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