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 tc_cfi_frame_initial_instructions
  45 # define tc_cfi_frame_initial_instructions() ((void)0)
  46 #endif
  47
  48
  49 struct cfi_insn_data
  50 {
  51   struct cfi_insn_data *next;
  52   int insn;
  53   union {
  54     struct {
  55       unsigned reg;
  56       offsetT offset;
  57     } ri;
  58
  59     struct {
  60       unsigned reg1;
  61       unsigned reg2;
  62     } rr;
  63
  64     unsigned r;
  65     offsetT i;
  66
  67     struct {
  68       symbolS *lab1;
  69       symbolS *lab2;
  70     } ll;
  71   } u;
  72 };
  73
  74 struct fde_entry
  75 {
  76   struct fde_entry *next;
  77   symbolS *start_address;
  78   symbolS *end_address;
  79   struct cfi_insn_data *data;
  80   struct cfi_insn_data **last;
  81   unsigned int return_column;
  82 };
  83
  84 struct cie_entry
  85 {
  86   struct cie_entry *next;
  87   symbolS *start_address;
  88   unsigned int return_column;
  89   struct cfi_insn_data *first, *last;
  90 };
  91
  92
  93 /* Current open FDE entry.  */
  94 static struct fde_entry *cur_fde_data;
  95 static symbolS *last_address;
  96 static offsetT cur_cfa_offset;
  97
  98 /* List of FDE entries.  */
  99 static struct fde_entry *all_fde_data;
 100 static struct fde_entry **last_fde_data = &all_fde_data;
 101
 102 /* List of CIEs so that they could be reused.  */
 103 static struct cie_entry *cie_root;
 104
 105 \f
 106 /* Construct a new FDE structure and add it to the end of the fde list.  */
 107
 108 static struct fde_entry *
 109 alloc_fde_entry (void)
 110 {
 111   struct fde_entry *fde = xcalloc (1, sizeof (struct fde_entry));
 112
 113   cur_fde_data = fde;
 114   *last_fde_data = fde;
 115   last_fde_data = &fde->next;
 116
 117   fde->last = &fde->data;
 118   fde->return_column = DWARF2_DEFAULT_RETURN_COLUMN;
 119
 120   return fde;
 121 }
 122
 123 /* The following functions are available for a backend to construct its
 124    own unwind information, usually from legacy unwind directives.  */
 125
 126 /* Construct a new INSN structure and add it to the end of the insn list
 127    for the currently active FDE.  */
 128
 129 static struct cfi_insn_data *
 130 alloc_cfi_insn_data (void)
 131 {
 132   struct cfi_insn_data *insn = xcalloc (1, sizeof (struct cfi_insn_data));
 133
 134   *cur_fde_data->last = insn;
 135   cur_fde_data->last = &insn->next;
 136
 137   return insn;
 138 }
 139
 140 /* Construct a new FDE structure that begins at LABEL.  */
 141
 142 void
 143 cfi_new_fde (symbolS *label)
 144 {
 145   struct fde_entry *fde = alloc_fde_entry ();
 146   fde->start_address = label;
 147   last_address = label;
 148 }
 149
 150 /* End the currently open FDE.  */
 151
 152 void
 153 cfi_end_fde (symbolS *label)
 154 {
 155   cur_fde_data->end_address = label;
 156   cur_fde_data = NULL;
 157 }
 158
 159 /* Set the return column for the current FDE.  */
 160
 161 void
 162 cfi_set_return_column (unsigned regno)
 163 {
 164   cur_fde_data->return_column = regno;
 165 }
 166
 167 /* Add a CFI insn to advance the PC from the last address to LABEL.  */
 168
 169 void
 170 cfi_add_advance_loc (symbolS *label)
 171 {
 172   struct cfi_insn_data *insn = alloc_cfi_insn_data ();
 173
 174   insn->insn = DW_CFA_advance_loc;
 175   insn->u.ll.lab1 = last_address;
 176   insn->u.ll.lab2 = label;
 177
 178   last_address = label;
 179 }
 180
 181 /* Add a DW_CFA_offset record to the CFI data.  */
 182
 183 void
 184 cfi_add_CFA_offset (unsigned regno, offsetT offset)
 185 {
 186   struct cfi_insn_data *insn = alloc_cfi_insn_data ();
 187
 188   insn->insn = DW_CFA_offset;
 189   insn->u.ri.reg = regno;
 190   insn->u.ri.offset = offset;
 191 }
 192
 193 /* Add a DW_CFA_def_cfa record to the CFI data.  */
 194
 195 void
 196 cfi_add_CFA_def_cfa (unsigned regno, offsetT offset)
 197 {
 198   struct cfi_insn_data *insn = alloc_cfi_insn_data ();
 199
 200   insn->insn = DW_CFA_def_cfa;
 201   insn->u.ri.reg = regno;
 202   insn->u.ri.offset = offset;
 203
 204   cur_cfa_offset = offset;
 205 }
 206
 207 /* Add a DW_CFA_register record to the CFI data.  */
 208
 209 void
 210 cfi_add_CFA_register (unsigned reg1, unsigned reg2)
 211 {
 212   struct cfi_insn_data *insn = alloc_cfi_insn_data ();
 213
 214   insn->insn = DW_CFA_register;
 215   insn->u.rr.reg1 = reg1;
 216   insn->u.rr.reg2 = reg2;
 217 }
 218
 219 /* Add a DW_CFA_def_cfa_register record to the CFI data.  */
 220
 221 void
 222 cfi_add_CFA_def_cfa_register (unsigned regno)
 223 {
 224   struct cfi_insn_data *insn = alloc_cfi_insn_data ();
 225
 226   insn->insn = DW_CFA_def_cfa_register;
 227   insn->u.r = regno;
 228 }
 229
 230 /* Add a DW_CFA_def_cfa_offset record to the CFI data.  */
 231
 232 void
 233 cfi_add_CFA_def_cfa_offset (offsetT offset)
 234 {
 235   struct cfi_insn_data *insn = alloc_cfi_insn_data ();
 236
 237   insn->insn = DW_CFA_def_cfa_offset;
 238   insn->u.i = offset;
 239
 240   cur_cfa_offset = offset;
 241 }
 242
 243 \f
 244 /* Parse CFI assembler directives.  */
 245
 246 static void dot_cfi (int);
 247 static void dot_cfi_startproc (int);
 248 static void dot_cfi_endproc (int);
 249
 250 /* Fake CFI type; outside the byte range of any real CFI insn.  */
 251 #define CFI_adjust_cfa_offset 0x100
 252
 253 const pseudo_typeS cfi_pseudo_table[] =
 254   {
 255     { "cfi_startproc", dot_cfi_startproc, 0 },
 256     { "cfi_endproc", dot_cfi_endproc, 0 },
 257     { "cfi_def_cfa", dot_cfi, DW_CFA_def_cfa },
 258     { "cfi_def_cfa_register", dot_cfi, DW_CFA_def_cfa_register },
 259     { "cfi_def_cfa_offset", dot_cfi, DW_CFA_def_cfa_offset },
 260     { "cfi_adjust_cfa_offset", dot_cfi, CFI_adjust_cfa_offset },
 261     { "cfi_offset", dot_cfi, DW_CFA_offset },
 262     { "cfi_register", dot_cfi, DW_CFA_register },
 263     { NULL, NULL, 0 }
 264   };
 265
 266 static void
 267 cfi_parse_separator (void)
 268 {
 269   SKIP_WHITESPACE ();
 270   if (*input_line_pointer == ',')
 271     input_line_pointer++;
 272   else
 273     as_bad (_("missing separator"));
 274 }
 275
 276 static unsigned
 277 cfi_parse_reg (void)
 278 {
 279   int regno;
 280   expressionS exp;
 281
 282 #ifdef tc_regname_to_dw2regnum
 283   SKIP_WHITESPACE ();
 284   if (is_name_beginner (*input_line_pointer)
 285       || (*input_line_pointer == '%'
 286           && is_name_beginner (*++input_line_pointer)))
 287     {
 288       char *name, c;
 289
 290       name = input_line_pointer;
 291       c = get_symbol_end ();
 292
 293       if ((regno = tc_regname_to_dw2regnum (name)) < 0)
 294         {
 295           as_bad (_("bad register expression"));
 296           regno = 0;
 297         }
 298
 299       *input_line_pointer = c;
 300       return regno;
 301     }
 302 #endif
 303
 304   expression (&exp);
 305   switch (exp.X_op)
 306     {
 307     case O_register:
 308     case O_constant:
 309       regno = exp.X_add_number;
 310       break;
 311
 312     default:
 313       as_bad (_("bad register expression"));
 314       regno = 0;
 315       break;
 316     }
 317
 318   return regno;
 319 }
 320
 321 static offsetT
 322 cfi_parse_const (void)
 323 {
 324   return get_absolute_expression ();
 325 }
 326
 327 static void
 328 dot_cfi (int arg)
 329 {
 330   offsetT offset;
 331   unsigned reg1, reg2;
 332
 333   if (!cur_fde_data)
 334     {
 335       as_bad (_("CFI instruction used without previous .cfi_startproc"));
 336       return;
 337     }
 338
 339   /* If the last address was not at the current PC, advance to current.  */
 340   if (symbol_get_frag (last_address) != frag_now
 341       || S_GET_VALUE (last_address) != frag_now_fix ())
 342     cfi_add_advance_loc (symbol_temp_new_now ());
 343
 344   switch (arg)
 345     {
 346       /* Instructions that take two arguments (register, integer). */
 347     case DW_CFA_offset:
 348     case DW_CFA_def_cfa:
 349       reg1 = cfi_parse_reg ();
 350       cfi_parse_separator ();
 351       offset = cfi_parse_const ();
 352
 353       if (arg == DW_CFA_def_cfa)
 354         cfi_add_CFA_def_cfa (reg1, offset);
 355       else
 356         cfi_add_CFA_offset (reg1, offset);
 357       break;
 358
 359       /* Instructions that take two arguments (register, register). */
 360     case DW_CFA_register:
 361       reg1 = cfi_parse_reg ();
 362       cfi_parse_separator ();
 363       reg2 = cfi_parse_reg ();
 364
 365       cfi_add_CFA_register (reg1, reg2);
 366       break;
 367
 368       /* Instructions that take one register argument.  */
 369     case DW_CFA_def_cfa_register:
 370       reg1 = cfi_parse_reg ();
 371       cfi_add_CFA_def_cfa_register (reg1);
 372       break;
 373
 374       /* Instructions that take one integer argument.  */
 375     case DW_CFA_def_cfa_offset:
 376       offset = cfi_parse_const ();
 377       cfi_add_CFA_def_cfa_offset (offset);
 378       break;
 379
 380       /* Special handling for pseudo-instruction.  */
 381     case CFI_adjust_cfa_offset:
 382       offset = cfi_parse_const ();
 383       cfi_add_CFA_def_cfa_offset (cur_cfa_offset + offset);
 384       break;
 385
 386     default:
 387       abort ();
 388     }
 389
 390   demand_empty_rest_of_line ();
 391 }
 392
 393 static void
 394 dot_cfi_startproc (int ignored ATTRIBUTE_UNUSED)
 395 {
 396   int simple = 0;
 397
 398   if (cur_fde_data)
 399     {
 400       as_bad (_("previous CFI entry not closed (missing .cfi_endproc)"));
 401       return;
 402     }
 403
 404   cfi_new_fde (symbol_temp_new_now ());
 405
 406   SKIP_WHITESPACE ();
 407   if (is_name_beginner (*input_line_pointer))
 408     {
 409       char *name, c;
 410
 411       name = input_line_pointer;
 412       c = get_symbol_end ();
 413
 414       if (strcmp (name, "simple") == 0)
 415         {
 416           simple = 1;
 417           *input_line_pointer = c;
 418         }
 419       else
 420         input_line_pointer = name;
 421     }
 422   demand_empty_rest_of_line ();
 423
 424   if (!simple)
 425     tc_cfi_frame_initial_instructions ();
 426 }
 427
 428 static void
 429 dot_cfi_endproc (int ignored ATTRIBUTE_UNUSED)
 430 {
 431   if (! cur_fde_data)
 432     {
 433       as_bad (_(".cfi_endproc without corresponding .cfi_startproc"));
 434       return;
 435     }
 436
 437   cfi_end_fde (symbol_temp_new_now ());
 438 }
 439
 440 \f
 441 /* Emit a single byte into the current segment.  */
 442
 443 static inline void
 444 out_one (int byte)
 445 {
 446   FRAG_APPEND_1_CHAR (byte);
 447 }
 448
 449 /* Emit a two-byte word into the current segment.  */
 450
 451 static inline void
 452 out_two (int data)
 453 {
 454   md_number_to_chars (frag_more (2), data, 2);
 455 }
 456
 457 /* Emit a four byte word into the current segment.  */
 458
 459 static inline void
 460 out_four (int data)
 461 {
 462   md_number_to_chars (frag_more (4), data, 4);
 463 }
 464
 465 /* Emit an unsigned "little-endian base 128" number.  */
 466
 467 static void
 468 out_uleb128 (addressT value)
 469 {
 470   output_leb128 (frag_more (sizeof_leb128 (value, 0)), value, 0);
 471 }
 472
 473 /* Emit an unsigned "little-endian base 128" number.  */
 474
 475 static void
 476 out_sleb128 (offsetT value)
 477 {
 478   output_leb128 (frag_more (sizeof_leb128 (value, 1)), value, 1);
 479 }
 480
 481 static void
 482 output_cfi_insn (struct cfi_insn_data *insn)
 483 {
 484   offsetT offset;
 485   unsigned int regno;
 486
 487   switch (insn->insn)
 488     {
 489     case DW_CFA_advance_loc:
 490       {
 491         symbolS *from = insn->u.ll.lab1;
 492         symbolS *to = insn->u.ll.lab2;
 493
 494         if (symbol_get_frag (to) == symbol_get_frag (from))
 495           {
 496             addressT delta = S_GET_VALUE (to) - S_GET_VALUE (from);
 497             addressT scaled = delta / DWARF2_LINE_MIN_INSN_LENGTH;
 498
 499             if (scaled <= 0x3F)
 500               out_one (DW_CFA_advance_loc + scaled);
 501             else if (delta <= 0xFF)
 502               {
 503                 out_one (DW_CFA_advance_loc1);
 504                 out_one (delta);
 505               }
 506             else if (delta <= 0xFFFF)
 507               {
 508                 out_one (DW_CFA_advance_loc2);
 509                 out_two (delta);
 510               }
 511             else
 512               {
 513                 out_one (DW_CFA_advance_loc4);
 514                 out_four (delta);
 515               }
 516           }
 517         else
 518           {
 519             expressionS exp;
 520
 521             exp.X_op = O_subtract;
 522             exp.X_add_symbol = to;
 523             exp.X_op_symbol = from;
 524             exp.X_add_number = 0;
 525
 526             /* The code in ehopt.c expects that one byte of the encoding
 527                is already allocated to the frag.  This comes from the way
 528                that it scans the .eh_frame section looking first for the
 529                .byte DW_CFA_advance_loc4.  */
 530             frag_more (1);
 531
 532             frag_var (rs_cfa, 4, 0, DWARF2_LINE_MIN_INSN_LENGTH << 3,
 533                       make_expr_symbol (&exp), frag_now_fix () - 1,
 534                       (char *) frag_now);
 535           }
 536       }
 537       break;
 538
 539     case DW_CFA_def_cfa:
 540       offset = insn->u.ri.offset;
 541       if (offset < 0)
 542         {
 543           out_one (DW_CFA_def_cfa_sf);
 544           out_uleb128 (insn->u.ri.reg);
 545           out_uleb128 (offset);
 546         }
 547       else
 548         {
 549           out_one (DW_CFA_def_cfa);
 550           out_uleb128 (insn->u.ri.reg);
 551           out_uleb128 (offset);
 552         }
 553       break;
 554
 555     case DW_CFA_def_cfa_register:
 556       out_one (DW_CFA_def_cfa_register);
 557       out_uleb128 (insn->u.i);
 558       break;
 559
 560     case DW_CFA_def_cfa_offset:
 561       offset = insn->u.i;
 562       if (offset < 0)
 563         {
 564           out_one (DW_CFA_def_cfa_offset_sf);
 565           out_sleb128 (offset);
 566         }
 567       else
 568         {
 569           out_one (DW_CFA_def_cfa_offset);
 570           out_uleb128 (offset);
 571         }
 572       break;
 573
 574     case DW_CFA_offset:
 575       regno = insn->u.ri.reg;
 576       offset = insn->u.ri.offset / DWARF2_CIE_DATA_ALIGNMENT;
 577       if (offset < 0)
 578         {
 579           out_one (DW_CFA_offset_extended);
 580           out_uleb128 (regno);
 581           out_sleb128 (offset);
 582         }
 583       else if (regno <= 0x3F)
 584         {
 585           out_one (DW_CFA_offset + regno);
 586           out_uleb128 (offset);
 587         }
 588       else
 589         {
 590           out_one (DW_CFA_offset_extended);
 591           out_uleb128 (regno);
 592           out_uleb128 (offset);
 593         }
 594       break;
 595
 596     case DW_CFA_register:
 597       out_one (DW_CFA_register);
 598       out_uleb128 (insn->u.rr.reg1);
 599       out_uleb128 (insn->u.rr.reg2);
 600       break;
 601
 602     case DW_CFA_nop:
 603       out_one (DW_CFA_nop);
 604       break;
 605
 606     default:
 607       abort ();
 608     }
 609 }
 610
 611 static void
 612 output_cie (struct cie_entry *cie)
 613 {
 614   symbolS *after_size_address, *end_address;
 615   expressionS exp;
 616   struct cfi_insn_data *i;
 617
 618   cie->start_address = symbol_temp_new_now ();
 619   after_size_address = symbol_temp_make ();
 620   end_address = symbol_temp_make ();
 621
 622   exp.X_op = O_subtract;
 623   exp.X_add_symbol = end_address;
 624   exp.X_op_symbol = after_size_address;
 625   exp.X_add_number = 0;
 626
 627   emit_expr (&exp, 4);                          /* Length */
 628   symbol_set_value_now (after_size_address);
 629   out_four (0);                                 /* CIE id */
 630   out_one (DW_CIE_VERSION);                     /* Version */
 631   out_one ('z');                                /* Augmentation */
 632   out_one ('R');
 633   out_one (0);
 634   out_uleb128 (DWARF2_LINE_MIN_INSN_LENGTH);    /* Code alignment */
 635   out_sleb128 (DWARF2_CIE_DATA_ALIGNMENT);      /* Data alignment */
 636   out_one (cie->return_column);                 /* Return column */
 637   out_uleb128 (1);                              /* Augmentation size */
 638   out_one (DW_EH_PE_pcrel | DW_EH_PE_sdata4);
 639
 640   if (cie->first)
 641     for (i = cie->first; i != cie->last; i = i->next)
 642       output_cfi_insn (i);
 643
 644   frag_align (2, 0, 0);
 645   symbol_set_value_now (end_address);
 646 }
 647
 648 static void
 649 output_fde (struct fde_entry *fde, struct cie_entry *cie,
 650             struct cfi_insn_data *first)
 651 {
 652   symbolS *after_size_address, *end_address;
 653   expressionS exp;
 654
 655   after_size_address = symbol_temp_make ();
 656   end_address = symbol_temp_make ();
 657
 658   exp.X_op = O_subtract;
 659   exp.X_add_symbol = end_address;
 660   exp.X_op_symbol = after_size_address;
 661   exp.X_add_number = 0;
 662   emit_expr (&exp, 4);                          /* Length */
 663   symbol_set_value_now (after_size_address);
 664
 665   exp.X_add_symbol = after_size_address;
 666   exp.X_op_symbol = cie->start_address;
 667   emit_expr (&exp, 4);                          /* CIE offset */
 668
 669   exp.X_add_symbol = fde->start_address;
 670   exp.X_op_symbol = symbol_temp_new_now ();
 671   emit_expr (&exp, 4);                          /* Code offset */
 672
 673   exp.X_add_symbol = fde->end_address;
 674   exp.X_op_symbol = fde->start_address;         /* Code length */
 675   emit_expr (&exp, 4);
 676
 677   out_uleb128 (0);                              /* Augmentation size */
 678
 679   for (; first; first = first->next)
 680     output_cfi_insn (first);
 681
 682   frag_align (2, 0, 0);
 683   symbol_set_value_now (end_address);
 684 }
 685
 686 static struct cie_entry *
 687 select_cie_for_fde (struct fde_entry *fde, struct cfi_insn_data **pfirst)
 688 {
 689   struct cfi_insn_data *i, *j;
 690   struct cie_entry *cie;
 691
 692   for (cie = cie_root; cie; cie = cie->next)
 693     {
 694       if (cie->return_column != fde->return_column)
 695         continue;
 696       for (i = cie->first, j = fde->data;
 697            i != cie->last && j != NULL;
 698            i = i->next, j = j->next)
 699         {
 700           if (i->insn != j->insn)
 701             goto fail;
 702           switch (i->insn)
 703             {
 704             case DW_CFA_advance_loc:
 705               /* We reached the first advance in the FDE, but did not
 706                  reach the end of the CIE list.  */
 707               goto fail;
 708
 709             case DW_CFA_offset:
 710             case DW_CFA_def_cfa:
 711               if (i->u.ri.reg != j->u.ri.reg)
 712                 goto fail;
 713               if (i->u.ri.offset != j->u.ri.offset)
 714                 goto fail;
 715               break;
 716
 717             case DW_CFA_register:
 718               if (i->u.rr.reg1 != j->u.rr.reg1)
 719                 goto fail;
 720               if (i->u.rr.reg2 != j->u.rr.reg2)
 721                 goto fail;
 722               break;
 723
 724             case DW_CFA_def_cfa_register:
 725               if (i->u.r != j->u.r)
 726                 goto fail;
 727               break;
 728
 729             case DW_CFA_def_cfa_offset:
 730               if (i->u.i != j->u.i)
 731                 goto fail;
 732               break;
 733
 734             default:
 735               abort ();
 736             }
 737         }
 738
 739       /* Success if we reached the end of the CIE list, and we've either
 740          run out of FDE entries or we've encountered an advance.  */
 741       if (i == cie->last && (!j || j->insn == DW_CFA_advance_loc))
 742         {
 743           *pfirst = j;
 744           return cie;
 745         }
 746
 747     fail:;
 748     }
 749
 750   cie = xmalloc (sizeof (struct cie_entry));
 751   cie->next = cie_root;
 752   cie_root = cie;
 753   cie->return_column = fde->return_column;
 754   cie->first = fde->data;
 755
 756   for (i = cie->first; i ; i = i->next)
 757     if (i->insn == DW_CFA_advance_loc)
 758       break;
 759
 760   cie->last = i;
 761   *pfirst = i;
 762
 763   output_cie (cie);
 764
 765   return cie;
 766 }
 767
 768 void
 769 cfi_finish (void)
 770 {
 771   segT cfi_seg;
 772   struct fde_entry *fde;
 773   int save_flag_traditional_format;
 774
 775   if (cur_fde_data)
 776     {
 777       as_bad (_("open CFI at the end of file; missing .cfi_endproc directive"));
 778       cur_fde_data->end_address = cur_fde_data->start_address;
 779     }
 780
 781   if (all_fde_data == 0)
 782     return;
 783
 784   /* Open .eh_frame section.  */
 785   cfi_seg = subseg_new (".eh_frame", 0);
 786 #ifdef BFD_ASSEMBLER
 787   bfd_set_section_flags (stdoutput, cfi_seg,
 788                          SEC_ALLOC | SEC_LOAD | SEC_DATA | SEC_READONLY);
 789 #endif
 790   subseg_set (cfi_seg, 0);
 791   record_alignment (cfi_seg, 2);
 792
 793   /* Make sure check_eh_frame doesn't do anything with our output.  */
 794   save_flag_traditional_format = flag_traditional_format;
 795   flag_traditional_format = 1;
 796
 797   for (fde = all_fde_data; fde ; fde = fde->next)
 798     {
 799       struct cfi_insn_data *first;
 800       struct cie_entry *cie;
 801
 802       cie = select_cie_for_fde (fde, &first);
 803       output_fde (fde, cie, first);
 804     }
 805
 806   flag_traditional_format = save_flag_traditional_format;
 807 }