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_null:
 617             attr_value.val.intval = 0;
 618             break;
 619           case elfcpp::DW_FORM_flag_present:
 620             attr_value.val.intval = 1;
 621             break;
 622           case elfcpp::DW_FORM_strp:
 623             {
 624               off_t str_off;
 625               if (this->dwinfo_->offset_size() == 4)
 626                 str_off = read_from_pointer<32>(&pattr);
 627               else
 628                 str_off = read_from_pointer<64>(&pattr);
 629               unsigned int shndx =
 630                   this->dwinfo_->lookup_reloc(attr_off, &str_off);
 631               attr_value.aux.shndx = shndx;
 632               attr_value.val.refval = str_off;
 633               break;
 634             }
 635           case elfcpp::DW_FORM_sec_offset:
 636             {
 637               off_t sec_off;
 638               if (this->dwinfo_->offset_size() == 4)
 639                 sec_off = read_from_pointer<32>(&pattr);
 640               else
 641                 sec_off = read_from_pointer<64>(&pattr);
 642               unsigned int shndx =
 643                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 644               attr_value.aux.shndx = shndx;
 645               attr_value.val.refval = sec_off;
 646               ref_form = true;
 647               break;
 648             }
 649           case elfcpp::DW_FORM_addr:
 650           case elfcpp::DW_FORM_ref_addr:
 651             {
 652               off_t sec_off;
 653               if (this->dwinfo_->address_size() == 4)
 654                 sec_off = read_from_pointer<32>(&pattr);
 655               else
 656                 sec_off = read_from_pointer<64>(&pattr);
 657               unsigned int shndx =
 658                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 659               attr_value.aux.shndx = shndx;
 660               attr_value.val.refval = sec_off;
 661               ref_form = true;
 662               break;
 663             }
 664           case elfcpp::DW_FORM_block1:
 665             attr_value.aux.blocklen = *pattr++;
 666             attr_value.val.blockval = pattr;
 667             pattr += attr_value.aux.blocklen;
 668             break;
 669           case elfcpp::DW_FORM_block2:
 670             attr_value.aux.blocklen = read_from_pointer<16>(&pattr);
 671             attr_value.val.blockval = pattr;
 672             pattr += attr_value.aux.blocklen;
 673             break;
 674           case elfcpp::DW_FORM_block4:
 675             attr_value.aux.blocklen = read_from_pointer<32>(&pattr);
 676             attr_value.val.blockval = pattr;
 677             pattr += attr_value.aux.blocklen;
 678             break;
 679           case elfcpp::DW_FORM_block:
 680           case elfcpp::DW_FORM_exprloc:
 681             attr_value.aux.blocklen = read_unsigned_LEB_128(pattr, &len);
 682             attr_value.val.blockval = pattr + len;
 683             pattr += len + attr_value.aux.blocklen;
 684             break;
 685           case elfcpp::DW_FORM_data1:
 686           case elfcpp::DW_FORM_flag:
 687             attr_value.val.intval = *pattr++;
 688             break;
 689           case elfcpp::DW_FORM_ref1:
 690             attr_value.val.refval = *pattr++;
 691             ref_form = true;
 692             break;
 693           case elfcpp::DW_FORM_data2:
 694             attr_value.val.intval = read_from_pointer<16>(&pattr);
 695             break;
 696           case elfcpp::DW_FORM_ref2:
 697             attr_value.val.refval = read_from_pointer<16>(&pattr);
 698             ref_form = true;
 699             break;
 700           case elfcpp::DW_FORM_data4:
 701             {
 702               off_t sec_off;
 703               sec_off = read_from_pointer<32>(&pattr);
 704               unsigned int shndx =
 705                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 706               attr_value.aux.shndx = shndx;
 707               attr_value.val.intval = sec_off;
 708               break;
 709             }
 710           case elfcpp::DW_FORM_ref4:
 711             {
 712               off_t sec_off;
 713               sec_off = read_from_pointer<32>(&pattr);
 714               unsigned int shndx =
 715                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 716               attr_value.aux.shndx = shndx;
 717               attr_value.val.refval = sec_off;
 718               ref_form = true;
 719               break;
 720             }
 721           case elfcpp::DW_FORM_data8:
 722             {
 723               off_t sec_off;
 724               sec_off = read_from_pointer<64>(&pattr);
 725               unsigned int shndx =
 726                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 727               attr_value.aux.shndx = shndx;
 728               attr_value.val.intval = sec_off;
 729               break;
 730             }
 731           case elfcpp::DW_FORM_ref_sig8:
 732             attr_value.val.uintval = read_from_pointer<64>(&pattr);
 733             break;
 734           case elfcpp::DW_FORM_ref8:
 735             {
 736               off_t sec_off;
 737               sec_off = read_from_pointer<64>(&pattr);
 738               unsigned int shndx =
 739                   this->dwinfo_->lookup_reloc(attr_off, &sec_off);
 740               attr_value.aux.shndx = shndx;
 741               attr_value.val.refval = sec_off;
 742               ref_form = true;
 743               break;
 744             }
 745           case elfcpp::DW_FORM_ref_udata:
 746             attr_value.val.refval = read_unsigned_LEB_128(pattr, &len);
 747             ref_form = true;
 748             pattr += len;
 749             break;
 750           case elfcpp::DW_FORM_udata:
 751             attr_value.val.uintval = read_unsigned_LEB_128(pattr, &len);
 752             pattr += len;
 753             break;
 754           case elfcpp::DW_FORM_sdata:
 755             attr_value.val.intval = read_signed_LEB_128(pattr, &len);
 756             pattr += len;
 757             break;
 758           case elfcpp::DW_FORM_string:
 759             attr_value.val.stringval = reinterpret_cast<const char*>(pattr);
 760             len = strlen(attr_value.val.stringval);
 761             pattr += len + 1;
 762             break;
 763           default:
 764             return false;
 765         }
 766
 767       // Cache the most frequently-requested attributes.
 768       switch (attr)
 769         {
 770           case elfcpp::DW_AT_name:
 771             if (form == elfcpp::DW_FORM_string)
 772               this->name_ = attr_value.val.stringval;
 773             else if (form == elfcpp::DW_FORM_strp)
 774               {
 775                 // All indirect strings should refer to the same
 776                 // string section, so we just save the last one seen.
 777                 this->string_shndx_ = attr_value.aux.shndx;
 778                 this->name_off_ = attr_value.val.refval;
 779               }
 780             break;
 781           case elfcpp::DW_AT_linkage_name:
 782           case elfcpp::DW_AT_MIPS_linkage_name:
 783             if (form == elfcpp::DW_FORM_string)
 784               this->linkage_name_ = attr_value.val.stringval;
 785             else if (form == elfcpp::DW_FORM_strp)
 786               {
 787                 // All indirect strings should refer to the same
 788                 // string section, so we just save the last one seen.
 789                 this->string_shndx_ = attr_value.aux.shndx;
 790                 this->linkage_name_off_ = attr_value.val.refval;
 791               }
 792             break;
 793           case elfcpp::DW_AT_specification:
 794             if (ref_form)
 795               this->specification_ = attr_value.val.refval;
 796             break;
 797           case elfcpp::DW_AT_abstract_origin:
 798             if (ref_form)
 799               this->abstract_origin_ = attr_value.val.refval;
 800             break;
 801           case elfcpp::DW_AT_sibling:
 802             if (ref_form && attr_value.aux.shndx == 0)
 803               this->sibling_offset_ = attr_value.val.refval;
 804           default:
 805             break;
 806         }
 807
 808       this->attributes_.push_back(attr_value);
 809     }
 810
 811   // Now that we know where the next DIE begins, record the offset
 812   // to avoid later recalculation.
 813   if (this->has_children())
 814     this->child_offset_ = this->die_offset_ + (pattr - pdie);
 815   else
 816     this->sibling_offset_ = this->die_offset_ + (pattr - pdie);
 817
 818   this->attributes_read_ = true;
 819   return true;
 820 }
 821
 822 // Skip all the attributes of the DIE and return the offset of the next DIE.
 823
 824 off_t
 825 Dwarf_die::skip_attributes()
 826 {
 827   typedef Dwarf_abbrev_table::Attribute Attribute;
 828
 829   gold_assert(this->abbrev_code_ != NULL);
 830
 831   const unsigned char* pdie =
 832       this->dwinfo_->buffer_at_offset(this->die_offset_);
 833   if (pdie == NULL)
 834     return 0;
 835   const unsigned char* pattr = pdie + this->attr_offset_;
 836
 837   for (unsigned int i = 0; i < this->abbrev_code_->attributes.size(); ++i)
 838     {
 839       size_t len;
 840       unsigned int form = this->abbrev_code_->attributes[i].form;
 841       if (form == elfcpp::DW_FORM_indirect)
 842         {
 843           form = read_unsigned_LEB_128(pattr, &len);
 844           pattr += len;
 845         }
 846       switch(form)
 847         {
 848           case elfcpp::DW_FORM_null:
 849           case elfcpp::DW_FORM_flag_present:
 850             break;
 851           case elfcpp::DW_FORM_strp:
 852           case elfcpp::DW_FORM_sec_offset:
 853             pattr += this->dwinfo_->offset_size();
 854             break;
 855           case elfcpp::DW_FORM_addr:
 856           case elfcpp::DW_FORM_ref_addr:
 857             pattr += this->dwinfo_->address_size();
 858             break;
 859           case elfcpp::DW_FORM_block1:
 860             pattr += 1 + *pattr;
 861             break;
 862           case elfcpp::DW_FORM_block2:
 863             {
 864               uint16_t block_size;
 865               block_size = read_from_pointer<16>(&pattr);
 866               pattr += block_size;
 867               break;
 868             }
 869           case elfcpp::DW_FORM_block4:
 870             {
 871               uint32_t block_size;
 872               block_size = read_from_pointer<32>(&pattr);
 873               pattr += block_size;
 874               break;
 875             }
 876           case elfcpp::DW_FORM_block:
 877           case elfcpp::DW_FORM_exprloc:
 878             {
 879               uint64_t block_size;
 880               block_size = read_unsigned_LEB_128(pattr, &len);
 881               pattr += len + block_size;
 882               break;
 883             }
 884           case elfcpp::DW_FORM_data1:
 885           case elfcpp::DW_FORM_ref1:
 886           case elfcpp::DW_FORM_flag:
 887             pattr += 1;
 888             break;
 889           case elfcpp::DW_FORM_data2:
 890           case elfcpp::DW_FORM_ref2:
 891             pattr += 2;
 892             break;
 893           case elfcpp::DW_FORM_data4:
 894           case elfcpp::DW_FORM_ref4:
 895             pattr += 4;
 896             break;
 897           case elfcpp::DW_FORM_data8:
 898           case elfcpp::DW_FORM_ref8:
 899           case elfcpp::DW_FORM_ref_sig8:
 900             pattr += 8;
 901             break;
 902           case elfcpp::DW_FORM_ref_udata:
 903           case elfcpp::DW_FORM_udata:
 904             read_unsigned_LEB_128(pattr, &len);
 905             pattr += len;
 906             break;
 907           case elfcpp::DW_FORM_sdata:
 908             read_signed_LEB_128(pattr, &len);
 909             pattr += len;
 910             break;
 911           case elfcpp::DW_FORM_string:
 912             len = strlen(reinterpret_cast<const char*>(pattr));
 913             pattr += len + 1;
 914             break;
 915           default:
 916             return 0;
 917         }
 918     }
 919
 920   return this->die_offset_ + (pattr - pdie);
 921 }
 922
 923 // Get the name of the DIE and cache it.
 924
 925 void
 926 Dwarf_die::set_name()
 927 {
 928   if (this->name_ != NULL || !this->read_attributes())
 929     return;
 930   if (this->name_off_ != -1)
 931     this->name_ = this->dwinfo_->get_string(this->name_off_,
 932                                             this->string_shndx_);
 933 }
 934
 935 // Get the linkage name of the DIE and cache it.
 936
 937 void
 938 Dwarf_die::set_linkage_name()
 939 {
 940   if (this->linkage_name_ != NULL || !this->read_attributes())
 941     return;
 942   if (this->linkage_name_off_ != -1)
 943     this->linkage_name_ = this->dwinfo_->get_string(this->linkage_name_off_,
 944                                                     this->string_shndx_);
 945 }
 946
 947 // Return the value of attribute ATTR.
 948
 949 const Dwarf_die::Attribute_value*
 950 Dwarf_die::attribute(unsigned int attr)
 951 {
 952   if (!this->read_attributes())
 953     return NULL;
 954   for (unsigned int i = 0; i < this->attributes_.size(); ++i)
 955     {
 956       if (this->attributes_[i].attr == attr)
 957         return &this->attributes_[i];
 958     }
 959   return NULL;
 960 }
 961
 962 const char*
 963 Dwarf_die::string_attribute(unsigned int attr)
 964 {
 965   const Attribute_value* attr_val = this->attribute(attr);
 966   if (attr_val == NULL)
 967     return NULL;
 968   switch (attr_val->form)
 969     {
 970       case elfcpp::DW_FORM_string:
 971         return attr_val->val.stringval;
 972       case elfcpp::DW_FORM_strp:
 973         return this->dwinfo_->get_string(attr_val->val.refval,
 974                                          attr_val->aux.shndx);
 975       default:
 976         return NULL;
 977     }
 978 }
 979
 980 int64_t
 981 Dwarf_die::int_attribute(unsigned int attr)
 982 {
 983   const Attribute_value* attr_val = this->attribute(attr);
 984   if (attr_val == NULL)
 985     return 0;
 986   switch (attr_val->form)
 987     {
 988       case elfcpp::DW_FORM_null:
 989       case elfcpp::DW_FORM_flag_present:
 990       case elfcpp::DW_FORM_data1:
 991       case elfcpp::DW_FORM_flag:
 992       case elfcpp::DW_FORM_data2:
 993       case elfcpp::DW_FORM_data4:
 994       case elfcpp::DW_FORM_data8:
 995       case elfcpp::DW_FORM_sdata:
 996         return attr_val->val.intval;
 997       default:
 998         return 0;
 999     }
1000 }
1001
1002 uint64_t
1003 Dwarf_die::uint_attribute(unsigned int attr)
1004 {
1005   const Attribute_value* attr_val = this->attribute(attr);
1006   if (attr_val == NULL)
1007     return 0;
1008   switch (attr_val->form)
1009     {
1010       case elfcpp::DW_FORM_null:
1011       case elfcpp::DW_FORM_flag_present:
1012       case elfcpp::DW_FORM_data1:
1013       case elfcpp::DW_FORM_flag:
1014       case elfcpp::DW_FORM_data4:
1015       case elfcpp::DW_FORM_data8:
1016       case elfcpp::DW_FORM_ref_sig8:
1017       case elfcpp::DW_FORM_udata:
1018         return attr_val->val.uintval;
1019       default:
1020         return 0;
1021     }
1022 }
1023
1024 off_t
1025 Dwarf_die::ref_attribute(unsigned int attr, unsigned int* shndx)
1026 {
1027   const Attribute_value* attr_val = this->attribute(attr);
1028   if (attr_val == NULL)
1029     return -1;
1030   switch (attr_val->form)
1031     {
1032       case elfcpp::DW_FORM_sec_offset:
1033       case elfcpp::DW_FORM_addr:
1034       case elfcpp::DW_FORM_ref_addr:
1035       case elfcpp::DW_FORM_ref1:
1036       case elfcpp::DW_FORM_ref2:
1037       case elfcpp::DW_FORM_ref4:
1038       case elfcpp::DW_FORM_ref8:
1039       case elfcpp::DW_FORM_ref_udata:
1040         *shndx = attr_val->aux.shndx;
1041         return attr_val->val.refval;
1042       case elfcpp::DW_FORM_ref_sig8:
1043         *shndx = attr_val->aux.shndx;
1044         return attr_val->val.uintval;
1045       case elfcpp::DW_FORM_data4:
1046       case elfcpp::DW_FORM_data8:
1047         *shndx = attr_val->aux.shndx;
1048         return attr_val->val.intval;
1049       default:
1050         return -1;
1051     }
1052 }
1053
1054 off_t
1055 Dwarf_die::address_attribute(unsigned int attr, unsigned int* shndx)
1056 {
1057   const Attribute_value* attr_val = this->attribute(attr);
1058   if (attr_val == NULL || attr_val->form != elfcpp::DW_FORM_addr)
1059     return -1;
1060
1061   *shndx = attr_val->aux.shndx;
1062   return attr_val->val.refval;
1063 }
1064
1065 // Return the offset of this DIE's first child.
1066
1067 off_t
1068 Dwarf_die::child_offset()
1069 {
1070   gold_assert(this->abbrev_code_ != NULL);
1071   if (!this->has_children())
1072     return 0;
1073   if (this->child_offset_ == 0)
1074     this->child_offset_ = this->skip_attributes();
1075   return this->child_offset_;
1076 }
1077
1078 // Return the offset of this DIE's next sibling.
1079
1080 off_t
1081 Dwarf_die::sibling_offset()
1082 {
1083   gold_assert(this->abbrev_code_ != NULL);
1084
1085   if (this->sibling_offset_ != 0)
1086     return this->sibling_offset_;
1087
1088   if (!this->has_children())
1089     {
1090       this->sibling_offset_ = this->skip_attributes();
1091       return this->sibling_offset_;
1092     }
1093
1094   if (this->has_sibling_attribute())
1095     {
1096       if (!this->read_attributes())
1097         return 0;
1098       if (this->sibling_offset_ != 0)
1099         return this->sibling_offset_;
1100     }
1101
1102   // Skip over the children.
1103   off_t child_offset = this->child_offset();
1104   while (child_offset > 0)
1105     {
1106       Dwarf_die die(this->dwinfo_, child_offset, this);
1107       // The Dwarf_die ctor will set this DIE's sibling offset
1108       // when it reads a zero abbrev code.
1109       if (die.tag() == 0)
1110         break;
1111       child_offset = die.sibling_offset();
1112     }
1113
1114   // This should be set by now.  If not, there was a problem reading
1115   // the DWARF info, and we return 0.
1116   return this->sibling_offset_;
1117 }
1118
1119 // class Dwarf_info_reader
1120
1121 // Check that the pointer P is within the current compilation unit.
1122
1123 inline bool
1124 Dwarf_info_reader::check_buffer(const unsigned char* p) const
1125 {
1126   if (p > this->buffer_ + this->cu_offset_ + this->cu_length_)
1127     {
1128       gold_warning(_("%s: corrupt debug info in %s"),
1129                    this->object_->name().c_str(),
1130                    this->object_->section_name(this->shndx_).c_str());
1131       return false;
1132     }
1133   return true;
1134 }
1135
1136 // Begin parsing the debug info.  This calls visit_compilation_unit()
1137 // or visit_type_unit() for each compilation or type unit found in the
1138 // section, and visit_die() for each top-level DIE.
1139
1140 void
1141 Dwarf_info_reader::parse()
1142 {
1143   switch (parameters->size_and_endianness())
1144     {
1145 #ifdef HAVE_TARGET_32_LITTLE
1146       case Parameters::TARGET_32_LITTLE:
1147         this->do_parse<false>();
1148         break;
1149 #endif
1150 #ifdef HAVE_TARGET_32_BIG
1151       case Parameters::TARGET_32_BIG:
1152         this->do_parse<true>();
1153         break;
1154 #endif
1155 #ifdef HAVE_TARGET_64_LITTLE
1156       case Parameters::TARGET_64_LITTLE:
1157         this->do_parse<false>();
1158         break;
1159 #endif
1160 #ifdef HAVE_TARGET_64_BIG
1161       case Parameters::TARGET_64_BIG:
1162         this->do_parse<true>();
1163         break;
1164 #endif
1165       default:
1166         gold_unreachable();
1167     }
1168 }
1169
1170 template<bool big_endian>
1171 void
1172 Dwarf_info_reader::do_parse()
1173 {
1174   // Get the section contents and decompress if necessary.
1175   section_size_type buffer_size;
1176   bool buffer_is_new;
1177   this->buffer_ = this->object_->decompressed_section_contents(this->shndx_,
1178                                                                &buffer_size,
1179                                                                &buffer_is_new);
1180   if (this->buffer_ == NULL || buffer_size == 0)
1181     return;
1182   this->buffer_end_ = this->buffer_ + buffer_size;
1183
1184   // The offset of this input section in the output section.
1185   off_t section_offset = this->object_->output_section_offset(this->shndx_);
1186
1187   // Start tracking relocations for this section.
1188   this->reloc_mapper_ = make_elf_reloc_mapper(this->object_, this->symtab_,
1189                                               this->symtab_size_);
1190   this->reloc_mapper_->initialize(this->reloc_shndx_, this->reloc_type_);
1191
1192   // Loop over compilation units (or type units).
1193   unsigned int abbrev_shndx = 0;
1194   off_t abbrev_offset = 0;
1195   const unsigned char* pinfo = this->buffer_;
1196   while (pinfo < this->buffer_end_)
1197     {
1198       // Read the compilation (or type) unit header.
1199       const unsigned char* cu_start = pinfo;
1200       this->cu_offset_ = cu_start - this->buffer_;
1201       this->cu_length_ = this->buffer_end_ - cu_start;
1202
1203       // Read unit_length (4 or 12 bytes).
1204       if (!this->check_buffer(pinfo + 4))
1205         break;
1206       uint32_t unit_length =
1207           elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo);
1208       pinfo += 4;
1209       if (unit_length == 0xffffffff)
1210         {
1211           if (!this->check_buffer(pinfo + 8))
1212             break;
1213           unit_length = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
1214           pinfo += 8;
1215           this->offset_size_ = 8;
1216         }
1217       else
1218         this->offset_size_ = 4;
1219       if (!this->check_buffer(pinfo + unit_length))
1220         break;
1221       const unsigned char* cu_end = pinfo + unit_length;
1222       this->cu_length_ = cu_end - cu_start;
1223       if (!this->check_buffer(pinfo + 2 + this->offset_size_ + 1))
1224         break;
1225
1226       // Read version (2 bytes).
1227       this->cu_version_ =
1228           elfcpp::Swap_unaligned<16, big_endian>::readval(pinfo);
1229       pinfo += 2;
1230
1231       // Read debug_abbrev_offset (4 or 8 bytes).
1232       if (this->offset_size_ == 4)
1233         abbrev_offset = elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo);
1234       else
1235         abbrev_offset = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
1236       if (this->reloc_shndx_ > 0)
1237         {
1238           off_t reloc_offset = pinfo - this->buffer_;
1239           off_t value;
1240           abbrev_shndx =
1241               this->reloc_mapper_->get_reloc_target(reloc_offset, &value);
1242           if (abbrev_shndx == 0)
1243             return;
1244           if (this->reloc_type_ == elfcpp::SHT_REL)
1245             abbrev_offset += value;
1246           else
1247             abbrev_offset = value;
1248         }
1249       pinfo += this->offset_size_;
1250
1251       // Read address_size (1 byte).
1252       this->address_size_ = *pinfo++;
1253
1254       // For type units, read the two extra fields.
1255       uint64_t signature = 0;
1256       off_t type_offset = 0;
1257       if (this->is_type_unit_)
1258         {
1259           if (!this->check_buffer(pinfo + 8 + this->offset_size_))
1260             break;
1261
1262           // Read type_signature (8 bytes).
1263           signature = elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
1264           pinfo += 8;
1265
1266           // Read type_offset (4 or 8 bytes).
1267           if (this->offset_size_ == 4)
1268             type_offset =
1269                 elfcpp::Swap_unaligned<32, big_endian>::readval(pinfo);
1270           else
1271             type_offset =
1272                 elfcpp::Swap_unaligned<64, big_endian>::readval(pinfo);
1273           pinfo += this->offset_size_;
1274         }
1275
1276       // Read the .debug_abbrev table.
1277       this->abbrev_table_.read_abbrevs(this->object_, abbrev_shndx,
1278                                        abbrev_offset);
1279
1280       // Visit the root DIE.
1281       Dwarf_die root_die(this,
1282                          pinfo - (this->buffer_ + this->cu_offset_),
1283                          NULL);
1284       if (root_die.tag() != 0)
1285         {
1286           // Visit the CU or TU.
1287           if (this->is_type_unit_)
1288             this->visit_type_unit(section_offset + this->cu_offset_,
1289                                   type_offset, signature, &root_die);
1290           else
1291             this->visit_compilation_unit(section_offset + this->cu_offset_,
1292                                          cu_end - cu_start, &root_die);
1293         }
1294
1295       // Advance to the next CU.
1296       pinfo = cu_end;
1297     }
1298
1299   if (buffer_is_new)
1300     {
1301       delete[] this->buffer_;
1302       this->buffer_ = NULL;
1303     }
1304 }
1305
1306 // Read the DWARF string table.
1307
1308 bool
1309 Dwarf_info_reader::do_read_string_table(unsigned int string_shndx)
1310 {
1311   Relobj* object = this->object_;
1312
1313   // If we don't have relocations, string_shndx will be 0, and
1314   // we'll have to hunt for the .debug_str section.
1315   if (string_shndx == 0)
1316     {
1317       for (unsigned int i = 1; i < this->object_->shnum(); ++i)
1318         {
1319           std::string name = object->section_name(i);
1320           if (name == ".debug_str")
1321             {
1322               string_shndx = i;
1323               this->string_output_section_offset_ =
1324                   object->output_section_offset(i);
1325               break;
1326             }
1327         }
1328       if (string_shndx == 0)
1329         return false;
1330     }
1331
1332   if (this->owns_string_buffer_ && this->string_buffer_ != NULL)
1333     {
1334       delete[] this->string_buffer_;
1335       this->owns_string_buffer_ = false;
1336     }
1337
1338   // Get the secton contents and decompress if necessary.
1339   section_size_type buffer_size;
1340   const unsigned char* buffer =
1341       object->decompressed_section_contents(string_shndx,
1342                                             &buffer_size,
1343                                             &this->owns_string_buffer_);
1344   this->string_buffer_ = reinterpret_cast<const char*>(buffer);
1345   this->string_buffer_end_ = this->string_buffer_ + buffer_size;
1346   this->string_shndx_ = string_shndx;
1347   return true;
1348 }
1349
1350 // Look for a relocation at offset ATTR_OFF in the dwarf info,
1351 // and return the section index and offset of the target.
1352
1353 unsigned int
1354 Dwarf_info_reader::lookup_reloc(off_t attr_off, off_t* target_off)
1355 {
1356   off_t value;
1357   attr_off += this->cu_offset_;
1358   unsigned int shndx = this->reloc_mapper_->get_reloc_target(attr_off, &value);
1359   if (shndx == 0)
1360     return 0;
1361   if (this->reloc_type_ == elfcpp::SHT_REL)
1362     *target_off += value;
1363   else
1364     *target_off = value;
1365   return shndx;
1366 }
1367
1368 // Return a string from the DWARF string table.
1369
1370 const char*
1371 Dwarf_info_reader::get_string(off_t str_off, unsigned int string_shndx)
1372 {
1373   if (!this->read_string_table(string_shndx))
1374     return NULL;
1375
1376   // Correct the offset.  For incremental update links, we have a
1377   // relocated offset that is relative to the output section, but
1378   // here we need an offset relative to the input section.
1379   str_off -= this->string_output_section_offset_;
1380
1381   const char* p = this->string_buffer_ + str_off;
1382
1383   if (p < this->string_buffer_ || p >= this->string_buffer_end_)
1384     return NULL;
1385
1386   return p;
1387 }
1388
1389 // The following are default, do-nothing, implementations of the
1390 // hook methods normally provided by a derived class.  We provide
1391 // default implementations rather than no implementation so that
1392 // a derived class needs to implement only the hooks that it needs
1393 // to use.
1394
1395 // Process a compilation unit and parse its child DIE.
1396
1397 void
1398 Dwarf_info_reader::visit_compilation_unit(off_t, off_t, Dwarf_die*)
1399 {
1400 }
1401
1402 // Process a type unit and parse its child DIE.
1403
1404 void
1405 Dwarf_info_reader::visit_type_unit(off_t, off_t, uint64_t, Dwarf_die*)
1406 {
1407 }
1408
1409 // class Sized_dwarf_line_info
1410
1411 struct LineStateMachine
1412 {
1413   int file_num;
1414   uint64_t address;
1415   int line_num;
1416   int column_num;
1417   unsigned int shndx;    // the section address refers to
1418   bool is_stmt;          // stmt means statement.
1419   bool basic_block;
1420   bool end_sequence;
1421 };
1422
1423 static void
1424 ResetLineStateMachine(struct LineStateMachine* lsm, bool default_is_stmt)
1425 {
1426   lsm->file_num = 1;
1427   lsm->address = 0;
1428   lsm->line_num = 1;
1429   lsm->column_num = 0;
1430   lsm->shndx = -1U;
1431   lsm->is_stmt = default_is_stmt;
1432   lsm->basic_block = false;
1433   lsm->end_sequence = false;
1434 }
1435
1436 template<int size, bool big_endian>
1437 Sized_dwarf_line_info<size, big_endian>::Sized_dwarf_line_info(
1438     Object* object,
1439     unsigned int read_shndx)
1440   : data_valid_(false), buffer_(NULL), buffer_start_(NULL),
1441     reloc_mapper_(NULL), symtab_buffer_(NULL), directories_(), files_(),
1442     current_header_index_(-1)
1443 {
1444   unsigned int debug_shndx;
1445
1446   for (debug_shndx = 1; debug_shndx < object->shnum(); ++debug_shndx)
1447     {
1448       // FIXME: do this more efficiently: section_name() isn't super-fast
1449       std::string name = object->section_name(debug_shndx);
1450       if (name == ".debug_line" || name == ".zdebug_line")
1451         {
1452           section_size_type buffer_size;
1453           bool is_new = false;
1454           this->buffer_ = object->decompressed_section_contents(debug_shndx,
1455                                                                 &buffer_size,
1456                                                                 &is_new);
1457           if (is_new)
1458             this->buffer_start_ = this->buffer_;
1459           this->buffer_end_ = this->buffer_ + buffer_size;
1460           break;
1461         }
1462     }
1463   if (this->buffer_ == NULL)
1464     return;
1465
1466   // Find the relocation section for ".debug_line".
1467   // We expect these for relobjs (.o's) but not dynobjs (.so's).
1468   unsigned int reloc_shndx = 0;
1469   for (unsigned int i = 0; i < object->shnum(); ++i)
1470     {
1471       unsigned int reloc_sh_type = object->section_type(i);
1472       if ((reloc_sh_type == elfcpp::SHT_REL
1473            || reloc_sh_type == elfcpp::SHT_RELA)
1474           && object->section_info(i) == debug_shndx)
1475         {
1476           reloc_shndx = i;
1477           this->track_relocs_type_ = reloc_sh_type;
1478           break;
1479         }
1480     }
1481
1482   // Finally, we need the symtab section to interpret the relocs.
1483   if (reloc_shndx != 0)
1484     {
1485       unsigned int symtab_shndx;
1486       for (symtab_shndx = 0; symtab_shndx < object->shnum(); ++symtab_shndx)
1487         if (object->section_type(symtab_shndx) == elfcpp::SHT_SYMTAB)
1488           {
1489             this->symtab_buffer_ = object->section_contents(
1490                 symtab_shndx, &this->symtab_buffer_size_, false);
1491             break;
1492           }
1493       if (this->symtab_buffer_ == NULL)
1494         return;
1495     }
1496
1497   this->reloc_mapper_ =
1498       new Sized_elf_reloc_mapper<size, big_endian>(object,
1499                                                    this->symtab_buffer_,
1500                                                    this->symtab_buffer_size_);
1501   if (!this->reloc_mapper_->initialize(reloc_shndx, this->track_relocs_type_))
1502     return;
1503
1504   // Now that we have successfully read all the data, parse the debug
1505   // info.
1506   this->data_valid_ = true;
1507   this->read_line_mappings(read_shndx);
1508 }
1509
1510 // Read the DWARF header.
1511
1512 template<int size, bool big_endian>
1513 const unsigned char*
1514 Sized_dwarf_line_info<size, big_endian>::read_header_prolog(
1515     const unsigned char* lineptr)
1516 {
1517   uint32_t initial_length = elfcpp::Swap_unaligned<32, big_endian>::readval(lineptr);
1518   lineptr += 4;
1519
1520   // In DWARF2/3, if the initial length is all 1 bits, then the offset
1521   // size is 8 and we need to read the next 8 bytes for the real length.
1522   if (initial_length == 0xffffffff)
1523     {
1524       header_.offset_size = 8;
1525       initial_length = elfcpp::Swap_unaligned<64, big_endian>::readval(lineptr);
1526       lineptr += 8;
1527     }
1528   else
1529     header_.offset_size = 4;
1530
1531   header_.total_length = initial_length;
1532
1533   gold_assert(lineptr + header_.total_length <= buffer_end_);
1534
1535   header_.version = elfcpp::Swap_unaligned<16, big_endian>::readval(lineptr);
1536   lineptr += 2;
1537
1538   if (header_.offset_size == 4)
1539     header_.prologue_length = elfcpp::Swap_unaligned<32, big_endian>::readval(lineptr);
1540   else
1541     header_.prologue_length = elfcpp::Swap_unaligned<64, big_endian>::readval(lineptr);
1542   lineptr += header_.offset_size;
1543
1544   header_.min_insn_length = *lineptr;
1545   lineptr += 1;
1546
1547   header_.default_is_stmt = *lineptr;
1548   lineptr += 1;
1549
1550   header_.line_base = *reinterpret_cast<const signed char*>(lineptr);
1551   lineptr += 1;
1552
1553   header_.line_range = *lineptr;
1554   lineptr += 1;
1555
1556   header_.opcode_base = *lineptr;
1557   lineptr += 1;
1558
1559   header_.std_opcode_lengths.resize(header_.opcode_base + 1);
1560   header_.std_opcode_lengths[0] = 0;
1561   for (int i = 1; i < header_.opcode_base; i++)
1562     {
1563       header_.std_opcode_lengths[i] = *lineptr;
1564       lineptr += 1;
1565     }
1566
1567   return lineptr;
1568 }
1569
1570 // The header for a debug_line section is mildly complicated, because
1571 // the line info is very tightly encoded.
1572
1573 template<int size, bool big_endian>
1574 const unsigned char*
1575 Sized_dwarf_line_info<size, big_endian>::read_header_tables(
1576     const unsigned char* lineptr)
1577 {
1578   ++this->current_header_index_;
1579
1580   // Create a new directories_ entry and a new files_ entry for our new
1581   // header.  We initialize each with a single empty element, because
1582   // dwarf indexes directory and filenames starting at 1.
1583   gold_assert(static_cast<int>(this->directories_.size())
1584               == this->current_header_index_);
1585   gold_assert(static_cast<int>(this->files_.size())
1586               == this->current_header_index_);
1587   this->directories_.push_back(std::vector<std::string>(1));
1588   this->files_.push_back(std::vector<std::pair<int, std::string> >(1));
1589
1590   // It is legal for the directory entry table to be empty.
1591   if (*lineptr)
1592     {
1593       int dirindex = 1;
1594       while (*lineptr)
1595         {
1596           const char* dirname = reinterpret_cast<const char*>(lineptr);
1597           gold_assert(dirindex
1598                       == static_cast<int>(this->directories_.back().size()));
1599           this->directories_.back().push_back(dirname);
1600           lineptr += this->directories_.back().back().size() + 1;
1601           dirindex++;
1602         }
1603     }
1604   lineptr++;
1605
1606   // It is also legal for the file entry table to be empty.
1607   if (*lineptr)
1608     {
1609       int fileindex = 1;
1610       size_t len;
1611       while (*lineptr)
1612         {
1613           const char* filename = reinterpret_cast<const char*>(lineptr);
1614           lineptr += strlen(filename) + 1;
1615
1616           uint64_t dirindex = read_unsigned_LEB_128(lineptr, &len);
1617           lineptr += len;
1618
1619           if (dirindex >= this->directories_.back().size())
1620             dirindex = 0;
1621           int dirindexi = static_cast<int>(dirindex);
1622
1623           read_unsigned_LEB_128(lineptr, &len);   // mod_time
1624           lineptr += len;
1625
1626           read_unsigned_LEB_128(lineptr, &len);   // filelength
1627           lineptr += len;
1628
1629           gold_assert(fileindex
1630                       == static_cast<int>(this->files_.back().size()));
1631           this->files_.back().push_back(std::make_pair(dirindexi, filename));
1632           fileindex++;
1633         }
1634     }
1635   lineptr++;
1636
1637   return lineptr;
1638 }
1639
1640 // Process a single opcode in the .debug.line structure.
1641
1642 template<int size, bool big_endian>
1643 bool
1644 Sized_dwarf_line_info<size, big_endian>::process_one_opcode(
1645     const unsigned char* start, struct LineStateMachine* lsm, size_t* len)
1646 {
1647   size_t oplen = 0;
1648   size_t templen;
1649   unsigned char opcode = *start;
1650   oplen++;
1651   start++;
1652
1653   // If the opcode is great than the opcode_base, it is a special
1654   // opcode. Most line programs consist mainly of special opcodes.
1655   if (opcode >= header_.opcode_base)
1656     {
1657       opcode -= header_.opcode_base;
1658       const int advance_address = ((opcode / header_.line_range)
1659                                    * header_.min_insn_length);
1660       lsm->address += advance_address;
1661
1662       const int advance_line = ((opcode % header_.line_range)
1663                                 + header_.line_base);
1664       lsm->line_num += advance_line;
1665       lsm->basic_block = true;
1666       *len = oplen;
1667       return true;
1668     }
1669
1670   // Otherwise, we have the regular opcodes
1671   switch (opcode)
1672     {
1673     case elfcpp::DW_LNS_copy:
1674       lsm->basic_block = false;
1675       *len = oplen;
1676       return true;
1677
1678     case elfcpp::DW_LNS_advance_pc:
1679       {
1680         const uint64_t advance_address
1681             = read_unsigned_LEB_128(start, &templen);
1682         oplen += templen;
1683         lsm->address += header_.min_insn_length * advance_address;
1684       }
1685       break;
1686
1687     case elfcpp::DW_LNS_advance_line:
1688       {
1689         const uint64_t advance_line = read_signed_LEB_128(start, &templen);
1690         oplen += templen;
1691         lsm->line_num += advance_line;
1692       }
1693       break;
1694
1695     case elfcpp::DW_LNS_set_file:
1696       {
1697         const uint64_t fileno = read_unsigned_LEB_128(start, &templen);
1698         oplen += templen;
1699         lsm->file_num = fileno;
1700       }
1701       break;
1702
1703     case elfcpp::DW_LNS_set_column:
1704       {
1705         const uint64_t colno = read_unsigned_LEB_128(start, &templen);
1706         oplen += templen;
1707         lsm->column_num = colno;
1708       }
1709       break;
1710
1711     case elfcpp::DW_LNS_negate_stmt:
1712       lsm->is_stmt = !lsm->is_stmt;
1713       break;
1714
1715     case elfcpp::DW_LNS_set_basic_block:
1716       lsm->basic_block = true;
1717       break;
1718
1719     case elfcpp::DW_LNS_fixed_advance_pc:
1720       {
1721         int advance_address;
1722         advance_address = elfcpp::Swap_unaligned<16, big_endian>::readval(start);
1723         oplen += 2;
1724         lsm->address += advance_address;
1725       }
1726       break;
1727
1728     case elfcpp::DW_LNS_const_add_pc:
1729       {
1730         const int advance_address = (header_.min_insn_length
1731                                      * ((255 - header_.opcode_base)
1732                                         / header_.line_range));
1733         lsm->address += advance_address;
1734       }
1735       break;
1736
1737     case elfcpp::DW_LNS_extended_op:
1738       {
1739         const uint64_t extended_op_len
1740             = read_unsigned_LEB_128(start, &templen);
1741         start += templen;
1742         oplen += templen + extended_op_len;
1743
1744         const unsigned char extended_op = *start;
1745         start++;
1746
1747         switch (extended_op)
1748           {
1749           case elfcpp::DW_LNE_end_sequence:
1750             // This means that the current byte is the one immediately
1751             // after a set of instructions.  Record the current line
1752             // for up to one less than the current address.
1753             lsm->line_num = -1;
1754             lsm->end_sequence = true;
1755             *len = oplen;
1756             return true;
1757
1758           case elfcpp::DW_LNE_set_address:
1759             {
1760               lsm->address =
1761                 elfcpp::Swap_unaligned<size, big_endian>::readval(start);
1762               typename Reloc_map::const_iterator it
1763                   = this->reloc_map_.find(start - this->buffer_);
1764               if (it != reloc_map_.end())
1765                 {
1766                   // If this is a SHT_RELA section, then ignore the
1767                   // section contents.  This assumes that this is a
1768                   // straight reloc which just uses the reloc addend.
1769                   // The reloc addend has already been included in the
1770                   // symbol value.
1771                   if (this->track_relocs_type_ == elfcpp::SHT_RELA)
1772                     lsm->address = 0;
1773                   // Add in the symbol value.
1774                   lsm->address += it->second.second;
1775                   lsm->shndx = it->second.first;
1776                 }
1777               else
1778                 {
1779                   // If we're a normal .o file, with relocs, every
1780                   // set_address should have an associated relocation.
1781                   if (this->input_is_relobj())
1782                     this->data_valid_ = false;
1783                 }
1784               break;
1785             }
1786           case elfcpp::DW_LNE_define_file:
1787             {
1788               const char* filename  = reinterpret_cast<const char*>(start);
1789               templen = strlen(filename) + 1;
1790               start += templen;
1791
1792               uint64_t dirindex = read_unsigned_LEB_128(start, &templen);
1793
1794               if (dirindex >= this->directories_.back().size())
1795                 dirindex = 0;
1796               int dirindexi = static_cast<int>(dirindex);
1797
1798               // This opcode takes two additional ULEB128 parameters
1799               // (mod_time and filelength), but we don't use those
1800               // values.  Because OPLEN already tells us how far to
1801               // skip to the next opcode, we don't need to read
1802               // them at all.
1803
1804               this->files_.back().push_back(std::make_pair(dirindexi,
1805                                                            filename));
1806             }
1807             break;
1808           }
1809       }
1810       break;
1811
1812     default:
1813       {
1814         // Ignore unknown opcode  silently
1815         for (int i = 0; i < header_.std_opcode_lengths[opcode]; i++)
1816           {
1817             size_t templen;
1818             read_unsigned_LEB_128(start, &templen);
1819             start += templen;
1820             oplen += templen;
1821           }
1822       }
1823       break;
1824   }
1825   *len = oplen;
1826   return false;
1827 }
1828
1829 // Read the debug information at LINEPTR and store it in the line
1830 // number map.
1831
1832 template<int size, bool big_endian>
1833 unsigned const char*
1834 Sized_dwarf_line_info<size, big_endian>::read_lines(unsigned const char* lineptr,
1835                                                     unsigned int shndx)
1836 {
1837   struct LineStateMachine lsm;
1838
1839   // LENGTHSTART is the place the length field is based on.  It is the
1840   // point in the header after the initial length field.
1841   const unsigned char* lengthstart = buffer_;
1842
1843   // In 64 bit dwarf, the initial length is 12 bytes, because of the
1844   // 0xffffffff at the start.
1845   if (header_.offset_size == 8)
1846     lengthstart += 12;
1847   else
1848     lengthstart += 4;
1849
1850   while (lineptr < lengthstart + header_.total_length)
1851     {
1852       ResetLineStateMachine(&lsm, header_.default_is_stmt);
1853       while (!lsm.end_sequence)
1854         {
1855           size_t oplength;
1856           bool add_line = this->process_one_opcode(lineptr, &lsm, &oplength);
1857           if (add_line
1858               && (shndx == -1U || lsm.shndx == -1U || shndx == lsm.shndx))
1859             {
1860               Offset_to_lineno_entry entry
1861                   = { static_cast<off_t>(lsm.address),
1862                       this->current_header_index_,
1863                       static_cast<unsigned int>(lsm.file_num),
1864                       true, lsm.line_num };
1865               std::vector<Offset_to_lineno_entry>&
1866                 map(this->line_number_map_[lsm.shndx]);
1867               // If we see two consecutive entries with the same
1868               // offset and a real line number, then mark the first
1869               // one as non-canonical.
1870               if (!map.empty()
1871                   && (map.back().offset == static_cast<off_t>(lsm.address))
1872                   && lsm.line_num != -1
1873                   && map.back().line_num != -1)
1874                 map.back().last_line_for_offset = false;
1875               map.push_back(entry);
1876             }
1877           lineptr += oplength;
1878         }
1879     }
1880
1881   return lengthstart + header_.total_length;
1882 }
1883
1884 // Read the relocations into a Reloc_map.
1885
1886 template<int size, bool big_endian>
1887 void
1888 Sized_dwarf_line_info<size, big_endian>::read_relocs()
1889 {
1890   if (this->symtab_buffer_ == NULL)
1891     return;
1892
1893   off_t value;
1894   off_t reloc_offset;
1895   while ((reloc_offset = this->reloc_mapper_->next_offset()) != -1)
1896     {
1897       const unsigned int shndx =
1898           this->reloc_mapper_->get_reloc_target(reloc_offset, &value);
1899
1900       // There is no reason to record non-ordinary section indexes, or
1901       // SHN_UNDEF, because they will never match the real section.
1902       if (shndx != 0)
1903         this->reloc_map_[reloc_offset] = std::make_pair(shndx, value);
1904
1905       this->reloc_mapper_->advance(reloc_offset + 1);
1906     }
1907 }
1908
1909 // Read the line number info.
1910
1911 template<int size, bool big_endian>
1912 void
1913 Sized_dwarf_line_info<size, big_endian>::read_line_mappings(unsigned int shndx)
1914 {
1915   gold_assert(this->data_valid_ == true);
1916
1917   this->read_relocs();
1918   while (this->buffer_ < this->buffer_end_)
1919     {
1920       const unsigned char* lineptr = this->buffer_;
1921       lineptr = this->read_header_prolog(lineptr);
1922       lineptr = this->read_header_tables(lineptr);
1923       lineptr = this->read_lines(lineptr, shndx);
1924       this->buffer_ = lineptr;
1925     }
1926
1927   // Sort the lines numbers, so addr2line can use binary search.
1928   for (typename Lineno_map::iterator it = line_number_map_.begin();
1929        it != line_number_map_.end();
1930        ++it)
1931     // Each vector needs to be sorted by offset.
1932     std::sort(it->second.begin(), it->second.end());
1933 }
1934
1935 // Some processing depends on whether the input is a .o file or not.
1936 // For instance, .o files have relocs, and have .debug_lines
1937 // information on a per section basis.  .so files, on the other hand,
1938 // lack relocs, and offsets are unique, so we can ignore the section
1939 // information.
1940
1941 template<int size, bool big_endian>
1942 bool
1943 Sized_dwarf_line_info<size, big_endian>::input_is_relobj()
1944 {
1945   // Only .o files have relocs and the symtab buffer that goes with them.
1946   return this->symtab_buffer_ != NULL;
1947 }
1948
1949 // Given an Offset_to_lineno_entry vector, and an offset, figure out
1950 // if the offset points into a function according to the vector (see
1951 // comments below for the algorithm).  If it does, return an iterator
1952 // into the vector that points to the line-number that contains that
1953 // offset.  If not, it returns vector::end().
1954
1955 static std::vector<Offset_to_lineno_entry>::const_iterator
1956 offset_to_iterator(const std::vector<Offset_to_lineno_entry>* offsets,
1957                    off_t offset)
1958 {
1959   const Offset_to_lineno_entry lookup_key = { offset, 0, 0, true, 0 };
1960
1961   // lower_bound() returns the smallest offset which is >= lookup_key.
1962   // If no offset in offsets is >= lookup_key, returns end().
1963   std::vector<Offset_to_lineno_entry>::const_iterator it
1964       = std::lower_bound(offsets->begin(), offsets->end(), lookup_key);
1965
1966   // This code is easiest to understand with a concrete example.
1967   // Here's a possible offsets array:
1968   // {{offset = 3211, header_num = 0, file_num = 1, last, line_num = 16},  // 0
1969   //  {offset = 3224, header_num = 0, file_num = 1, last, line_num = 20},  // 1
1970   //  {offset = 3226, header_num = 0, file_num = 1, last, line_num = 22},  // 2
1971   //  {offset = 3231, header_num = 0, file_num = 1, last, line_num = 25},  // 3
1972   //  {offset = 3232, header_num = 0, file_num = 1, last, line_num = -1},  // 4
1973   //  {offset = 3232, header_num = 0, file_num = 1, last, line_num = 65},  // 5
1974   //  {offset = 3235, header_num = 0, file_num = 1, last, line_num = 66},  // 6
1975   //  {offset = 3236, header_num = 0, file_num = 1, last, line_num = -1},  // 7
1976   //  {offset = 5764, header_num = 0, file_num = 1, last, line_num = 48},  // 8
1977   //  {offset = 5764, header_num = 0, file_num = 1,!last, line_num = 47},  // 9
1978   //  {offset = 5765, header_num = 0, file_num = 1, last, line_num = 49},  // 10
1979   //  {offset = 5767, header_num = 0, file_num = 1, last, line_num = 50},  // 11
1980   //  {offset = 5768, header_num = 0, file_num = 1, last, line_num = 51},  // 12
1981   //  {offset = 5773, header_num = 0, file_num = 1, last, line_num = -1},  // 13
1982   //  {offset = 5787, header_num = 1, file_num = 1, last, line_num = 19},  // 14
1983   //  {offset = 5790, header_num = 1, file_num = 1, last, line_num = 20},  // 15
1984   //  {offset = 5793, header_num = 1, file_num = 1, last, line_num = 67},  // 16
1985   //  {offset = 5793, header_num = 1, file_num = 1, last, line_num = -1},  // 17
1986   //  {offset = 5793, header_num = 1, file_num = 1,!last, line_num = 66},  // 18
1987   //  {offset = 5795, header_num = 1, file_num = 1, last, line_num = 68},  // 19
1988   //  {offset = 5798, header_num = 1, file_num = 1, last, line_num = -1},  // 20
1989   // The entries with line_num == -1 mark the end of a function: the
1990   // associated offset is one past the last instruction in the
1991   // function.  This can correspond to the beginning of the next
1992   // function (as is true for offset 3232); alternately, there can be
1993   // a gap between the end of one function and the start of the next
1994   // (as is true for some others, most obviously from 3236->5764).
1995   //
1996   // Case 1: lookup_key has offset == 10.  lower_bound returns
1997   //         offsets[0].  Since it's not an exact match and we're
1998   //         at the beginning of offsets, we return end() (invalid).
1999   // Case 2: lookup_key has offset 10000.  lower_bound returns
2000   //         offset[21] (end()).  We return end() (invalid).
2001   // Case 3: lookup_key has offset == 3211.  lower_bound matches
2002   //         offsets[0] exactly, and that's the entry we return.
2003   // Case 4: lookup_key has offset == 3232.  lower_bound returns
2004   //         offsets[4].  That's an exact match, but indicates
2005   //         end-of-function.  We check if offsets[5] is also an
2006   //         exact match but not end-of-function.  It is, so we
2007   //         return offsets[5].
2008   // Case 5: lookup_key has offset == 3214.  lower_bound returns
2009   //         offsets[1].  Since it's not an exact match, we back
2010   //         up to the offset that's < lookup_key, offsets[0].
2011   //         We note offsets[0] is a valid entry (not end-of-function),
2012   //         so that's the entry we return.
2013   // Case 6: lookup_key has offset == 4000.  lower_bound returns
2014   //         offsets[8].  Since it's not an exact match, we back
2015   //         up to offsets[7].  Since offsets[7] indicates
2016   //         end-of-function, we know lookup_key is between
2017   //         functions, so we return end() (not a valid offset).
2018   // Case 7: lookup_key has offset == 5794.  lower_bound returns
2019   //         offsets[19].  Since it's not an exact match, we back
2020   //         up to offsets[16].  Note we back up to the *first*
2021   //         entry with offset 5793, not just offsets[19-1].
2022   //         We note offsets[16] is a valid entry, so we return it.
2023   //         If offsets[16] had had line_num == -1, we would have
2024   //         checked offsets[17].  The reason for this is that
2025   //         16 and 17 can be in an arbitrary order, since we sort
2026   //         only by offset and last_line_for_offset.  (Note it
2027   //         doesn't help to use line_number as a tertiary sort key,
2028   //         since sometimes we want the -1 to be first and sometimes
2029   //         we want it to be last.)
2030
2031   // This deals with cases (1) and (2).
2032   if ((it == offsets->begin() && offset < it->offset)
2033       || it == offsets->end())
2034     return offsets->end();
2035
2036   // This deals with cases (3) and (4).
2037   if (offset == it->offset)
2038     {
2039       while (it != offsets->end()
2040              && it->offset == offset
2041              && it->line_num == -1)
2042         ++it;
2043       if (it == offsets->end() || it->offset != offset)
2044         return offsets->end();
2045       else
2046         return it;
2047     }
2048
2049   // This handles the first part of case (7) -- we back up to the
2050   // *first* entry that has the offset that's behind us.
2051   gold_assert(it != offsets->begin());
2052   std::vector<Offset_to_lineno_entry>::const_iterator range_end = it;
2053   --it;
2054   const off_t range_value = it->offset;
2055   while (it != offsets->begin() && (it-1)->offset == range_value)
2056     --it;
2057
2058   // This handles cases (5), (6), and (7): if any entry in the
2059   // equal_range [it, range_end) has a line_num != -1, it's a valid
2060   // match.  If not, we're not in a function.  The line number we saw
2061   // last for an offset will be sorted first, so it'll get returned if
2062   // it's present.
2063   for (; it != range_end; ++it)
2064     if (it->line_num != -1)
2065       return it;
2066   return offsets->end();
2067 }
2068
2069 // Returns the canonical filename:lineno for the address passed in.
2070 // If other_lines is not NULL, appends the non-canonical lines
2071 // assigned to the same address.
2072
2073 template<int size, bool big_endian>
2074 std::string
2075 Sized_dwarf_line_info<size, big_endian>::do_addr2line(
2076     unsigned int shndx,
2077     off_t offset,
2078     std::vector<std::string>* other_lines)
2079 {
2080   if (this->data_valid_ == false)
2081     return "";
2082
2083   const std::vector<Offset_to_lineno_entry>* offsets;
2084   // If we do not have reloc information, then our input is a .so or
2085   // some similar data structure where all the information is held in
2086   // the offset.  In that case, we ignore the input shndx.
2087   if (this->input_is_relobj())
2088     offsets = &this->line_number_map_[shndx];
2089   else
2090     offsets = &this->line_number_map_[-1U];
2091   if (offsets->empty())
2092     return "";
2093
2094   typename std::vector<Offset_to_lineno_entry>::const_iterator it
2095       = offset_to_iterator(offsets, offset);
2096   if (it == offsets->end())
2097     return "";
2098
2099   std::string result = this->format_file_lineno(*it);
2100   if (other_lines != NULL)
2101     for (++it; it != offsets->end() && it->offset == offset; ++it)
2102       {
2103         if (it->line_num == -1)
2104           continue;  // The end of a previous function.
2105         other_lines->push_back(this->format_file_lineno(*it));
2106       }
2107   return result;
2108 }
2109
2110 // Convert the file_num + line_num into a string.
2111
2112 template<int size, bool big_endian>
2113 std::string
2114 Sized_dwarf_line_info<size, big_endian>::format_file_lineno(
2115     const Offset_to_lineno_entry& loc) const
2116 {
2117   std::string ret;
2118
2119   gold_assert(loc.header_num < static_cast<int>(this->files_.size()));
2120   gold_assert(loc.file_num
2121               < static_cast<unsigned int>(this->files_[loc.header_num].size()));
2122   const std::pair<int, std::string>& filename_pair
2123       = this->files_[loc.header_num][loc.file_num];
2124   const std::string& filename = filename_pair.second;
2125
2126   gold_assert(loc.header_num < static_cast<int>(this->directories_.size()));
2127   gold_assert(filename_pair.first
2128               < static_cast<int>(this->directories_[loc.header_num].size()));
2129   const std::string& dirname
2130       = this->directories_[loc.header_num][filename_pair.first];
2131
2132   if (!dirname.empty())
2133     {
2134       ret += dirname;
2135       ret += "/";
2136     }
2137   ret += filename;
2138   if (ret.empty())
2139     ret = "(unknown)";
2140
2141   char buffer[64];   // enough to hold a line number
2142   snprintf(buffer, sizeof(buffer), "%d", loc.line_num);
2143   ret += ":";
2144   ret += buffer;
2145
2146   return ret;
2147 }
2148
2149 // Dwarf_line_info routines.
2150
2151 static unsigned int next_generation_count = 0;
2152
2153 struct Addr2line_cache_entry
2154 {
2155   Object* object;
2156   unsigned int shndx;
2157   Dwarf_line_info* dwarf_line_info;
2158   unsigned int generation_count;
2159   unsigned int access_count;
2160
2161   Addr2line_cache_entry(Object* o, unsigned int s, Dwarf_line_info* d)
2162       : object(o), shndx(s), dwarf_line_info(d),
2163         generation_count(next_generation_count), access_count(0)
2164   {
2165     if (next_generation_count < (1U << 31))
2166       ++next_generation_count;
2167   }
2168 };
2169 // We expect this cache to be small, so don't bother with a hashtable
2170 // or priority queue or anything: just use a simple vector.
2171 static std::vector<Addr2line_cache_entry> addr2line_cache;
2172
2173 std::string
2174 Dwarf_line_info::one_addr2line(Object* object,
2175                                unsigned int shndx, off_t offset,
2176                                size_t cache_size,
2177                                std::vector<std::string>* other_lines)
2178 {
2179   Dwarf_line_info* lineinfo = NULL;
2180   std::vector<Addr2line_cache_entry>::iterator it;
2181
2182   // First, check the cache.  If we hit, update the counts.
2183   for (it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it)
2184     {
2185       if (it->object == object && it->shndx == shndx)
2186         {
2187           lineinfo = it->dwarf_line_info;
2188           it->generation_count = next_generation_count;
2189           // We cap generation_count at 2^31 -1 to avoid overflow.
2190           if (next_generation_count < (1U << 31))
2191             ++next_generation_count;
2192           // We cap access_count at 31 so 2^access_count doesn't overflow
2193           if (it->access_count < 31)
2194             ++it->access_count;
2195           break;
2196         }
2197     }
2198
2199   // If we don't hit the cache, create a new object and insert into the
2200   // cache.
2201   if (lineinfo == NULL)
2202   {
2203     switch (parameters->size_and_endianness())
2204       {
2205 #ifdef HAVE_TARGET_32_LITTLE
2206         case Parameters::TARGET_32_LITTLE:
2207           lineinfo = new Sized_dwarf_line_info<32, false>(object, shndx); break;
2208 #endif
2209 #ifdef HAVE_TARGET_32_BIG
2210         case Parameters::TARGET_32_BIG:
2211           lineinfo = new Sized_dwarf_line_info<32, true>(object, shndx); break;
2212 #endif
2213 #ifdef HAVE_TARGET_64_LITTLE
2214         case Parameters::TARGET_64_LITTLE:
2215           lineinfo = new Sized_dwarf_line_info<64, false>(object, shndx); break;
2216 #endif
2217 #ifdef HAVE_TARGET_64_BIG
2218         case Parameters::TARGET_64_BIG:
2219           lineinfo = new Sized_dwarf_line_info<64, true>(object, shndx); break;
2220 #endif
2221         default:
2222           gold_unreachable();
2223       }
2224     addr2line_cache.push_back(Addr2line_cache_entry(object, shndx, lineinfo));
2225   }
2226
2227   // Now that we have our object, figure out the answer
2228   std::string retval = lineinfo->addr2line(shndx, offset, other_lines);
2229
2230   // Finally, if our cache has grown too big, delete old objects.  We
2231   // assume the common (probably only) case is deleting only one object.
2232   // We use a pretty simple scheme to evict: function of LRU and MFU.
2233   while (addr2line_cache.size() > cache_size)
2234     {
2235       unsigned int lowest_score = ~0U;
2236       std::vector<Addr2line_cache_entry>::iterator lowest
2237           = addr2line_cache.end();
2238       for (it = addr2line_cache.begin(); it != addr2line_cache.end(); ++it)
2239         {
2240           const unsigned int score = (it->generation_count
2241                                       + (1U << it->access_count));
2242           if (score < lowest_score)
2243             {
2244               lowest_score = score;
2245               lowest = it;
2246             }
2247         }
2248       if (lowest != addr2line_cache.end())
2249         {
2250           delete lowest->dwarf_line_info;
2251           addr2line_cache.erase(lowest);
2252         }
2253     }
2254
2255   return retval;
2256 }
2257
2258 void
2259 Dwarf_line_info::clear_addr2line_cache()
2260 {
2261   for (std::vector<Addr2line_cache_entry>::iterator it = addr2line_cache.begin();
2262        it != addr2line_cache.end();
2263        ++it)
2264     delete it->dwarf_line_info;
2265   addr2line_cache.clear();
2266 }
2267
2268 #ifdef HAVE_TARGET_32_LITTLE
2269 template
2270 class Sized_dwarf_line_info<32, false>;
2271 #endif
2272
2273 #ifdef HAVE_TARGET_32_BIG
2274 template
2275 class Sized_dwarf_line_info<32, true>;
2276 #endif
2277
2278 #ifdef HAVE_TARGET_64_LITTLE
2279 template
2280 class Sized_dwarf_line_info<64, false>;
2281 #endif
2282
2283 #ifdef HAVE_TARGET_64_BIG
2284 template
2285 class Sized_dwarf_line_info<64, true>;
2286 #endif
2287
2288 } // End namespace gold.