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1//===-- Symtab.cpp --------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include <map>10#include <set>11 12#include "lldb/Core/DataFileCache.h"13#include "lldb/Core/Module.h"14#include "lldb/Core/RichManglingContext.h"15#include "lldb/Core/Section.h"16#include "lldb/Symbol/ObjectFile.h"17#include "lldb/Symbol/Symbol.h"18#include "lldb/Symbol/SymbolContext.h"19#include "lldb/Symbol/Symtab.h"20#include "lldb/Target/Language.h"21#include "lldb/Utility/DataEncoder.h"22#include "lldb/Utility/Endian.h"23#include "lldb/Utility/RegularExpression.h"24#include "lldb/Utility/Stream.h"25#include "lldb/Utility/Timer.h"26 27#include "llvm/ADT/ArrayRef.h"28#include "llvm/ADT/StringRef.h"29#include "llvm/Support/DJB.h"30 31using namespace lldb;32using namespace lldb_private;33 34Symtab::Symtab(ObjectFile *objfile)35    : m_objfile(objfile), m_symbols(), m_file_addr_to_index(*this),36      m_name_to_symbol_indices(), m_mutex(),37      m_file_addr_to_index_computed(false), m_name_indexes_computed(false),38      m_loaded_from_cache(false), m_saved_to_cache(false) {39  m_name_to_symbol_indices.emplace(std::make_pair(40      lldb::eFunctionNameTypeNone, UniqueCStringMap<uint32_t>()));41  m_name_to_symbol_indices.emplace(std::make_pair(42      lldb::eFunctionNameTypeBase, UniqueCStringMap<uint32_t>()));43  m_name_to_symbol_indices.emplace(std::make_pair(44      lldb::eFunctionNameTypeMethod, UniqueCStringMap<uint32_t>()));45  m_name_to_symbol_indices.emplace(std::make_pair(46      lldb::eFunctionNameTypeSelector, UniqueCStringMap<uint32_t>()));47}48 49Symtab::~Symtab() = default;50 51void Symtab::Reserve(size_t count) {52  // Clients should grab the mutex from this symbol table and lock it manually53  // when calling this function to avoid performance issues.54  m_symbols.reserve(count);55}56 57Symbol *Symtab::Resize(size_t count) {58  // Clients should grab the mutex from this symbol table and lock it manually59  // when calling this function to avoid performance issues.60  m_symbols.resize(count);61  return m_symbols.empty() ? nullptr : &m_symbols[0];62}63 64uint32_t Symtab::AddSymbol(const Symbol &symbol) {65  // Clients should grab the mutex from this symbol table and lock it manually66  // when calling this function to avoid performance issues.67  uint32_t symbol_idx = m_symbols.size();68  auto &name_to_index = GetNameToSymbolIndexMap(lldb::eFunctionNameTypeNone);69  name_to_index.Clear();70  m_file_addr_to_index.Clear();71  m_symbols.push_back(symbol);72  m_file_addr_to_index_computed = false;73  m_name_indexes_computed = false;74  return symbol_idx;75}76 77size_t Symtab::GetNumSymbols() const {78  std::lock_guard<std::recursive_mutex> guard(m_mutex);79  return m_symbols.size();80}81 82void Symtab::SectionFileAddressesChanged() {83  m_file_addr_to_index.Clear();84  m_file_addr_to_index_computed = false;85}86 87void Symtab::Dump(Stream *s, Target *target, SortOrder sort_order,88                  Mangled::NamePreference name_preference) {89  std::lock_guard<std::recursive_mutex> guard(m_mutex);90 91  //    s->Printf("%.*p: ", (int)sizeof(void*) * 2, this);92  s->Indent();93  const FileSpec &file_spec = m_objfile->GetFileSpec();94  const char *object_name = nullptr;95  if (m_objfile->GetModule())96    object_name = m_objfile->GetModule()->GetObjectName().GetCString();97 98  if (file_spec)99    s->Printf("Symtab, file = %s%s%s%s, num_symbols = %" PRIu64,100              file_spec.GetPath().c_str(), object_name ? "(" : "",101              object_name ? object_name : "", object_name ? ")" : "",102              (uint64_t)m_symbols.size());103  else104    s->Printf("Symtab, num_symbols = %" PRIu64 "", (uint64_t)m_symbols.size());105 106  if (!m_symbols.empty()) {107    switch (sort_order) {108    case eSortOrderNone: {109      s->PutCString(":\n");110      DumpSymbolHeader(s);111      const_iterator begin = m_symbols.begin();112      const_iterator end = m_symbols.end();113      for (const_iterator pos = m_symbols.begin(); pos != end; ++pos) {114        s->Indent();115        pos->Dump(s, target, std::distance(begin, pos), name_preference);116      }117    }118    break;119 120    case eSortOrderByName: {121      // Although we maintain a lookup by exact name map, the table isn't122      // sorted by name. So we must make the ordered symbol list up ourselves.123      s->PutCString(" (sorted by name):\n");124      DumpSymbolHeader(s);125 126      std::multimap<llvm::StringRef, const Symbol *> name_map;127      for (const Symbol &symbol : m_symbols)128        name_map.emplace(symbol.GetName().GetStringRef(), &symbol);129 130      for (const auto &name_to_symbol : name_map) {131        const Symbol *symbol = name_to_symbol.second;132        s->Indent();133        symbol->Dump(s, target, symbol - &m_symbols[0], name_preference);134      }135    } break;136 137    case eSortOrderBySize: {138      s->PutCString(" (sorted by size):\n");139      DumpSymbolHeader(s);140 141      std::multimap<size_t, const Symbol *, std::greater<size_t>> size_map;142      for (const Symbol &symbol : m_symbols)143        size_map.emplace(symbol.GetByteSize(), &symbol);144 145      size_t idx = 0;146      for (const auto &size_to_symbol : size_map) {147        const Symbol *symbol = size_to_symbol.second;148        s->Indent();149        symbol->Dump(s, target, idx++, name_preference);150      }151    } break;152 153    case eSortOrderByAddress:154      s->PutCString(" (sorted by address):\n");155      DumpSymbolHeader(s);156      if (!m_file_addr_to_index_computed)157        InitAddressIndexes();158      const size_t num_entries = m_file_addr_to_index.GetSize();159      for (size_t i = 0; i < num_entries; ++i) {160        s->Indent();161        const uint32_t symbol_idx = m_file_addr_to_index.GetEntryRef(i).data;162        m_symbols[symbol_idx].Dump(s, target, symbol_idx, name_preference);163      }164      break;165    }166  } else {167    s->PutCString("\n");168  }169}170 171void Symtab::Dump(Stream *s, Target *target, std::vector<uint32_t> &indexes,172                  Mangled::NamePreference name_preference) const {173  std::lock_guard<std::recursive_mutex> guard(m_mutex);174 175  const size_t num_symbols = GetNumSymbols();176  // s->Printf("%.*p: ", (int)sizeof(void*) * 2, this);177  s->Indent();178  s->Printf("Symtab %" PRIu64 " symbol indexes (%" PRIu64 " symbols total):\n",179            (uint64_t)indexes.size(), (uint64_t)m_symbols.size());180  s->IndentMore();181 182  if (!indexes.empty()) {183    std::vector<uint32_t>::const_iterator pos;184    std::vector<uint32_t>::const_iterator end = indexes.end();185    DumpSymbolHeader(s);186    for (pos = indexes.begin(); pos != end; ++pos) {187      size_t idx = *pos;188      if (idx < num_symbols) {189        s->Indent();190        m_symbols[idx].Dump(s, target, idx, name_preference);191      }192    }193  }194  s->IndentLess();195}196 197void Symtab::DumpSymbolHeader(Stream *s) {198  s->Indent("               Debug symbol\n");199  s->Indent("               |Synthetic symbol\n");200  s->Indent("               ||Externally Visible\n");201  s->Indent("               |||\n");202  s->Indent("Index   UserID DSX Type            File Address/Value Load "203            "Address       Size               Flags      Name\n");204  s->Indent("------- ------ --- --------------- ------------------ "205            "------------------ ------------------ ---------- "206            "----------------------------------\n");207}208 209static int CompareSymbolID(const void *key, const void *p) {210  const user_id_t match_uid = *(const user_id_t *)key;211  const user_id_t symbol_uid = ((const Symbol *)p)->GetID();212  if (match_uid < symbol_uid)213    return -1;214  if (match_uid > symbol_uid)215    return 1;216  return 0;217}218 219Symbol *Symtab::FindSymbolByID(lldb::user_id_t symbol_uid) const {220  std::lock_guard<std::recursive_mutex> guard(m_mutex);221 222  Symbol *symbol =223      (Symbol *)::bsearch(&symbol_uid, &m_symbols[0], m_symbols.size(),224                          sizeof(m_symbols[0]), CompareSymbolID);225  return symbol;226}227 228Symbol *Symtab::SymbolAtIndex(size_t idx) {229  // Clients should grab the mutex from this symbol table and lock it manually230  // when calling this function to avoid performance issues.231  if (idx < m_symbols.size())232    return &m_symbols[idx];233  return nullptr;234}235 236const Symbol *Symtab::SymbolAtIndex(size_t idx) const {237  // Clients should grab the mutex from this symbol table and lock it manually238  // when calling this function to avoid performance issues.239  if (idx < m_symbols.size())240    return &m_symbols[idx];241  return nullptr;242}243 244static bool lldb_skip_name(llvm::StringRef mangled,245                           Mangled::ManglingScheme scheme) {246  switch (scheme) {247  case Mangled::eManglingSchemeItanium: {248    if (mangled.size() < 3 || !mangled.starts_with("_Z"))249      return true;250 251    // Avoid the following types of symbols in the index.252    switch (mangled[2]) {253    case 'G': // guard variables254    case 'T': // virtual tables, VTT structures, typeinfo structures + names255    case 'Z': // named local entities (if we eventually handle256              // eSymbolTypeData, we will want this back)257      return true;258 259    default:260      break;261    }262 263    // Include this name in the index.264    return false;265  }266 267  // No filters for this scheme yet. Include all names in indexing.268  case Mangled::eManglingSchemeMSVC:269  case Mangled::eManglingSchemeRustV0:270  case Mangled::eManglingSchemeD:271  case Mangled::eManglingSchemeSwift:272    return false;273 274  // Don't try and demangle things we can't categorize.275  case Mangled::eManglingSchemeNone:276    return true;277  }278  llvm_unreachable("unknown scheme!");279}280 281void Symtab::InitNameIndexes() {282  // Protected function, no need to lock mutex...283  if (!m_name_indexes_computed) {284    m_name_indexes_computed = true;285    ElapsedTime elapsed(m_objfile->GetModule()->GetSymtabIndexTime());286    LLDB_SCOPED_TIMER();287 288    // Collect all loaded language plugins.289    std::vector<Language *> languages;290    Language::ForEach([&languages](Language *l) {291      languages.push_back(l);292      return IterationAction::Continue;293    });294 295    auto &name_to_index = GetNameToSymbolIndexMap(lldb::eFunctionNameTypeNone);296    auto &basename_to_index =297        GetNameToSymbolIndexMap(lldb::eFunctionNameTypeBase);298    auto &method_to_index =299        GetNameToSymbolIndexMap(lldb::eFunctionNameTypeMethod);300    auto &selector_to_index =301        GetNameToSymbolIndexMap(lldb::eFunctionNameTypeSelector);302    // Create the name index vector to be able to quickly search by name303    const size_t num_symbols = m_symbols.size();304    name_to_index.Reserve(num_symbols);305 306    // The "const char *" in "class_contexts" and backlog::value_type::second307    // must come from a ConstString::GetCString()308    std::set<const char *> class_contexts;309    std::vector<std::pair<NameToIndexMap::Entry, const char *>> backlog;310    backlog.reserve(num_symbols / 2);311 312    // Instantiation of the demangler is expensive, so better use a single one313    // for all entries during batch processing.314    RichManglingContext rmc;315    for (uint32_t value = 0; value < num_symbols; ++value) {316      Symbol *symbol = &m_symbols[value];317 318      // Don't let trampolines get into the lookup by name map If we ever need319      // the trampoline symbols to be searchable by name we can remove this and320      // then possibly add a new bool to any of the Symtab functions that321      // lookup symbols by name to indicate if they want trampolines. We also322      // don't want any synthetic symbols with auto generated names in the323      // name lookups.324      if (symbol->IsTrampoline() || symbol->IsSyntheticWithAutoGeneratedName())325        continue;326 327      // If the symbol's name string matched a Mangled::ManglingScheme, it is328      // stored in the mangled field.329      Mangled &mangled = symbol->GetMangled();330      if (ConstString name = mangled.GetMangledName()) {331        name_to_index.Append(name, value);332 333        if (symbol->ContainsLinkerAnnotations()) {334          // If the symbol has linker annotations, also add the version without335          // the annotations.336          ConstString stripped = ConstString(337              m_objfile->StripLinkerSymbolAnnotations(name.GetStringRef()));338          name_to_index.Append(stripped, value);339        }340 341        const SymbolType type = symbol->GetType();342        if (type == eSymbolTypeCode || type == eSymbolTypeResolver) {343          if (mangled.GetRichManglingInfo(rmc, lldb_skip_name)) {344            RegisterMangledNameEntry(value, class_contexts, backlog, rmc);345            continue;346          }347        }348      }349 350      // Symbol name strings that didn't match a Mangled::ManglingScheme, are351      // stored in the demangled field.352      if (ConstString name = mangled.GetDemangledName()) {353        name_to_index.Append(name, value);354 355        if (symbol->ContainsLinkerAnnotations()) {356          // If the symbol has linker annotations, also add the version without357          // the annotations.358          name = ConstString(359              m_objfile->StripLinkerSymbolAnnotations(name.GetStringRef()));360          name_to_index.Append(name, value);361        }362 363        // If the demangled name turns out to be an ObjC name, and is a category364        // name, add the version without categories to the index too.365        for (Language *lang : languages) {366          for (auto variant : lang->GetMethodNameVariants(name)) {367            if (variant.GetType() & lldb::eFunctionNameTypeSelector)368              selector_to_index.Append(variant.GetName(), value);369            else if (variant.GetType() & lldb::eFunctionNameTypeFull)370              name_to_index.Append(variant.GetName(), value);371            else if (variant.GetType() & lldb::eFunctionNameTypeMethod)372              method_to_index.Append(variant.GetName(), value);373            else if (variant.GetType() & lldb::eFunctionNameTypeBase)374              basename_to_index.Append(variant.GetName(), value);375          }376        }377      }378    }379 380    for (const auto &record : backlog) {381      RegisterBacklogEntry(record.first, record.second, class_contexts);382    }383 384    name_to_index.Sort();385    name_to_index.SizeToFit();386    selector_to_index.Sort();387    selector_to_index.SizeToFit();388    basename_to_index.Sort();389    basename_to_index.SizeToFit();390    method_to_index.Sort();391    method_to_index.SizeToFit();392  }393}394 395void Symtab::RegisterMangledNameEntry(396    uint32_t value, std::set<const char *> &class_contexts,397    std::vector<std::pair<NameToIndexMap::Entry, const char *>> &backlog,398    RichManglingContext &rmc) {399  // Only register functions that have a base name.400  llvm::StringRef base_name = rmc.ParseFunctionBaseName();401  if (base_name.empty())402    return;403 404  // The base name will be our entry's name.405  NameToIndexMap::Entry entry(ConstString(base_name), value);406  llvm::StringRef decl_context = rmc.ParseFunctionDeclContextName();407 408  // Register functions with no context.409  if (decl_context.empty()) {410    // This has to be a basename411    auto &basename_to_index =412        GetNameToSymbolIndexMap(lldb::eFunctionNameTypeBase);413    basename_to_index.Append(entry);414    // If there is no context (no namespaces or class scopes that come before415    // the function name) then this also could be a fullname.416    auto &name_to_index = GetNameToSymbolIndexMap(lldb::eFunctionNameTypeNone);417    name_to_index.Append(entry);418    return;419  }420 421  // Make sure we have a pool-string pointer and see if we already know the422  // context name.423  const char *decl_context_ccstr = ConstString(decl_context).GetCString();424  auto it = class_contexts.find(decl_context_ccstr);425 426  auto &method_to_index =427      GetNameToSymbolIndexMap(lldb::eFunctionNameTypeMethod);428  // Register constructors and destructors. They are methods and create429  // declaration contexts.430  if (rmc.IsCtorOrDtor()) {431    method_to_index.Append(entry);432    if (it == class_contexts.end())433      class_contexts.insert(it, decl_context_ccstr);434    return;435  }436 437  // Register regular methods with a known declaration context.438  if (it != class_contexts.end()) {439    method_to_index.Append(entry);440    return;441  }442 443  // Regular methods in unknown declaration contexts are put to the backlog. We444  // will revisit them once we processed all remaining symbols.445  backlog.push_back(std::make_pair(entry, decl_context_ccstr));446}447 448void Symtab::RegisterBacklogEntry(449    const NameToIndexMap::Entry &entry, const char *decl_context,450    const std::set<const char *> &class_contexts) {451  auto &method_to_index =452      GetNameToSymbolIndexMap(lldb::eFunctionNameTypeMethod);453  auto it = class_contexts.find(decl_context);454  if (it != class_contexts.end()) {455    method_to_index.Append(entry);456  } else {457    // If we got here, we have something that had a context (was inside458    // a namespace or class) yet we don't know the entry459    method_to_index.Append(entry);460    auto &basename_to_index =461        GetNameToSymbolIndexMap(lldb::eFunctionNameTypeBase);462    basename_to_index.Append(entry);463  }464}465 466void Symtab::PreloadSymbols() {467  std::lock_guard<std::recursive_mutex> guard(m_mutex);468  InitNameIndexes();469}470 471void Symtab::AppendSymbolNamesToMap(const IndexCollection &indexes,472                                    bool add_demangled, bool add_mangled,473                                    NameToIndexMap &name_to_index_map) const {474  LLDB_SCOPED_TIMER();475  if (add_demangled || add_mangled) {476    std::lock_guard<std::recursive_mutex> guard(m_mutex);477 478    // Create the name index vector to be able to quickly search by name479    const size_t num_indexes = indexes.size();480    for (size_t i = 0; i < num_indexes; ++i) {481      uint32_t value = indexes[i];482      assert(i < m_symbols.size());483      const Symbol *symbol = &m_symbols[value];484 485      const Mangled &mangled = symbol->GetMangled();486      if (add_demangled) {487        if (ConstString name = mangled.GetDemangledName())488          name_to_index_map.Append(name, value);489      }490 491      if (add_mangled) {492        if (ConstString name = mangled.GetMangledName())493          name_to_index_map.Append(name, value);494      }495    }496  }497}498 499uint32_t Symtab::AppendSymbolIndexesWithType(SymbolType symbol_type,500                                             std::vector<uint32_t> &indexes,501                                             uint32_t start_idx,502                                             uint32_t end_index) const {503  std::lock_guard<std::recursive_mutex> guard(m_mutex);504 505  uint32_t prev_size = indexes.size();506 507  const uint32_t count = std::min<uint32_t>(m_symbols.size(), end_index);508 509  for (uint32_t i = start_idx; i < count; ++i) {510    if (symbol_type == eSymbolTypeAny || m_symbols[i].GetType() == symbol_type)511      indexes.push_back(i);512  }513 514  return indexes.size() - prev_size;515}516 517uint32_t Symtab::AppendSymbolIndexesWithTypeAndFlagsValue(518    SymbolType symbol_type, uint32_t flags_value,519    std::vector<uint32_t> &indexes, uint32_t start_idx,520    uint32_t end_index) const {521  std::lock_guard<std::recursive_mutex> guard(m_mutex);522 523  uint32_t prev_size = indexes.size();524 525  const uint32_t count = std::min<uint32_t>(m_symbols.size(), end_index);526 527  for (uint32_t i = start_idx; i < count; ++i) {528    if ((symbol_type == eSymbolTypeAny ||529         m_symbols[i].GetType() == symbol_type) &&530        m_symbols[i].GetFlags() == flags_value)531      indexes.push_back(i);532  }533 534  return indexes.size() - prev_size;535}536 537uint32_t Symtab::AppendSymbolIndexesWithType(SymbolType symbol_type,538                                             Debug symbol_debug_type,539                                             Visibility symbol_visibility,540                                             std::vector<uint32_t> &indexes,541                                             uint32_t start_idx,542                                             uint32_t end_index) const {543  std::lock_guard<std::recursive_mutex> guard(m_mutex);544 545  uint32_t prev_size = indexes.size();546 547  const uint32_t count = std::min<uint32_t>(m_symbols.size(), end_index);548 549  for (uint32_t i = start_idx; i < count; ++i) {550    if (symbol_type == eSymbolTypeAny ||551        m_symbols[i].GetType() == symbol_type) {552      if (CheckSymbolAtIndex(i, symbol_debug_type, symbol_visibility))553        indexes.push_back(i);554    }555  }556 557  return indexes.size() - prev_size;558}559 560uint32_t Symtab::GetIndexForSymbol(const Symbol *symbol) const {561  if (!m_symbols.empty()) {562    const Symbol *first_symbol = &m_symbols[0];563    if (symbol >= first_symbol && symbol < first_symbol + m_symbols.size())564      return symbol - first_symbol;565  }566  return UINT32_MAX;567}568 569struct SymbolSortInfo {570  const bool sort_by_load_addr;571  const Symbol *symbols;572};573 574namespace {575struct SymbolIndexComparator {576  const std::vector<Symbol> &symbols;577  std::vector<lldb::addr_t> &addr_cache;578 579  // Getting from the symbol to the Address to the File Address involves some580  // work. Since there are potentially many symbols here, and we're using this581  // for sorting so we're going to be computing the address many times, cache582  // that in addr_cache. The array passed in has to be the same size as the583  // symbols array passed into the member variable symbols, and should be584  // initialized with LLDB_INVALID_ADDRESS.585  // NOTE: You have to make addr_cache externally and pass it in because586  // std::stable_sort587  // makes copies of the comparator it is initially passed in, and you end up588  // spending huge amounts of time copying this array...589 590  SymbolIndexComparator(const std::vector<Symbol> &s,591                        std::vector<lldb::addr_t> &a)592      : symbols(s), addr_cache(a) {593    assert(symbols.size() == addr_cache.size());594  }595  bool operator()(uint32_t index_a, uint32_t index_b) {596    addr_t value_a = addr_cache[index_a];597    if (value_a == LLDB_INVALID_ADDRESS) {598      value_a = symbols[index_a].GetAddressRef().GetFileAddress();599      addr_cache[index_a] = value_a;600    }601 602    addr_t value_b = addr_cache[index_b];603    if (value_b == LLDB_INVALID_ADDRESS) {604      value_b = symbols[index_b].GetAddressRef().GetFileAddress();605      addr_cache[index_b] = value_b;606    }607 608    if (value_a == value_b) {609      // The if the values are equal, use the original symbol user ID610      lldb::user_id_t uid_a = symbols[index_a].GetID();611      lldb::user_id_t uid_b = symbols[index_b].GetID();612      if (uid_a < uid_b)613        return true;614      if (uid_a > uid_b)615        return false;616      return false;617    } else if (value_a < value_b)618      return true;619 620    return false;621  }622};623}624 625void Symtab::SortSymbolIndexesByValue(std::vector<uint32_t> &indexes,626                                      bool remove_duplicates) const {627  std::lock_guard<std::recursive_mutex> guard(m_mutex);628  LLDB_SCOPED_TIMER();629  // No need to sort if we have zero or one items...630  if (indexes.size() <= 1)631    return;632 633  // Sort the indexes in place using std::stable_sort.634  // NOTE: The use of std::stable_sort instead of llvm::sort here is strictly635  // for performance, not correctness.  The indexes vector tends to be "close"636  // to sorted, which the stable sort handles better.637 638  std::vector<lldb::addr_t> addr_cache(m_symbols.size(), LLDB_INVALID_ADDRESS);639 640  SymbolIndexComparator comparator(m_symbols, addr_cache);641  llvm::stable_sort(indexes, comparator);642 643  // Remove any duplicates if requested644  if (remove_duplicates) {645    auto last = llvm::unique(indexes);646    indexes.erase(last, indexes.end());647  }648}649 650uint32_t Symtab::GetNameIndexes(ConstString symbol_name,651                                std::vector<uint32_t> &indexes) {652  auto &name_to_index = GetNameToSymbolIndexMap(lldb::eFunctionNameTypeNone);653  const uint32_t count = name_to_index.GetValues(symbol_name, indexes);654  if (count)655    return count;656  // Synthetic symbol names are not added to the name indexes, but they start657  // with a prefix and end with the symbol file address. This allows users to658  // find these symbols without having to add them to the name indexes. These659  // queries will not happen very often since the names don't mean anything, so660  // performance is not paramount in this case.661  llvm::StringRef name = symbol_name.GetStringRef();662  // String the synthetic prefix if the name starts with it.663  if (!name.consume_front(Symbol::GetSyntheticSymbolPrefix()))664    return 0; // Not a synthetic symbol name665 666  // Extract the file address from the symbol name667  unsigned long long file_address = 0;668  if (getAsUnsignedInteger(name, /*Radix=*/16, file_address))669    return 0; // Failed to extract the user ID as an integer670 671  Symbol *symbol = FindSymbolAtFileAddress(static_cast<addr_t>(file_address));672  if (symbol == nullptr)673    return 0;674  const uint32_t symbol_idx = GetIndexForSymbol(symbol);675  if (symbol_idx == UINT32_MAX)676    return 0;677  indexes.push_back(symbol_idx);678  return 1;679}680 681uint32_t Symtab::AppendSymbolIndexesWithName(ConstString symbol_name,682                                             std::vector<uint32_t> &indexes) {683  std::lock_guard<std::recursive_mutex> guard(m_mutex);684 685  if (symbol_name) {686    if (!m_name_indexes_computed)687      InitNameIndexes();688 689    return GetNameIndexes(symbol_name, indexes);690  }691  return 0;692}693 694uint32_t Symtab::AppendSymbolIndexesWithName(ConstString symbol_name,695                                             Debug symbol_debug_type,696                                             Visibility symbol_visibility,697                                             std::vector<uint32_t> &indexes) {698  std::lock_guard<std::recursive_mutex> guard(m_mutex);699 700  LLDB_SCOPED_TIMER();701  if (symbol_name) {702    const size_t old_size = indexes.size();703    if (!m_name_indexes_computed)704      InitNameIndexes();705 706    std::vector<uint32_t> all_name_indexes;707    const size_t name_match_count =708        GetNameIndexes(symbol_name, all_name_indexes);709    for (size_t i = 0; i < name_match_count; ++i) {710      if (CheckSymbolAtIndex(all_name_indexes[i], symbol_debug_type,711                             symbol_visibility))712        indexes.push_back(all_name_indexes[i]);713    }714    return indexes.size() - old_size;715  }716  return 0;717}718 719uint32_t720Symtab::AppendSymbolIndexesWithNameAndType(ConstString symbol_name,721                                           SymbolType symbol_type,722                                           std::vector<uint32_t> &indexes) {723  std::lock_guard<std::recursive_mutex> guard(m_mutex);724 725  if (AppendSymbolIndexesWithName(symbol_name, indexes) > 0 &&726      symbol_type != eSymbolTypeAny) {727    llvm::erase_if(indexes, [this, symbol_type](uint32_t index) {728      return m_symbols[index].GetType() != symbol_type;729    });730  }731  return indexes.size();732}733 734uint32_t Symtab::AppendSymbolIndexesWithNameAndType(735    ConstString symbol_name, SymbolType symbol_type,736    Debug symbol_debug_type, Visibility symbol_visibility,737    std::vector<uint32_t> &indexes) {738  std::lock_guard<std::recursive_mutex> guard(m_mutex);739 740  if (AppendSymbolIndexesWithName(symbol_name, symbol_debug_type,741                                  symbol_visibility, indexes) > 0 &&742      symbol_type != eSymbolTypeAny) {743    llvm::erase_if(indexes, [this, symbol_type](uint32_t index) {744      return m_symbols[index].GetType() != symbol_type;745    });746  }747  return indexes.size();748}749 750uint32_t Symtab::AppendSymbolIndexesMatchingRegExAndType(751    const RegularExpression &regexp, SymbolType symbol_type,752    std::vector<uint32_t> &indexes, Mangled::NamePreference name_preference) {753  std::lock_guard<std::recursive_mutex> guard(m_mutex);754 755  uint32_t prev_size = indexes.size();756  uint32_t sym_end = m_symbols.size();757 758  for (uint32_t i = 0; i < sym_end; i++) {759    if (symbol_type == eSymbolTypeAny ||760        m_symbols[i].GetType() == symbol_type) {761      const char *name =762          m_symbols[i].GetMangled().GetName(name_preference).AsCString();763      if (name) {764        if (regexp.Execute(name))765          indexes.push_back(i);766      }767    }768  }769  return indexes.size() - prev_size;770}771 772uint32_t Symtab::AppendSymbolIndexesMatchingRegExAndType(773    const RegularExpression &regexp, SymbolType symbol_type,774    Debug symbol_debug_type, Visibility symbol_visibility,775    std::vector<uint32_t> &indexes, Mangled::NamePreference name_preference) {776  std::lock_guard<std::recursive_mutex> guard(m_mutex);777 778  uint32_t prev_size = indexes.size();779  uint32_t sym_end = m_symbols.size();780 781  for (uint32_t i = 0; i < sym_end; i++) {782    if (symbol_type == eSymbolTypeAny ||783        m_symbols[i].GetType() == symbol_type) {784      if (!CheckSymbolAtIndex(i, symbol_debug_type, symbol_visibility))785        continue;786 787      const char *name =788          m_symbols[i].GetMangled().GetName(name_preference).AsCString();789      if (name) {790        if (regexp.Execute(name))791          indexes.push_back(i);792      }793    }794  }795  return indexes.size() - prev_size;796}797 798Symbol *Symtab::FindSymbolWithType(SymbolType symbol_type,799                                   Debug symbol_debug_type,800                                   Visibility symbol_visibility,801                                   uint32_t &start_idx) {802  std::lock_guard<std::recursive_mutex> guard(m_mutex);803 804  const size_t count = m_symbols.size();805  for (size_t idx = start_idx; idx < count; ++idx) {806    if (symbol_type == eSymbolTypeAny ||807        m_symbols[idx].GetType() == symbol_type) {808      if (CheckSymbolAtIndex(idx, symbol_debug_type, symbol_visibility)) {809        start_idx = idx;810        return &m_symbols[idx];811      }812    }813  }814  return nullptr;815}816 817void818Symtab::FindAllSymbolsWithNameAndType(ConstString name,819                                      SymbolType symbol_type,820                                      std::vector<uint32_t> &symbol_indexes) {821  std::lock_guard<std::recursive_mutex> guard(m_mutex);822 823  // Initialize all of the lookup by name indexes before converting NAME to a824  // uniqued string NAME_STR below.825  if (!m_name_indexes_computed)826    InitNameIndexes();827 828  if (name) {829    // The string table did have a string that matched, but we need to check830    // the symbols and match the symbol_type if any was given.831    AppendSymbolIndexesWithNameAndType(name, symbol_type, symbol_indexes);832  }833}834 835void Symtab::FindAllSymbolsWithNameAndType(836    ConstString name, SymbolType symbol_type, Debug symbol_debug_type,837    Visibility symbol_visibility, std::vector<uint32_t> &symbol_indexes) {838  std::lock_guard<std::recursive_mutex> guard(m_mutex);839 840  LLDB_SCOPED_TIMER();841  // Initialize all of the lookup by name indexes before converting NAME to a842  // uniqued string NAME_STR below.843  if (!m_name_indexes_computed)844    InitNameIndexes();845 846  if (name) {847    // The string table did have a string that matched, but we need to check848    // the symbols and match the symbol_type if any was given.849    AppendSymbolIndexesWithNameAndType(name, symbol_type, symbol_debug_type,850                                       symbol_visibility, symbol_indexes);851  }852}853 854void Symtab::FindAllSymbolsMatchingRexExAndType(855    const RegularExpression &regex, SymbolType symbol_type,856    Debug symbol_debug_type, Visibility symbol_visibility,857    std::vector<uint32_t> &symbol_indexes,858    Mangled::NamePreference name_preference) {859  std::lock_guard<std::recursive_mutex> guard(m_mutex);860 861  AppendSymbolIndexesMatchingRegExAndType(regex, symbol_type, symbol_debug_type,862                                          symbol_visibility, symbol_indexes,863                                          name_preference);864}865 866Symbol *Symtab::FindFirstSymbolWithNameAndType(ConstString name,867                                               SymbolType symbol_type,868                                               Debug symbol_debug_type,869                                               Visibility symbol_visibility) {870  std::lock_guard<std::recursive_mutex> guard(m_mutex);871  LLDB_SCOPED_TIMER();872  if (!m_name_indexes_computed)873    InitNameIndexes();874 875  if (name) {876    std::vector<uint32_t> matching_indexes;877    // The string table did have a string that matched, but we need to check878    // the symbols and match the symbol_type if any was given.879    if (AppendSymbolIndexesWithNameAndType(name, symbol_type, symbol_debug_type,880                                           symbol_visibility,881                                           matching_indexes)) {882      std::vector<uint32_t>::const_iterator pos, end = matching_indexes.end();883      for (pos = matching_indexes.begin(); pos != end; ++pos) {884        Symbol *symbol = SymbolAtIndex(*pos);885 886        if (symbol->Compare(name, symbol_type))887          return symbol;888      }889    }890  }891  return nullptr;892}893 894typedef struct {895  const Symtab *symtab;896  const addr_t file_addr;897  Symbol *match_symbol;898  const uint32_t *match_index_ptr;899  addr_t match_offset;900} SymbolSearchInfo;901 902// Add all the section file start address & size to the RangeVector, recusively903// adding any children sections.904static void AddSectionsToRangeMap(SectionList *sectlist,905                                  RangeVector<addr_t, addr_t> &section_ranges) {906  const int num_sections = sectlist->GetNumSections(0);907  for (int i = 0; i < num_sections; i++) {908    SectionSP sect_sp = sectlist->GetSectionAtIndex(i);909    if (sect_sp) {910      SectionList &child_sectlist = sect_sp->GetChildren();911 912      // If this section has children, add the children to the RangeVector.913      // Else add this section to the RangeVector.914      if (child_sectlist.GetNumSections(0) > 0) {915        AddSectionsToRangeMap(&child_sectlist, section_ranges);916      } else {917        size_t size = sect_sp->GetByteSize();918        if (size > 0) {919          addr_t base_addr = sect_sp->GetFileAddress();920          RangeVector<addr_t, addr_t>::Entry entry;921          entry.SetRangeBase(base_addr);922          entry.SetByteSize(size);923          section_ranges.Append(entry);924        }925      }926    }927  }928}929 930void Symtab::InitAddressIndexes() {931  // Protected function, no need to lock mutex...932  if (!m_file_addr_to_index_computed && !m_symbols.empty()) {933    m_file_addr_to_index_computed = true;934 935    FileRangeToIndexMap::Entry entry;936    const_iterator begin = m_symbols.begin();937    const_iterator end = m_symbols.end();938    for (const_iterator pos = m_symbols.begin(); pos != end; ++pos) {939      if (pos->ValueIsAddress()) {940        entry.SetRangeBase(pos->GetAddressRef().GetFileAddress());941        entry.SetByteSize(pos->GetByteSize());942        entry.data = std::distance(begin, pos);943        m_file_addr_to_index.Append(entry);944      }945    }946    const size_t num_entries = m_file_addr_to_index.GetSize();947    if (num_entries > 0) {948      m_file_addr_to_index.Sort();949 950      // Create a RangeVector with the start & size of all the sections for951      // this objfile.  We'll need to check this for any FileRangeToIndexMap952      // entries with an uninitialized size, which could potentially be a large953      // number so reconstituting the weak pointer is busywork when it is954      // invariant information.955      SectionList *sectlist = m_objfile->GetSectionList();956      RangeVector<addr_t, addr_t> section_ranges;957      if (sectlist) {958        AddSectionsToRangeMap(sectlist, section_ranges);959        section_ranges.Sort();960      }961 962      // Iterate through the FileRangeToIndexMap and fill in the size for any963      // entries that didn't already have a size from the Symbol (e.g. if we964      // have a plain linker symbol with an address only, instead of debug info965      // where we get an address and a size and a type, etc.)966      for (size_t i = 0; i < num_entries; i++) {967        FileRangeToIndexMap::Entry *entry =968            m_file_addr_to_index.GetMutableEntryAtIndex(i);969        if (entry->GetByteSize() == 0) {970          addr_t curr_base_addr = entry->GetRangeBase();971          const RangeVector<addr_t, addr_t>::Entry *containing_section =972              section_ranges.FindEntryThatContains(curr_base_addr);973 974          // Use the end of the section as the default max size of the symbol975          addr_t sym_size = 0;976          if (containing_section) {977            sym_size =978                containing_section->GetByteSize() -979                (entry->GetRangeBase() - containing_section->GetRangeBase());980          }981 982          for (size_t j = i; j < num_entries; j++) {983            FileRangeToIndexMap::Entry *next_entry =984                m_file_addr_to_index.GetMutableEntryAtIndex(j);985            addr_t next_base_addr = next_entry->GetRangeBase();986            if (next_base_addr > curr_base_addr) {987              addr_t size_to_next_symbol = next_base_addr - curr_base_addr;988 989              // Take the difference between this symbol and the next one as990              // its size, if it is less than the size of the section.991              if (sym_size == 0 || size_to_next_symbol < sym_size) {992                sym_size = size_to_next_symbol;993              }994              break;995            }996          }997 998          if (sym_size > 0) {999            entry->SetByteSize(sym_size);1000            Symbol &symbol = m_symbols[entry->data];1001            symbol.SetByteSize(sym_size);1002            symbol.SetSizeIsSynthesized(true);1003          }1004        }1005      }1006 1007      // Sort again in case the range size changes the ordering1008      m_file_addr_to_index.Sort();1009    }1010  }1011}1012 1013void Symtab::Finalize() {1014  std::lock_guard<std::recursive_mutex> guard(m_mutex);1015  // Calculate the size of symbols inside InitAddressIndexes.1016  InitAddressIndexes();1017  // Shrink to fit the symbols so we don't waste memory1018  m_symbols.shrink_to_fit();1019  SaveToCache();1020}1021 1022Symbol *Symtab::FindSymbolAtFileAddress(addr_t file_addr) {1023  std::lock_guard<std::recursive_mutex> guard(m_mutex);1024  if (!m_file_addr_to_index_computed)1025    InitAddressIndexes();1026 1027  const FileRangeToIndexMap::Entry *entry =1028      m_file_addr_to_index.FindEntryStartsAt(file_addr);1029  if (entry) {1030    Symbol *symbol = SymbolAtIndex(entry->data);1031    if (symbol->GetFileAddress() == file_addr)1032      return symbol;1033  }1034  return nullptr;1035}1036 1037Symbol *Symtab::FindSymbolContainingFileAddress(addr_t file_addr) {1038  std::lock_guard<std::recursive_mutex> guard(m_mutex);1039 1040  if (!m_file_addr_to_index_computed)1041    InitAddressIndexes();1042 1043  const FileRangeToIndexMap::Entry *entry =1044      m_file_addr_to_index.FindEntryThatContains(file_addr);1045  if (entry) {1046    Symbol *symbol = SymbolAtIndex(entry->data);1047    if (symbol->ContainsFileAddress(file_addr))1048      return symbol;1049  }1050  return nullptr;1051}1052 1053void Symtab::ForEachSymbolContainingFileAddress(1054    addr_t file_addr, std::function<bool(Symbol *)> const &callback) {1055  std::lock_guard<std::recursive_mutex> guard(m_mutex);1056 1057  if (!m_file_addr_to_index_computed)1058    InitAddressIndexes();1059 1060  std::vector<uint32_t> all_addr_indexes;1061 1062  // Get all symbols with file_addr1063  const size_t addr_match_count =1064      m_file_addr_to_index.FindEntryIndexesThatContain(file_addr,1065                                                       all_addr_indexes);1066 1067  for (size_t i = 0; i < addr_match_count; ++i) {1068    Symbol *symbol = SymbolAtIndex(all_addr_indexes[i]);1069    if (symbol->ContainsFileAddress(file_addr)) {1070      if (!callback(symbol))1071        break;1072    }1073  }1074}1075 1076void Symtab::SymbolIndicesToSymbolContextList(1077    std::vector<uint32_t> &symbol_indexes, SymbolContextList &sc_list) {1078  // No need to protect this call using m_mutex all other method calls are1079  // already thread safe.1080 1081  const bool merge_symbol_into_function = true;1082  size_t num_indices = symbol_indexes.size();1083  if (num_indices > 0) {1084    SymbolContext sc;1085    sc.module_sp = m_objfile->GetModule();1086    for (size_t i = 0; i < num_indices; i++) {1087      sc.symbol = SymbolAtIndex(symbol_indexes[i]);1088      if (sc.symbol)1089        sc_list.AppendIfUnique(sc, merge_symbol_into_function);1090    }1091  }1092}1093 1094void Symtab::FindFunctionSymbols(ConstString name, uint32_t name_type_mask,1095                                 SymbolContextList &sc_list) {1096  std::vector<uint32_t> symbol_indexes;1097 1098  // eFunctionNameTypeAuto should be pre-resolved by a call to1099  // Module::LookupInfo::LookupInfo()1100  assert((name_type_mask & eFunctionNameTypeAuto) == 0);1101 1102  if (name_type_mask & (eFunctionNameTypeBase | eFunctionNameTypeFull)) {1103    std::vector<uint32_t> temp_symbol_indexes;1104    FindAllSymbolsWithNameAndType(name, eSymbolTypeAny, temp_symbol_indexes);1105 1106    unsigned temp_symbol_indexes_size = temp_symbol_indexes.size();1107    if (temp_symbol_indexes_size > 0) {1108      std::lock_guard<std::recursive_mutex> guard(m_mutex);1109      for (unsigned i = 0; i < temp_symbol_indexes_size; i++) {1110        SymbolContext sym_ctx;1111        sym_ctx.symbol = SymbolAtIndex(temp_symbol_indexes[i]);1112        if (sym_ctx.symbol) {1113          switch (sym_ctx.symbol->GetType()) {1114          case eSymbolTypeCode:1115          case eSymbolTypeResolver:1116          case eSymbolTypeReExported:1117          case eSymbolTypeAbsolute:1118            symbol_indexes.push_back(temp_symbol_indexes[i]);1119            break;1120          default:1121            break;1122          }1123        }1124      }1125    }1126  }1127 1128  if (!m_name_indexes_computed)1129    InitNameIndexes();1130 1131  for (lldb::FunctionNameType type :1132       {lldb::eFunctionNameTypeBase, lldb::eFunctionNameTypeMethod,1133        lldb::eFunctionNameTypeSelector}) {1134    if (name_type_mask & type) {1135      auto map = GetNameToSymbolIndexMap(type);1136 1137      const UniqueCStringMap<uint32_t>::Entry *match;1138      for (match = map.FindFirstValueForName(name); match != nullptr;1139           match = map.FindNextValueForName(match)) {1140        symbol_indexes.push_back(match->value);1141      }1142    }1143  }1144 1145  if (!symbol_indexes.empty()) {1146    llvm::sort(symbol_indexes);1147    symbol_indexes.erase(llvm::unique(symbol_indexes), symbol_indexes.end());1148    SymbolIndicesToSymbolContextList(symbol_indexes, sc_list);1149  }1150}1151 1152const Symbol *Symtab::GetParent(Symbol *child_symbol) const {1153  uint32_t child_idx = GetIndexForSymbol(child_symbol);1154  if (child_idx != UINT32_MAX && child_idx > 0) {1155    for (uint32_t idx = child_idx - 1; idx != UINT32_MAX; --idx) {1156      const Symbol *symbol = SymbolAtIndex(idx);1157      const uint32_t sibling_idx = symbol->GetSiblingIndex();1158      if (sibling_idx != UINT32_MAX && sibling_idx > child_idx)1159        return symbol;1160    }1161  }1162  return nullptr;1163}1164 1165std::string Symtab::GetCacheKey() {1166  std::string key;1167  llvm::raw_string_ostream strm(key);1168  // Symbol table can come from different object files for the same module. A1169  // module can have one object file as the main executable and might have1170  // another object file in a separate symbol file.1171  strm << m_objfile->GetModule()->GetCacheKey() << "-symtab-"1172      << llvm::format_hex(m_objfile->GetCacheHash(), 10);1173  return key;1174}1175 1176void Symtab::SaveToCache() {1177  DataFileCache *cache = Module::GetIndexCache();1178  if (!cache)1179    return; // Caching is not enabled.1180  InitNameIndexes(); // Init the name indexes so we can cache them as well.1181  const auto byte_order = endian::InlHostByteOrder();1182  DataEncoder file(byte_order, /*addr_size=*/8);1183  // Encode will return false if the symbol table's object file doesn't have1184  // anything to make a signature from.1185  if (Encode(file))1186    if (cache->SetCachedData(GetCacheKey(), file.GetData()))1187      SetWasSavedToCache();1188}1189 1190constexpr llvm::StringLiteral kIdentifierCStrMap("CMAP");1191 1192static void EncodeCStrMap(DataEncoder &encoder, ConstStringTable &strtab,1193                          const UniqueCStringMap<uint32_t> &cstr_map) {1194  encoder.AppendData(kIdentifierCStrMap);1195  encoder.AppendU32(cstr_map.GetSize());1196  for (const auto &entry: cstr_map) {1197    // Make sure there are no empty strings.1198    assert((bool)entry.cstring);1199    encoder.AppendU32(strtab.Add(entry.cstring));1200    encoder.AppendU32(entry.value);1201  }1202}1203 1204bool DecodeCStrMap(const DataExtractor &data, lldb::offset_t *offset_ptr,1205                   const StringTableReader &strtab,1206                   UniqueCStringMap<uint32_t> &cstr_map) {1207  llvm::StringRef identifier((const char *)data.GetData(offset_ptr, 4), 4);1208  if (identifier != kIdentifierCStrMap)1209    return false;1210  const uint32_t count = data.GetU32(offset_ptr);1211  cstr_map.Reserve(count);1212  for (uint32_t i=0; i<count; ++i)1213  {1214    llvm::StringRef str(strtab.Get(data.GetU32(offset_ptr)));1215    uint32_t value = data.GetU32(offset_ptr);1216    // No empty strings in the name indexes in Symtab1217    if (str.empty())1218      return false;1219    cstr_map.Append(ConstString(str), value);1220  }1221  // We must sort the UniqueCStringMap after decoding it since it is a vector1222  // of UniqueCStringMap::Entry objects which contain a ConstString and type T.1223  // ConstString objects are sorted by "const char *" and then type T and1224  // the "const char *" are point values that will depend on the order in which1225  // ConstString objects are created and in which of the 256 string pools they1226  // are created in. So after we decode all of the entries, we must sort the1227  // name map to ensure name lookups succeed. If we encode and decode within1228  // the same process we wouldn't need to sort, so unit testing didn't catch1229  // this issue when first checked in.1230  cstr_map.Sort();1231  return true;1232}1233 1234constexpr llvm::StringLiteral kIdentifierSymbolTable("SYMB");1235constexpr uint32_t CURRENT_CACHE_VERSION = 1;1236 1237/// The encoding format for the symbol table is as follows:1238///1239/// Signature signature;1240/// ConstStringTable strtab;1241/// Identifier four character code: 'SYMB'1242/// uint32_t version;1243/// uint32_t num_symbols;1244/// Symbol symbols[num_symbols];1245/// uint8_t num_cstr_maps;1246/// UniqueCStringMap<uint32_t> cstr_maps[num_cstr_maps]1247bool Symtab::Encode(DataEncoder &encoder) const {1248  // Name indexes must be computed before calling this function.1249  assert(m_name_indexes_computed);1250 1251  // Encode the object file's signature1252  CacheSignature signature(m_objfile);1253  if (!signature.Encode(encoder))1254    return false;1255  ConstStringTable strtab;1256 1257  // Encoder the symbol table into a separate encoder first. This allows us1258  // gather all of the strings we willl need in "strtab" as we will need to1259  // write the string table out before the symbol table.1260  DataEncoder symtab_encoder(encoder.GetByteOrder(),1261                              encoder.GetAddressByteSize());1262  symtab_encoder.AppendData(kIdentifierSymbolTable);1263  // Encode the symtab data version.1264  symtab_encoder.AppendU32(CURRENT_CACHE_VERSION);1265  // Encode the number of symbols.1266  symtab_encoder.AppendU32(m_symbols.size());1267  // Encode the symbol data for all symbols.1268  for (const auto &symbol: m_symbols)1269    symbol.Encode(symtab_encoder, strtab);1270 1271  // Emit a byte for how many C string maps we emit. We will fix this up after1272  // we emit the C string maps since we skip emitting C string maps if they are1273  // empty.1274  size_t num_cmaps_offset = symtab_encoder.GetByteSize();1275  uint8_t num_cmaps = 0;1276  symtab_encoder.AppendU8(0);1277  for (const auto &pair: m_name_to_symbol_indices) {1278    if (pair.second.IsEmpty())1279      continue;1280    ++num_cmaps;1281    symtab_encoder.AppendU8(pair.first);1282    EncodeCStrMap(symtab_encoder, strtab, pair.second);1283  }1284  if (num_cmaps > 0)1285    symtab_encoder.PutU8(num_cmaps_offset, num_cmaps);1286 1287  // Now that all strings have been gathered, we will emit the string table.1288  strtab.Encode(encoder);1289  // Followed by the symbol table data.1290  encoder.AppendData(symtab_encoder.GetData());1291  return true;1292}1293 1294bool Symtab::Decode(const DataExtractor &data, lldb::offset_t *offset_ptr,1295                    bool &signature_mismatch) {1296  signature_mismatch = false;1297  CacheSignature signature;1298  StringTableReader strtab;1299  { // Scope for "elapsed" object below so it can measure the time parse.1300    ElapsedTime elapsed(m_objfile->GetModule()->GetSymtabParseTime());1301    if (!signature.Decode(data, offset_ptr))1302      return false;1303    if (CacheSignature(m_objfile) != signature) {1304      signature_mismatch = true;1305      return false;1306    }1307    // We now decode the string table for all strings in the data cache file.1308    if (!strtab.Decode(data, offset_ptr))1309      return false;1310 1311    // And now we can decode the symbol table with string table we just decoded.1312    llvm::StringRef identifier((const char *)data.GetData(offset_ptr, 4), 4);1313    if (identifier != kIdentifierSymbolTable)1314      return false;1315    const uint32_t version = data.GetU32(offset_ptr);1316    if (version != CURRENT_CACHE_VERSION)1317      return false;1318    const uint32_t num_symbols = data.GetU32(offset_ptr);1319    if (num_symbols == 0)1320      return true;1321    m_symbols.resize(num_symbols);1322    SectionList *sections = m_objfile->GetModule()->GetSectionList();1323    for (uint32_t i=0; i<num_symbols; ++i) {1324      if (!m_symbols[i].Decode(data, offset_ptr, sections, strtab))1325        return false;1326    }1327  }1328 1329  { // Scope for "elapsed" object below so it can measure the time to index.1330    ElapsedTime elapsed(m_objfile->GetModule()->GetSymtabIndexTime());1331    const uint8_t num_cstr_maps = data.GetU8(offset_ptr);1332    for (uint8_t i=0; i<num_cstr_maps; ++i) {1333      uint8_t type = data.GetU8(offset_ptr);1334      UniqueCStringMap<uint32_t> &cstr_map =1335          GetNameToSymbolIndexMap((lldb::FunctionNameType)type);1336      if (!DecodeCStrMap(data, offset_ptr, strtab, cstr_map))1337        return false;1338    }1339    m_name_indexes_computed = true;1340  }1341  return true;1342}1343 1344bool Symtab::LoadFromCache() {1345  DataFileCache *cache = Module::GetIndexCache();1346  if (!cache)1347    return false;1348 1349  std::unique_ptr<llvm::MemoryBuffer> mem_buffer_up =1350      cache->GetCachedData(GetCacheKey());1351  if (!mem_buffer_up)1352    return false;1353  DataExtractor data(mem_buffer_up->getBufferStart(),1354                     mem_buffer_up->getBufferSize(),1355                     m_objfile->GetByteOrder(),1356                     m_objfile->GetAddressByteSize());1357  bool signature_mismatch = false;1358  lldb::offset_t offset = 0;1359  const bool result = Decode(data, &offset, signature_mismatch);1360  if (signature_mismatch)1361    cache->RemoveCacheFile(GetCacheKey());1362  if (result)1363    SetWasLoadedFromCache();1364  return result;1365}1366