1;
 676         symbolS *to = insn->u.ll.lab2;
 677
 678         if (symbol_get_frag (to) == symbol_get_frag (from))
 679           {
 680             addressT delta = S_GET_VALUE (to) - S_GET_VALUE (from);
 681             addressT scaled = delta / DWARF2_LINE_MIN_INSN_LENGTH;
 682
 683             if (scaled <= 0x3F)
 684               out_one (DW_CFA_advance_loc + scaled);
 685             else if (delta <= 0xFF)
 686               {
 687                 out_one (DW_CFA_advance_loc1);
 688                 out_one (delta);
 689               }
 690             else if (delta <= 0xFFFF)
 691               {
 692                 out_one (DW_CFA_advance_loc2);
 693                 out_two (delta);
 694               }
 695             else
 696               {
 697                 out_one (DW_CFA_advance_loc4);
 698                 out_four (delta);
 699               }
 700           }
 701         else
 702           {
 703             expressionS exp;
 704
 705             exp.X_op = O_subtract;
 706             exp.X_add_symbol = to;
 707             exp.X_op_symbol = from;
 708             exp.X_add_number = 0;
 709
 710             /* The code in ehopt.c expects that one byte of the encoding
 711                is already allocated to the frag.  This comes from the way
 712                that it scans the .eh_frame section looking first for the
 713                .byte DW_CFA_advance_loc4.  */
 714             frag_more (1);
 715
 716             frag_var (rs_cfa, 4, 0, DWARF2_LINE_MIN_INSN_LENGTH << 3,
 717                       make_expr_symbol (&exp), frag_now_fix () - 1,
 718                       (char *) frag_now);
 719           }
 720       }
 721       break;
 722
 723     case DW_CFA_def_cfa:
 724       offset = insn->u.ri.offset;
 725       if (offset < 0)
 726         {
 727           out_one (DW_CFA_def_cfa_sf);
 728           out_uleb128 (insn->u.ri.reg);
 729           out_uleb128 (offset);
 730         }
 731       else
 732         {
 733           out_one (DW_CFA_def_cfa);
 734           out_uleb128 (insn->u.ri.reg);
 735           out_uleb128 (offset);
 736         }
 737       break;
 738
 739     case DW_CFA_def_cfa_register:
 740     case DW_CFA_undefined:
 741     case DW_CFA_same_value:
 742       out_one (insn->insn);
 743       out_uleb128 (insn->u.r);
 744       break;
 745
 746     case DW_CFA_def_cfa_offset:
 747       offset = insn->u.i;
 748       if (offset < 0)
 749         {
 750           out_one (DW_CFA_def_cfa_offset_sf);
 751           out_sleb128 (offset);
 752         }
 753       else
 754         {
 755           out_one (DW_CFA_def_cfa_offset);
 756           out_uleb128 (offset);
 757         }
 758       break;
 759
 760     case DW_CFA_restore:
 761       regno = insn->u.r;
 762       if (regno <= 0x3F)
 763         {
 764           out_one (DW_CFA_restore + regno);
 765         }
 766       else
 767         {
 768           out_one (DW_CFA_restore_extended);
 769           out_uleb128 (regno);
 770         }
 771       break;
 772
 773     case DW_CFA_offset:
 774       regno = insn->u.ri.reg;
 775       offset = insn->u.ri.offset / DWARF2_CIE_DATA_ALIGNMENT;
 776       if (offset < 0)
 777         {
 778           out_one (DW_CFA_offset_extended_sf);
 779           out_uleb128 (regno);
 780           out_sleb128 (offset);
 781         }
 782       else if (regno <= 0x3F)
 783         {
 784           out_one (DW_CFA_offset + regno);
 785           out_uleb128 (offset);
 786         }
 787       else
 788         {
 789           out_one (DW_CFA_offset_extended);
 790           out_uleb128 (regno);
 791           out_uleb128 (offset);
 792         }
 793       break;
 794
 795     case DW_CFA_register:
 796       out_one (DW_CFA_register);
 797       out_uleb128 (insn->u.rr.reg1);
 798       out_uleb128 (insn->u.rr.reg2);
 799       break;
 800
 801     case DW_CFA_remember_state:
 802     case DW_CFA_restore_state:
 803       out_one (insn->insn);
 804       break;
 805
 806     case DW_CFA_GNU_window_save:
 807       out_one (DW_CFA_GNU_window_save);
 808       break;
 809
 810     case CFI_escape:
 811       {
 812         struct cfi_escape_data *e;
 813         for (e = insn->u.esc; e ; e = e->next)
 814           emit_expr (&e->exp, 1);
 815         break;
 816       }
 817
 818     default:
 819       abort ();
 820     }
 821 }
 822
 823 static void
 824 output_cie (struct cie_entry *cie)
 825 {
 826   symbolS *after_size_address, *end_address;
 827   expressionS exp;
 828   struct cfi_insn_data *i;
 829
 830   cie->start_address = symbol_temp_new_now ();
 831   after_size_address = symbol_temp_make ();
 832   end_address = symbol_temp_make ();
 833
 834   exp.X_op = O_subtract;
 835   exp.X_add_symbol = end_address;
 836   exp.X_op_symbol = after_size_address;
 837   exp.X_add_number = 0;
 838
 839   emit_expr (&exp, 4);                          /* Length */
 840   symbol_set_value_now (after_size_address);
 841   out_four (0);                                 /* CIE id */
 842   out_one (DW_CIE_VERSION);                     /* Version */
 843   out_one ('z');                                /* Augmentation */
 844   out_one ('R');
 845   out_one (0);
 846   out_uleb128 (DWARF2_LINE_MIN_INSN_LENGTH);    /* Code alignment */
 847   out_sleb128 (DWARF2_CIE_DATA_ALIGNMENT);      /* Data alignment */
 848   out_one (cie->return_column);                 /* Return column */
 849   out_uleb128 (1);                              /* Augmentation size */
 850 #if defined DIFF_EXPR_OK || defined tc_cfi_emit_pcrel_expr
 851   out_one (DW_EH_PE_pcrel | DW_EH_PE_sdata4);
 852 #else
 853   out_one (DW_EH_PE_sdata4);
 854 #endif
 855
 856   if (cie->first)
 857     for (i = cie->first; i != cie->last; i = i->next)
 858       output_cfi_insn (i);
 859
 860   symbol_set_value_now (end_address);
 861 }
 862
 863 static void
 864 output_fde (struct fde_entry *fde, struct cie_entry *cie,
 865             struct cfi_insn_data *first, int align)
 866 {
 867   symbolS *after_size_address, *end_address;
 868   expressionS exp;
 869
 870   after_size_address = symbol_temp_make ();
 871   end_address = symbol_temp_make ();
 872
 873   exp.X_op = O_subtract;
 874   exp.X_add_symbol = end_address;
 875   exp.X_op_symbol = after_size_address;
 876   exp.X_add_number = 0;
 877   emit_expr (&exp, 4);                          /* Length */
 878   symbol_set_value_now (after_size_address);
 879
 880   exp.X_add_symbol = after_size_address;
 881   exp.X_op_symbol = cie->start_address;
 882   emit_expr (&exp, 4);                          /* CIE offset */
 883
 884 #ifdef DIFF_EXPR_OK
 885   exp.X_add_symbol = fde->start_address;
 886   exp.X_op_symbol = symbol_temp_new_now ();
 887   emit_expr (&exp, 4);                          /* Code offset */
 888 #else
 889   exp.X_op = O_symbol;
 890   exp.X_add_symbol = fde->start_address;
 891   exp.X_op_symbol = NULL;
 892 #ifdef tc_cfi_emit_pcrel_expr
 893   tc_cfi_emit_pcrel_expr (&exp, 4);             /* Code offset */
 894 #else
 895   emit_expr (&exp, 4);                          /* Code offset */
 896 #endif
 897   exp.X_op = O_subtract;
 898 #endif
 899
 900   exp.X_add_symbol = fde->end_address;
 901   exp.X_op_symbol = fde->start_address;         /* Code length */
 902   emit_expr (&exp, 4);
 903
 904   out_uleb128 (0);                              /* Augmentation size */
 905
 906   for (; first; first = first->next)
 907     output_cfi_insn (first);
 908
 909   if (align)
 910     frag_align (align, 0, 0);
 911   symbol_set_value_now (end_address);
 912 }
 913
 914 static struct cie_entry *
 915 select_cie_for_fde (struct fde_entry *fde, struct cfi_insn_data **pfirst)
 916 {
 917   struct cfi_insn_data *i, *j;
 918   struct cie_entry *cie;
 919
 920   for (cie = cie_root; cie; cie = cie->next)
 921     {
 922       if (cie->return_column != fde->return_column)
 923         continue;
 924       for (i = cie->first, j = fde->data;
 925            i != cie->last && j != NULL;
 926            i = i->next, j = j->next)
 927         {
 928           if (i->insn != j->insn)
 929             goto fail;
 930           switch (i->insn)
 931             {
 932             case DW_CFA_advance_loc:
 933               /* We reached the first advance in the FDE, but did not
 934                  reach the end of the CIE list.  */
 935               goto fail;
 936
 937             case DW_CFA_offset:
 938             case DW_CFA_def_cfa:
 939               if (i->u.ri.reg != j->u.ri.reg)
 940                 goto fail;
 941               if (i->u.ri.offset != j->u.ri.offset)
 942                 goto fail;
 943               break;
 944
 945             case DW_CFA_register:
 946               if (i->u.rr.reg1 != j->u.rr.reg1)
 947                 goto fail;
 948               if (i->u.rr.reg2 != j->u.rr.reg2)
 949                 goto fail;
 950               break;
 951
 952             case DW_CFA_def_cfa_register:
 953             case DW_CFA_restore:
 954             case DW_CFA_undefined:
 955             case DW_CFA_same_value:
 956               if (i->u.r != j->u.r)
 957                 goto fail;
 958               break;
 959
 960             case DW_CFA_def_cfa_offset:
 961               if (i->u.i != j->u.i)
 962                 goto fail;
 963               break;
 964
 965             case CFI_escape:
 966               /* Don't bother matching these for now.  */
 967               goto fail;
 968
 969             default:
 970               abort ();
 971             }
 972         }
 973
 974       /* Success if we reached the end of the CIE list, and we've either
 975          run out of FDE entries or we've encountered an advance.  */
 976       if (i == cie->last && (!j || j->insn == DW_CFA_advance_loc))
 977         {
 978           *pfirst = j;
 979           return cie;
 980         }
 981
 982     fail:;
 983     }
 984
 985   cie = xmalloc (sizeof (struct cie_entry));
 986   cie->next = cie_root;
 987   cie_root = cie;
 988   cie->return_column = fde->return_column;
 989   cie->first = fde->data;
 990
 991   for (i = cie->first; i ; i = i->next)
 992     if (i->insn == DW_CFA_advance_loc)
 993       break;
 994
 995   cie->last = i;
 996   *pfirst = i;
 997
 998   output_cie (cie);
 999
1000   return cie;
1001 }
1002
1003 void
1004 cfi_finish (void)
1005 {
1006   segT cfi_seg;
1007   struct fde_entry *fde;
1008   int save_flag_traditional_format;
1009
1010   if (cur_fde_data)
1011     {
1012       as_bad (_("open CFI at the end of file; missing .cfi_endproc directive"));
1013       cur_fde_data->end_address = cur_fde_data->start_address;
1014     }
1015
1016   if (all_fde_data == 0)
1017     return;
1018
1019   /* Open .eh_frame section.  */
1020   cfi_seg = subseg_new (".eh_frame", 0);
1021 #ifdef BFD_ASSEMBLER
1022   bfd_set_section_flags (stdoutput, cfi_seg,
1023                          SEC_ALLOC | SEC_LOAD | SEC_DATA | SEC_READONLY);
1024 #endif
1025   subseg_set (cfi_seg, 0);
1026   record_alignment (cfi_seg, EH_FRAME_ALIGNMENT);
1027
1028   /* Make sure check_eh_frame doesn't do anything with our output.  */
1029   save_flag_traditional_format = flag_traditional_format;
1030   flag_traditional_format = 1;
1031
1032   for (fde = all_fde_data; fde ; fde = fde->next)
1033     {
1034       struct cfi_insn_data *first;
1035       struct cie_entry *cie;
1036
1037       cie = select_cie_for_fde (fde, &first);
1038       output_fde (fde, cie, first, fde->next == NULL ? EH_FRAME_ALIGNMENT : 0);
1039     }
1040
1041   flag_traditional_format = save_flag_traditional_format;
1042 }