gold/dwarf_reader.cc

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