gas/dw2gencfi.c

   1 /* dw2gencfi.c - Support for generating Dwarf2 CFI information.
   2    Copyright 2003, 2004, 2005 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   else
 345     as_bad (_("CFI state restore without previous remember"));
 346 }
 347
 348 \f
 349 /* Parse CFI assembler directives.  */
 350
 351 static void dot_cfi (int);
 352 static void dot_cfi_escape (int);
 353 static void dot_cfi_startproc (int);
 354 static void dot_cfi_endproc (int);
 355
 356 /* Fake CFI type; outside the byte range of any real CFI insn.  */
 357 #define CFI_adjust_cfa_offset   0x100
 358 #define CFI_return_column       0x101
 359 #define CFI_rel_offset          0x102
 360 #define CFI_escape              0x103
 361
 362 const pseudo_typeS cfi_pseudo_table[] =
 363   {
 364     { "cfi_startproc", dot_cfi_startproc, 0 },
 365     { "cfi_endproc", dot_cfi_endproc, 0 },
 366     { "cfi_def_cfa", dot_cfi, DW_CFA_def_cfa },
 367     { "cfi_def_cfa_register", dot_cfi, DW_CFA_def_cfa_register },
 368     { "cfi_def_cfa_offset", dot_cfi, DW_CFA_def_cfa_offset },
 369     { "cfi_adjust_cfa_offset", dot_cfi, CFI_adjust_cfa_offset },
 370     { "cfi_offset", dot_cfi, DW_CFA_offset },
 371     { "cfi_rel_offset", dot_cfi, CFI_rel_offset },
 372     { "cfi_register", dot_cfi, DW_CFA_register },
 373     { "cfi_return_column", dot_cfi, CFI_return_column },
 374     { "cfi_restore", dot_cfi, DW_CFA_restore },
 375     { "cfi_undefined", dot_cfi, DW_CFA_undefined },
 376     { "cfi_same_value", dot_cfi, DW_CFA_same_value },
 377     { "cfi_remember_state", dot_cfi, DW_CFA_remember_state },
 378     { "cfi_restore_state", dot_cfi, DW_CFA_restore_state },
 379     { "cfi_window_save", dot_cfi, DW_CFA_GNU_window_save },
 380     { "cfi_escape", dot_cfi_escape, 0 },
 381     { NULL, NULL, 0 }
 382   };
 383
 384 static void
 385 cfi_parse_separator (void)
 386 {
 387   SKIP_WHITESPACE ();
 388   if (*input_line_pointer == ',')
 389     input_line_pointer++;
 390   else
 391     as_bad (_("missing separator"));
 392 }
 393
 394 static unsigned
 395 cfi_parse_reg (void)
 396 {
 397   int regno;
 398   expressionS exp;
 399
 400 #ifdef tc_regname_to_dw2regnum
 401   SKIP_WHITESPACE ();
 402   if (is_name_beginner (*input_line_pointer)
 403       || (*input_line_pointer == '%'
 404           && is_name_beginner (*++input_line_pointer)))
 405     {
 406       char *name, c;
 407
 408       name = input_line_pointer;
 409       c = get_symbol_end ();
 410
 411       if ((regno = tc_regname_to_dw2regnum (name)) < 0)
 412         {
 413           as_bad (_("bad register expression"));
 414           regno = 0;
 415         }
 416
 417       *input_line_pointer = c;
 418       return regno;
 419     }
 420 #endif
 421
 422   expression (&exp);
 423   switch (exp.X_op)
 424     {
 425     case O_register:
 426     case O_constant:
 427       regno = exp.X_add_number;
 428       break;
 429
 430     default:
 431       as_bad (_("bad register expression"));
 432       regno = 0;
 433       break;
 434     }
 435
 436   return regno;
 437 }
 438
 439 static offsetT
 440 cfi_parse_const (void)
 441 {
 442   return get_absolute_expression ();
 443 }
 444
 445 static void
 446 dot_cfi (int arg)
 447 {
 448   offsetT offset;
 449   unsigned reg1, reg2;
 450
 451   if (!cur_fde_data)
 452     {
 453       as_bad (_("CFI instruction used without previous .cfi_startproc"));
 454       return;
 455     }
 456
 457   /* If the last address was not at the current PC, advance to current.  */
 458   if (symbol_get_frag (last_address) != frag_now
 459       || S_GET_VALUE (last_address) != frag_now_fix ())
 460     cfi_add_advance_loc (symbol_temp_new_now ());
 461
 462   switch (arg)
 463     {
 464     case DW_CFA_offset:
 465       reg1 = cfi_parse_reg ();
 466       cfi_parse_separator ();
 467       offset = cfi_parse_const ();
 468       cfi_add_CFA_offset (reg1, offset);
 469       break;
 470
 471     case CFI_rel_offset:
 472       reg1 = cfi_parse_reg ();
 473       cfi_parse_separator ();
 474       offset = cfi_parse_const ();
 475       cfi_add_CFA_offset (reg1, offset - cur_cfa_offset);
 476       break;
 477
 478     case DW_CFA_def_cfa:
 479       reg1 = cfi_parse_reg ();
 480       cfi_parse_separator ();
 481       offset = cfi_parse_const ();
 482       cfi_add_CFA_def_cfa (reg1, offset);
 483       break;
 484
 485     case DW_CFA_register:
 486       reg1 = cfi_parse_reg ();
 487       cfi_parse_separator ();
 488       reg2 = cfi_parse_reg ();
 489       cfi_add_CFA_register (reg1, reg2);
 490       break;
 491
 492     case DW_CFA_def_cfa_register:
 493       reg1 = cfi_parse_reg ();
 494       cfi_add_CFA_def_cfa_register (reg1);
 495       break;
 496
 497     case DW_CFA_def_cfa_offset:
 498       offset = cfi_parse_const ();
 499       cfi_add_CFA_def_cfa_offset (offset);
 500       break;
 501
 502     case CFI_adjust_cfa_offset:
 503       offset = cfi_parse_const ();
 504       cfi_add_CFA_def_cfa_offset (cur_cfa_offset + offset);
 505       break;
 506
 507     case DW_CFA_restore:
 508       reg1 = cfi_parse_reg ();
 509       cfi_add_CFA_restore (reg1);
 510       break;
 511
 512     case DW_CFA_undefined:
 513       reg1 = cfi_parse_reg ();
 514       cfi_add_CFA_undefined (reg1);
 515       break;
 516
 517     case DW_CFA_same_value:
 518       reg1 = cfi_parse_reg ();
 519       cfi_add_CFA_same_value (reg1);
 520       break;
 521
 522     case CFI_return_column:
 523       reg1 = cfi_parse_reg ();
 524       cfi_set_return_column (reg1);
 525       break;
 526
 527     case DW_CFA_remember_state:
 528       cfi_add_CFA_remember_state ();
 529       break;
 530
 531     case DW_CFA_restore_state:
 532       cfi_add_CFA_restore_state ();
 533       break;
 534
 535     case DW_CFA_GNU_window_save:
 536       cfi_add_CFA_insn (DW_CFA_GNU_window_save);
 537       break;
 538
 539     default:
 540       abort ();
 541     }
 542
 543   demand_empty_rest_of_line ();
 544 }
 545
 546 static void
 547 dot_cfi_escape (int ignored ATTRIBUTE_UNUSED)
 548 {
 549   struct cfi_escape_data *head, **tail, *e;
 550   struct cfi_insn_data *insn;
 551
 552   if (!cur_fde_data)
 553     {
 554       as_bad (_("CFI instruction used without previous .cfi_startproc"));
 555       return;
 556     }
 557
 558   /* If the last address was not at the current PC, advance to current.  */
 559   if (symbol_get_frag (last_address) != frag_now
 560       || S_GET_VALUE (last_address) != frag_now_fix ())
 561     cfi_add_advance_loc (symbol_temp_new_now ());
 562
 563   tail = &head;
 564   do
 565     {
 566       e = xmalloc (sizeof (*e));
 567       do_parse_cons_expression (&e->exp, 1);
 568       *tail = e;
 569       tail = &e->next;
 570     }
 571   while (*input_line_pointer++ == ',');
 572   *tail = NULL;
 573
 574   insn = alloc_cfi_insn_data ();
 575   insn->insn = CFI_escape;
 576   insn->u.esc = head;
 577 }
 578
 579 static void
 580 dot_cfi_startproc (int ignored ATTRIBUTE_UNUSED)
 581 {
 582   int simple = 0;
 583
 584   if (cur_fde_data)
 585     {
 586       as_bad (_("previous CFI entry not closed (missing .cfi_endproc)"));
 587       return;
 588     }
 589
 590   cfi_new_fde (symbol_temp_new_now ());
 591
 592   SKIP_WHITESPACE ();
 593   if (is_name_beginner (*input_line_pointer))
 594     {
 595       char *name, c;
 596
 597       name = input_line_pointer;
 598       c = get_symbol_end ();
 599
 600       if (strcmp (name, "simple") == 0)
 601         {
 602           simple = 1;
 603           *input_line_pointer = c;
 604         }
 605       else
 606         input_line_pointer = name;
 607     }
 608   demand_empty_rest_of_line ();
 609
 610   cur_cfa_offset = 0;
 611   if (!simple)
 612     tc_cfi_frame_initial_instructions ();
 613 }
 614
 615 static void
 616 dot_cfi_endproc (int ignored ATTRIBUTE_UNUSED)
 617 {
 618   if (! cur_fde_data)
 619     {
 620       as_bad (_(".cfi_endproc without corresponding .cfi_startproc"));
 621       return;
 622     }
 623
 624   cfi_end_fde (symbol_temp_new_now ());
 625 }
 626
 627 \f
 628 /* Emit a single byte into the current segment.  */
 629
 630 static inline void
 631 out_one (int byte)
 632 {
 633   FRAG_APPEND_1_CHAR (byte);
 634 }
 635
 636 /* Emit a two-byte word into the current segment.  */
 637
 638 static inline void
 639 out_two (int data)
 640 {
 641   md_number_to_chars (frag_more (2), data, 2);
 642 }
 643
 644 /* Emit a four byte word into the current segment.  */
 645
 646 static inline void
 647 out_four (int data)
 648 {
 649   md_number_to_chars (frag_more (4), data, 4);
 650 }
 651
 652 /* Emit an unsigned "little-endian base 128" number.  */
 653
 654 static void
 655 out_uleb128 (addressT value)
 656 {
 657   output_leb128 (frag_more (sizeof_leb128 (value, 0)), value, 0);
 658 }
 659
 660 /* Emit an unsigned "little-endian base 128" number.  */
 661
 662 static void
 663 out_sleb128 (offsetT value)
 664 {
 665   output_leb128 (frag_more (sizeof_leb128 (value, 1)), value, 1);
 666 }
 667
 668 static void
 669 output_cfi_insn (struct cfi_insn_data *insn)
 670 {
 671   offsetT offset;
 672   unsigned int regno;
 673
 674   switch (insn->insn)
 675     {
 676     case DW_CFA_advance_loc:
 677       {
 678         symbolS *from = insn->u.ll.lab1;
 679         symbolS *to = insn->u.ll.lab2;
 680
 681         if (symbol_get_frag (to) == symbol_get_frag (from))
 682           {
 683             addressT delta = S_GET_VALUE (to) - S_GET_VALUE (from);
 684             addressT scaled = delta / DWARF2_LINE_MIN_INSN_LENGTH;
 685
 686             if (scaled <= 0x3F)
 687               out_one (DW_CFA_advance_loc + scaled);
 688             else if (delta <= 0xFF)
 689               {
 690                 out_one (DW_CFA_advance_loc1);
 691                 out_one (delta);
 692               }
 693             else if (delta <= 0xFFFF)
 694               {
 695                 out_one (DW_CFA_advance_loc2);
 696                 out_two (delta);
 697               }
 698             else
 699               {
 700                 out_one (DW_CFA_advance_loc4);
 701                 out_four (delta);
 702               }
 703           }
 704         else
 705           {
 706             expressionS exp;
 707
 708             exp.X_op = O_subtract;
 709             exp.X_add_symbol = to;
 710             exp.X_op_symbol = from;
 711             exp.X_add_number = 0;
 712
 713             /* The code in ehopt.c expects that one byte of the encoding
 714                is already allocated to the frag.  This comes from the way
 715                that it scans the .eh_frame section looking first for the
 716                .byte DW_CFA_advance_loc4.  */
 717             frag_more (1);
 718
 719             frag_var (rs_cfa, 4, 0, DWARF2_LINE_MIN_INSN_LENGTH << 3,
 720                       make_expr_symbol (&exp), frag_now_fix () - 1,
 721                       (char *) frag_now);
 722           }
 723       }
 724       break;
 725
 726     case DW_CFA_def_cfa:
 727       offset = insn->u.ri.offset;
 728       if (offset < 0)
 729         {
 730           out_one (DW_CFA_def_cfa_sf);
 731           out_uleb128 (insn->u.ri.reg);
 732           out_sleb128 (offset / DWARF2_CIE_DATA_ALIGNMENT);
 733         }
 734       else
 735         {
 736           out_one (DW_CFA_def_cfa);
 737           out_uleb128 (insn->u.ri.reg);
 738           out_uleb128 (offset);
 739         }
 740       break;
 741
 742     case DW_CFA_def_cfa_register:
 743     case DW_CFA_undefined:
 744     case DW_CFA_same_value:
 745       out_one (insn->insn);
 746       out_uleb128 (insn->u.r);
 747       break;
 748
 749     case DW_CFA_def_cfa_offset:
 750       offset = insn->u.i;
 751       if (offset < 0)
 752         {
 753           out_one (DW_CFA_def_cfa_offset_sf);
 754           out_sleb128 (offset / DWARF2_CIE_DATA_ALIGNMENT);
 755         }
 756       else
 757         {
 758           out_one (DW_CFA_def_cfa_offset);
 759           out_uleb128 (offset);
 760         }
 761       break;
 762
 763     case DW_CFA_restore:
 764       regno = insn->u.r;
 765       if (regno <= 0x3F)
 766         {
 767           out_one (DW_CFA_restore + regno);
 768         }
 769       else
 770         {
 771           out_one (DW_CFA_restore_extended);
 772           out_uleb128 (regno);
 773         }
 774       break;
 775
 776     case DW_CFA_offset:
 777       regno = insn->u.ri.reg;
 778       offset = insn->u.ri.offset / DWARF2_CIE_DATA_ALIGNMENT;
 779       if (offset < 0)
 780         {
 781           out_one (DW_CFA_offset_extended_sf);
 782           out_uleb128 (regno);
 783           out_sleb128 (offset);
 784         }
 785       else if (regno <= 0x3F)
 786         {
 787           out_one (DW_CFA_offset + regno);
 788           out_uleb128 (offset);
 789         }
 790       else
 791         {
 792           out_one (DW_CFA_offset_extended);
 793           out_uleb128 (regno);
 794           out_uleb128 (offset);
 795         }
 796       break;
 797
 798     case DW_CFA_register:
 799       out_one (DW_CFA_register);
 800       out_uleb128 (insn->u.rr.reg1);
 801       out_uleb128 (insn->u.rr.reg2);
 802       break;
 803
 804     case DW_CFA_remember_state:
 805     case DW_CFA_restore_state:
 806       out_one (insn->insn);
 807       break;
 808
 809     case DW_CFA_GNU_window_save:
 810       out_one (DW_CFA_GNU_window_save);
 811       break;
 812
 813     case CFI_escape:
 814       {
 815         struct cfi_escape_data *e;
 816         for (e = insn->u.esc; e ; e = e->next)
 817           emit_expr (&e->exp, 1);
 818         break;
 819       }
 820
 821     default:
 822       abort ();
 823     }
 824 }
 825
 826 static void
 827 output_cie (struct cie_entry *cie)
 828 {
 829   symbolS *after_size_address, *end_address;
 830   expressionS exp;
 831   struct cfi_insn_data *i;
 832
 833   cie->start_address = symbol_temp_new_now ();
 834   after_size_address = symbol_temp_make ();
 835   end_address = symbol_temp_make ();
 836
 837   exp.X_op = O_subtract;
 838   exp.X_add_symbol = end_address;
 839   exp.X_op_symbol = after_size_address;
 840   exp.X_add_number = 0;
 841
 842   emit_expr (&exp, 4);                          /* Length.  */
 843   symbol_set_value_now (after_size_address);
 844   out_four (0);                                 /* CIE id.  */
 845   out_one (DW_CIE_VERSION);                     /* Version.  */
 846   out_one ('z');                                /* Augmentation.  */
 847   out_one ('R');
 848   out_one (0);
 849   out_uleb128 (DWARF2_LINE_MIN_INSN_LENGTH);    /* Code alignment.  */
 850   out_sleb128 (DWARF2_CIE_DATA_ALIGNMENT);      /* Data alignment.  */
 851   if (DW_CIE_VERSION == 1)                      /* Return column.  */
 852     out_one (cie->return_column);
 853   else
 854     out_uleb128 (cie->return_column);
 855   out_uleb128 (1);                              /* Augmentation size.  */
 856 #if defined DIFF_EXPR_OK || defined tc_cfi_emit_pcrel_expr
 857   out_one (DW_EH_PE_pcrel | DW_EH_PE_sdata4);
 858 #else
 859   out_one (DW_EH_PE_sdata4);
 860 #endif
 861
 862   if (cie->first)
 863     for (i = cie->first; i != cie->last; i = i->next)
 864       output_cfi_insn (i);
 865
 866   frag_align (2, DW_CFA_nop, 0);
 867   symbol_set_value_now (end_address);
 868 }
 869
 870 static void
 871 output_fde (struct fde_entry *fde, struct cie_entry *cie,
 872             struct cfi_insn_data *first, int align)
 873 {
 874   symbolS *after_size_address, *end_address;
 875   expressionS exp;
 876
 877   after_size_address = symbol_temp_make ();
 878   end_address = symbol_temp_make ();
 879
 880   exp.X_op = O_subtract;
 881   exp.X_add_symbol = end_address;
 882   exp.X_op_symbol = after_size_address;
 883   exp.X_add_number = 0;
 884   emit_expr (&exp, 4);                          /* Length.  */
 885   symbol_set_value_now (after_size_address);
 886
 887   exp.X_add_symbol = after_size_address;
 888   exp.X_op_symbol = cie->start_address;
 889   emit_expr (&exp, 4);                          /* CIE offset.  */
 890
 891 #ifdef DIFF_EXPR_OK
 892   exp.X_add_symbol = fde->start_address;
 893   exp.X_op_symbol = symbol_temp_new_now ();
 894   emit_expr (&exp, 4);                          /* Code offset.  */
 895 #else
 896   exp.X_op = O_symbol;
 897   exp.X_add_symbol = fde->start_address;
 898   exp.X_op_symbol = NULL;
 899 #ifdef tc_cfi_emit_pcrel_expr
 900   tc_cfi_emit_pcrel_expr (&exp, 4);             /* Code offset.  */
 901 #else
 902   emit_expr (&exp, 4);                          /* Code offset.  */
 903 #endif
 904   exp.X_op = O_subtract;
 905 #endif
 906
 907   exp.X_add_symbol = fde->end_address;
 908   exp.X_op_symbol = fde->start_address;         /* Code length.  */
 909   emit_expr (&exp, 4);
 910
 911   out_uleb128 (0);                              /* Augmentation size.  */
 912
 913   for (; first; first = first->next)
 914     output_cfi_insn (first);
 915
 916   frag_align (align, DW_CFA_nop, 0);
 917   symbol_set_value_now (end_address);
 918 }
 919
 920 static struct cie_entry *
 921 select_cie_for_fde (struct fde_entry *fde, struct cfi_insn_data **pfirst)
 922 {
 923   struct cfi_insn_data *i, *j;
 924   struct cie_entry *cie;
 925
 926   for (cie = cie_root; cie; cie = cie->next)
 927     {
 928       if (cie->return_column != fde->return_column)
 929         continue;
 930       for (i = cie->first, j = fde->data;
 931            i != cie->last && j != NULL;
 932            i = i->next, j = j->next)
 933         {
 934           if (i->insn != j->insn)
 935             goto fail;
 936           switch (i->insn)
 937             {
 938             case DW_CFA_advance_loc:
 939             case DW_CFA_remember_state:
 940               /* We reached the first advance/remember in the FDE,
 941                  but did not reach the end of the CIE list.  */
 942               goto fail;
 943
 944             case DW_CFA_offset:
 945             case DW_CFA_def_cfa:
 946               if (i->u.ri.reg != j->u.ri.reg)
 947                 goto fail;
 948               if (i->u.ri.offset != j->u.ri.offset)
 949                 goto fail;
 950               break;
 951
 952             case DW_CFA_register:
 953               if (i->u.rr.reg1 != j->u.rr.reg1)
 954                 goto fail;
 955               if (i->u.rr.reg2 != j->u.rr.reg2)
 956                 goto fail;
 957               break;
 958
 959             case DW_CFA_def_cfa_register:
 960             case DW_CFA_restore:
 961             case DW_CFA_undefined:
 962             case DW_CFA_same_value:
 963               if (i->u.r != j->u.r)
 964                 goto fail;
 965               break;
 966
 967             case DW_CFA_def_cfa_offset:
 968               if (i->u.i != j->u.i)
 969                 goto fail;
 970               break;
 971
 972             case CFI_escape:
 973               /* Don't bother matching these for now.  */
 974               goto fail;
 975
 976             default:
 977               abort ();
 978             }
 979         }
 980
 981       /* Success if we reached the end of the CIE list, and we've either
 982          run out of FDE entries or we've encountered an advance,
 983          remember, or escape.  */
 984       if (i == cie->last
 985           && (!j
 986               || j->insn == DW_CFA_advance_loc
 987               || j->insn == DW_CFA_remember_state
 988               || j->insn == CFI_escape))
 989         {
 990           *pfirst = j;
 991           return cie;
 992         }
 993
 994     fail:;
 995     }
 996
 997   cie = xmalloc (sizeof (struct cie_entry));
 998   cie->next = cie_root;
 999   cie_root = cie;
1000   cie->return_column = fde->return_column;
1001   cie->first = fde->data;
1002
1003   for (i = cie->first; i ; i = i->next)
1004     if (i->insn == DW_CFA_advance_loc
1005         || i->insn == DW_CFA_remember_state
1006         || i->insn == CFI_escape)
1007       break;
1008
1009   cie->last = i;
1010   *pfirst = i;
1011
1012   output_cie (cie);
1013
1014   return cie;
1015 }
1016
1017 void
1018 cfi_finish (void)
1019 {
1020   segT cfi_seg;
1021   struct fde_entry *fde;
1022   int save_flag_traditional_format;
1023
1024   if (cur_fde_data)
1025     {
1026       as_bad (_("open CFI at the end of file; missing .cfi_endproc directive"));
1027       cur_fde_data->end_address = cur_fde_data->start_address;
1028     }
1029
1030   if (all_fde_data == 0)
1031     return;
1032
1033   /* Open .eh_frame section.  */
1034   cfi_seg = subseg_new (".eh_frame", 0);
1035 #ifdef BFD_ASSEMBLER
1036   bfd_set_section_flags (stdoutput, cfi_seg,
1037                          SEC_ALLOC | SEC_LOAD | SEC_DATA | SEC_READONLY);
1038 #endif
1039   subseg_set (cfi_seg, 0);
1040   record_alignment (cfi_seg, EH_FRAME_ALIGNMENT);
1041
1042   /* Make sure check_eh_frame doesn't do anything with our output.  */
1043   save_flag_traditional_format = flag_traditional_format;
1044   flag_traditional_format = 1;
1045
1046   for (fde = all_fde_data; fde ; fde = fde->next)
1047     {
1048       struct cfi_insn_data *first;
1049       struct cie_entry *cie;
1050
1051       cie = select_cie_for_fde (fde, &first);
1052       output_fde (fde, cie, first, fde->next == NULL ? EH_FRAME_ALIGNMENT : 2);
1053     }
1054
1055   flag_traditional_format = save_flag_traditional_format;
1056 }