gold/dwarf_reader.cc

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