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