gold/dwarf_reader.cc

   1 // dwarf_reader.cc -- parse dwarf2/3 debug information
   2
   3 // Copyright (C) 2007-2018 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 #include "gold.h"
  24
  25 #include <algorithm>
  26 #include <utility>
  27 #include <vector>
  28
  29 #include "elfcpp_swap.h"
  30 #include "dwarf.h"
  31 #include "object.h"
  32 #include "reloc.h"
  33 #include "dwarf_reader.h"
  34 #include "int_encoding.h"
  35 #include "compressed_output.h"
  36
  37 namespace gold {
  38
  39 // Class Sized_elf_reloc_mapper
  40
  41 // Initialize the relocation tracker for section RELOC_SHNDX.
  42
  43 template<int size, bool big_endian>
  44 bool
  45 Sized_elf_reloc_mapper<size, big_endian>::do_initialize(
  46     unsigned int reloc_shndx, unsigned int reloc_type)
  47 {
  48   this->reloc_type_ = reloc_type;
  49   return this->track_relocs_.initialize(this->object_, reloc_shndx,
  50                                         reloc_type);
  51 }
  52
  53 // Looks in the symtab to see what section a symbol is in.
  54
  55 template<int size, bool big_endian>
  56 unsigned int
  57 Sized_elf_reloc_mapper<size, big_endian>::symbol_section(
  58     unsigned int symndx, Address* value, bool* is_ordinary)
  59 {
  60   const int symsize = elfcpp::Elf_sizes<size>::sym_size;
  61   gold_assert(static_cast<off_t>((symndx + 1) * symsize) <= this->symtab_size_);
  62   elfcpp::Sym<size, big_endian> elfsym(this->symtab_ + symndx * symsize);
  63   *value = elfsym.get_st_value();
  64   return this->object_->adjust_sym_shndx(symndx, elfsym.get_st_shndx(),
  65                                          is_ordinary);
  66 }
  67
  68 // Return the section index and offset within the section of
  69 // the target of the relocation for RELOC_OFFSET.
  70
  71 template<int size, bool big_endian>
  72 unsigned int
  73 Sized_elf_reloc_mapper<size, big_endian>::do_get_reloc_target(
  74     off_t reloc_offset, off_t* target_offset)
  75 {
  76   this->track_relocs_.advance(reloc_offset);
  77   if (reloc_offset != this->track_relocs_.next_offset())
  78     return 0;
  79   unsigned int symndx = this->track_relocs_.next_symndx();
  80   typename elfcpp::Elf_types<size>::Elf_Addr value;
  81   bool is_ordinary;
  82   unsigned int target_shndx = this->symbol_section(symndx, &value,
  83                                                    &is_ordinary);
  84   if (!is_ordinary)
  85     return 0;
  86   if (this->reloc_type_ == elfcpp::SHT_RELA)
  87     value += this->track_relocs_.next_addend();
  88   *target_offset = value;
  89   return target_shndx;
  90 }
  91
  92 static inline Elf_reloc_mapper*
  93 make_elf_reloc_mapper(Relobj* object, const unsigned char* symtab,
  94                       off_t symtab_size)
  95 {
  96   if (object->elfsize() == 32)
  97     {
  98       if (object->is_big_endian())
  99         {
 100 #ifdef HAVE_TARGET_32_BIG
 101           return new Sized_elf_reloc_mapper<32, true>(object, symtab,
 102                                                       symtab_size);
 103 #else
 104           gold_unreachable();
 105 #endif
 106         }
 107       else
 108         {
 109 #ifdef HAVE_TARGET_32_LITTLE
 110           return new Sized_elf_reloc_mapper<32, false>(object, symtab,
 111                                                        symtab_size);
 112 #else
 113           gold_unreachable();
 114 #endif
 115         }
 116     }
 117   else if (object->elfsize() == 64)
 118     {
 119       if (object->is_big_endian())
 120         {
 121 #ifdef HAVE_TARGET_64_BIG
 122           return new Sized_elf_reloc_mapper<64, true>(object, symtab,
 123                                                       symtab_size);
 124 #else
 125           gold_unreachable();
 126 #endif
 127         }
 128       else
 129         {
 130 #ifdef HAVE_TARGET_64_LITTLE
 131           return new Sized_elf_reloc_mapper<64, false>(object, symtab,
 132                                                        symtab_size);
 133 #else
 134           gold_unreachable();
 135 #endif
 136         }
 137     }
 138   else
 139     gold_unreachable();
 140 }
 141
 142 // class Dwarf_abbrev_table
 143
 144 void
 145 Dwarf_abbrev_table::clear_abbrev_codes()
 146 {
 147   for (unsigned int code = 0; code < this->low_abbrev_code_max_; ++code)
 148     {
 149       if (this->low_abbrev_codes_[code] != NULL)
 150         {
 151           delete this->low_abbrev_codes_[code];
 152           this->low_abbrev_codes_[code] = NULL;
 153         }
 154     }
 155   for (Abbrev_code_table::iterator it = this->high_abbrev_codes_.begin();
 156        it != this->high_abbrev_codes_.end();
 157        ++it)
 158     {
 159       if (it->second != NULL)
 160         delete it->second;
 161     }
 162   this->high_abbrev_codes_.clear();
 163 }
 164
 165 // Read the abbrev table from an object file.
 166
 167 bool
 168 Dwarf_abbrev_table::do_read_abbrevs(
 169     Relobj* object,
 170     unsigned int abbrev_shndx,
 171     off_t abbrev_offset)
 172 {
 173   this->clear_abbrev_codes();
 174
 175   // If we don't have relocations, abbrev_shndx will be 0, and
 176   // we'll have to hunt for the .debug_abbrev section.
 177   if (abbrev_shndx == 0 && this->abbrev_shndx_ > 0)
 178     abbrev_shndx = this->abbrev_shndx_;
 179   else if (abbrev_shndx == 0)
 180     {
 181       for (unsigned int i = 1; i < object->shnum(); ++i)
 182         {
 183           std::string name = object->section_name(i);
 184           if (name == ".debug_abbrev" || name == ".zdebug_abbrev")
 185             {
 186               abbrev_shndx = i;
 187               // Correct the offset.  For incremental update links, we have a
 188               // relocated offset that is relative to the output section, but
 189               // here we need an offset relative to the input section.
 190               abbrev_offset -= object->output_section_offset(i);
 191               break;
 192             }
 193         }
 194       if (abbrev_shndx == 0)
 195         return false;
 196     }
 197
 198   // Get the section contents and decompress if necessary.
 199   if (abbrev_shndx != this->abbrev_shndx_)
 200     {
 201       if (this->owns_buffer_ && this->buffer_ != NULL)
 202         {
 203           delete[] this->buffer_;
 204           this->owns_buffer_ = false;
 205         }
 206
 207       section_size_type buffer_size;
 208       this->buffer_ =
 209           object->decompressed_section_contents(abbrev_shndx,
 210                                                 &buffer_size,
 211                                                 &this->owns_buffer_);
 212       this->buffer_end_ = this->buffer_ + buffer_size;
 213       this->abbrev_shndx_ = abbrev_shndx;
 214     }
 215
 216   this->buffer_pos_ = this->buffer_ + abbrev_offset;
 217   return true;
 218 }
 219
 220 // Lookup the abbrev code entry for CODE.  This function is called
 221 // only when the abbrev code is not in the direct lookup table.
 222 // It may be in the hash table, it may not have been read yet,
 223 // or it may not exist in the abbrev table.
 224
 225 const Dwarf_abbrev_table::Abbrev_code*
 226 Dwarf_abbrev_table::do_get_abbrev(unsigned int code)
 227 {
 228   // See if the abbrev code is already in the hash table.
 229   Abbrev_code_table::const_iterator it = this->high_abbrev_codes_.find(code);
 230   if (it != this->high_abbrev_codes_.end())
 231     return it->second;
 232
 233   // Read and store abbrev code definitions until we find the
 234   // one we're looking for.
 235   for (;;)
 236     {
 237       // Read the abbrev code.  A zero here indicates the end of the
 238       // abbrev table.
 239       size_t len;
 240       if (this->buffer_pos_ >= this->buffer_end_)
 241         return NULL;
 242       uint64_t nextcode = read_unsigned_LEB_128(this->buffer_pos_, &len);
 243       if (nextcode == 0)
 244         {
 245           this->buffer_pos_ = this->buffer_end_;
 246           return NULL;
 247         }
 248       this->buffer_pos_ += len;
 249
 250       // Read the tag.
 251       if (this->buffer_pos_ >= this->buffer_end_)
 252         return NULL;
 253       uint64_t tag = read_unsigned_LEB_128(this->buffer_pos_, &len);
 254       this->buffer_pos_ += len;
 255
 256       // Read the has_children flag.
 257       if (this->buffer_pos_ >= this->buffer_end_)
 258         return NULL;
 259       bool has_children = *this->buffer_pos_ == elfcpp::DW_CHILDREN_yes;
 260       this->buffer_pos_ += 1;
 261
 262       // Read the list of (attribute, form) pairs.
 263       Abbrev_code* entry = new Abbrev_code(tag, has_children);
 264       for (;;)
 265         {
 266           // Read the attribute.
 267           if (this->buffer_pos_ >= this->buffer_end_)
 268             return NULL;
 269           uint64_t attr = read_unsigned_LEB_128(this->buffer_pos_, &len);
 270           this->buffer_pos_ += len;
 271
 272           // Read the form.
 273           if (this->buffer_pos_ >= this->buffer_end_)
 274             return NULL;
 275           uint64_t form = read_unsigned_LEB_128(this->buffer_pos_, &len);
 276           this->buffer_pos_ += len;
 277
 278           // A (0,0) pair terminates the list.
 279           if (attr == 0 && form == 0)
 280             break;
 281
 282           if (attr == elfcpp::DW_AT_sibling)
 283             entry->has_sibling_attribute = true;
 284
 285           entry->add_attribute(attr, form);
 286         }
 287
 288       this->store_abbrev(nextcode, entry);
 289       if (nextcode == code)
 290         return entry;
 291     }
 292
 293   return NULL;
 294 }
 295
 296 // class Dwarf_ranges_table
 297
 298 // Read the ranges table from an object file.
 299
 300 bool
 301 Dwarf_ranges_table::read_ranges_table(
 302     Relobj* object,
 303     const unsigned char* symtab,
 304     off_t symtab_size,
 305     unsigned int ranges_shndx)
 306 {
 307   // If we've already read this abbrev table, return immediately.
 308   if (this->ranges_shndx_ > 0
 309       && this->ranges_shndx_ == ranges_shndx)
 310     return true;
 311
 312   // If we don't have relocations, ranges_shndx will be 0, and
 313   // we'll have to hunt for the .debug_ranges section.
 314   if (ranges_shndx == 0 && this->ranges_shndx_ > 0)
 315     ranges_shndx = this->ranges_shndx_;
 316   else if (ranges_shndx == 0)
 317     {
 318       for (unsigned int i = 1; i < object->shnum(); ++i)
 319         {
 320           std::string name = object->section_name(i);
 321           if (name == ".debug_ranges" || name == ".zdebug_ranges")
 322             {
 323               ranges_shndx = i;
 324               this->output_section_offset_ = object->output_section_offset(i);
 325               break;
 326             }
 327         }
 328       if (ranges_shndx == 0)
 329         return false;
 330     }
 331
 332   // Get the section contents and decompress if necessary.
 333   if (ranges_shndx != this->ranges_shndx_)
 334     {
 335       if (this->owns_ranges_buffer_ && this->ranges_buffer_ != NULL)
 336         {
 337           delete[] this->ranges_buffer_;
 338           this->owns_ranges_buffer_ = false;
 339         }
 340
 341       section_size_type buffer_size;
 342       this->ranges_buffer_ =
 343           object->decompressed_section_contents(ranges_shndx,
 344                                                 &buffer_size,
 345                                                 &this->owns_ranges_buffer_);
 346       this->ranges_buffer_end_ = this->ranges_buffer_ + buffer_size;
 347       this->ranges_shndx_ = ranges_shndx;
 348     }
 349
 350   if (this->ranges_reloc_mapper_ != NULL)
 351     {
 352       delete this->ranges_reloc_mapper_;
 353       this->ranges_reloc_mapper_ = NULL;
 354     }
 355
 356   // For incremental objects, we have no relocations.
 357   if (object->is_incremental())
 358     return true;
 359
 360   // Find the relocation section for ".debug_ranges".
 361   unsigned int reloc_shndx = 0;
 362   unsigned int reloc_type = 0;
 363   for (unsigned int i = 0; i < object->shnum(); ++i)
 364     {
 365       reloc_type = object->section_type(i);
 366       if ((reloc_type == elfcpp::SHT_REL
 367            || reloc_type == elfcpp::SHT_RELA)
 368           && object->section_info(i) == ranges_shndx)
 369         {
 370           reloc_shndx = i;
 371           break;
 372         }
 373     }
 374
 375   this->ranges_reloc_mapper_ = make_elf_reloc_mapper(object, symtab,
 376                                                      symtab_size);
 377   this->ranges_reloc_mapper_->initialize(reloc_shndx, reloc_type);
 378   this->reloc_type_ = reloc_type;
 379
 380   return true;
 381 }
 382
 383 // Read a range list from section RANGES_SHNDX at offset RANGES_OFFSET.
 384
 385 Dwarf_range_list*
 386 Dwarf_ranges_table::read_range_list(
 387     Relobj* object,
 388     const unsigned char* symtab,
 389     off_t symtab_size,
 390     unsigned int addr_size,
 391     unsigned int ranges_shndx,
 392     off_t offset)
 393 {
 394   Dwarf_range_list* ranges;
 395
 396   if (!this->read_ranges_table(object, symtab, symtab_size, ranges_shndx))
 397     return NULL;
 398
 399   // Correct the offset.  For incremental update links, we have a
 400   // relocated offset that is relative to the output section, but
 401   // here we need an offset relative to the input section.
 402   offset -= this->output_section_offset_;
 403
 404   // Read the range list at OFFSET.
 405   ranges = new Dwarf_range_list();
 406   off_t base = 0;
 407   for (;
 408        this->ranges_buffer_ + offset < this->ranges_buffer_end_;
 409        offset += 2 * addr_size)
 410     {
 411       off_t start;
 412       off_t end;
 413
 414       // Read the raw contents of the section.
 415       if (addr_size == 4)
 416         {
 417           start = this->dwinfo_->read_from_pointer<32>(this->ranges_buffer_
 418                                                        + offset);
 419           end = this->dwinfo_->read_from_pointer<32>(this->ranges_buffer_
 420                                                      + offset + 4);
 421         }
 422       else
 423         {
 424           start = this->dwinfo_->read_from_pointer<64>(this->ranges_buffer_
 425                                                        + offset);
 426           end = this->dwinfo_->read_from_pointer<64>(this->ranges_buffer_
 427                                                      + offset + 8);
 428         }
 429
 430       // Check for relocations and adjust the values.
 431       unsigned int shndx1 = 0;
 432       unsigned int shndx2 = 0;
 433       if (this->ranges_reloc_mapper_ != NULL)
 434         {
 435           shndx1 = this->lookup_reloc(offset, &start);
 436           shndx2 = this->lookup_reloc(offset + addr_size, &end);
 437         }
 438
 439       // End of list is marked by a pair of zeroes.
 440       if (shndx1 == 0 && start == 0 && end == 0)
 441         break;
 442
 443       // A "base address selection entry" is identified by
 444       // 0xffffffff for the first value of the pair.  The second
 445       // value is used as a base for subsequent range list entries.
 446       if (shndx1 == 0 && start == -1)
 447         base = end;
 448       else if (shndx1 == shndx2)
 449         {
 450           if (shndx1 == 0 || object->is_section_included(shndx1))
 451             ranges->add(shndx1, base + start, base + end);
 452         }
 453       else
 454         gold_warning(_("%s: DWARF info may be corrupt; offsets in a "
 455                        "range list entry are in different sections"),
 456                      object->name().c_str());
 457     }
 458
 459   return ranges;
 460 }
 461
 462 // Look for a relocation at offset OFF in the range table,
 463 // and return the section index and offset of the target.
 464
 465 unsigned int
 466 Dwarf_ranges_table::lookup_reloc(off_t off, off_t* target_off)
 467 {
 468   off_t value;
 469   unsigned int shndx =
 470       this->ranges_reloc_mapper_->get_reloc_target(off, &value);
 471   if (shndx == 0)
 472     return 0;
 473   if (this->reloc_type_ == elfcpp::SHT_REL)
 474     *target_off += value;
 475   else
 476     *target_off = value;
 477   return shndx;
 478 }
 479
 480 // class Dwarf_pubnames_table
 481
 482 // Read the pubnames section from the object file.
 483
 484 bool
 485 Dwarf_pubnames_table::read_section(Relobj* object, const unsigned char* symtab,
 486                                    off_t symtab_size)
 487 {
 488   section_size_type buffer_size;
 489   unsigned int shndx = 0;
 490   const char* name = this->is_pubtypes_ ? "pubtypes" : "pubnames";
 491   const char* gnu_name = (this->is_pubtypes_
 492                           ? "gnu_pubtypes"
 493                           : "gnu_pubnames");
 494
 495   for (unsigned int i = 1; i < object->shnum(); ++i)
 496     {
 497       std::string section_name = object->section_name(i);
 498       const char* section_name_suffix = section_name.c_str();
 499       if (is_prefix_of(".debug_", section_name_suffix))
 500         section_name_suffix += 7;
 501       else if (is_prefix_of(".zdebug_", section_name_suffix))
 502         section_name_suffix += 8;
 503       else
 504         continue;
 505       if (strcmp(section_name_suffix, name) == 0)
 506         {
 507           shndx = i;
 508           break;
 509         }
 510       else if (strcmp(section_name_suffix, gnu_name) == 0)
 511         {
 512           shndx = i;
 513           this->is_gnu_style_ = true;
 514           break;
 515         }
 516     }
 517   if (shndx == 0)
 518     return false;
 519
 520   this->buffer_ = object->decompressed_section_contents(shndx,
 521                                                         &buffer_size,
 522                                                         &this->owns_buffer_);
 523   if (this->buffer_ == NULL)
 524     return false;
 525   this->buffer_end_ = this->buffer_ + buffer_size;
 526
 527   // For incremental objects, we have no relocations.
 528   if (object->is_incremental())
 529     return true;
 530
 531   // Find the relocation section
 532   unsigned int reloc_shndx = 0;
 533   unsigned int reloc_type = 0;
 534   for (unsigned int i = 0; i < object->shnum(); ++i)
 535     {
 536       reloc_type = object->section_type(i);
 537       if ((reloc_type == elfcpp::SHT_REL
 538            || reloc_type == elfcpp::SHT_RELA)
 539           && object->section_info(i) == shndx)
 540         {
 541           reloc_shndx = i;
 542           break;
 543         }
 544     }
 545
 546   this->reloc_mapper_ = make_elf_reloc_mapper(object, symtab, symtab_size);
 547   this->reloc_mapper_->initialize(reloc_shndx, reloc_type);
 548   this->reloc_type_ = reloc_type;
 549
 550   return true;
 551 }
 552
 553 // Read the header for the set at OFFSET.
 554
 555 bool
 556 Dwarf_pubnames_table::read_header(off_t offset)
 557 {
 558   // Make sure we have actually read the section.
 559   gold_assert(this->buffer_ != NULL);
 560
 561   if (offset < 0 || offset + 14 >= this->buffer_end_ - this->buffer_)
 562     return false;
 563
 564   const unsigned char* pinfo = this->buffer_ + offset;
 565
 566   // Read the unit_length field.
 567   uint64_t unit_length = this->dwinfo_->read_from_pointer<32>(pinfo);
 568   pinfo += 4;
 569   if (unit_length == 0xffffffff)
 570     {
 571       unit_length = this->dwinfo_->read_from_pointer<64>(pinfo);
 572       this->unit_length_ = unit_length + 12;
 573       pinfo += 8;
 574       this->offset_size_ = 8;
 575     }
 576   else
 577     {
 578       this->unit_length_ = unit_length + 4;
 579       this->offset_size_ = 4;
 580     }
 581   this->end_of_table_ = pinfo + unit_length;
 582
 583   // If unit_length is too big, maybe we should reject the whole table,
 584   // but in cases we know about, it seems OK to assume that the table
 585   // is valid through the actual end of the section.
 586   if (this->end_of_table_ > this->buffer_end_)
 587     this->end_of_table_ = this->buffer_end_;
 588
 589   // Check the version.
 590   unsigned int version = this->dwinfo_->read_from_pointer<16>(pinfo);
 591   pinfo += 2;
 592   if (version != 2)
 593     return false;
 594
 595   this->reloc_mapper_->get_reloc_target(pinfo - this->buffer_,
 596                                         &this->cu_offset_);
 597
 598   // Skip the debug_info_offset and debug_info_size fields.
 599   pinfo += 2 * this->offset_size_;
 600
 601   if (pinfo >= this->buffer_end_)
 602     return false;
 603
 604   this->pinfo_ = pinfo;
 605   return true;
 606 }
 607
 608 // Read the next name from the set.
 609
 610 const char*
 611 Dwarf_pubnames_table::next_name(uint8_t* flag_byte)
 612 {
 613   const unsigned char* pinfo = this->pinfo_;
 614
 615   // Check for end of list.  The table should be terminated by an
 616   // entry containing nothing but a DIE offset of 0.
 617   if (pinfo + this->offset_size_ >= this->end_of_table_)
 618     return NULL;
 619
 620   // Skip the offset within the CU.  If this is zero, but we're not
 621   // at the end of the table, then we have a real pubnames entry
 622   // whose DIE offset is 0 (likely to be a GCC bug).  Since we
 623   // don't actually use the DIE offset in building .gdb_index,
 624   // it's harmless.
 625   pinfo += this->offset_size_;
 626
 627   if (this->is_gnu_style_)
 628     *flag_byte = *pinfo++;
 629   else
 630     *flag_byte = 0;
 631
 632   // Return a pointer to the string at the current location,
 633   // and advance the pointer to the next entry.
 634   const char* ret = reinterpret_cast<const char*>(pinfo);
 635   while (pinfo < this->buffer_end_ && *pinfo != '\0')
 636     ++pinfo;
 637   if (pinfo < this->buffer_end_)
 638     ++pinfo;
 639
 640   this->pinfo_ = pinfo;
 641   return ret;
 642 }
 643
 644 // class Dwarf_die
 645
 646 Dwarf_die::Dwarf_die(
 647     Dwarf_info_reader* dwinfo,
 648     off_t die_offset,
 649     Dwarf_die* parent)
 650   : dwinfo_(dwinfo), parent_(parent), die_offset_(die_offset),
 651     child_offset_(0), sibling_offset_(0), abbrev_code_(NULL), attributes_(),
 652     attributes_read_(false), name_(NULL), name_off_(-1), linkage_name_(NULL),
 653     linkage_name_off_(-1), string_shndx_(0), specification_(0),
 654     abstract_origin_(0)
 655 {
 656   size_t len;
 657   const unsigned char* pdie = dwinfo->buffer_at_offset(die_offset);
 658   if (pdie == NULL)
 659     return;
 660   unsigned int code = read_unsigned_LEB_128(pdie, &len);
 661   if (code == 0)
 662     {
 663       if (parent != NULL)
 664         parent->set_sibling_offset(die_offset + len);
 665       return;
 666     }
 667   this->attr_offset_ = len;
 668
 669   // Lookup the abbrev code in the abbrev table.
 670   this->abbrev_code_ = dwinfo->get_abbrev(code);
 671 }
 672
 673 // Read all the attributes of the DIE.
 674
 675 bool
 676 Dwarf_die::read_attributes()
 677 {
 678   if (this->attributes_read_)
 679     return true;
 680
 681   gold_assert(this->abbrev_code_ != NULL);
 682
 683   const unsigned char* pdie =
 684       this->dwinfo_->buffer_at_offset(this->die_offset_);
 685   if (pdie == NULL)
 686     return false;
 687   const unsigned char* pattr = pdie + this->attr_offset_;
 688
 689   unsigned int nattr = this->abbrev_code_->attributes.size();
 690   this->attributes_.reserve(nattr);
 691   for (unsigned int i = 0; i < nattr; ++i)
 692     {
 693       size_t len;
 694       unsigned int attr = this->abbrev_code_->attributes[i].attr;
 695       unsigned int form = this->abbrev_code_->attributes[i].form;
 696       if (form == elfcpp::DW_FORM_indirect)
 697         {
 698           form = read_unsigned_LEB_128(pattr, &len);
 699           pattr += len;
 700         }
 701       off_t attr_off = this->die_offset_ + (pattr - pdie);
 702       bool ref_form = false;
 703       Attribute_value attr_value;
 704       attr_value.attr = attr;
 705       attr_value.form = form;
 706       attr_value.aux.shndx = 0;
 707       switch(form)
 708         {
 709           case elfcpp::DW_FORM_flag_present:
 710             attr_value.val.intval = 1;
 711             break;
 712           case elfcpp::DW_FORM_strp:
 713             {
 714               off_t str_off;
 715               if (this->dwinfo_->offset_size() == 4)
 716                 str_off = this->dwinfo_->read_from_pointer<32>(&pattr);
 717               else
 718                 str_off = this->dwinfo_->read_from_pointer<64>(&pattr);
 719               unsigned int shndx =
 720                   this->dwinfo_->lookup_reloc(attr_off, &str_off);
 721               attr_value.aux.shndx = shndx;
 722               attr_value.val.refval = str_off;
 723               break;
 724             }
 725           case elfcpp::DW_FORM_sec_offset:
 726             {
 727               off_t sec_off;
 728               if (this->dwinfo_->offset_size() == 4)
 729                 sec_off = this->dwinfo_->read_from_pointer<32>(&pattr);
 730               else
 731                 sec_off = this->dwinfo_->read_from_pointer<64>(&pattr);
 732               unsigned int shndx =
 733                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 734               attr_value.aux.shndx = shndx;
 735               attr_value.val.refval = sec_off;
 736               ref_form = true;
 737               break;
 738             }
 739           case elfcpp::DW_FORM_addr:
 740             {
 741               off_t sec_off;
 742               if (this->dwinfo_->address_size() == 4)
 743                 sec_off = this->dwinfo_->read_from_pointer<32>(&pattr);
 744               else
 745                 sec_off = this->dwinfo_->read_from_pointer<64>(&pattr);
 746               unsigned int shndx =
 747                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 748               attr_value.aux.shndx = shndx;
 749               attr_value.val.refval = sec_off;
 750               ref_form = true;
 751               break;
 752             }
 753           case elfcpp::DW_FORM_ref_addr:
 754             {
 755               off_t sec_off;
 756               if (this->dwinfo_->ref_addr_size() == 4)
 757                 sec_off = this->dwinfo_->read_from_pointer<32>(&pattr);
 758               else
 759                 sec_off = this->dwinfo_->read_from_pointer<64>(&pattr);
 760               unsigned int shndx =
 761                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 762               attr_value.aux.shndx = shndx;
 763               attr_value.val.refval = sec_off;
 764               ref_form = true;
 765               break;
 766             }
 767           case elfcpp::DW_FORM_block1:
 768             attr_value.aux.blocklen = *pattr++;
 769             attr_value.val.blockval = pattr;
 770             pattr += attr_value.aux.blocklen;
 771             break;
 772           case elfcpp::DW_FORM_block2:
 773             attr_value.aux.blocklen =
 774                 this->dwinfo_->read_from_pointer<16>(&pattr);
 775             attr_value.val.blockval = pattr;
 776             pattr += attr_value.aux.blocklen;
 777             break;
 778           case elfcpp::DW_FORM_block4:
 779             attr_value.aux.blocklen =
 780                 this->dwinfo_->read_from_pointer<32>(&pattr);
 781             attr_value.val.blockval = pattr;
 782             pattr += attr_value.aux.blocklen;
 783             break;
 784           case elfcpp::DW_FORM_block:
 785           case elfcpp::DW_FORM_exprloc:
 786             attr_value.aux.blocklen = read_unsigned_LEB_128(pattr, &len);
 787             attr_value.val.blockval = pattr + len;
 788             pattr += len + attr_value.aux.blocklen;
 789             break;
 790           case elfcpp::DW_FORM_data1:
 791           case elfcpp::DW_FORM_flag:
 792             attr_value.val.intval = *pattr++;
 793             break;
 794           case elfcpp::DW_FORM_ref1:
 795             attr_value.val.refval = *pattr++;
 796             ref_form = true;
 797             break;
 798           case elfcpp::DW_FORM_data2:
 799             attr_value.val.intval =
 800                 this->dwinfo_->read_from_pointer<16>(&pattr);
 801             break;
 802           case elfcpp::DW_FORM_ref2:
 803             attr_value.val.refval =
 804                 this->dwinfo_->read_from_pointer<16>(&pattr);
 805             ref_form = true;
 806             break;
 807           case elfcpp::DW_FORM_data4:
 808             {
 809               off_t sec_off;
 810               sec_off = this->dwinfo_->read_from_pointer<32>(&pattr);
 811               unsigned int shndx =
 812                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 813               attr_value.aux.shndx = shndx;
 814               attr_value.val.intval = sec_off;
 815               break;
 816             }
 817           case elfcpp::DW_FORM_ref4:
 818             {
 819               off_t sec_off;
 820               sec_off = this->dwinfo_->read_from_pointer<32>(&pattr);
 821               unsigned int shndx =
 822                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 823               attr_value.aux.shndx = shndx;
 824               attr_value.val.refval = sec_off;
 825               ref_form = true;
 826               break;
 827             }
 828           case elfcpp::DW_FORM_data8:
 829             {
 830               off_t sec_off;
 831               sec_off = this->dwinfo_->read_from_pointer<64>(&pattr);
 832               unsigned int shndx =
 833                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 834               attr_value.aux.shndx = shndx;
 835               attr_value.val.intval = sec_off;
 836               break;
 837             }
 838           case elfcpp::DW_FORM_ref_sig8:
 839             attr_value.val.uintval =
 840                 this->dwinfo_->read_from_pointer<64>(&pattr);
 841             break;
 842           case elfcpp::DW_FORM_ref8:
 843             {
 844               off_t sec_off;
 845               sec_off = this->dwinfo_->read_from_pointer<64>(&pattr);
 846               unsigned int shndx =
 847                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 848               attr_value.aux.shndx = shndx;
 849               attr_value.val.refval = sec_off;
 850               ref_form = true;
 851               break;
 852             }
 853           case elfcpp::DW_FORM_ref_udata:
 854             attr_value.val.refval = read_unsigned_LEB_128(pattr, &len);
 855             ref_form = true;
 856             pattr += len;
 857             break;
 858           case elfcpp::DW_FORM_udata:
 859           case elfcpp::DW_FORM_GNU_addr_index:
 860           case elfcpp::DW_FORM_GNU_str_index:
 861             attr_value.val.uintval = read_unsigned_LEB_128(pattr, &len);
 862             pattr += len;
 863             break;
 864           case elfcpp::DW_FORM_sdata:
 865             attr_value.val.intval = read_signed_LEB_128(pattr, &len);
 866             pattr += len;
 867             break;
 868           case elfcpp::DW_FORM_string:
 869             attr_value.val.stringval = reinterpret_cast<const char*>(pattr);
 870             len = strlen(attr_value.val.stringval);
 871             pattr += len + 1;
 872             break;
 873           default:
 874             return false;
 875         }
 876
 877       // Cache the most frequently-requested attributes.
 878       switch (attr)
 879         {
 880           case elfcpp::DW_AT_name:
 881             if (form == elfcpp::DW_FORM_string)
 882               this->name_ = attr_value.val.stringval;
 883             else if (form == elfcpp::DW_FORM_strp)
 884               {
 885                 // All indirect strings should refer to the same
 886                 // string section, so we just save the last one seen.
 887                 this->string_shndx_ = attr_value.aux.shndx;
 888                 this->name_off_ = attr_value.val.refval;
 889               }
 890             break;
 891           case elfcpp::DW_AT_linkage_name:
 892           case elfcpp::DW_AT_MIPS_linkage_name:
 893             if (form == elfcpp::DW_FORM_string)
 894               this->linkage_name_ = attr_value.val.stringval;
 895             else if (form == elfcpp::DW_FORM_strp)
 896               {
 897                 // All indirect strings should refer to the same
 898                 // string section, so we just save the last one seen.
 899                 this->string_shndx_ = attr_value.aux.shndx;
 900                 this->linkage_name_off_ = attr_value.val.refval;
 901               }
 902             break;
 903           case elfcpp::DW_AT_specification:
 904             if (ref_form)
 905               this->specification_ = attr_value.val.refval;
 906             break;
 907           case elfcpp::DW_AT_abstract_origin:
 908             if (ref_form)
 909               this->abstract_origin_ = attr_value.val.refval;
 910             break;
 911           case elfcpp::DW_AT_sibling:
 912             if (ref_form && attr_value.aux.shndx == 0)
 913               this->sibling_offset_ = attr_value.val.refval;
 914           default:
 915             break;
 916         }
 917
 918       this->attributes_.push_back(attr_value);
 919     }
 920
 921   // Now that we know where the next DIE begins, record the offset
 922   // to avoid later recalculation.
 923   if (this->has_children())
 924     this->child_offset_ = this->die_offset_ + (pattr - pdie);
 925   else
 926     this->sibling_offset_ = this->die_offset_ + (pattr - pdie);
 927
 928   this->attributes_read_ = true;
 929   return true;
 930 }
 931
 932 // Skip all the attributes of the DIE and return the offset of the next DIE.
 933
 934 off_t
 935 Dwarf_die::skip_attributes()
 936 {
 937   gold_assert(this->abbrev_code_ != NULL);
 938
 939   const unsigned char* pdie =
 940       this->dwinfo_->buffer_at_offset(this->die_offset_);
 941   if (pdie == NULL)
 942     return 0;
 943   const unsigned char* pattr = pdie + this->attr_offset_;
 944
 945   for (unsigned int i = 0; i < this->abbrev_code_->attributes.size(); ++i)
 946     {
 947       size_t len;
 948       unsigned int form = this->abbrev_code_->attributes[i].form;
 949       if (form == elfcpp::DW_FORM_indirect)
 950         {
 951           form = read_unsigned_LEB_128(pattr, &len);
 952           pattr += len;
 953         }
 954       switch(form)
 955         {
 956           case elfcpp::DW_FORM_flag_present:
 957             break;
 958           case elfcpp::DW_FORM_strp:
 959           case elfcpp::DW_FORM_sec_offset:
 960             pattr += this->dwinfo_->offset_size();
 961             break;
 962           case elfcpp::DW_FORM_addr:
 963             pattr += this->dwinfo_->address_size();
 964             break;
 965           case elfcpp::DW_FORM_ref_addr:
 966             pattr += this->dwinfo_->ref_addr_size();
 967             break;
 968           case elfcpp::DW_FORM_block1:
 969             pattr += 1 + *pattr;
 970             break;
 971           case elfcpp::DW_FORM_block2:
 972             {
 973               uint16_t block_size;
 974               block_size = this->dwinfo_->read_from_pointer<16>(&pattr);
 975               pattr += block_size;
 976               break;
 977             }
 978           case elfcpp::DW_FORM_block4:
 979             {
 980               uint32_t block_size;
 981               block_size = this->dwinfo_->read_from_pointer<32>(&pattr);
 982               pattr += block_size;
 983               break;
 984             }
 985           case elfcpp::DW_FORM_block:
 986           case elfcpp::DW_FORM_exprloc:
 987             {
 988               uint64_t block_size;
 989               block_size = read_unsigned_LEB_128(pattr, &len);
 990               pattr += len + block_size;
 991               break;
 992             }
 993           case elfcpp::DW_FORM_data1:
 994           case elfcpp::DW_FORM_ref1:
 995           case elfcpp::DW_FORM_flag:
 996             pattr += 1;
 997             break;
 998           case elfcpp::DW_FORM_data2:
 999           case elfcpp::DW_FORM_ref2:
1000             pattr += 2;
1001             break;
1002           case elfcpp::DW_FORM_data4:
1003           case elfcpp::DW_FORM_ref4:
1004             pattr += 4;
1005             break;
1006           case elfcpp::DW_FORM_data8:
1007           case elfcpp::DW_FORM_ref8:
1008           case elfcpp::DW_FORM_ref_sig8:
1009             pattr += 8;
1010             break;
1011           case elfcpp::DW_FORM_ref_udata:
1012           case elfcpp::DW_FORM_udata:
1013           case elfcpp::DW_FORM_GNU_addr_index:
1014           case elfcpp::DW_FORM_GNU_str_index:
1015             read_unsigned_LEB_128(pattr, &len);
1016             pattr += len;
1017             break;
1018           case elfcpp::DW_FORM_sdata:
1019             read_signed_LEB_128(pattr, &len);
1020             pattr += len;
1021             break;
1022           case elfcpp::DW_FORM_string:
1023             len = strlen(reinterpret_cast<const char*>(pattr));
1024             pattr += len + 1;
1025             break;
1026           default:
1027             return 0;
1028         }
1029     }
1030
1031   return this->die_offset_ + (pattr - pdie);
1032 }
1033
1034 // Get the name of the DIE and cache it.
1035
1036 void
1037 Dwarf_die::set_name()
1038 {
1039   if (this->name_ != NULL || !this->read_attributes())
1040     return;
1041   if (this->name_off_ != -1)
1042     this->name_ = this->dwinfo_->get_string(this->name_off_,
1043                                             this->string_shndx_);
1044 }
1045
1046 // Get the linkage name of the DIE and cache it.
1047
1048 void
1049 Dwarf_die::set_linkage_name()
1050 {
1051   if (this->linkage_name_ != NULL || !this->read_attributes())
1052     return;
1053   if (this->linkage_name_off_ != -1)
1054     this->linkage_name_ = this->dwinfo_->get_string(this->linkage_name_off_,
1055                                                     this->string_shndx_);
1056 }
1057
1058 // Return the value of attribute ATTR.
1059
1060 const Dwarf_die::Attribute_value*
1061 Dwarf_die::attribute(unsigned int attr)
1062 {
1063   if (!this->read_attributes())
1064     return NULL;
1065   for (unsigned int i = 0; i < this->attributes_.size(); ++i)
1066     {
1067       if (this->attributes_[i].attr == attr)
1068         return &this->attributes_[i];
1069     }
1070   return NULL;
1071 }
1072
1073 const char*
1074 Dwarf_die::string_attribute(unsigned int attr)
1075 {
1076   const Attribute_value* attr_val = this->attribute(attr);
1077   if (attr_val == NULL)
1078     return NULL;
1079   switch (attr_val->form)
1080     {
1081       case elfcpp::DW_FORM_string:
1082         return attr_val->val.stringval;
1083       case elfcpp::DW_FORM_strp:
1084         return this->dwinfo_->get_string(attr_val->val.refval,
1085                                          attr_val->aux.shndx);
1086       default:
1087         return NULL;
1088     }
1089 }
1090
1091 int64_t
1092 Dwarf_die::int_attribute(unsigned int attr)
1093 {
1094   const Attribute_value* attr_val = this->attribute(attr);
1095   if (attr_val == NULL)
1096     return 0;
1097   switch (attr_val->form)
1098     {
1099       case elfcpp::DW_FORM_flag_present:
1100       case elfcpp::DW_FORM_data1:
1101       case elfcpp::DW_FORM_flag:
1102       case elfcpp::DW_FORM_data2:
1103       case elfcpp::DW_FORM_data4:
1104       case elfcpp::DW_FORM_data8:
1105       case elfcpp::DW_FORM_sdata:
1106         return attr_val->val.intval;
1107       default:
1108         return 0;
1109     }
1110 }
1111
1112 uint64_t
1113 Dwarf_die::uint_attribute(unsigned int attr)
1114 {
1115   const Attribute_value* attr_val = this->attribute(attr);
1116   if (attr_val == NULL)
1117     return 0;
1118   switch (attr_val->form)
1119     {
1120       case elfcpp::DW_FORM_flag_present:
1121       case elfcpp::DW_FORM_data1:
1122       case elfcpp::DW_FORM_flag:
1123       case elfcpp::DW_FORM_data4:
1124       case elfcpp::DW_FORM_data8:
1125       case elfcpp::DW_FORM_ref_sig8:
1126       case elfcpp::DW_FORM_udata:
1127         return attr_val->val.uintval;
1128       default:
1129         return 0;
1130     }
1131 }
1132
1133 off_t
1134 Dwarf_die::ref_attribute(unsigned int attr, unsigned int* shndx)
1135 {
1136   const Attribute_value* attr_val = this->attribute(attr);
1137   if (attr_val == NULL)
1138     return -1;
1139   switch (attr_val->form)
1140     {
1141       case elfcpp::DW_FORM_sec_offset:
1142       case elfcpp::DW_FORM_addr:
1143       case elfcpp::DW_FORM_ref_addr:
1144       case elfcpp::DW_FORM_ref1:
1145       case elfcpp::DW_FORM_ref2:
1146       case elfcpp::DW_FORM_ref4:
1147       case elfcpp::DW_FORM_ref8:
1148       case elfcpp::DW_FORM_ref_udata:
1149         *shndx = attr_val->aux.shndx;
1150         return attr_val->val.refval;
1151       case elfcpp::DW_FORM_ref_sig8:
1152         *shndx = attr_val->aux.shndx;
1153         return attr_val->val.uintval;
1154       case elfcpp::DW_FORM_data4:
1155       case elfcpp::DW_FORM_data8:
1156         *shndx = attr_val->aux.shndx;
1157         return attr_val->val.intval;
1158       default:
1159         return -1;
1160     }
1161 }
1162
1163 off_t
1164 Dwarf_die::address_attribute(unsigned int attr, unsigned int* shndx)
1165 {
1166   const Attribute_value* attr_val = this->attribute(attr);
1167   if (attr_val == NULL || attr_val->form != elfcpp::DW_FORM_addr)
1168     return -1;
1169
1170   *shndx = attr_val->aux.shndx;
1171   return attr_val->val.refval;
1172 }
1173
1174 // Return the offset of this DIE's first child.
1175
1176 off_t
1177 Dwarf_die::child_offset()
1178 {
1179   gold_assert(this->abbrev_code_ != NULL);
1180   if (!this->has_children())
1181     return 0;
1182   if (this->child_offset_ == 0)
1183     this->child_offset_ = this->skip_attributes();
1184   return this->child_offset_;
1185 }
1186
1187 // Return the offset of this DIE's next sibling.
1188
1189 off_t
1190 Dwarf_die::sibling_offset()
1191 {
1192   gold_assert(this->abbrev_code_ != NULL);
1193
1194   if (this->sibling_offset_ != 0)
1195     return this->sibling_offset_;
1196
1197   if (!this->has_children())
1198     {
1199       this->sibling_offset_ = this->skip_attributes();
1200       return this->sibling_offset_;
1201     }
1202
1203   if (this->has_sibling_attribute())
1204     {
1205       if (!this->read_attributes())
1206         return 0;
1207       if (this->sibling_offset_ != 0)
1208         return this->sibling_offset_;
1209     }
1210
1211   // Skip over the children.
1212   off_t child_offset = this->child_offset();
1213   while (child_offset > 0)
1214     {
1215       Dwarf_die die(this->dwinfo_, child_offset, this);
1216       // The Dwarf_die ctor will set this DIE's sibling offset
1217       // when it reads a zero abbrev code.
1218       if (die.tag() == 0)
1219         break;
1220       child_offset = die.sibling_offset();
1221     }
1222
1223   // This should be set by now.  If not, there was a problem reading
1224   // the DWARF info, and we return 0.
1225   return this->sibling_offset_;
1226 }
1227
1228 // class Dwarf_info_reader
1229
1230 // Begin parsing the debug info.  This calls visit_compilation_unit()
1231 // or visit_type_unit() for each compilation or type unit found in the
1232 // section, and visit_die() for each top-level DIE.
1233
1234 void
1235 Dwarf_info_reader::parse()
1236 {
1237   if (this->object_->is_big_endian())
1238     {
1239 #if defined(HAVE_TARGET_32_BIG) || defined(HAVE_TARGET_64_BIG)
1240       this->do_parse<true>();
1241 #else
1242       gold_unreachable();
1243 #endif
1244     }
1245   else
1246     {
1247 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_64_LITTLE)
1248       this->do_parse<false>();
1249 #else
1250       gold_unreachable();
1251 #endif
1252     }
1253 }
1254
1255 template<bool big_endian>
1256 void
1257 Dwarf_info_reader::do_parse()
1258 {
1259   // Get the section contents and decompress if necessary.
1260   section_size_type buffer_size;
1261   bool buffer_is_new;
1262   this->buffer_ = this->object_->decompressed_section_contents(this->shndx_,
1263                                                                &buffer_size,
1264                                                                &buffer_is_new);
1265   if (this->buffer_ == NULL || buffer_size == 0)
1266     return;
1267   this->buffer_end_ = this->buffer_ + buffer_size;
1268
1269   // The offset of this input section in the output section.
1270   off_t section_offset = this->object_->output_section_offset(this->shndx_);
1271
1272   // Start tracking relocations for this section.
1273   this->reloc_mapper_ = make_elf_reloc_mapper(this->object_, this->symtab_,
1274                                               this->symtab_size_);
1275   this->reloc_mapper_->initialize(this->reloc_shndx_, this->reloc_type_);
1276
1277   // Loop over compilation units (or type units).
1278   unsigned int abbrev_shndx = this->abbrev_shndx_;
1279   off_t abbrev_offset = 0;
1280   const unsigned char* pinfo = this->buffer_;
1281   while (pinfo < this->buffer_end_)
1282     {
1283       // Read the compilation (or type) unit header.
1284       const unsigned char* cu_start = pinfo;
1285       this->cu_offset_ = cu_start - this->buffer_;
1286       this->cu_length_ = this->buffer_end_ - cu_start;
1287
1288       // Read unit_length (4 or 12 bytes).
1289       if (!this->check_buffer(pinfo + 4))
1290         break;
1291       uint32_t unit_length =
1292           elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo);
1293       pinfo += 4;
1294       if (unit_length == 0xffffffff)
1295         {
1296           if (!this->check_buffer(pinfo + 8))
1297             break;
1298           unit_length = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
1299           pinfo += 8;
1300           this->offset_size_ = 8;
1301         }
1302       else
1303         this->offset_size_ = 4;
1304       if (!this->check_buffer(pinfo + unit_length))
1305         break;
1306       const unsigned char* cu_end = pinfo + unit_length;
1307       this->cu_length_ = cu_end - cu_start;
1308       if (!this->check_buffer(pinfo + 2 + this->offset_size_ + 1))
1309         break;
1310
1311       // Read version (2 bytes).
1312       this->cu_version_ =
1313           elfcpp::Swap_unaligned<16, big_endian>::readval(pinfo);
1314       pinfo += 2;
1315
1316       // Read debug_abbrev_offset (4 or 8 bytes).
1317       if (this->offset_size_ == 4)
1318         abbrev_offset = elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo);
1319       else
1320         abbrev_offset = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
1321       if (this->reloc_shndx_ > 0)
1322         {
1323           off_t reloc_offset = pinfo - this->buffer_;
1324           off_t value;
1325           abbrev_shndx =
1326               this->reloc_mapper_->get_reloc_target(reloc_offset, &value);
1327           if (abbrev_shndx == 0)
1328             return;
1329           if (this->reloc_type_ == elfcpp::SHT_REL)
1330             abbrev_offset += value;
1331           else
1332             abbrev_offset = value;
1333         }
1334       pinfo += this->offset_size_;
1335
1336       // Read address_size (1 byte).
1337       this->address_size_ = *pinfo++;
1338
1339       // For type units, read the two extra fields.
1340       uint64_t signature = 0;
1341       off_t type_offset = 0;
1342       if (this->is_type_unit_)
1343         {
1344           if (!this->check_buffer(pinfo + 8 + this->offset_size_))
1345             break;
1346
1347           // Read type_signature (8 bytes).
1348           signature = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
1349           pinfo += 8;
1350
1351           // Read type_offset (4 or 8 bytes).
1352           if (this->offset_size_ == 4)
1353             type_offset =
1354                 elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo);
1355           else
1356             type_offset =
1357                 elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
1358           pinfo += this->offset_size_;
1359         }
1360
1361       // Read the .debug_abbrev table.
1362       this->abbrev_table_.read_abbrevs(this->object_, abbrev_shndx,
1363                                        abbrev_offset);
1364
1365       // Visit the root DIE.
1366       Dwarf_die root_die(this,
1367                          pinfo - (this->buffer_ + this->cu_offset_),
1368                          NULL);
1369       if (root_die.tag() != 0)
1370         {
1371           // Visit the CU or TU.
1372           if (this->is_type_unit_)
1373             this->visit_type_unit(section_offset + this->cu_offset_,
1374                                   cu_end - cu_start, type_offset, signature,
1375                                   &root_die);
1376           else
1377             this->visit_compilation_unit(section_offset + this->cu_offset_,
1378                                          cu_end - cu_start, &root_die);
1379         }
1380
1381       // Advance to the next CU.
1382       pinfo = cu_end;
1383     }
1384
1385   if (buffer_is_new)
1386     {
1387       delete[] this->buffer_;
1388       this->buffer_ = NULL;
1389     }
1390 }
1391
1392 // Read the DWARF string table.
1393
1394 bool
1395 Dwarf_info_reader::do_read_string_table(unsigned int string_shndx)
1396 {
1397   Relobj* object = this->object_;
1398
1399   // If we don't have relocations, string_shndx will be 0, and
1400   // we'll have to hunt for the .debug_str section.
1401   if (string_shndx == 0)
1402     {
1403       for (unsigned int i = 1; i < this->object_->shnum(); ++i)
1404         {
1405           std::string name = object->section_name(i);
1406           if (name == ".debug_str" || name == ".zdebug_str")
1407             {
1408               string_shndx = i;
1409               this->string_output_section_offset_ =
1410                   object->output_section_offset(i);
1411               break;
1412             }
1413         }
1414       if (string_shndx == 0)
1415         return false;
1416     }
1417
1418   if (this->owns_string_buffer_ && this->string_buffer_ != NULL)
1419     {
1420       delete[] this->string_buffer_;
1421       this->owns_string_buffer_ = false;
1422     }
1423
1424   // Get the secton contents and decompress if necessary.
1425   section_size_type buffer_size;
1426   const unsigned char* buffer =
1427       object->decompressed_section_contents(string_shndx,
1428                                             &buffer_size,
1429                                             &this->owns_string_buffer_);
1430   this->string_buffer_ = reinterpret_cast<const char*>(buffer);
1431   this->string_buffer_end_ = this->string_buffer_ + buffer_size;
1432   this->string_shndx_ = string_shndx;
1433   return true;
1434 }
1435
1436 // Read a possibly unaligned integer of SIZE.
1437 template <int valsize>
1438 inline typename elfcpp::Valtype_base<valsize>::Valtype
1439 Dwarf_info_reader::read_from_pointer(const unsigned char* source)
1440 {
1441   typename elfcpp::Valtype_base<valsize>::Valtype return_value;
1442   if (this->object_->is_big_endian())
1443     return_value = elfcpp::Swap_unaligned<valsize, true>::readval(source);
1444   else
1445     return_value = elfcpp::Swap_unaligned<valsize, false>::readval(source);
1446   return return_value;
1447 }
1448
1449 // Read a possibly unaligned integer of SIZE.  Update SOURCE after read.
1450 template <int valsize>
1451 inline typename elfcpp::Valtype_base<valsize>::Valtype
1452 Dwarf_info_reader::read_from_pointer(const unsigned char** source)
1453 {
1454   typename elfcpp::Valtype_base<valsize>::Valtype return_value;
1455   if (this->object_->is_big_endian())
1456     return_value = elfcpp::Swap_unaligned<valsize, true>::readval(*source);
1457   else
1458     return_value = elfcpp::Swap_unaligned<valsize, false>::readval(*source);
1459   *source += valsize / 8;
1460   return return_value;
1461 }
1462
1463 // Look for a relocation at offset ATTR_OFF in the dwarf info,
1464 // and return the section index and offset of the target.
1465
1466 unsigned int
1467 Dwarf_info_reader::lookup_reloc(off_t attr_off, off_t* target_off)
1468 {
1469   off_t value;
1470   attr_off += this->cu_offset_;
1471   unsigned int shndx = this->reloc_mapper_->get_reloc_target(attr_off, &value);
1472   if (shndx == 0)
1473     return 0;
1474   if (this->reloc_type_ == elfcpp::SHT_REL)
1475     *target_off += value;
1476   else
1477     *target_off = value;
1478   return shndx;
1479 }
1480
1481 // Return a string from the DWARF string table.
1482
1483 const char*
1484 Dwarf_info_reader::get_string(off_t str_off, unsigned int string_shndx)
1485 {
1486   if (!this->read_string_table(string_shndx))
1487     return NULL;
1488
1489   // Correct the offset.  For incremental update links, we have a
1490   // relocated offset that is relative to the output section, but
1491   // here we need an offset relative to the input section.
1492   str_off -= this->string_output_section_offset_;
1493
1494   const char* p = this->string_buffer_ + str_off;
1495
1496   if (p < this->string_buffer_ || p >= this->string_buffer_end_)
1497     return NULL;
1498
1499   return p;
1500 }
1501
1502 // The following are default, do-nothing, implementations of the
1503 // hook methods normally provided by a derived class.  We provide
1504 // default implementations rather than no implementation so that
1505 // a derived class needs to implement only the hooks that it needs
1506 // to use.
1507
1508 // Process a compilation unit and parse its child DIE.
1509
1510 void
1511 Dwarf_info_reader::visit_compilation_unit(off_t, off_t, Dwarf_die*)
1512 {
1513 }
1514
1515 // Process a type unit and parse its child DIE.
1516
1517 void
1518 Dwarf_info_reader::visit_type_unit(off_t, off_t, off_t, uint64_t, Dwarf_die*)
1519 {
1520 }
1521
1522 // Print a warning about a corrupt debug section.
1523
1524 void
1525 Dwarf_info_reader::warn_corrupt_debug_section() const
1526 {
1527   gold_warning(_("%s: corrupt debug info in %s"),
1528                this->object_->name().c_str(),
1529                this->object_->section_name(this->shndx_).c_str());
1530 }
1531
1532 // class Sized_dwarf_line_info
1533
1534 struct LineStateMachine
1535 {
1536   int file_num;
1537   uint64_t address;
1538   int line_num;
1539   int column_num;
1540   unsigned int shndx;    // the section address refers to
1541   bool is_stmt;          // stmt means statement.
1542   bool basic_block;
1543   bool end_sequence;
1544 };
1545
1546 static void
1547 ResetLineStateMachine(struct LineStateMachine* lsm, bool default_is_stmt)
1548 {
1549   lsm->file_num = 1;
1550   lsm->address = 0;
1551   lsm->line_num = 1;
1552   lsm->column_num = 0;
1553   lsm->shndx = -1U;
1554   lsm->is_stmt = default_is_stmt;
1555   lsm->basic_block = false;
1556   lsm->end_sequence = false;
1557 }
1558
1559 template<int size, bool big_endian>
1560 Sized_dwarf_line_info<size, big_endian>::Sized_dwarf_line_info(
1561     Object* object,
1562     unsigned int read_shndx)
1563   : data_valid_(false), buffer_(NULL), buffer_start_(NULL),
1564     reloc_mapper_(NULL), symtab_buffer_(NULL), directories_(), files_(),
1565     current_header_index_(-1)
1566 {
1567   unsigned int debug_shndx;
1568
1569   for (debug_shndx = 1; debug_shndx < object->shnum(); ++debug_shndx)
1570     {
1571       // FIXME: do this more efficiently: section_name() isn't super-fast
1572       std::string name = object->section_name(debug_shndx);
1573       if (name == ".debug_line" || name == ".zdebug_line")
1574         {
1575           section_size_type buffer_size;
1576           bool is_new = false;
1577           this->buffer_ = object->decompressed_section_contents(debug_shndx,
1578                                                                 &buffer_size,
1579                                                                 &is_new);
1580           if (is_new)
1581             this->buffer_start_ = this->buffer_;
1582           this->buffer_end_ = this->buffer_ + buffer_size;
1583           break;
1584         }
1585     }
1586   if (this->buffer_ == NULL)
1587     return;
1588
1589   // Find the relocation section for ".debug_line".
1590   // We expect these for relobjs (.o's) but not dynobjs (.so's).
1591   unsigned int reloc_shndx = 0;
1592   for (unsigned int i = 0; i < object->shnum(); ++i)
1593     {
1594       unsigned int reloc_sh_type = object->section_type(i);
1595       if ((reloc_sh_type == elfcpp::SHT_REL
1596            || reloc_sh_type == elfcpp::SHT_RELA)
1597           && object->section_info(i) == debug_shndx)
1598         {
1599           reloc_shndx = i;
1600           this->track_relocs_type_ = reloc_sh_type;
1601           break;
1602         }
1603     }
1604
1605   // Finally, we need the symtab section to interpret the relocs.
1606   if (reloc_shndx != 0)
1607     {
1608       unsigned int symtab_shndx;
1609       for (symtab_shndx = 0; symtab_shndx < object->shnum(); ++symtab_shndx)
1610         if (object->section_type(symtab_shndx) == elfcpp::SHT_SYMTAB)
1611           {
1612             this->symtab_buffer_ = object->section_contents(
1613                 symtab_shndx, &this->symtab_buffer_size_, false);
1614             break;
1615           }
1616       if (this->symtab_buffer_ == NULL)
1617         return;
1618     }
1619
1620   this->reloc_mapper_ =
1621       new Sized_elf_reloc_mapper<size, big_endian>(object,
1622                                                    this->symtab_buffer_,
1623                                                    this->symtab_buffer_size_);
1624   if (!this->reloc_mapper_->initialize(reloc_shndx, this->track_relocs_type_))
1625     return;
1626
1627   // Now that we have successfully read all the data, parse the debug
1628   // info.
1629   this->data_valid_ = true;
1630   this->read_line_mappings(read_shndx);
1631 }
1632
1633 // Read the DWARF header.
1634
1635 template<int size, bool big_endian>
1636 const unsigned char*
1637 Sized_dwarf_line_info<size, big_endian>::read_header_prolog(
1638     const unsigned char* lineptr)
1639 {
1640   uint32_t initial_length = elfcpp::Swap_unaligned<32, big_endian>::readval(lineptr);
1641   lineptr += 4;
1642
1643   // In DWARF2/3, if the initial length is all 1 bits, then the offset
1644   // size is 8 and we need to read the next 8 bytes for the real length.
1645   if (initial_length == 0xffffffff)
1646     {
1647       header_.offset_size = 8;
1648       initial_length = elfcpp::Swap_unaligned<64, big_endian>::readval(lineptr);
1649       lineptr += 8;
1650     }
1651   else
1652     header_.offset_size = 4;
1653
1654   header_.total_length = initial_length;
1655
1656   gold_assert(lineptr + header_.total_length <= buffer_end_);
1657
1658   header_.version = elfcpp::Swap_unaligned<16, big_endian>::readval(lineptr);
1659   lineptr += 2;
1660
1661   if (header_.offset_size == 4)
1662     header_.prologue_length = elfcpp::Swap_unaligned<32, big_endian>::readval(lineptr);
1663   else
1664     header_.prologue_length = elfcpp::Swap_unaligned<64, big_endian>::readval(lineptr);
1665   lineptr += header_.offset_size;
1666
1667   header_.min_insn_length = *lineptr;
1668   lineptr += 1;
1669
1670   if (header_.version < 4)
1671     header_.max_ops_per_insn = 1;
1672   else
1673     {
1674       // DWARF 4 added the maximum_operations_per_instruction field.
1675       header_.max_ops_per_insn = *lineptr;
1676       lineptr += 1;
1677       // TODO: Add support for values other than 1.
1678       gold_assert(header_.max_ops_per_insn == 1);
1679     }
1680
1681   header_.default_is_stmt = *lineptr;
1682   lineptr += 1;
1683
1684   header_.line_base = *reinterpret_cast<const signed char*>(lineptr);
1685   lineptr += 1;
1686
1687   header_.line_range = *lineptr;
1688   lineptr += 1;
1689
1690   header_.opcode_base = *lineptr;
1691   lineptr += 1;
1692
1693   header_.std_opcode_lengths.resize(header_.opcode_base + 1);
1694   header_.std_opcode_lengths[0] = 0;
1695   for (int i = 1; i < header_.opcode_base; i++)
1696     {
1697       header_.std_opcode_lengths[i] = *lineptr;
1698       lineptr += 1;
1699     }
1700
1701   return lineptr;
1702 }
1703
1704 // The header for a debug_line section is mildly complicated, because
1705 // the line info is very tightly encoded.
1706
1707 template<int size, bool big_endian>
1708 const unsigned char*
1709 Sized_dwarf_line_info<size, big_endian>::read_header_tables(
1710     const unsigned char* lineptr)
1711 {
1712   ++this->current_header_index_;
1713
1714   // Create a new directories_ entry and a new files_ entry for our new
1715   // header.  We initialize each with a single empty element, because
1716   // dwarf indexes directory and filenames starting at 1.
1717   gold_assert(static_cast<int>(this->directories_.size())
1718               == this->current_header_index_);
1719   gold_assert(static_cast<int>(this->files_.size())
1720               == this->current_header_index_);
1721   this->directories_.push_back(std::vector<std::string>(1));
1722   this->files_.push_back(std::vector<std::pair<int, std::string> >(1));
1723
1724   // It is legal for the directory entry table to be empty.
1725   if (*lineptr)
1726     {
1727       int dirindex = 1;
1728       while (*lineptr)
1729         {
1730           const char* dirname = reinterpret_cast<const char*>(lineptr);
1731           gold_assert(dirindex
1732                       == static_cast<int>(this->directories_.back().size()));
1733           this->directories_.back().push_back(dirname);
1734           lineptr += this->directories_.back().back().size() + 1;
1735           dirindex++;
1736         }
1737     }
1738   lineptr++;
1739
1740   // It is also legal for the file entry table to be empty.
1741   if (*lineptr)
1742     {
1743       int fileindex = 1;
1744       size_t len;
1745       while (*lineptr)
1746         {
1747           const char* filename = reinterpret_cast<const char*>(lineptr);
1748           lineptr += strlen(filename) + 1;
1749
1750           uint64_t dirindex = read_unsigned_LEB_128(lineptr, &len);
1751           lineptr += len;
1752
1753           if (dirindex >= this->directories_.back().size())
1754             dirindex = 0;
1755           int dirindexi = static_cast<int>(dirindex);
1756
1757           read_unsigned_LEB_128(lineptr, &len);   // mod_time
1758           lineptr += len;
1759
1760           read_unsigned_LEB_128(lineptr, &len);   // filelength
1761           lineptr += len;
1762
1763           gold_assert(fileindex
1764                       == static_cast<int>(this->files_.back().size()));
1765           this->files_.back().push_back(std::make_pair(dirindexi, filename));
1766           fileindex++;
1767         }
1768     }
1769   lineptr++;
1770
1771   return lineptr;
1772 }
1773
1774 // Process a single opcode in the .debug.line structure.
1775
1776 template<int size, bool big_endian>
1777 bool
1778 Sized_dwarf_line_info<size, big_endian>::process_one_opcode(
1779     const unsigned char* start, struct LineStateMachine* lsm, size_t* len)
1780 {
1781   size_t oplen = 0;
1782   size_t templen;
1783   unsigned char opcode = *start;
1784   oplen++;
1785   start++;
1786
1787   // If the opcode is great than the opcode_base, it is a special
1788   // opcode. Most line programs consist mainly of special opcodes.
1789   if (opcode >= header_.opcode_base)
1790     {
1791       opcode -= header_.opcode_base;
1792       const int advance_address = ((opcode / header_.line_range)
1793                                    * header_.min_insn_length);
1794       lsm->address += advance_address;
1795
1796       const int advance_line = ((opcode % header_.line_range)
1797                                 + header_.line_base);
1798       lsm->line_num += advance_line;
1799       lsm->basic_block = true;
1800       *len = oplen;
1801       return true;
1802     }
1803
1804   // Otherwise, we have the regular opcodes
1805   switch (opcode)
1806     {
1807     case elfcpp::DW_LNS_copy:
1808       lsm->basic_block = false;
1809       *len = oplen;
1810       return true;
1811
1812     case elfcpp::DW_LNS_advance_pc:
1813       {
1814         const uint64_t advance_address
1815             = read_unsigned_LEB_128(start, &templen);
1816         oplen += templen;
1817         lsm->address += header_.min_insn_length * advance_address;
1818       }
1819       break;
1820
1821     case elfcpp::DW_LNS_advance_line:
1822       {
1823         const uint64_t advance_line = read_signed_LEB_128(start, &templen);
1824         oplen += templen;
1825         lsm->line_num += advance_line;
1826       }
1827       break;
1828
1829     case elfcpp::DW_LNS_set_file:
1830       {
1831         const uint64_t fileno = read_unsigned_LEB_128(start, &templen);
1832         oplen += templen;
1833         lsm->file_num = fileno;
1834       }
1835       break;
1836
1837     case elfcpp::DW_LNS_set_column:
1838       {
1839         const uint64_t colno = read_unsigned_LEB_128(start, &templen);
1840         oplen += templen;
1841         lsm->column_num = colno;
1842       }
1843       break;
1844
1845     case elfcpp::DW_LNS_negate_stmt:
1846       lsm->is_stmt = !lsm->is_stmt;
1847       break;
1848
1849     case elfcpp::DW_LNS_set_basic_block:
1850       lsm->basic_block = true;
1851       break;
1852
1853     case elfcpp::DW_LNS_fixed_advance_pc:
1854       {
1855         int advance_address;
1856         advance_address = elfcpp::Swap_unaligned<16, big_endian>::readval(start);
1857         oplen += 2;
1858         lsm->address += advance_address;
1859       }
1860       break;
1861
1862     case elfcpp::DW_LNS_const_add_pc:
1863       {
1864         const int advance_address = (header_.min_insn_length
1865                                      * ((255 - header_.opcode_base)
1866                                         / header_.line_range));
1867         lsm->address += advance_address;
1868       }
1869       break;
1870
1871     case elfcpp::DW_LNS_extended_op:
1872       {
1873         const uint64_t extended_op_len
1874             = read_unsigned_LEB_128(start, &templen);
1875         start += templen;
1876         oplen += templen + extended_op_len;
1877
1878         const unsigned char extended_op = *start;
1879         start++;
1880
1881         switch (extended_op)
1882           {
1883           case elfcpp::DW_LNE_end_sequence:
1884             // This means that the current byte is the one immediately
1885             // after a set of instructions.  Record the current line
1886             // for up to one less than the current address.
1887             lsm->line_num = -1;
1888             lsm->end_sequence = true;
1889             *len = oplen;
1890             return true;
1891
1892           case elfcpp::DW_LNE_set_address:
1893             {
1894               lsm->address =
1895                 elfcpp::Swap_unaligned<size, big_endian>::readval(start);
1896               typename Reloc_map::const_iterator it
1897                   = this->reloc_map_.find(start - this->buffer_);
1898               if (it != reloc_map_.end())
1899                 {
1900                   // If this is a SHT_RELA section, then ignore the
1901                   // section contents.  This assumes that this is a
1902                   // straight reloc which just uses the reloc addend.
1903                   // The reloc addend has already been included in the
1904                   // symbol value.
1905                   if (this->track_relocs_type_ == elfcpp::SHT_RELA)
1906                     lsm->address = 0;
1907                   // Add in the symbol value.
1908                   lsm->address += it->second.second;
1909                   lsm->shndx = it->second.first;
1910                 }
1911               else
1912                 {
1913                   // If we're a normal .o file, with relocs, every
1914                   // set_address should have an associated relocation.
1915                   if (this->input_is_relobj())
1916                     this->data_valid_ = false;
1917                 }
1918               break;
1919             }
1920           case elfcpp::DW_LNE_define_file:
1921             {
1922               const char* filename  = reinterpret_cast<const char*>(start);
1923               templen = strlen(filename) + 1;
1924               start += templen;
1925
1926               uint64_t dirindex = read_unsigned_LEB_128(start, &templen);
1927
1928               if (dirindex >= this->directories_.back().size())
1929                 dirindex = 0;
1930               int dirindexi = static_cast<int>(dirindex);
1931
1932               // This opcode takes two additional ULEB128 parameters
1933               // (mod_time and filelength), but we don't use those
1934               // values.  Because OPLEN already tells us how far to
1935               // skip to the next opcode, we don't need to read
1936               // them at all.
1937
1938               this->files_.back().push_back(std::make_pair(dirindexi,
1939                                                            filename));
1940             }
1941             break;
1942           }
1943       }
1944       break;
1945
1946     default:
1947       {
1948         // Ignore unknown opcode  silently
1949         for (int i = 0; i < header_.std_opcode_lengths[opcode]; i++)
1950           {
1951             size_t templen;
1952             read_unsigned_LEB_128(start, &templen);
1953             start += templen;
1954             oplen += templen;
1955           }
1956       }
1957       break;
1958   }
1959   *len = oplen;
1960   return false;
1961 }
1962
1963 // Read the debug information at LINEPTR and store it in the line
1964 // number map.
1965
1966 template<int size, bool big_endian>
1967 unsigned const char*
1968 Sized_dwarf_line_info<size, big_endian>::read_lines(unsigned const char* lineptr,
1969                                                     unsigned int shndx)
1970 {
1971   struct LineStateMachine lsm;
1972
1973   // LENGTHSTART is the place the length field is based on.  It is the
1974   // point in the header after the initial length field.
1975   const unsigned char* lengthstart = buffer_;
1976
1977   // In 64 bit dwarf, the initial length is 12 bytes, because of the
1978   // 0xffffffff at the start.
1979   if (header_.offset_size == 8)
1980     lengthstart += 12;
1981   else
1982     lengthstart += 4;
1983
1984   while (lineptr < lengthstart + header_.total_length)
1985     {
1986       ResetLineStateMachine(&lsm, header_.default_is_stmt);
1987       while (!lsm.end_sequence)
1988         {
1989           size_t oplength;
1990           bool add_line = this->process_one_opcode(lineptr, &lsm, &oplength);
1991           if (add_line
1992               && (shndx == -1U || lsm.shndx == -1U || shndx == lsm.shndx))
1993             {
1994               Offset_to_lineno_entry entry
1995                   = { static_cast<off_t>(lsm.address),
1996                       this->current_header_index_,
1997                       static_cast<unsigned int>(lsm.file_num),
1998                       true, lsm.line_num };
1999               std::vector<Offset_to_lineno_entry>&
2000                 map(this->line_number_map_[lsm.shndx]);
2001               // If we see two consecutive entries with the same
2002               // offset and a real line number, then mark the first
2003               // one as non-canonical.
2004               if (!map.empty()
2005                   && (map.back().offset == static_cast<off_t>(lsm.address))
2006                   && lsm.line_num != -1
2007                   && map.back().line_num != -1)
2008                 map.back().last_line_for_offset = false;
2009               map.push_back(entry);
2010             }
2011           lineptr += oplength;
2012         }
2013     }
2014
2015   return lengthstart + header_.total_length;
2016 }
2017
2018 // Read the relocations into a Reloc_map.
2019
2020 template<int size, bool big_endian>
2021 void
2022 Sized_dwarf_line_info<size, big_endian>::read_relocs()
2023 {
2024   if (this->symtab_buffer_ == NULL)
2025     return;
2026
2027   off_t value;
2028   off_t reloc_offset;
2029   while ((reloc_offset = this->reloc_mapper_->next_offset()) != -1)
2030     {
2031       const unsigned int shndx =
2032           this->reloc_mapper_->get_reloc_target(reloc_offset, &value);
2033
2034       // There is no reason to record non-ordinary section indexes, or
2035       // SHN_UNDEF, because they will never match the real section.
2036       if (shndx != 0)
2037         this->reloc_map_[reloc_offset] = std::make_pair(shndx, value);
2038
2039       this->reloc_mapper_->advance(reloc_offset + 1);
2040     }
2041 }
2042
2043 // Read the line number info.
2044
2045 template<int size, bool big_endian>
2046 void
2047 Sized_dwarf_line_info<size, big_endian>::read_line_mappings(unsigned int shndx)
2048 {
2049   gold_assert(this->data_valid_ == true);
2050
2051   this->read_relocs();
2052   while (this->buffer_ < this->buffer_end_)
2053     {
2054       const unsigned char* lineptr = this->buffer_;
2055       lineptr = this->read_header_prolog(lineptr);
2056       lineptr = this->read_header_tables(lineptr);
2057       lineptr = this->read_lines(lineptr, shndx);
2058       this->buffer_ = lineptr;
2059     }
2060
2061   // Sort the lines numbers, so addr2line can use binary search.
2062   for (typename Lineno_map::iterator it = line_number_map_.begin();
2063        it != line_number_map_.end();
2064        ++it)
2065     // Each vector needs to be sorted by offset.
2066     std::sort(it->second.begin(), it->second.end());
2067 }
2068
2069 // Some processing depends on whether the input is a .o file or not.
2070 // For instance, .o files have relocs, and have .debug_lines
2071 // information on a per section basis.  .so files, on the other hand,
2072 // lack relocs, and offsets are unique, so we can ignore the section
2073 // information.
2074
2075 template<int size, bool big_endian>
2076 bool
2077 Sized_dwarf_line_info<size, big_endian>::input_is_relobj()
2078 {
2079   // Only .o files have relocs and the symtab buffer that goes with them.
2080   return this->symtab_buffer_ != NULL;
2081 }
2082
2083 // Given an Offset_to_lineno_entry vector, and an offset, figure out
2084 // if the offset points into a function according to the vector (see
2085 // comments below for the algorithm).  If it does, return an iterator
2086 // into the vector that points to the line-number that contains that
2087 // offset.  If not, it returns vector::end().
2088
2089 static std::vector<Offset_to_lineno_entry>::const_iterator
2090 offset_to_iterator(const std::vector<Offset_to_lineno_entry>* offsets,
2091                    off_t offset)
2092 {
2093   const Offset_to_lineno_entry lookup_key = { offset, 0, 0, true, 0 };
2094
2095   // lower_bound() returns the smallest offset which is >= lookup_key.
2096   // If no offset in offsets is >= lookup_key, returns end().
2097   std::vector<Offset_to_lineno_entry>::const_iterator it
2098       = std::lower_bound(offsets->begin(), offsets->end(), lookup_key);
2099
2100   // This code is easiest to understand with a concrete example.
2101   // Here's a possible offsets array:
2102   // {{offset = 3211, header_num = 0, file_num = 1, last, line_num = 16},  // 0
2103   //  {offset = 3224, header_num = 0, file_num = 1, last, line_num = 20},  // 1
2104   //  {offset = 3226, header_num = 0, file_num = 1, last, line_num = 22},  // 2
2105   //  {offset = 3231, header_num = 0, file_num = 1, last, line_num = 25},  // 3
2106   //  {offset = 3232, header_num = 0, file_num = 1, last, line_num = -1},  // 4
2107   //  {offset = 3232, header_num = 0, file_num = 1, last, line_num = 65},  // 5
2108   //  {offset = 3235, header_num = 0, file_num = 1, last, line_num = 66},  // 6
2109   //  {offset = 3236, header_num = 0, file_num = 1, last, line_num = -1},  // 7
2110   //  {offset = 5764, header_num = 0, file_num = 1, last, line_num = 48},  // 8
2111   //  {offset = 5764, header_num = 0, file_num = 1,!last, line_num = 47},  // 9
2112   //  {offset = 5765, header_num = 0, file_num = 1, last, line_num = 49},  // 10
2113   //  {offset = 5767, header_num = 0, file_num = 1, last, line_num = 50},  // 11
2114   //  {offset = 5768, header_num = 0, file_num = 1, last, line_num = 51},  // 12
2115   //  {offset = 5773, header_num = 0, file_num = 1, last, line_num = -1},  // 13
2116   //  {offset = 5787, header_num = 1, file_num = 1, last, line_num = 19},  // 14
2117   //  {offset = 5790, header_num = 1, file_num = 1, last, line_num = 20},  // 15
2118   //  {offset = 5793, header_num = 1, file_num = 1, last, line_num = 67},  // 16
2119   //  {offset = 5793, header_num = 1, file_num = 1, last, line_num = -1},  // 17
2120   //  {offset = 5793, header_num = 1, file_num = 1,!last, line_num = 66},  // 18
2121   //  {offset = 5795, header_num = 1, file_num = 1, last, line_num = 68},  // 19
2122   //  {offset = 5798, header_num = 1, file_num = 1, last, line_num = -1},  // 20
2123   // The entries with line_num == -1 mark the end of a function: the
2124   // associated offset is one past the last instruction in the
2125   // function.  This can correspond to the beginning of the next
2126   // function (as is true for offset 3232); alternately, there can be
2127   // a gap between the end of one function and the start of the next
2128   // (as is true for some others, most obviously from 3236->5764).
2129   //
2130   // Case 1: lookup_key has offset == 10.  lower_bound returns
2131   //         offsets[0].  Since it's not an exact match and we're
2132   //         at the beginning of offsets, we return end() (invalid).
2133   // Case 2: lookup_key has offset 10000.  lower_bound returns
2134   //         offset[21] (end()).  We return end() (invalid).
2135   // Case 3: lookup_key has offset == 3211.  lower_bound matches
2136   //         offsets[0] exactly, and that's the entry we return.
2137   // Case 4: lookup_key has offset == 3232.  lower_bound returns
2138   //         offsets[4].  That's an exact match, but indicates
2139   //         end-of-function.  We check if offsets[5] is also an
2140   //         exact match but not end-of-function.  It is, so we
2141   //         return offsets[5].
2142   // Case 5: lookup_key has offset == 3214.  lower_bound returns
2143   //         offsets[1].  Since it's not an exact match, we back
2144   //         up to the offset that's < lookup_key, offsets[0].
2145   //         We note offsets[0] is a valid entry (not end-of-function),
2146   //         so that's the entry we return.
2147   // Case 6: lookup_key has offset == 4000.  lower_bound returns
2148   //         offsets[8].  Since it's not an exact match, we back
2149   //         up to offsets[7].  Since offsets[7] indicates
2150   //         end-of-function, we know lookup_key is between
2151   //         functions, so we return end() (not a valid offset).
2152   // Case 7: lookup_key has offset == 5794.  lower_bound returns
2153   //         offsets[19].  Since it's not an exact match, we back
2154   //         up to offsets[16].  Note we back up to the *first*
2155   //         entry with offset 5793, not just offsets[19-1].
2156   //         We note offsets[16] is a valid entry, so we return it.
2157   //         If offsets[16] had had line_num == -1, we would have
2158   //         checked offsets[17].  The reason for this is that
2159   //         16 and 17 can be in an arbitrary order, since we sort
2160   //         only by offset and last_line_for_offset.  (Note it
2161   //         doesn't help to use line_number as a tertiary sort key,
2162   //         since sometimes we want the -1 to be first and sometimes
2163   //         we want it to be last.)
2164
2165   // This deals with cases (1) and (2).
2166   if ((it == offsets->begin() && offset < it->offset)
2167       || it == offsets->end())
2168     return offsets->end();
2169
2170   // This deals with cases (3) and (4).
2171   if (offset == it->offset)
2172     {
2173       while (it != offsets->end()
2174              && it->offset == offset
2175              && it->line_num == -1)
2176         ++it;
2177       if (it == offsets->end() || it->offset != offset)
2178         return offsets->end();
2179       else
2180         return it;
2181     }
2182
2183   // This handles the first part of case (7) -- we back up to the
2184   // *first* entry that has the offset that's behind us.
2185   gold_assert(it != offsets->begin());
2186   std::vector<Offset_to_lineno_entry>::const_iterator range_end = it;
2187   --it;
2188   const off_t range_value = it->offset;
2189   while (it != offsets->begin() && (it-1)->offset == range_value)
2190     --it;
2191
2192   // This handles cases (5), (6), and (7): if any entry in the
2193   // equal_range [it, range_end) has a line_num != -1, it's a valid
2194   // match.  If not, we're not in a function.  The line number we saw
2195   // last for an offset will be sorted first, so it'll get returned if
2196   // it's present.
2197   for (; it != range_end; ++it)
2198     if (it->line_num != -1)
2199       return it;
2200   return offsets->end();
2201 }
2202
2203 // Returns the canonical filename:lineno for the address passed in.
2204 // If other_lines is not NULL, appends the non-canonical lines
2205 // assigned to the same address.
2206
2207 template<int size, bool big_endian>
2208 std::string
2209 Sized_dwarf_line_info<size, big_endian>::do_addr2line(
2210     unsigned int shndx,
2211     off_t offset,
2212     std::vector<std::string>* other_lines)
2213 {
2214   if (this->data_valid_ == false)
2215     return "";
2216
2217   const std::vector<Offset_to_lineno_entry>* offsets;
2218   // If we do not have reloc information, then our input is a .so or
2219   // some similar data structure where all the information is held in
2220   // the offset.  In that case, we ignore the input shndx.
2221   if (this->input_is_relobj())
2222     offsets = &this->line_number_map_[shndx];
2223   else
2224     offsets = &this->line_number_map_[-1U];
2225   if (offsets->empty())
2226     return "";
2227
2228   typename std::vector<Offset_to_lineno_entry>::const_iterator it
2229       = offset_to_iterator(offsets, offset);
2230   if (it == offsets->end())
2231     return "";
2232
2233   std::string result = this->format_file_lineno(*it);
2234   gold_debug(DEBUG_LOCATION, "do_addr2line: canonical result: %s",
2235              result.c_str());
2236   if (other_lines != NULL)
2237     {
2238       unsigned int last_file_num = it->file_num;
2239       int last_line_num = it->line_num;
2240       // Return up to 4 more locations from the beginning of the function
2241       // for fuzzy matching.
2242       for (++it; it != offsets->end(); ++it)
2243         {
2244           if (it->offset == offset && it->line_num == -1)
2245             continue;  // The end of a previous function.
2246           if (it->line_num == -1)
2247             break;  // The end of the current function.
2248           if (it->file_num != last_file_num || it->line_num != last_line_num)
2249             {
2250               other_lines->push_back(this->format_file_lineno(*it));
2251               gold_debug(DEBUG_LOCATION, "do_addr2line: other: %s",
2252                          other_lines->back().c_str());
2253               last_file_num = it->file_num;
2254               last_line_num = it->line_num;
2255             }
2256           if (it->offset > offset && other_lines->size() >= 4)
2257             break;
2258         }
2259     }
2260
2261   return result;
2262 }
2263
2264 // Convert the file_num + line_num into a string.
2265
2266 template<int size, bool big_endian>
2267 std::string
2268 Sized_dwarf_line_info<size, big_endian>::format_file_lineno(
2269     const Offset_to_lineno_entry& loc) const
2270 {
2271   std::string ret;
2272
2273   gold_assert(loc.header_num < static_cast<int>(this->files_.size()));
2274   gold_assert(loc.file_num
2275               < static_cast<unsigned int>(this->files_[loc.header_num].size()));
2276   const std::pair<int, std::string>& filename_pair
2277       = this->files_[loc.header_num][loc.file_num];
2278   const std::string& filename = filename_pair.second;
2279
2280   gold_assert(loc.header_num < static_cast<int>(this->directories_.size()));
2281   gold_assert(filename_pair.first
2282               < static_cast<int>(this->directories_[loc.header_num].size()));
2283   const std::string& dirname
2284       = this->directories_[loc.header_num][filename_pair.first];
2285
2286   if (!dirname.empty())
2287     {
2288       ret += dirname;
2289       ret += "/";
2290     }
2291   ret += filename;
2292   if (ret.empty())
2293     ret = "(unknown)";
2294
2295   char buffer[64];   // enough to hold a line number
2296   snprintf(buffer, sizeof(buffer), "%d", loc.line_num);
2297   ret += ":";
2298   ret += buffer;
2299
2300   return ret;
2301 }
2302
2303 // Dwarf_line_info routines.
2304
2305 static unsigned int next_generation_count = 0;
2306
2307 struct Addr2line_cache_entry
2308 {
2309   Object* object;
2310   unsigned int shndx;
2311   Dwarf_line_info* dwarf_line_info;
2312   unsigned int generation_count;
2313   unsigned int access_count;
2314
2315   Addr2line_cache_entry(Object* o, unsigned int s, Dwarf_line_info* d)
2316       : object(o), shndx(s), dwarf_line_info(d),
2317         generation_count(next_generation_count), access_count(0)
2318   {
2319     if (next_generation_count < (1U << 31))
2320       ++next_generation_count;
2321   }
2322 };
2323 // We expect this cache to be small, so don't bother with a hashtable
2324 // or priority queue or anything: just use a simple vector.
2325 static std::vector<Addr2line_cache_entry> addr2line_cache;
2326
2327 std::string
2328 Dwarf_line_info::one_addr2line(Object* object,
2329                                unsigned int shndx, off_t offset,
2330                                size_t cache_size,
2331                                std::vector<std::string>* other_lines)
2332 {
2333   Dwarf_line_info* lineinfo = NULL;
2334   std::vector<Addr2line_cache_entry>::iterator it;
2335
2336   // First, check the cache.  If we hit, update the counts.
2337   for (it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it)
2338     {
2339       if (it->object == object && it->shndx == shndx)
2340         {
2341           lineinfo = it->dwarf_line_info;
2342           it->generation_count = next_generation_count;
2343           // We cap generation_count at 2^31 -1 to avoid overflow.
2344           if (next_generation_count < (1U << 31))
2345             ++next_generation_count;
2346           // We cap access_count at 31 so 2^access_count doesn't overflow
2347           if (it->access_count < 31)
2348             ++it->access_count;
2349           break;
2350         }
2351     }
2352
2353   // If we don't hit the cache, create a new object and insert into the
2354   // cache.
2355   if (lineinfo == NULL)
2356   {
2357     switch (parameters->size_and_endianness())
2358       {
2359 #ifdef HAVE_TARGET_32_LITTLE
2360         case Parameters::TARGET_32_LITTLE:
2361           lineinfo = new Sized_dwarf_line_info<32, false>(object, shndx); break;
2362 #endif
2363 #ifdef HAVE_TARGET_32_BIG
2364         case Parameters::TARGET_32_BIG:
2365           lineinfo = new Sized_dwarf_line_info<32, true>(object, shndx); break;
2366 #endif
2367 #ifdef HAVE_TARGET_64_LITTLE
2368         case Parameters::TARGET_64_LITTLE:
2369           lineinfo = new Sized_dwarf_line_info<64, false>(object, shndx); break;
2370 #endif
2371 #ifdef HAVE_TARGET_64_BIG
2372         case Parameters::TARGET_64_BIG:
2373           lineinfo = new Sized_dwarf_line_info<64, true>(object, shndx); break;
2374 #endif
2375         default:
2376           gold_unreachable();
2377       }
2378     addr2line_cache.push_back(Addr2line_cache_entry(object, shndx, lineinfo));
2379   }
2380
2381   // Now that we have our object, figure out the answer
2382   std::string retval = lineinfo->addr2line(shndx, offset, other_lines);
2383
2384   // Finally, if our cache has grown too big, delete old objects.  We
2385   // assume the common (probably only) case is deleting only one object.
2386   // We use a pretty simple scheme to evict: function of LRU and MFU.
2387   while (addr2line_cache.size() > cache_size)
2388     {
2389       unsigned int lowest_score = ~0U;
2390       std::vector<Addr2line_cache_entry>::iterator lowest
2391           = addr2line_cache.end();
2392       for (it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it)
2393         {
2394           const unsigned int score = (it->generation_count
2395                                       + (1U << it->access_count));
2396           if (score < lowest_score)
2397             {
2398               lowest_score = score;
2399               lowest = it;
2400             }
2401         }
2402       if (lowest != addr2line_cache.end())
2403         {
2404           delete lowest->dwarf_line_info;
2405           addr2line_cache.erase(lowest);
2406         }
2407     }
2408
2409   return retval;
2410 }
2411
2412 void
2413 Dwarf_line_info::clear_addr2line_cache()
2414 {
2415   for (std::vector<Addr2line_cache_entry>::iterator it = addr2line_cache.begin();
2416        it != addr2line_cache.end();
2417        ++it)
2418     delete it->dwarf_line_info;
2419   addr2line_cache.clear();
2420 }
2421
2422 #ifdef HAVE_TARGET_32_LITTLE
2423 template
2424 class Sized_dwarf_line_info<32, false>;
2425 #endif
2426
2427 #ifdef HAVE_TARGET_32_BIG
2428 template
2429 class Sized_dwarf_line_info<32, true>;
2430 #endif
2431
2432 #ifdef HAVE_TARGET_64_LITTLE
2433 template
2434 class Sized_dwarf_line_info<64, false>;
2435 #endif
2436
2437 #ifdef HAVE_TARGET_64_BIG
2438 template
2439 class Sized_dwarf_line_info<64, true>;
2440 #endif
2441
2442 } // End namespace gold.