gold/dwarf_reader.cc

   1 // dwarf_reader.cc -- parse dwarf2/3 debug information
   2
   3 // Copyright (C) 2007-2016 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           case elfcpp::DW_FORM_ref_addr:
 741             {
 742               off_t sec_off;
 743               if (this->dwinfo_->address_size() == 4)
 744                 sec_off = this->dwinfo_->read_from_pointer<32>(&pattr);
 745               else
 746                 sec_off = this->dwinfo_->read_from_pointer<64>(&pattr);
 747               unsigned int shndx =
 748                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 749               attr_value.aux.shndx = shndx;
 750               attr_value.val.refval = sec_off;
 751               ref_form = true;
 752               break;
 753             }
 754           case elfcpp::DW_FORM_block1:
 755             attr_value.aux.blocklen = *pattr++;
 756             attr_value.val.blockval = pattr;
 757             pattr += attr_value.aux.blocklen;
 758             break;
 759           case elfcpp::DW_FORM_block2:
 760             attr_value.aux.blocklen =
 761                 this->dwinfo_->read_from_pointer<16>(&pattr);
 762             attr_value.val.blockval = pattr;
 763             pattr += attr_value.aux.blocklen;
 764             break;
 765           case elfcpp::DW_FORM_block4:
 766             attr_value.aux.blocklen =
 767                 this->dwinfo_->read_from_pointer<32>(&pattr);
 768             attr_value.val.blockval = pattr;
 769             pattr += attr_value.aux.blocklen;
 770             break;
 771           case elfcpp::DW_FORM_block:
 772           case elfcpp::DW_FORM_exprloc:
 773             attr_value.aux.blocklen = read_unsigned_LEB_128(pattr, &len);
 774             attr_value.val.blockval = pattr + len;
 775             pattr += len + attr_value.aux.blocklen;
 776             break;
 777           case elfcpp::DW_FORM_data1:
 778           case elfcpp::DW_FORM_flag:
 779             attr_value.val.intval = *pattr++;
 780             break;
 781           case elfcpp::DW_FORM_ref1:
 782             attr_value.val.refval = *pattr++;
 783             ref_form = true;
 784             break;
 785           case elfcpp::DW_FORM_data2:
 786             attr_value.val.intval =
 787                 this->dwinfo_->read_from_pointer<16>(&pattr);
 788             break;
 789           case elfcpp::DW_FORM_ref2:
 790             attr_value.val.refval =
 791                 this->dwinfo_->read_from_pointer<16>(&pattr);
 792             ref_form = true;
 793             break;
 794           case elfcpp::DW_FORM_data4:
 795             {
 796               off_t sec_off;
 797               sec_off = this->dwinfo_->read_from_pointer<32>(&pattr);
 798               unsigned int shndx =
 799                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 800               attr_value.aux.shndx = shndx;
 801               attr_value.val.intval = sec_off;
 802               break;
 803             }
 804           case elfcpp::DW_FORM_ref4:
 805             {
 806               off_t sec_off;
 807               sec_off = this->dwinfo_->read_from_pointer<32>(&pattr);
 808               unsigned int shndx =
 809                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 810               attr_value.aux.shndx = shndx;
 811               attr_value.val.refval = sec_off;
 812               ref_form = true;
 813               break;
 814             }
 815           case elfcpp::DW_FORM_data8:
 816             {
 817               off_t sec_off;
 818               sec_off = this->dwinfo_->read_from_pointer<64>(&pattr);
 819               unsigned int shndx =
 820                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 821               attr_value.aux.shndx = shndx;
 822               attr_value.val.intval = sec_off;
 823               break;
 824             }
 825           case elfcpp::DW_FORM_ref_sig8:
 826             attr_value.val.uintval =
 827                 this->dwinfo_->read_from_pointer<64>(&pattr);
 828             break;
 829           case elfcpp::DW_FORM_ref8:
 830             {
 831               off_t sec_off;
 832               sec_off = this->dwinfo_->read_from_pointer<64>(&pattr);
 833               unsigned int shndx =
 834                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 835               attr_value.aux.shndx = shndx;
 836               attr_value.val.refval = sec_off;
 837               ref_form = true;
 838               break;
 839             }
 840           case elfcpp::DW_FORM_ref_udata:
 841             attr_value.val.refval = read_unsigned_LEB_128(pattr, &len);
 842             ref_form = true;
 843             pattr += len;
 844             break;
 845           case elfcpp::DW_FORM_udata:
 846           case elfcpp::DW_FORM_GNU_addr_index:
 847           case elfcpp::DW_FORM_GNU_str_index:
 848             attr_value.val.uintval = read_unsigned_LEB_128(pattr, &len);
 849             pattr += len;
 850             break;
 851           case elfcpp::DW_FORM_sdata:
 852             attr_value.val.intval = read_signed_LEB_128(pattr, &len);
 853             pattr += len;
 854             break;
 855           case elfcpp::DW_FORM_string:
 856             attr_value.val.stringval = reinterpret_cast<const char*>(pattr);
 857             len = strlen(attr_value.val.stringval);
 858             pattr += len + 1;
 859             break;
 860           default:
 861             return false;
 862         }
 863
 864       // Cache the most frequently-requested attributes.
 865       switch (attr)
 866         {
 867           case elfcpp::DW_AT_name:
 868             if (form == elfcpp::DW_FORM_string)
 869               this->name_ = attr_value.val.stringval;
 870             else if (form == elfcpp::DW_FORM_strp)
 871               {
 872                 // All indirect strings should refer to the same
 873                 // string section, so we just save the last one seen.
 874                 this->string_shndx_ = attr_value.aux.shndx;
 875                 this->name_off_ = attr_value.val.refval;
 876               }
 877             break;
 878           case elfcpp::DW_AT_linkage_name:
 879           case elfcpp::DW_AT_MIPS_linkage_name:
 880             if (form == elfcpp::DW_FORM_string)
 881               this->linkage_name_ = attr_value.val.stringval;
 882             else if (form == elfcpp::DW_FORM_strp)
 883               {
 884                 // All indirect strings should refer to the same
 885                 // string section, so we just save the last one seen.
 886                 this->string_shndx_ = attr_value.aux.shndx;
 887                 this->linkage_name_off_ = attr_value.val.refval;
 888               }
 889             break;
 890           case elfcpp::DW_AT_specification:
 891             if (ref_form)
 892               this->specification_ = attr_value.val.refval;
 893             break;
 894           case elfcpp::DW_AT_abstract_origin:
 895             if (ref_form)
 896               this->abstract_origin_ = attr_value.val.refval;
 897             break;
 898           case elfcpp::DW_AT_sibling:
 899             if (ref_form && attr_value.aux.shndx == 0)
 900               this->sibling_offset_ = attr_value.val.refval;
 901           default:
 902             break;
 903         }
 904
 905       this->attributes_.push_back(attr_value);
 906     }
 907
 908   // Now that we know where the next DIE begins, record the offset
 909   // to avoid later recalculation.
 910   if (this->has_children())
 911     this->child_offset_ = this->die_offset_ + (pattr - pdie);
 912   else
 913     this->sibling_offset_ = this->die_offset_ + (pattr - pdie);
 914
 915   this->attributes_read_ = true;
 916   return true;
 917 }
 918
 919 // Skip all the attributes of the DIE and return the offset of the next DIE.
 920
 921 off_t
 922 Dwarf_die::skip_attributes()
 923 {
 924   gold_assert(this->abbrev_code_ != NULL);
 925
 926   const unsigned char* pdie =
 927       this->dwinfo_->buffer_at_offset(this->die_offset_);
 928   if (pdie == NULL)
 929     return 0;
 930   const unsigned char* pattr = pdie + this->attr_offset_;
 931
 932   for (unsigned int i = 0; i < this->abbrev_code_->attributes.size(); ++i)
 933     {
 934       size_t len;
 935       unsigned int form = this->abbrev_code_->attributes[i].form;
 936       if (form == elfcpp::DW_FORM_indirect)
 937         {
 938           form = read_unsigned_LEB_128(pattr, &len);
 939           pattr += len;
 940         }
 941       switch(form)
 942         {
 943           case elfcpp::DW_FORM_flag_present:
 944             break;
 945           case elfcpp::DW_FORM_strp:
 946           case elfcpp::DW_FORM_sec_offset:
 947             pattr += this->dwinfo_->offset_size();
 948             break;
 949           case elfcpp::DW_FORM_addr:
 950           case elfcpp::DW_FORM_ref_addr:
 951             pattr += this->dwinfo_->address_size();
 952             break;
 953           case elfcpp::DW_FORM_block1:
 954             pattr += 1 + *pattr;
 955             break;
 956           case elfcpp::DW_FORM_block2:
 957             {
 958               uint16_t block_size;
 959               block_size = this->dwinfo_->read_from_pointer<16>(&pattr);
 960               pattr += block_size;
 961               break;
 962             }
 963           case elfcpp::DW_FORM_block4:
 964             {
 965               uint32_t block_size;
 966               block_size = this->dwinfo_->read_from_pointer<32>(&pattr);
 967               pattr += block_size;
 968               break;
 969             }
 970           case elfcpp::DW_FORM_block:
 971           case elfcpp::DW_FORM_exprloc:
 972             {
 973               uint64_t block_size;
 974               block_size = read_unsigned_LEB_128(pattr, &len);
 975               pattr += len + block_size;
 976               break;
 977             }
 978           case elfcpp::DW_FORM_data1:
 979           case elfcpp::DW_FORM_ref1:
 980           case elfcpp::DW_FORM_flag:
 981             pattr += 1;
 982             break;
 983           case elfcpp::DW_FORM_data2:
 984           case elfcpp::DW_FORM_ref2:
 985             pattr += 2;
 986             break;
 987           case elfcpp::DW_FORM_data4:
 988           case elfcpp::DW_FORM_ref4:
 989             pattr += 4;
 990             break;
 991           case elfcpp::DW_FORM_data8:
 992           case elfcpp::DW_FORM_ref8:
 993           case elfcpp::DW_FORM_ref_sig8:
 994             pattr += 8;
 995             break;
 996           case elfcpp::DW_FORM_ref_udata:
 997           case elfcpp::DW_FORM_udata:
 998           case elfcpp::DW_FORM_GNU_addr_index:
 999           case elfcpp::DW_FORM_GNU_str_index:
1000             read_unsigned_LEB_128(pattr, &len);
1001             pattr += len;
1002             break;
1003           case elfcpp::DW_FORM_sdata:
1004             read_signed_LEB_128(pattr, &len);
1005             pattr += len;
1006             break;
1007           case elfcpp::DW_FORM_string:
1008             len = strlen(reinterpret_cast<const char*>(pattr));
1009             pattr += len + 1;
1010             break;
1011           default:
1012             return 0;
1013         }
1014     }
1015
1016   return this->die_offset_ + (pattr - pdie);
1017 }
1018
1019 // Get the name of the DIE and cache it.
1020
1021 void
1022 Dwarf_die::set_name()
1023 {
1024   if (this->name_ != NULL || !this->read_attributes())
1025     return;
1026   if (this->name_off_ != -1)
1027     this->name_ = this->dwinfo_->get_string(this->name_off_,
1028                                             this->string_shndx_);
1029 }
1030
1031 // Get the linkage name of the DIE and cache it.
1032
1033 void
1034 Dwarf_die::set_linkage_name()
1035 {
1036   if (this->linkage_name_ != NULL || !this->read_attributes())
1037     return;
1038   if (this->linkage_name_off_ != -1)
1039     this->linkage_name_ = this->dwinfo_->get_string(this->linkage_name_off_,
1040                                                     this->string_shndx_);
1041 }
1042
1043 // Return the value of attribute ATTR.
1044
1045 const Dwarf_die::Attribute_value*
1046 Dwarf_die::attribute(unsigned int attr)
1047 {
1048   if (!this->read_attributes())
1049     return NULL;
1050   for (unsigned int i = 0; i < this->attributes_.size(); ++i)
1051     {
1052       if (this->attributes_[i].attr == attr)
1053         return &this->attributes_[i];
1054     }
1055   return NULL;
1056 }
1057
1058 const char*
1059 Dwarf_die::string_attribute(unsigned int attr)
1060 {
1061   const Attribute_value* attr_val = this->attribute(attr);
1062   if (attr_val == NULL)
1063     return NULL;
1064   switch (attr_val->form)
1065     {
1066       case elfcpp::DW_FORM_string:
1067         return attr_val->val.stringval;
1068       case elfcpp::DW_FORM_strp:
1069         return this->dwinfo_->get_string(attr_val->val.refval,
1070                                          attr_val->aux.shndx);
1071       default:
1072         return NULL;
1073     }
1074 }
1075
1076 int64_t
1077 Dwarf_die::int_attribute(unsigned int attr)
1078 {
1079   const Attribute_value* attr_val = this->attribute(attr);
1080   if (attr_val == NULL)
1081     return 0;
1082   switch (attr_val->form)
1083     {
1084       case elfcpp::DW_FORM_flag_present:
1085       case elfcpp::DW_FORM_data1:
1086       case elfcpp::DW_FORM_flag:
1087       case elfcpp::DW_FORM_data2:
1088       case elfcpp::DW_FORM_data4:
1089       case elfcpp::DW_FORM_data8:
1090       case elfcpp::DW_FORM_sdata:
1091         return attr_val->val.intval;
1092       default:
1093         return 0;
1094     }
1095 }
1096
1097 uint64_t
1098 Dwarf_die::uint_attribute(unsigned int attr)
1099 {
1100   const Attribute_value* attr_val = this->attribute(attr);
1101   if (attr_val == NULL)
1102     return 0;
1103   switch (attr_val->form)
1104     {
1105       case elfcpp::DW_FORM_flag_present:
1106       case elfcpp::DW_FORM_data1:
1107       case elfcpp::DW_FORM_flag:
1108       case elfcpp::DW_FORM_data4:
1109       case elfcpp::DW_FORM_data8:
1110       case elfcpp::DW_FORM_ref_sig8:
1111       case elfcpp::DW_FORM_udata:
1112         return attr_val->val.uintval;
1113       default:
1114         return 0;
1115     }
1116 }
1117
1118 off_t
1119 Dwarf_die::ref_attribute(unsigned int attr, unsigned int* shndx)
1120 {
1121   const Attribute_value* attr_val = this->attribute(attr);
1122   if (attr_val == NULL)
1123     return -1;
1124   switch (attr_val->form)
1125     {
1126       case elfcpp::DW_FORM_sec_offset:
1127       case elfcpp::DW_FORM_addr:
1128       case elfcpp::DW_FORM_ref_addr:
1129       case elfcpp::DW_FORM_ref1:
1130       case elfcpp::DW_FORM_ref2:
1131       case elfcpp::DW_FORM_ref4:
1132       case elfcpp::DW_FORM_ref8:
1133       case elfcpp::DW_FORM_ref_udata:
1134         *shndx = attr_val->aux.shndx;
1135         return attr_val->val.refval;
1136       case elfcpp::DW_FORM_ref_sig8:
1137         *shndx = attr_val->aux.shndx;
1138         return attr_val->val.uintval;
1139       case elfcpp::DW_FORM_data4:
1140       case elfcpp::DW_FORM_data8:
1141         *shndx = attr_val->aux.shndx;
1142         return attr_val->val.intval;
1143       default:
1144         return -1;
1145     }
1146 }
1147
1148 off_t
1149 Dwarf_die::address_attribute(unsigned int attr, unsigned int* shndx)
1150 {
1151   const Attribute_value* attr_val = this->attribute(attr);
1152   if (attr_val == NULL || attr_val->form != elfcpp::DW_FORM_addr)
1153     return -1;
1154
1155   *shndx = attr_val->aux.shndx;
1156   return attr_val->val.refval;
1157 }
1158
1159 // Return the offset of this DIE's first child.
1160
1161 off_t
1162 Dwarf_die::child_offset()
1163 {
1164   gold_assert(this->abbrev_code_ != NULL);
1165   if (!this->has_children())
1166     return 0;
1167   if (this->child_offset_ == 0)
1168     this->child_offset_ = this->skip_attributes();
1169   return this->child_offset_;
1170 }
1171
1172 // Return the offset of this DIE's next sibling.
1173
1174 off_t
1175 Dwarf_die::sibling_offset()
1176 {
1177   gold_assert(this->abbrev_code_ != NULL);
1178
1179   if (this->sibling_offset_ != 0)
1180     return this->sibling_offset_;
1181
1182   if (!this->has_children())
1183     {
1184       this->sibling_offset_ = this->skip_attributes();
1185       return this->sibling_offset_;
1186     }
1187
1188   if (this->has_sibling_attribute())
1189     {
1190       if (!this->read_attributes())
1191         return 0;
1192       if (this->sibling_offset_ != 0)
1193         return this->sibling_offset_;
1194     }
1195
1196   // Skip over the children.
1197   off_t child_offset = this->child_offset();
1198   while (child_offset > 0)
1199     {
1200       Dwarf_die die(this->dwinfo_, child_offset, this);
1201       // The Dwarf_die ctor will set this DIE's sibling offset
1202       // when it reads a zero abbrev code.
1203       if (die.tag() == 0)
1204         break;
1205       child_offset = die.sibling_offset();
1206     }
1207
1208   // This should be set by now.  If not, there was a problem reading
1209   // the DWARF info, and we return 0.
1210   return this->sibling_offset_;
1211 }
1212
1213 // class Dwarf_info_reader
1214
1215 // Begin parsing the debug info.  This calls visit_compilation_unit()
1216 // or visit_type_unit() for each compilation or type unit found in the
1217 // section, and visit_die() for each top-level DIE.
1218
1219 void
1220 Dwarf_info_reader::parse()
1221 {
1222   if (this->object_->is_big_endian())
1223     {
1224 #if defined(HAVE_TARGET_32_BIG) || defined(HAVE_TARGET_64_BIG)
1225       this->do_parse<true>();
1226 #else
1227       gold_unreachable();
1228 #endif
1229     }
1230   else
1231     {
1232 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_64_LITTLE)
1233       this->do_parse<false>();
1234 #else
1235       gold_unreachable();
1236 #endif
1237     }
1238 }
1239
1240 template<bool big_endian>
1241 void
1242 Dwarf_info_reader::do_parse()
1243 {
1244   // Get the section contents and decompress if necessary.
1245   section_size_type buffer_size;
1246   bool buffer_is_new;
1247   this->buffer_ = this->object_->decompressed_section_contents(this->shndx_,
1248                                                                &buffer_size,
1249                                                                &buffer_is_new);
1250   if (this->buffer_ == NULL || buffer_size == 0)
1251     return;
1252   this->buffer_end_ = this->buffer_ + buffer_size;
1253
1254   // The offset of this input section in the output section.
1255   off_t section_offset = this->object_->output_section_offset(this->shndx_);
1256
1257   // Start tracking relocations for this section.
1258   this->reloc_mapper_ = make_elf_reloc_mapper(this->object_, this->symtab_,
1259                                               this->symtab_size_);
1260   this->reloc_mapper_->initialize(this->reloc_shndx_, this->reloc_type_);
1261
1262   // Loop over compilation units (or type units).
1263   unsigned int abbrev_shndx = this->abbrev_shndx_;
1264   off_t abbrev_offset = 0;
1265   const unsigned char* pinfo = this->buffer_;
1266   while (pinfo < this->buffer_end_)
1267     {
1268       // Read the compilation (or type) unit header.
1269       const unsigned char* cu_start = pinfo;
1270       this->cu_offset_ = cu_start - this->buffer_;
1271       this->cu_length_ = this->buffer_end_ - cu_start;
1272
1273       // Read unit_length (4 or 12 bytes).
1274       if (!this->check_buffer(pinfo + 4))
1275         break;
1276       uint32_t unit_length =
1277           elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo);
1278       pinfo += 4;
1279       if (unit_length == 0xffffffff)
1280         {
1281           if (!this->check_buffer(pinfo + 8))
1282             break;
1283           unit_length = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
1284           pinfo += 8;
1285           this->offset_size_ = 8;
1286         }
1287       else
1288         this->offset_size_ = 4;
1289       if (!this->check_buffer(pinfo + unit_length))
1290         break;
1291       const unsigned char* cu_end = pinfo + unit_length;
1292       this->cu_length_ = cu_end - cu_start;
1293       if (!this->check_buffer(pinfo + 2 + this->offset_size_ + 1))
1294         break;
1295
1296       // Read version (2 bytes).
1297       this->cu_version_ =
1298           elfcpp::Swap_unaligned<16, big_endian>::readval(pinfo);
1299       pinfo += 2;
1300
1301       // Read debug_abbrev_offset (4 or 8 bytes).
1302       if (this->offset_size_ == 4)
1303         abbrev_offset = elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo);
1304       else
1305         abbrev_offset = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
1306       if (this->reloc_shndx_ > 0)
1307         {
1308           off_t reloc_offset = pinfo - this->buffer_;
1309           off_t value;
1310           abbrev_shndx =
1311               this->reloc_mapper_->get_reloc_target(reloc_offset, &value);
1312           if (abbrev_shndx == 0)
1313             return;
1314           if (this->reloc_type_ == elfcpp::SHT_REL)
1315             abbrev_offset += value;
1316           else
1317             abbrev_offset = value;
1318         }
1319       pinfo += this->offset_size_;
1320
1321       // Read address_size (1 byte).
1322       this->address_size_ = *pinfo++;
1323
1324       // For type units, read the two extra fields.
1325       uint64_t signature = 0;
1326       off_t type_offset = 0;
1327       if (this->is_type_unit_)
1328         {
1329           if (!this->check_buffer(pinfo + 8 + this->offset_size_))
1330             break;
1331
1332           // Read type_signature (8 bytes).
1333           signature = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
1334           pinfo += 8;
1335
1336           // Read type_offset (4 or 8 bytes).
1337           if (this->offset_size_ == 4)
1338             type_offset =
1339                 elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo);
1340           else
1341             type_offset =
1342                 elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
1343           pinfo += this->offset_size_;
1344         }
1345
1346       // Read the .debug_abbrev table.
1347       this->abbrev_table_.read_abbrevs(this->object_, abbrev_shndx,
1348                                        abbrev_offset);
1349
1350       // Visit the root DIE.
1351       Dwarf_die root_die(this,
1352                          pinfo - (this->buffer_ + this->cu_offset_),
1353                          NULL);
1354       if (root_die.tag() != 0)
1355         {
1356           // Visit the CU or TU.
1357           if (this->is_type_unit_)
1358             this->visit_type_unit(section_offset + this->cu_offset_,
1359                                   cu_end - cu_start, type_offset, signature,
1360                                   &root_die);
1361           else
1362             this->visit_compilation_unit(section_offset + this->cu_offset_,
1363                                          cu_end - cu_start, &root_die);
1364         }
1365
1366       // Advance to the next CU.
1367       pinfo = cu_end;
1368     }
1369
1370   if (buffer_is_new)
1371     {
1372       delete[] this->buffer_;
1373       this->buffer_ = NULL;
1374     }
1375 }
1376
1377 // Read the DWARF string table.
1378
1379 bool
1380 Dwarf_info_reader::do_read_string_table(unsigned int string_shndx)
1381 {
1382   Relobj* object = this->object_;
1383
1384   // If we don't have relocations, string_shndx will be 0, and
1385   // we'll have to hunt for the .debug_str section.
1386   if (string_shndx == 0)
1387     {
1388       for (unsigned int i = 1; i < this->object_->shnum(); ++i)
1389         {
1390           std::string name = object->section_name(i);
1391           if (name == ".debug_str" || name == ".zdebug_str")
1392             {
1393               string_shndx = i;
1394               this->string_output_section_offset_ =
1395                   object->output_section_offset(i);
1396               break;
1397             }
1398         }
1399       if (string_shndx == 0)
1400         return false;
1401     }
1402
1403   if (this->owns_string_buffer_ && this->string_buffer_ != NULL)
1404     {
1405       delete[] this->string_buffer_;
1406       this->owns_string_buffer_ = false;
1407     }
1408
1409   // Get the secton contents and decompress if necessary.
1410   section_size_type buffer_size;
1411   const unsigned char* buffer =
1412       object->decompressed_section_contents(string_shndx,
1413                                             &buffer_size,
1414                                             &this->owns_string_buffer_);
1415   this->string_buffer_ = reinterpret_cast<const char*>(buffer);
1416   this->string_buffer_end_ = this->string_buffer_ + buffer_size;
1417   this->string_shndx_ = string_shndx;
1418   return true;
1419 }
1420
1421 // Read a possibly unaligned integer of SIZE.
1422 template <int valsize>
1423 inline typename elfcpp::Valtype_base<valsize>::Valtype
1424 Dwarf_info_reader::read_from_pointer(const unsigned char* source)
1425 {
1426   typename elfcpp::Valtype_base<valsize>::Valtype return_value;
1427   if (this->object_->is_big_endian())
1428     return_value = elfcpp::Swap_unaligned<valsize, true>::readval(source);
1429   else
1430     return_value = elfcpp::Swap_unaligned<valsize, false>::readval(source);
1431   return return_value;
1432 }
1433
1434 // Read a possibly unaligned integer of SIZE.  Update SOURCE after read.
1435 template <int valsize>
1436 inline typename elfcpp::Valtype_base<valsize>::Valtype
1437 Dwarf_info_reader::read_from_pointer(const unsigned char** source)
1438 {
1439   typename elfcpp::Valtype_base<valsize>::Valtype return_value;
1440   if (this->object_->is_big_endian())
1441     return_value = elfcpp::Swap_unaligned<valsize, true>::readval(*source);
1442   else
1443     return_value = elfcpp::Swap_unaligned<valsize, false>::readval(*source);
1444   *source += valsize / 8;
1445   return return_value;
1446 }
1447
1448 // Look for a relocation at offset ATTR_OFF in the dwarf info,
1449 // and return the section index and offset of the target.
1450
1451 unsigned int
1452 Dwarf_info_reader::lookup_reloc(off_t attr_off, off_t* target_off)
1453 {
1454   off_t value;
1455   attr_off += this->cu_offset_;
1456   unsigned int shndx = this->reloc_mapper_->get_reloc_target(attr_off, &value);
1457   if (shndx == 0)
1458     return 0;
1459   if (this->reloc_type_ == elfcpp::SHT_REL)
1460     *target_off += value;
1461   else
1462     *target_off = value;
1463   return shndx;
1464 }
1465
1466 // Return a string from the DWARF string table.
1467
1468 const char*
1469 Dwarf_info_reader::get_string(off_t str_off, unsigned int string_shndx)
1470 {
1471   if (!this->read_string_table(string_shndx))
1472     return NULL;
1473
1474   // Correct the offset.  For incremental update links, we have a
1475   // relocated offset that is relative to the output section, but
1476   // here we need an offset relative to the input section.
1477   str_off -= this->string_output_section_offset_;
1478
1479   const char* p = this->string_buffer_ + str_off;
1480
1481   if (p < this->string_buffer_ || p >= this->string_buffer_end_)
1482     return NULL;
1483
1484   return p;
1485 }
1486
1487 // The following are default, do-nothing, implementations of the
1488 // hook methods normally provided by a derived class.  We provide
1489 // default implementations rather than no implementation so that
1490 // a derived class needs to implement only the hooks that it needs
1491 // to use.
1492
1493 // Process a compilation unit and parse its child DIE.
1494
1495 void
1496 Dwarf_info_reader::visit_compilation_unit(off_t, off_t, Dwarf_die*)
1497 {
1498 }
1499
1500 // Process a type unit and parse its child DIE.
1501
1502 void
1503 Dwarf_info_reader::visit_type_unit(off_t, off_t, off_t, uint64_t, Dwarf_die*)
1504 {
1505 }
1506
1507 // Print a warning about a corrupt debug section.
1508
1509 void
1510 Dwarf_info_reader::warn_corrupt_debug_section() const
1511 {
1512   gold_warning(_("%s: corrupt debug info in %s"),
1513                this->object_->name().c_str(),
1514                this->object_->section_name(this->shndx_).c_str());
1515 }
1516
1517 // class Sized_dwarf_line_info
1518
1519 struct LineStateMachine
1520 {
1521   int file_num;
1522   uint64_t address;
1523   int line_num;
1524   int column_num;
1525   unsigned int shndx;    // the section address refers to
1526   bool is_stmt;          // stmt means statement.
1527   bool basic_block;
1528   bool end_sequence;
1529 };
1530
1531 static void
1532 ResetLineStateMachine(struct LineStateMachine* lsm, bool default_is_stmt)
1533 {
1534   lsm->file_num = 1;
1535   lsm->address = 0;
1536   lsm->line_num = 1;
1537   lsm->column_num = 0;
1538   lsm->shndx = -1U;
1539   lsm->is_stmt = default_is_stmt;
1540   lsm->basic_block = false;
1541   lsm->end_sequence = false;
1542 }
1543
1544 template<int size, bool big_endian>
1545 Sized_dwarf_line_info<size, big_endian>::Sized_dwarf_line_info(
1546     Object* object,
1547     unsigned int read_shndx)
1548   : data_valid_(false), buffer_(NULL), buffer_start_(NULL),
1549     reloc_mapper_(NULL), symtab_buffer_(NULL), directories_(), files_(),
1550     current_header_index_(-1)
1551 {
1552   unsigned int debug_shndx;
1553
1554   for (debug_shndx = 1; debug_shndx < object->shnum(); ++debug_shndx)
1555     {
1556       // FIXME: do this more efficiently: section_name() isn't super-fast
1557       std::string name = object->section_name(debug_shndx);
1558       if (name == ".debug_line" || name == ".zdebug_line")
1559         {
1560           section_size_type buffer_size;
1561           bool is_new = false;
1562           this->buffer_ = object->decompressed_section_contents(debug_shndx,
1563                                                                 &buffer_size,
1564                                                                 &is_new);
1565           if (is_new)
1566             this->buffer_start_ = this->buffer_;
1567           this->buffer_end_ = this->buffer_ + buffer_size;
1568           break;
1569         }
1570     }
1571   if (this->buffer_ == NULL)
1572     return;
1573
1574   // Find the relocation section for ".debug_line".
1575   // We expect these for relobjs (.o's) but not dynobjs (.so's).
1576   unsigned int reloc_shndx = 0;
1577   for (unsigned int i = 0; i < object->shnum(); ++i)
1578     {
1579       unsigned int reloc_sh_type = object->section_type(i);
1580       if ((reloc_sh_type == elfcpp::SHT_REL
1581            || reloc_sh_type == elfcpp::SHT_RELA)
1582           && object->section_info(i) == debug_shndx)
1583         {
1584           reloc_shndx = i;
1585           this->track_relocs_type_ = reloc_sh_type;
1586           break;
1587         }
1588     }
1589
1590   // Finally, we need the symtab section to interpret the relocs.
1591   if (reloc_shndx != 0)
1592     {
1593       unsigned int symtab_shndx;
1594       for (symtab_shndx = 0; symtab_shndx < object->shnum(); ++symtab_shndx)
1595         if (object->section_type(symtab_shndx) == elfcpp::SHT_SYMTAB)
1596           {
1597             this->symtab_buffer_ = object->section_contents(
1598                 symtab_shndx, &this->symtab_buffer_size_, false);
1599             break;
1600           }
1601       if (this->symtab_buffer_ == NULL)
1602         return;
1603     }
1604
1605   this->reloc_mapper_ =
1606       new Sized_elf_reloc_mapper<size, big_endian>(object,
1607                                                    this->symtab_buffer_,
1608                                                    this->symtab_buffer_size_);
1609   if (!this->reloc_mapper_->initialize(reloc_shndx, this->track_relocs_type_))
1610     return;
1611
1612   // Now that we have successfully read all the data, parse the debug
1613   // info.
1614   this->data_valid_ = true;
1615   this->read_line_mappings(read_shndx);
1616 }
1617
1618 // Read the DWARF header.
1619
1620 template<int size, bool big_endian>
1621 const unsigned char*
1622 Sized_dwarf_line_info<size, big_endian>::read_header_prolog(
1623     const unsigned char* lineptr)
1624 {
1625   uint32_t initial_length = elfcpp::Swap_unaligned<32, big_endian>::readval(lineptr);
1626   lineptr += 4;
1627
1628   // In DWARF2/3, if the initial length is all 1 bits, then the offset
1629   // size is 8 and we need to read the next 8 bytes for the real length.
1630   if (initial_length == 0xffffffff)
1631     {
1632       header_.offset_size = 8;
1633       initial_length = elfcpp::Swap_unaligned<64, big_endian>::readval(lineptr);
1634       lineptr += 8;
1635     }
1636   else
1637     header_.offset_size = 4;
1638
1639   header_.total_length = initial_length;
1640
1641   gold_assert(lineptr + header_.total_length <= buffer_end_);
1642
1643   header_.version = elfcpp::Swap_unaligned<16, big_endian>::readval(lineptr);
1644   lineptr += 2;
1645
1646   if (header_.offset_size == 4)
1647     header_.prologue_length = elfcpp::Swap_unaligned<32, big_endian>::readval(lineptr);
1648   else
1649     header_.prologue_length = elfcpp::Swap_unaligned<64, big_endian>::readval(lineptr);
1650   lineptr += header_.offset_size;
1651
1652   header_.min_insn_length = *lineptr;
1653   lineptr += 1;
1654
1655   header_.default_is_stmt = *lineptr;
1656   lineptr += 1;
1657
1658   header_.line_base = *reinterpret_cast<const signed char*>(lineptr);
1659   lineptr += 1;
1660
1661   header_.line_range = *lineptr;
1662   lineptr += 1;
1663
1664   header_.opcode_base = *lineptr;
1665   lineptr += 1;
1666
1667   header_.std_opcode_lengths.resize(header_.opcode_base + 1);
1668   header_.std_opcode_lengths[0] = 0;
1669   for (int i = 1; i < header_.opcode_base; i++)
1670     {
1671       header_.std_opcode_lengths[i] = *lineptr;
1672       lineptr += 1;
1673     }
1674
1675   return lineptr;
1676 }
1677
1678 // The header for a debug_line section is mildly complicated, because
1679 // the line info is very tightly encoded.
1680
1681 template<int size, bool big_endian>
1682 const unsigned char*
1683 Sized_dwarf_line_info<size, big_endian>::read_header_tables(
1684     const unsigned char* lineptr)
1685 {
1686   ++this->current_header_index_;
1687
1688   // Create a new directories_ entry and a new files_ entry for our new
1689   // header.  We initialize each with a single empty element, because
1690   // dwarf indexes directory and filenames starting at 1.
1691   gold_assert(static_cast<int>(this->directories_.size())
1692               == this->current_header_index_);
1693   gold_assert(static_cast<int>(this->files_.size())
1694               == this->current_header_index_);
1695   this->directories_.push_back(std::vector<std::string>(1));
1696   this->files_.push_back(std::vector<std::pair<int, std::string> >(1));
1697
1698   // It is legal for the directory entry table to be empty.
1699   if (*lineptr)
1700     {
1701       int dirindex = 1;
1702       while (*lineptr)
1703         {
1704           const char* dirname = reinterpret_cast<const char*>(lineptr);
1705           gold_assert(dirindex
1706                       == static_cast<int>(this->directories_.back().size()));
1707           this->directories_.back().push_back(dirname);
1708           lineptr += this->directories_.back().back().size() + 1;
1709           dirindex++;
1710         }
1711     }
1712   lineptr++;
1713
1714   // It is also legal for the file entry table to be empty.
1715   if (*lineptr)
1716     {
1717       int fileindex = 1;
1718       size_t len;
1719       while (*lineptr)
1720         {
1721           const char* filename = reinterpret_cast<const char*>(lineptr);
1722           lineptr += strlen(filename) + 1;
1723
1724           uint64_t dirindex = read_unsigned_LEB_128(lineptr, &len);
1725           lineptr += len;
1726
1727           if (dirindex >= this->directories_.back().size())
1728             dirindex = 0;
1729           int dirindexi = static_cast<int>(dirindex);
1730
1731           read_unsigned_LEB_128(lineptr, &len);   // mod_time
1732           lineptr += len;
1733
1734           read_unsigned_LEB_128(lineptr, &len);   // filelength
1735           lineptr += len;
1736
1737           gold_assert(fileindex
1738                       == static_cast<int>(this->files_.back().size()));
1739           this->files_.back().push_back(std::make_pair(dirindexi, filename));
1740           fileindex++;
1741         }
1742     }
1743   lineptr++;
1744
1745   return lineptr;
1746 }
1747
1748 // Process a single opcode in the .debug.line structure.
1749
1750 template<int size, bool big_endian>
1751 bool
1752 Sized_dwarf_line_info<size, big_endian>::process_one_opcode(
1753     const unsigned char* start, struct LineStateMachine* lsm, size_t* len)
1754 {
1755   size_t oplen = 0;
1756   size_t templen;
1757   unsigned char opcode = *start;
1758   oplen++;
1759   start++;
1760
1761   // If the opcode is great than the opcode_base, it is a special
1762   // opcode. Most line programs consist mainly of special opcodes.
1763   if (opcode >= header_.opcode_base)
1764     {
1765       opcode -= header_.opcode_base;
1766       const int advance_address = ((opcode / header_.line_range)
1767                                    * header_.min_insn_length);
1768       lsm->address += advance_address;
1769
1770       const int advance_line = ((opcode % header_.line_range)
1771                                 + header_.line_base);
1772       lsm->line_num += advance_line;
1773       lsm->basic_block = true;
1774       *len = oplen;
1775       return true;
1776     }
1777
1778   // Otherwise, we have the regular opcodes
1779   switch (opcode)
1780     {
1781     case elfcpp::DW_LNS_copy:
1782       lsm->basic_block = false;
1783       *len = oplen;
1784       return true;
1785
1786     case elfcpp::DW_LNS_advance_pc:
1787       {
1788         const uint64_t advance_address
1789             = read_unsigned_LEB_128(start, &templen);
1790         oplen += templen;
1791         lsm->address += header_.min_insn_length * advance_address;
1792       }
1793       break;
1794
1795     case elfcpp::DW_LNS_advance_line:
1796       {
1797         const uint64_t advance_line = read_signed_LEB_128(start, &templen);
1798         oplen += templen;
1799         lsm->line_num += advance_line;
1800       }
1801       break;
1802
1803     case elfcpp::DW_LNS_set_file:
1804       {
1805         const uint64_t fileno = read_unsigned_LEB_128(start, &templen);
1806         oplen += templen;
1807         lsm->file_num = fileno;
1808       }
1809       break;
1810
1811     case elfcpp::DW_LNS_set_column:
1812       {
1813         const uint64_t colno = read_unsigned_LEB_128(start, &templen);
1814         oplen += templen;
1815         lsm->column_num = colno;
1816       }
1817       break;
1818
1819     case elfcpp::DW_LNS_negate_stmt:
1820       lsm->is_stmt = !lsm->is_stmt;
1821       break;
1822
1823     case elfcpp::DW_LNS_set_basic_block:
1824       lsm->basic_block = true;
1825       break;
1826
1827     case elfcpp::DW_LNS_fixed_advance_pc:
1828       {
1829         int advance_address;
1830         advance_address = elfcpp::Swap_unaligned<16, big_endian>::readval(start);
1831         oplen += 2;
1832         lsm->address += advance_address;
1833       }
1834       break;
1835
1836     case elfcpp::DW_LNS_const_add_pc:
1837       {
1838         const int advance_address = (header_.min_insn_length
1839                                      * ((255 - header_.opcode_base)
1840                                         / header_.line_range));
1841         lsm->address += advance_address;
1842       }
1843       break;
1844
1845     case elfcpp::DW_LNS_extended_op:
1846       {
1847         const uint64_t extended_op_len
1848             = read_unsigned_LEB_128(start, &templen);
1849         start += templen;
1850         oplen += templen + extended_op_len;
1851
1852         const unsigned char extended_op = *start;
1853         start++;
1854
1855         switch (extended_op)
1856           {
1857           case elfcpp::DW_LNE_end_sequence:
1858             // This means that the current byte is the one immediately
1859             // after a set of instructions.  Record the current line
1860             // for up to one less than the current address.
1861             lsm->line_num = -1;
1862             lsm->end_sequence = true;
1863             *len = oplen;
1864             return true;
1865
1866           case elfcpp::DW_LNE_set_address:
1867             {
1868               lsm->address =
1869                 elfcpp::Swap_unaligned<size, big_endian>::readval(start);
1870               typename Reloc_map::const_iterator it
1871                   = this->reloc_map_.find(start - this->buffer_);
1872               if (it != reloc_map_.end())
1873                 {
1874                   // If this is a SHT_RELA section, then ignore the
1875                   // section contents.  This assumes that this is a
1876                   // straight reloc which just uses the reloc addend.
1877                   // The reloc addend has already been included in the
1878                   // symbol value.
1879                   if (this->track_relocs_type_ == elfcpp::SHT_RELA)
1880                     lsm->address = 0;
1881                   // Add in the symbol value.
1882                   lsm->address += it->second.second;
1883                   lsm->shndx = it->second.first;
1884                 }
1885               else
1886                 {
1887                   // If we're a normal .o file, with relocs, every
1888                   // set_address should have an associated relocation.
1889                   if (this->input_is_relobj())
1890                     this->data_valid_ = false;
1891                 }
1892               break;
1893             }
1894           case elfcpp::DW_LNE_define_file:
1895             {
1896               const char* filename  = reinterpret_cast<const char*>(start);
1897               templen = strlen(filename) + 1;
1898               start += templen;
1899
1900               uint64_t dirindex = read_unsigned_LEB_128(start, &templen);
1901
1902               if (dirindex >= this->directories_.back().size())
1903                 dirindex = 0;
1904               int dirindexi = static_cast<int>(dirindex);
1905
1906               // This opcode takes two additional ULEB128 parameters
1907               // (mod_time and filelength), but we don't use those
1908               // values.  Because OPLEN already tells us how far to
1909               // skip to the next opcode, we don't need to read
1910               // them at all.
1911
1912               this->files_.back().push_back(std::make_pair(dirindexi,
1913                                                            filename));
1914             }
1915             break;
1916           }
1917       }
1918       break;
1919
1920     default:
1921       {
1922         // Ignore unknown opcode  silently
1923         for (int i = 0; i < header_.std_opcode_lengths[opcode]; i++)
1924           {
1925             size_t templen;
1926             read_unsigned_LEB_128(start, &templen);
1927             start += templen;
1928             oplen += templen;
1929           }
1930       }
1931       break;
1932   }
1933   *len = oplen;
1934   return false;
1935 }
1936
1937 // Read the debug information at LINEPTR and store it in the line
1938 // number map.
1939
1940 template<int size, bool big_endian>
1941 unsigned const char*
1942 Sized_dwarf_line_info<size, big_endian>::read_lines(unsigned const char* lineptr,
1943                                                     unsigned int shndx)
1944 {
1945   struct LineStateMachine lsm;
1946
1947   // LENGTHSTART is the place the length field is based on.  It is the
1948   // point in the header after the initial length field.
1949   const unsigned char* lengthstart = buffer_;
1950
1951   // In 64 bit dwarf, the initial length is 12 bytes, because of the
1952   // 0xffffffff at the start.
1953   if (header_.offset_size == 8)
1954     lengthstart += 12;
1955   else
1956     lengthstart += 4;
1957
1958   while (lineptr < lengthstart + header_.total_length)
1959     {
1960       ResetLineStateMachine(&lsm, header_.default_is_stmt);
1961       while (!lsm.end_sequence)
1962         {
1963           size_t oplength;
1964           bool add_line = this->process_one_opcode(lineptr, &lsm, &oplength);
1965           if (add_line
1966               && (shndx == -1U || lsm.shndx == -1U || shndx == lsm.shndx))
1967             {
1968               Offset_to_lineno_entry entry
1969                   = { static_cast<off_t>(lsm.address),
1970                       this->current_header_index_,
1971                       static_cast<unsigned int>(lsm.file_num),
1972                       true, lsm.line_num };
1973               std::vector<Offset_to_lineno_entry>&
1974                 map(this->line_number_map_[lsm.shndx]);
1975               // If we see two consecutive entries with the same
1976               // offset and a real line number, then mark the first
1977               // one as non-canonical.
1978               if (!map.empty()
1979                   && (map.back().offset == static_cast<off_t>(lsm.address))
1980                   && lsm.line_num != -1
1981                   && map.back().line_num != -1)
1982                 map.back().last_line_for_offset = false;
1983               map.push_back(entry);
1984             }
1985           lineptr += oplength;
1986         }
1987     }
1988
1989   return lengthstart + header_.total_length;
1990 }
1991
1992 // Read the relocations into a Reloc_map.
1993
1994 template<int size, bool big_endian>
1995 void
1996 Sized_dwarf_line_info<size, big_endian>::read_relocs()
1997 {
1998   if (this->symtab_buffer_ == NULL)
1999     return;
2000
2001   off_t value;
2002   off_t reloc_offset;
2003   while ((reloc_offset = this->reloc_mapper_->next_offset()) != -1)
2004     {
2005       const unsigned int shndx =
2006           this->reloc_mapper_->get_reloc_target(reloc_offset, &value);
2007
2008       // There is no reason to record non-ordinary section indexes, or
2009       // SHN_UNDEF, because they will never match the real section.
2010       if (shndx != 0)
2011         this->reloc_map_[reloc_offset] = std::make_pair(shndx, value);
2012
2013       this->reloc_mapper_->advance(reloc_offset + 1);
2014     }
2015 }
2016
2017 // Read the line number info.
2018
2019 template<int size, bool big_endian>
2020 void
2021 Sized_dwarf_line_info<size, big_endian>::read_line_mappings(unsigned int shndx)
2022 {
2023   gold_assert(this->data_valid_ == true);
2024
2025   this->read_relocs();
2026   while (this->buffer_ < this->buffer_end_)
2027     {
2028       const unsigned char* lineptr = this->buffer_;
2029       lineptr = this->read_header_prolog(lineptr);
2030       lineptr = this->read_header_tables(lineptr);
2031       lineptr = this->read_lines(lineptr, shndx);
2032       this->buffer_ = lineptr;
2033     }
2034
2035   // Sort the lines numbers, so addr2line can use binary search.
2036   for (typename Lineno_map::iterator it = line_number_map_.begin();
2037        it != line_number_map_.end();
2038        ++it)
2039     // Each vector needs to be sorted by offset.
2040     std::sort(it->second.begin(), it->second.end());
2041 }
2042
2043 // Some processing depends on whether the input is a .o file or not.
2044 // For instance, .o files have relocs, and have .debug_lines
2045 // information on a per section basis.  .so files, on the other hand,
2046 // lack relocs, and offsets are unique, so we can ignore the section
2047 // information.
2048
2049 template<int size, bool big_endian>
2050 bool
2051 Sized_dwarf_line_info<size, big_endian>::input_is_relobj()
2052 {
2053   // Only .o files have relocs and the symtab buffer that goes with them.
2054   return this->symtab_buffer_ != NULL;
2055 }
2056
2057 // Given an Offset_to_lineno_entry vector, and an offset, figure out
2058 // if the offset points into a function according to the vector (see
2059 // comments below for the algorithm).  If it does, return an iterator
2060 // into the vector that points to the line-number that contains that
2061 // offset.  If not, it returns vector::end().
2062
2063 static std::vector<Offset_to_lineno_entry>::const_iterator
2064 offset_to_iterator(const std::vector<Offset_to_lineno_entry>* offsets,
2065                    off_t offset)
2066 {
2067   const Offset_to_lineno_entry lookup_key = { offset, 0, 0, true, 0 };
2068
2069   // lower_bound() returns the smallest offset which is >= lookup_key.
2070   // If no offset in offsets is >= lookup_key, returns end().
2071   std::vector<Offset_to_lineno_entry>::const_iterator it
2072       = std::lower_bound(offsets->begin(), offsets->end(), lookup_key);
2073
2074   // This code is easiest to understand with a concrete example.
2075   // Here's a possible offsets array:
2076   // {{offset = 3211, header_num = 0, file_num = 1, last, line_num = 16},  // 0
2077   //  {offset = 3224, header_num = 0, file_num = 1, last, line_num = 20},  // 1
2078   //  {offset = 3226, header_num = 0, file_num = 1, last, line_num = 22},  // 2
2079   //  {offset = 3231, header_num = 0, file_num = 1, last, line_num = 25},  // 3
2080   //  {offset = 3232, header_num = 0, file_num = 1, last, line_num = -1},  // 4
2081   //  {offset = 3232, header_num = 0, file_num = 1, last, line_num = 65},  // 5
2082   //  {offset = 3235, header_num = 0, file_num = 1, last, line_num = 66},  // 6
2083   //  {offset = 3236, header_num = 0, file_num = 1, last, line_num = -1},  // 7
2084   //  {offset = 5764, header_num = 0, file_num = 1, last, line_num = 48},  // 8
2085   //  {offset = 5764, header_num = 0, file_num = 1,!last, line_num = 47},  // 9
2086   //  {offset = 5765, header_num = 0, file_num = 1, last, line_num = 49},  // 10
2087   //  {offset = 5767, header_num = 0, file_num = 1, last, line_num = 50},  // 11
2088   //  {offset = 5768, header_num = 0, file_num = 1, last, line_num = 51},  // 12
2089   //  {offset = 5773, header_num = 0, file_num = 1, last, line_num = -1},  // 13
2090   //  {offset = 5787, header_num = 1, file_num = 1, last, line_num = 19},  // 14
2091   //  {offset = 5790, header_num = 1, file_num = 1, last, line_num = 20},  // 15
2092   //  {offset = 5793, header_num = 1, file_num = 1, last, line_num = 67},  // 16
2093   //  {offset = 5793, header_num = 1, file_num = 1, last, line_num = -1},  // 17
2094   //  {offset = 5793, header_num = 1, file_num = 1,!last, line_num = 66},  // 18
2095   //  {offset = 5795, header_num = 1, file_num = 1, last, line_num = 68},  // 19
2096   //  {offset = 5798, header_num = 1, file_num = 1, last, line_num = -1},  // 20
2097   // The entries with line_num == -1 mark the end of a function: the
2098   // associated offset is one past the last instruction in the
2099   // function.  This can correspond to the beginning of the next
2100   // function (as is true for offset 3232); alternately, there can be
2101   // a gap between the end of one function and the start of the next
2102   // (as is true for some others, most obviously from 3236->5764).
2103   //
2104   // Case 1: lookup_key has offset == 10.  lower_bound returns
2105   //         offsets[0].  Since it's not an exact match and we're
2106   //         at the beginning of offsets, we return end() (invalid).
2107   // Case 2: lookup_key has offset 10000.  lower_bound returns
2108   //         offset[21] (end()).  We return end() (invalid).
2109   // Case 3: lookup_key has offset == 3211.  lower_bound matches
2110   //         offsets[0] exactly, and that's the entry we return.
2111   // Case 4: lookup_key has offset == 3232.  lower_bound returns
2112   //         offsets[4].  That's an exact match, but indicates
2113   //         end-of-function.  We check if offsets[5] is also an
2114   //         exact match but not end-of-function.  It is, so we
2115   //         return offsets[5].
2116   // Case 5: lookup_key has offset == 3214.  lower_bound returns
2117   //         offsets[1].  Since it's not an exact match, we back
2118   //         up to the offset that's < lookup_key, offsets[0].
2119   //         We note offsets[0] is a valid entry (not end-of-function),
2120   //         so that's the entry we return.
2121   // Case 6: lookup_key has offset == 4000.  lower_bound returns
2122   //         offsets[8].  Since it's not an exact match, we back
2123   //         up to offsets[7].  Since offsets[7] indicates
2124   //         end-of-function, we know lookup_key is between
2125   //         functions, so we return end() (not a valid offset).
2126   // Case 7: lookup_key has offset == 5794.  lower_bound returns
2127   //         offsets[19].  Since it's not an exact match, we back
2128   //         up to offsets[16].  Note we back up to the *first*
2129   //         entry with offset 5793, not just offsets[19-1].
2130   //         We note offsets[16] is a valid entry, so we return it.
2131   //         If offsets[16] had had line_num == -1, we would have
2132   //         checked offsets[17].  The reason for this is that
2133   //         16 and 17 can be in an arbitrary order, since we sort
2134   //         only by offset and last_line_for_offset.  (Note it
2135   //         doesn't help to use line_number as a tertiary sort key,
2136   //         since sometimes we want the -1 to be first and sometimes
2137   //         we want it to be last.)
2138
2139   // This deals with cases (1) and (2).
2140   if ((it == offsets->begin() && offset < it->offset)
2141       || it == offsets->end())
2142     return offsets->end();
2143
2144   // This deals with cases (3) and (4).
2145   if (offset == it->offset)
2146     {
2147       while (it != offsets->end()
2148              && it->offset == offset
2149              && it->line_num == -1)
2150         ++it;
2151       if (it == offsets->end() || it->offset != offset)
2152         return offsets->end();
2153       else
2154         return it;
2155     }
2156
2157   // This handles the first part of case (7) -- we back up to the
2158   // *first* entry that has the offset that's behind us.
2159   gold_assert(it != offsets->begin());
2160   std::vector<Offset_to_lineno_entry>::const_iterator range_end = it;
2161   --it;
2162   const off_t range_value = it->offset;
2163   while (it != offsets->begin() && (it-1)->offset == range_value)
2164     --it;
2165
2166   // This handles cases (5), (6), and (7): if any entry in the
2167   // equal_range [it, range_end) has a line_num != -1, it's a valid
2168   // match.  If not, we're not in a function.  The line number we saw
2169   // last for an offset will be sorted first, so it'll get returned if
2170   // it's present.
2171   for (; it != range_end; ++it)
2172     if (it->line_num != -1)
2173       return it;
2174   return offsets->end();
2175 }
2176
2177 // Returns the canonical filename:lineno for the address passed in.
2178 // If other_lines is not NULL, appends the non-canonical lines
2179 // assigned to the same address.
2180
2181 template<int size, bool big_endian>
2182 std::string
2183 Sized_dwarf_line_info<size, big_endian>::do_addr2line(
2184     unsigned int shndx,
2185     off_t offset,
2186     std::vector<std::string>* other_lines)
2187 {
2188   if (this->data_valid_ == false)
2189     return "";
2190
2191   const std::vector<Offset_to_lineno_entry>* offsets;
2192   // If we do not have reloc information, then our input is a .so or
2193   // some similar data structure where all the information is held in
2194   // the offset.  In that case, we ignore the input shndx.
2195   if (this->input_is_relobj())
2196     offsets = &this->line_number_map_[shndx];
2197   else
2198     offsets = &this->line_number_map_[-1U];
2199   if (offsets->empty())
2200     return "";
2201
2202   typename std::vector<Offset_to_lineno_entry>::const_iterator it
2203       = offset_to_iterator(offsets, offset);
2204   if (it == offsets->end())
2205     return "";
2206
2207   std::string result = this->format_file_lineno(*it);
2208   gold_debug(DEBUG_LOCATION, "do_addr2line: canonical result: %s",
2209              result.c_str());
2210   if (other_lines != NULL)
2211     {
2212       unsigned int last_file_num = it->file_num;
2213       int last_line_num = it->line_num;
2214       // Return up to 4 more locations from the beginning of the function
2215       // for fuzzy matching.
2216       for (++it; it != offsets->end(); ++it)
2217         {
2218           if (it->offset == offset && it->line_num == -1)
2219             continue;  // The end of a previous function.
2220           if (it->line_num == -1)
2221             break;  // The end of the current function.
2222           if (it->file_num != last_file_num || it->line_num != last_line_num)
2223             {
2224               other_lines->push_back(this->format_file_lineno(*it));
2225               gold_debug(DEBUG_LOCATION, "do_addr2line: other: %s",
2226                          other_lines->back().c_str());
2227               last_file_num = it->file_num;
2228               last_line_num = it->line_num;
2229             }
2230           if (it->offset > offset && other_lines->size() >= 4)
2231             break;
2232         }
2233     }
2234
2235   return result;
2236 }
2237
2238 // Convert the file_num + line_num into a string.
2239
2240 template<int size, bool big_endian>
2241 std::string
2242 Sized_dwarf_line_info<size, big_endian>::format_file_lineno(
2243     const Offset_to_lineno_entry& loc) const
2244 {
2245   std::string ret;
2246
2247   gold_assert(loc.header_num < static_cast<int>(this->files_.size()));
2248   gold_assert(loc.file_num
2249               < static_cast<unsigned int>(this->files_[loc.header_num].size()));
2250   const std::pair<int, std::string>& filename_pair
2251       = this->files_[loc.header_num][loc.file_num];
2252   const std::string& filename = filename_pair.second;
2253
2254   gold_assert(loc.header_num < static_cast<int>(this->directories_.size()));
2255   gold_assert(filename_pair.first
2256               < static_cast<int>(this->directories_[loc.header_num].size()));
2257   const std::string& dirname
2258       = this->directories_[loc.header_num][filename_pair.first];
2259
2260   if (!dirname.empty())
2261     {
2262       ret += dirname;
2263       ret += "/";
2264     }
2265   ret += filename;
2266   if (ret.empty())
2267     ret = "(unknown)";
2268
2269   char buffer[64];   // enough to hold a line number
2270   snprintf(buffer, sizeof(buffer), "%d", loc.line_num);
2271   ret += ":";
2272   ret += buffer;
2273
2274   return ret;
2275 }
2276
2277 // Dwarf_line_info routines.
2278
2279 static unsigned int next_generation_count = 0;
2280
2281 struct Addr2line_cache_entry
2282 {
2283   Object* object;
2284   unsigned int shndx;
2285   Dwarf_line_info* dwarf_line_info;
2286   unsigned int generation_count;
2287   unsigned int access_count;
2288
2289   Addr2line_cache_entry(Object* o, unsigned int s, Dwarf_line_info* d)
2290       : object(o), shndx(s), dwarf_line_info(d),
2291         generation_count(next_generation_count), access_count(0)
2292   {
2293     if (next_generation_count < (1U << 31))
2294       ++next_generation_count;
2295   }
2296 };
2297 // We expect this cache to be small, so don't bother with a hashtable
2298 // or priority queue or anything: just use a simple vector.
2299 static std::vector<Addr2line_cache_entry> addr2line_cache;
2300
2301 std::string
2302 Dwarf_line_info::one_addr2line(Object* object,
2303                                unsigned int shndx, off_t offset,
2304                                size_t cache_size,
2305                                std::vector<std::string>* other_lines)
2306 {
2307   Dwarf_line_info* lineinfo = NULL;
2308   std::vector<Addr2line_cache_entry>::iterator it;
2309
2310   // First, check the cache.  If we hit, update the counts.
2311   for (it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it)
2312     {
2313       if (it->object == object && it->shndx == shndx)
2314         {
2315           lineinfo = it->dwarf_line_info;
2316           it->generation_count = next_generation_count;
2317           // We cap generation_count at 2^31 -1 to avoid overflow.
2318           if (next_generation_count < (1U << 31))
2319             ++next_generation_count;
2320           // We cap access_count at 31 so 2^access_count doesn't overflow
2321           if (it->access_count < 31)
2322             ++it->access_count;
2323           break;
2324         }
2325     }
2326
2327   // If we don't hit the cache, create a new object and insert into the
2328   // cache.
2329   if (lineinfo == NULL)
2330   {
2331     switch (parameters->size_and_endianness())
2332       {
2333 #ifdef HAVE_TARGET_32_LITTLE
2334         case Parameters::TARGET_32_LITTLE:
2335           lineinfo = new Sized_dwarf_line_info<32, false>(object, shndx); break;
2336 #endif
2337 #ifdef HAVE_TARGET_32_BIG
2338         case Parameters::TARGET_32_BIG:
2339           lineinfo = new Sized_dwarf_line_info<32, true>(object, shndx); break;
2340 #endif
2341 #ifdef HAVE_TARGET_64_LITTLE
2342         case Parameters::TARGET_64_LITTLE:
2343           lineinfo = new Sized_dwarf_line_info<64, false>(object, shndx); break;
2344 #endif
2345 #ifdef HAVE_TARGET_64_BIG
2346         case Parameters::TARGET_64_BIG:
2347           lineinfo = new Sized_dwarf_line_info<64, true>(object, shndx); break;
2348 #endif
2349         default:
2350           gold_unreachable();
2351       }
2352     addr2line_cache.push_back(Addr2line_cache_entry(object, shndx, lineinfo));
2353   }
2354
2355   // Now that we have our object, figure out the answer
2356   std::string retval = lineinfo->addr2line(shndx, offset, other_lines);
2357
2358   // Finally, if our cache has grown too big, delete old objects.  We
2359   // assume the common (probably only) case is deleting only one object.
2360   // We use a pretty simple scheme to evict: function of LRU and MFU.
2361   while (addr2line_cache.size() > cache_size)
2362     {
2363       unsigned int lowest_score = ~0U;
2364       std::vector<Addr2line_cache_entry>::iterator lowest
2365           = addr2line_cache.end();
2366       for (it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it)
2367         {
2368           const unsigned int score = (it->generation_count
2369                                       + (1U << it->access_count));
2370           if (score < lowest_score)
2371             {
2372               lowest_score = score;
2373               lowest = it;
2374             }
2375         }
2376       if (lowest != addr2line_cache.end())
2377         {
2378           delete lowest->dwarf_line_info;
2379           addr2line_cache.erase(lowest);
2380         }
2381     }
2382
2383   return retval;
2384 }
2385
2386 void
2387 Dwarf_line_info::clear_addr2line_cache()
2388 {
2389   for (std::vector<Addr2line_cache_entry>::iterator it = addr2line_cache.begin();
2390        it != addr2line_cache.end();
2391        ++it)
2392     delete it->dwarf_line_info;
2393   addr2line_cache.clear();
2394 }
2395
2396 #ifdef HAVE_TARGET_32_LITTLE
2397 template
2398 class Sized_dwarf_line_info<32, false>;
2399 #endif
2400
2401 #ifdef HAVE_TARGET_32_BIG
2402 template
2403 class Sized_dwarf_line_info<32, true>;
2404 #endif
2405
2406 #ifdef HAVE_TARGET_64_LITTLE
2407 template
2408 class Sized_dwarf_line_info<64, false>;
2409 #endif
2410
2411 #ifdef HAVE_TARGET_64_BIG
2412 template
2413 class Sized_dwarf_line_info<64, true>;
2414 #endif
2415
2416 } // End namespace gold.