vendor/lld/lld-trunk-r366426

1 files changed, 1002 insertions, 704 deletions

diff --git a/ELF/InputFiles.cpp b/ELF/InputFiles.cpp
index e4d1dec7cbcb..98b88283cf09 100644
--- a/ELF/InputFiles.cpp
+++ b/ELF/InputFiles.cpp
@@ -1,13 +1,13 @@
 //===- InputFiles.cpp -----------------------------------------------------===//
 //
-//                             The LLVM Linker
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "InputFiles.h"
+#include "Driver.h"
 #include "InputSection.h"
 #include "LinkerScript.h"
 #include "SymbolTable.h"
@@ -25,6 +25,7 @@
 #include "llvm/Object/ELFObjectFile.h"
 #include "llvm/Support/ARMAttributeParser.h"
 #include "llvm/Support/ARMBuildAttributes.h"
+#include "llvm/Support/Endian.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/TarWriter.h"
 #include "llvm/Support/raw_ostream.h"
@@ -34,145 +35,272 @@ using namespace llvm::ELF;
 using namespace llvm::object;
 using namespace llvm::sys;
 using namespace llvm::sys::fs;
+using namespace llvm::support::endian;
 
 using namespace lld;
 using namespace lld::elf;
 
-bool InputFile::IsInGroup;
-uint32_t InputFile::NextGroupId;
-std::vector<BinaryFile *> elf::BinaryFiles;
-std::vector<BitcodeFile *> elf::BitcodeFiles;
-std::vector<LazyObjFile *> elf::LazyObjFiles;
-std::vector<InputFile *> elf::ObjectFiles;
-std::vector<InputFile *> elf::SharedFiles;
-
-std::unique_ptr<TarWriter> elf::Tar;
+bool InputFile::isInGroup;
+uint32_t InputFile::nextGroupId;
+std::vector<BinaryFile *> elf::binaryFiles;
+std::vector<BitcodeFile *> elf::bitcodeFiles;
+std::vector<LazyObjFile *> elf::lazyObjFiles;
+std::vector<InputFile *> elf::objectFiles;
+std::vector<SharedFile *> elf::sharedFiles;
+
+std::unique_ptr<TarWriter> elf::tar;
+
+static ELFKind getELFKind(MemoryBufferRef mb, StringRef archiveName) {
+  unsigned char size;
+  unsigned char endian;
+  std::tie(size, endian) = getElfArchType(mb.getBuffer());
+
+  auto report = [&](StringRef msg) {
+    StringRef filename = mb.getBufferIdentifier();
+    if (archiveName.empty())
+      fatal(filename + ": " + msg);
+    else
+      fatal(archiveName + "(" + filename + "): " + msg);
+  };
+
+  if (!mb.getBuffer().startswith(ElfMagic))
+    report("not an ELF file");
+  if (endian != ELFDATA2LSB && endian != ELFDATA2MSB)
+    report("corrupted ELF file: invalid data encoding");
+  if (size != ELFCLASS32 && size != ELFCLASS64)
+    report("corrupted ELF file: invalid file class");
+
+  size_t bufSize = mb.getBuffer().size();
+  if ((size == ELFCLASS32 && bufSize < sizeof(Elf32_Ehdr)) ||
+      (size == ELFCLASS64 && bufSize < sizeof(Elf64_Ehdr)))
+    report("corrupted ELF file: file is too short");
+
+  if (size == ELFCLASS32)
+    return (endian == ELFDATA2LSB) ? ELF32LEKind : ELF32BEKind;
+  return (endian == ELFDATA2LSB) ? ELF64LEKind : ELF64BEKind;
+}
 
-InputFile::InputFile(Kind K, MemoryBufferRef M)
-    : MB(M), GroupId(NextGroupId), FileKind(K) {
+InputFile::InputFile(Kind k, MemoryBufferRef m)
+    : mb(m), groupId(nextGroupId), fileKind(k) {
   // All files within the same --{start,end}-group get the same group ID.
   // Otherwise, a new file will get a new group ID.
-  if (!IsInGroup)
-    ++NextGroupId;
+  if (!isInGroup)
+    ++nextGroupId;
 }
 
-Optional<MemoryBufferRef> elf::readFile(StringRef Path) {
+Optional<MemoryBufferRef> elf::readFile(StringRef path) {
   // The --chroot option changes our virtual root directory.
   // This is useful when you are dealing with files created by --reproduce.
-  if (!Config->Chroot.empty() && Path.startswith("/"))
-    Path = Saver.save(Config->Chroot + Path);
+  if (!config->chroot.empty() && path.startswith("/"))
+    path = saver.save(config->chroot + path);
 
-  log(Path);
+  log(path);
 
-  auto MBOrErr = MemoryBuffer::getFile(Path, -1, false);
-  if (auto EC = MBOrErr.getError()) {
-    error("cannot open " + Path + ": " + EC.message());
+  auto mbOrErr = MemoryBuffer::getFile(path, -1, false);
+  if (auto ec = mbOrErr.getError()) {
+    error("cannot open " + path + ": " + ec.message());
     return None;
   }
 
-  std::unique_ptr<MemoryBuffer> &MB = *MBOrErr;
-  MemoryBufferRef MBRef = MB->getMemBufferRef();
-  make<std::unique_ptr<MemoryBuffer>>(std::move(MB)); // take MB ownership
+  std::unique_ptr<MemoryBuffer> &mb = *mbOrErr;
+  MemoryBufferRef mbref = mb->getMemBufferRef();
+  make<std::unique_ptr<MemoryBuffer>>(std::move(mb)); // take MB ownership
+
+  if (tar)
+    tar->append(relativeToRoot(path), mbref.getBuffer());
+  return mbref;
+}
+
+// All input object files must be for the same architecture
+// (e.g. it does not make sense to link x86 object files with
+// MIPS object files.) This function checks for that error.
+static bool isCompatible(InputFile *file) {
+  if (!file->isElf() && !isa<BitcodeFile>(file))
+    return true;
+
+  if (file->ekind == config->ekind && file->emachine == config->emachine) {
+    if (config->emachine != EM_MIPS)
+      return true;
+    if (isMipsN32Abi(file) == config->mipsN32Abi)
+      return true;
+  }
+
+  if (!config->emulation.empty()) {
+    error(toString(file) + " is incompatible with " + config->emulation);
+  } else {
+    InputFile *existing;
+    if (!objectFiles.empty())
+      existing = objectFiles[0];
+    else if (!sharedFiles.empty())
+      existing = sharedFiles[0];
+    else
+      existing = bitcodeFiles[0];
+
+    error(toString(file) + " is incompatible with " + toString(existing));
+  }
+
+  return false;
+}
+
+template <class ELFT> static void doParseFile(InputFile *file) {
+  if (!isCompatible(file))
+    return;
+
+  // Binary file
+  if (auto *f = dyn_cast<BinaryFile>(file)) {
+    binaryFiles.push_back(f);
+    f->parse();
+    return;
+  }
+
+  // .a file
+  if (auto *f = dyn_cast<ArchiveFile>(file)) {
+    f->parse();
+    return;
+  }
+
+  // Lazy object file
+  if (auto *f = dyn_cast<LazyObjFile>(file)) {
+    lazyObjFiles.push_back(f);
+    f->parse<ELFT>();
+    return;
+  }
+
+  if (config->trace)
+    message(toString(file));
+
+  // .so file
+  if (auto *f = dyn_cast<SharedFile>(file)) {
+    f->parse<ELFT>();
+    return;
+  }
+
+  // LLVM bitcode file
+  if (auto *f = dyn_cast<BitcodeFile>(file)) {
+    bitcodeFiles.push_back(f);
+    f->parse<ELFT>();
+    return;
+  }
 
-  if (Tar)
-    Tar->append(relativeToRoot(Path), MBRef.getBuffer());
-  return MBRef;
+  // Regular object file
+  objectFiles.push_back(file);
+  cast<ObjFile<ELFT>>(file)->parse();
+}
+
+// Add symbols in File to the symbol table.
+void elf::parseFile(InputFile *file) {
+  switch (config->ekind) {
+  case ELF32LEKind:
+    doParseFile<ELF32LE>(file);
+    return;
+  case ELF32BEKind:
+    doParseFile<ELF32BE>(file);
+    return;
+  case ELF64LEKind:
+    doParseFile<ELF64LE>(file);
+    return;
+  case ELF64BEKind:
+    doParseFile<ELF64BE>(file);
+    return;
+  default:
+    llvm_unreachable("unknown ELFT");
+  }
 }
 
 // Concatenates arguments to construct a string representing an error location.
-static std::string createFileLineMsg(StringRef Path, unsigned Line) {
-  std::string Filename = path::filename(Path);
-  std::string Lineno = ":" + std::to_string(Line);
-  if (Filename == Path)
-    return Filename + Lineno;
-  return Filename + Lineno + " (" + Path.str() + Lineno + ")";
+static std::string createFileLineMsg(StringRef path, unsigned line) {
+  std::string filename = path::filename(path);
+  std::string lineno = ":" + std::to_string(line);
+  if (filename == path)
+    return filename + lineno;
+  return filename + lineno + " (" + path.str() + lineno + ")";
 }
 
 template <class ELFT>
-static std::string getSrcMsgAux(ObjFile<ELFT> &File, const Symbol &Sym,
-                                InputSectionBase &Sec, uint64_t Offset) {
+static std::string getSrcMsgAux(ObjFile<ELFT> &file, const Symbol &sym,
+                                InputSectionBase &sec, uint64_t offset) {
   // In DWARF, functions and variables are stored to different places.
   // First, lookup a function for a given offset.
-  if (Optional<DILineInfo> Info = File.getDILineInfo(&Sec, Offset))
-    return createFileLineMsg(Info->FileName, Info->Line);
+  if (Optional<DILineInfo> info = file.getDILineInfo(&sec, offset))
+    return createFileLineMsg(info->FileName, info->Line);
 
   // If it failed, lookup again as a variable.
-  if (Optional<std::pair<std::string, unsigned>> FileLine =
-          File.getVariableLoc(Sym.getName()))
-    return createFileLineMsg(FileLine->first, FileLine->second);
+  if (Optional<std::pair<std::string, unsigned>> fileLine =
+          file.getVariableLoc(sym.getName()))
+    return createFileLineMsg(fileLine->first, fileLine->second);
 
-  // File.SourceFile contains STT_FILE symbol, and that is a last resort.
-  return File.SourceFile;
+  // File.sourceFile contains STT_FILE symbol, and that is a last resort.
+  return file.sourceFile;
 }
 
-std::string InputFile::getSrcMsg(const Symbol &Sym, InputSectionBase &Sec,
-                                 uint64_t Offset) {
+std::string InputFile::getSrcMsg(const Symbol &sym, InputSectionBase &sec,
+                                 uint64_t offset) {
   if (kind() != ObjKind)
     return "";
-  switch (Config->EKind) {
+  switch (config->ekind) {
   default:
     llvm_unreachable("Invalid kind");
   case ELF32LEKind:
-    return getSrcMsgAux(cast<ObjFile<ELF32LE>>(*this), Sym, Sec, Offset);
+    return getSrcMsgAux(cast<ObjFile<ELF32LE>>(*this), sym, sec, offset);
   case ELF32BEKind:
-    return getSrcMsgAux(cast<ObjFile<ELF32BE>>(*this), Sym, Sec, Offset);
+    return getSrcMsgAux(cast<ObjFile<ELF32BE>>(*this), sym, sec, offset);
   case ELF64LEKind:
-    return getSrcMsgAux(cast<ObjFile<ELF64LE>>(*this), Sym, Sec, Offset);
+    return getSrcMsgAux(cast<ObjFile<ELF64LE>>(*this), sym, sec, offset);
   case ELF64BEKind:
-    return getSrcMsgAux(cast<ObjFile<ELF64BE>>(*this), Sym, Sec, Offset);
+    return getSrcMsgAux(cast<ObjFile<ELF64BE>>(*this), sym, sec, offset);
   }
 }
 
 template <class ELFT> void ObjFile<ELFT>::initializeDwarf() {
-  Dwarf = llvm::make_unique<DWARFContext>(make_unique<LLDDwarfObj<ELFT>>(this));
-  for (std::unique_ptr<DWARFUnit> &CU : Dwarf->compile_units()) {
-    auto Report = [](Error Err) {
-      handleAllErrors(std::move(Err),
-                      [](ErrorInfoBase &Info) { warn(Info.message()); });
+  dwarf = llvm::make_unique<DWARFContext>(make_unique<LLDDwarfObj<ELFT>>(this));
+  for (std::unique_ptr<DWARFUnit> &cu : dwarf->compile_units()) {
+    auto report = [](Error err) {
+      handleAllErrors(std::move(err),
+                      [](ErrorInfoBase &info) { warn(info.message()); });
     };
-    Expected<const DWARFDebugLine::LineTable *> ExpectedLT =
-        Dwarf->getLineTableForUnit(CU.get(), Report);
-    const DWARFDebugLine::LineTable *LT = nullptr;
-    if (ExpectedLT)
-      LT = *ExpectedLT;
+    Expected<const DWARFDebugLine::LineTable *> expectedLT =
+        dwarf->getLineTableForUnit(cu.get(), report);
+    const DWARFDebugLine::LineTable *lt = nullptr;
+    if (expectedLT)
+      lt = *expectedLT;
     else
-      Report(ExpectedLT.takeError());
-    if (!LT)
+      report(expectedLT.takeError());
+    if (!lt)
       continue;
-    LineTables.push_back(LT);
+    lineTables.push_back(lt);
 
-    // Loop over variable records and insert them to VariableLoc.
-    for (const auto &Entry : CU->dies()) {
-      DWARFDie Die(CU.get(), &Entry);
+    // Loop over variable records and insert them to variableLoc.
+    for (const auto &entry : cu->dies()) {
+      DWARFDie die(cu.get(), &entry);
       // Skip all tags that are not variables.
-      if (Die.getTag() != dwarf::DW_TAG_variable)
+      if (die.getTag() != dwarf::DW_TAG_variable)
         continue;
 
       // Skip if a local variable because we don't need them for generating
       // error messages. In general, only non-local symbols can fail to be
       // linked.
-      if (!dwarf::toUnsigned(Die.find(dwarf::DW_AT_external), 0))
+      if (!dwarf::toUnsigned(die.find(dwarf::DW_AT_external), 0))
         continue;
 
       // Get the source filename index for the variable.
-      unsigned File = dwarf::toUnsigned(Die.find(dwarf::DW_AT_decl_file), 0);
-      if (!LT->hasFileAtIndex(File))
+      unsigned file = dwarf::toUnsigned(die.find(dwarf::DW_AT_decl_file), 0);
+      if (!lt->hasFileAtIndex(file))
         continue;
 
       // Get the line number on which the variable is declared.
-      unsigned Line = dwarf::toUnsigned(Die.find(dwarf::DW_AT_decl_line), 0);
+      unsigned line = dwarf::toUnsigned(die.find(dwarf::DW_AT_decl_line), 0);
 
-      // Here we want to take the variable name to add it into VariableLoc.
+      // Here we want to take the variable name to add it into variableLoc.
       // Variable can have regular and linkage name associated. At first, we try
       // to get linkage name as it can be different, for example when we have
       // two variables in different namespaces of the same object. Use common
       // name otherwise, but handle the case when it also absent in case if the
       // input object file lacks some debug info.
-      StringRef Name =
-          dwarf::toString(Die.find(dwarf::DW_AT_linkage_name),
-                          dwarf::toString(Die.find(dwarf::DW_AT_name), ""));
-      if (!Name.empty())
-        VariableLoc.insert({Name, {LT, File, Line}});
+      StringRef name =
+          dwarf::toString(die.find(dwarf::DW_AT_linkage_name),
+                          dwarf::toString(die.find(dwarf::DW_AT_name), ""));
+      if (!name.empty())
+        variableLoc.insert({name, {lt, file, line}});
     }
   }
 }
@@ -181,112 +309,152 @@ template <class ELFT> void ObjFile<ELFT>::initializeDwarf() {
 // object (variable, array, etc) definition.
 template <class ELFT>
 Optional<std::pair<std::string, unsigned>>
-ObjFile<ELFT>::getVariableLoc(StringRef Name) {
-  llvm::call_once(InitDwarfLine, [this]() { initializeDwarf(); });
+ObjFile<ELFT>::getVariableLoc(StringRef name) {
+  llvm::call_once(initDwarfLine, [this]() { initializeDwarf(); });
 
   // Return if we have no debug information about data object.
-  auto It = VariableLoc.find(Name);
-  if (It == VariableLoc.end())
+  auto it = variableLoc.find(name);
+  if (it == variableLoc.end())
     return None;
 
   // Take file name string from line table.
-  std::string FileName;
-  if (!It->second.LT->getFileNameByIndex(
-          It->second.File, nullptr,
-          DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, FileName))
+  std::string fileName;
+  if (!it->second.lt->getFileNameByIndex(
+          it->second.file, {},
+          DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, fileName))
     return None;
 
-  return std::make_pair(FileName, It->second.Line);
+  return std::make_pair(fileName, it->second.line);
 }
 
 // Returns source line information for a given offset
 // using DWARF debug info.
 template <class ELFT>
-Optional<DILineInfo> ObjFile<ELFT>::getDILineInfo(InputSectionBase *S,
-                                                  uint64_t Offset) {
-  llvm::call_once(InitDwarfLine, [this]() { initializeDwarf(); });
+Optional<DILineInfo> ObjFile<ELFT>::getDILineInfo(InputSectionBase *s,
+                                                  uint64_t offset) {
+  llvm::call_once(initDwarfLine, [this]() { initializeDwarf(); });
+
+  // Detect SectionIndex for specified section.
+  uint64_t sectionIndex = object::SectionedAddress::UndefSection;
+  ArrayRef<InputSectionBase *> sections = s->file->getSections();
+  for (uint64_t curIndex = 0; curIndex < sections.size(); ++curIndex) {
+    if (s == sections[curIndex]) {
+      sectionIndex = curIndex;
+      break;
+    }
+  }
 
   // Use fake address calcuated by adding section file offset and offset in
   // section. See comments for ObjectInfo class.
-  DILineInfo Info;
-  for (const llvm::DWARFDebugLine::LineTable *LT : LineTables)
-    if (LT->getFileLineInfoForAddress(
-            S->getOffsetInFile() + Offset, nullptr,
-            DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, Info))
-      return Info;
+  DILineInfo info;
+  for (const llvm::DWARFDebugLine::LineTable *lt : lineTables) {
+    if (lt->getFileLineInfoForAddress(
+            {s->getOffsetInFile() + offset, sectionIndex}, nullptr,
+            DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, info))
+      return info;
+  }
   return None;
 }
 
 // Returns "<internal>", "foo.a(bar.o)" or "baz.o".
-std::string lld::toString(const InputFile *F) {
-  if (!F)
+std::string lld::toString(const InputFile *f) {
+  if (!f)
     return "<internal>";
 
-  if (F->ToStringCache.empty()) {
-    if (F->ArchiveName.empty())
-      F->ToStringCache = F->getName();
+  if (f->toStringCache.empty()) {
+    if (f->archiveName.empty())
+      f->toStringCache = f->getName();
     else
-      F->ToStringCache = (F->ArchiveName + "(" + F->getName() + ")").str();
+      f->toStringCache = (f->archiveName + "(" + f->getName() + ")").str();
   }
-  return F->ToStringCache;
+  return f->toStringCache;
 }
 
-template <class ELFT>
-ELFFileBase<ELFT>::ELFFileBase(Kind K, MemoryBufferRef MB) : InputFile(K, MB) {
-  if (ELFT::TargetEndianness == support::little)
-    EKind = ELFT::Is64Bits ? ELF64LEKind : ELF32LEKind;
-  else
-    EKind = ELFT::Is64Bits ? ELF64BEKind : ELF32BEKind;
+ELFFileBase::ELFFileBase(Kind k, MemoryBufferRef mb) : InputFile(k, mb) {
+  ekind = getELFKind(mb, "");
 
-  EMachine = getObj().getHeader()->e_machine;
-  OSABI = getObj().getHeader()->e_ident[llvm::ELF::EI_OSABI];
+  switch (ekind) {
+  case ELF32LEKind:
+    init<ELF32LE>();
+    break;
+  case ELF32BEKind:
+    init<ELF32BE>();
+    break;
+  case ELF64LEKind:
+    init<ELF64LE>();
+    break;
+  case ELF64BEKind:
+    init<ELF64BE>();
+    break;
+  default:
+    llvm_unreachable("getELFKind");
+  }
 }
 
-template <class ELFT>
-typename ELFT::SymRange ELFFileBase<ELFT>::getGlobalELFSyms() {
-  return makeArrayRef(ELFSyms.begin() + FirstGlobal, ELFSyms.end());
+template <typename Elf_Shdr>
+static const Elf_Shdr *findSection(ArrayRef<Elf_Shdr> sections, uint32_t type) {
+  for (const Elf_Shdr &sec : sections)
+    if (sec.sh_type == type)
+      return &sec;
+  return nullptr;
 }
 
-template <class ELFT>
-uint32_t ELFFileBase<ELFT>::getSectionIndex(const Elf_Sym &Sym) const {
-  return CHECK(getObj().getSectionIndex(&Sym, ELFSyms, SymtabSHNDX), this);
-}
+template <class ELFT> void ELFFileBase::init() {
+  using Elf_Shdr = typename ELFT::Shdr;
+  using Elf_Sym = typename ELFT::Sym;
 
-template <class ELFT>
-void ELFFileBase<ELFT>::initSymtab(ArrayRef<Elf_Shdr> Sections,
-                                   const Elf_Shdr *Symtab) {
-  FirstGlobal = Symtab->sh_info;
-  ELFSyms = CHECK(getObj().symbols(Symtab), this);
-  if (FirstGlobal == 0 || FirstGlobal > ELFSyms.size())
+  // Initialize trivial attributes.
+  const ELFFile<ELFT> &obj = getObj<ELFT>();
+  emachine = obj.getHeader()->e_machine;
+  osabi = obj.getHeader()->e_ident[llvm::ELF::EI_OSABI];
+  abiVersion = obj.getHeader()->e_ident[llvm::ELF::EI_ABIVERSION];
+
+  ArrayRef<Elf_Shdr> sections = CHECK(obj.sections(), this);
+
+  // Find a symbol table.
+  bool isDSO =
+      (identify_magic(mb.getBuffer()) == file_magic::elf_shared_object);
+  const Elf_Shdr *symtabSec =
+      findSection(sections, isDSO ? SHT_DYNSYM : SHT_SYMTAB);
+
+  if (!symtabSec)
+    return;
+
+  // Initialize members corresponding to a symbol table.
+  firstGlobal = symtabSec->sh_info;
+
+  ArrayRef<Elf_Sym> eSyms = CHECK(obj.symbols(symtabSec), this);
+  if (firstGlobal == 0 || firstGlobal > eSyms.size())
     fatal(toString(this) + ": invalid sh_info in symbol table");
 
-  StringTable =
-      CHECK(getObj().getStringTableForSymtab(*Symtab, Sections), this);
+  elfSyms = reinterpret_cast<const void *>(eSyms.data());
+  numELFSyms = eSyms.size();
+  stringTable = CHECK(obj.getStringTableForSymtab(*symtabSec, sections), this);
 }
 
 template <class ELFT>
-ObjFile<ELFT>::ObjFile(MemoryBufferRef M, StringRef ArchiveName)
-    : ELFFileBase<ELFT>(Base::ObjKind, M) {
-  this->ArchiveName = ArchiveName;
+uint32_t ObjFile<ELFT>::getSectionIndex(const Elf_Sym &sym) const {
+  return CHECK(
+      this->getObj().getSectionIndex(&sym, getELFSyms<ELFT>(), shndxTable),
+      this);
 }
 
 template <class ELFT> ArrayRef<Symbol *> ObjFile<ELFT>::getLocalSymbols() {
-  if (this->Symbols.empty())
+  if (this->symbols.empty())
     return {};
-  return makeArrayRef(this->Symbols).slice(1, this->FirstGlobal - 1);
+  return makeArrayRef(this->symbols).slice(1, this->firstGlobal - 1);
 }
 
 template <class ELFT> ArrayRef<Symbol *> ObjFile<ELFT>::getGlobalSymbols() {
-  return makeArrayRef(this->Symbols).slice(this->FirstGlobal);
+  return makeArrayRef(this->symbols).slice(this->firstGlobal);
 }
 
-template <class ELFT>
-void ObjFile<ELFT>::parse(DenseSet<CachedHashStringRef> &ComdatGroups) {
-  // Read a section table. JustSymbols is usually false.
-  if (this->JustSymbols)
+template <class ELFT> void ObjFile<ELFT>::parse(bool ignoreComdats) {
+  // Read a section table. justSymbols is usually false.
+  if (this->justSymbols)
     initializeJustSymbols();
   else
-    initializeSections(ComdatGroups);
+    initializeSections(ignoreComdats);
 
   // Read a symbol table.
   initializeSymbols();
@@ -296,17 +464,13 @@ void ObjFile<ELFT>::parse(DenseSet<CachedHashStringRef> &ComdatGroups) {
 // They are identified and deduplicated by group name. This function
 // returns a group name.
 template <class ELFT>
-StringRef ObjFile<ELFT>::getShtGroupSignature(ArrayRef<Elf_Shdr> Sections,
-                                              const Elf_Shdr &Sec) {
-  // Group signatures are stored as symbol names in object files.
-  // sh_info contains a symbol index, so we fetch a symbol and read its name.
-  if (this->ELFSyms.empty())
-    this->initSymtab(
-        Sections, CHECK(object::getSection<ELFT>(Sections, Sec.sh_link), this));
-
-  const Elf_Sym *Sym =
-      CHECK(object::getSymbol<ELFT>(this->ELFSyms, Sec.sh_info), this);
-  StringRef Signature = CHECK(Sym->getName(this->StringTable), this);
+StringRef ObjFile<ELFT>::getShtGroupSignature(ArrayRef<Elf_Shdr> sections,
+                                              const Elf_Shdr &sec) {
+  typename ELFT::SymRange symbols = this->getELFSyms<ELFT>();
+  if (sec.sh_info >= symbols.size())
+    fatal(toString(this) + ": invalid symbol index");
+  const typename ELFT::Sym &sym = symbols[sec.sh_info];
+  StringRef signature = CHECK(sym.getName(this->stringTable), this);
 
   // As a special case, if a symbol is a section symbol and has no name,
   // we use a section name as a signature.
@@ -315,23 +479,12 @@ StringRef ObjFile<ELFT>::getShtGroupSignature(ArrayRef<Elf_Shdr> Sections,
   // standard, but GNU gold 1.14 (the newest version as of July 2017) or
   // older produce such sections as outputs for the -r option, so we need
   // a bug-compatibility.
-  if (Signature.empty() && Sym->getType() == STT_SECTION)
-    return getSectionName(Sec);
-  return Signature;
-}
-
-template <class ELFT>
-ArrayRef<typename ObjFile<ELFT>::Elf_Word>
-ObjFile<ELFT>::getShtGroupEntries(const Elf_Shdr &Sec) {
-  const ELFFile<ELFT> &Obj = this->getObj();
-  ArrayRef<Elf_Word> Entries =
-      CHECK(Obj.template getSectionContentsAsArray<Elf_Word>(&Sec), this);
-  if (Entries.empty() || Entries[0] != GRP_COMDAT)
-    fatal(toString(this) + ": unsupported SHT_GROUP format");
-  return Entries.slice(1);
+  if (signature.empty() && sym.getType() == STT_SECTION)
+    return getSectionName(sec);
+  return signature;
 }
 
-template <class ELFT> bool ObjFile<ELFT>::shouldMerge(const Elf_Shdr &Sec) {
+template <class ELFT> bool ObjFile<ELFT>::shouldMerge(const Elf_Shdr &sec) {
   // On a regular link we don't merge sections if -O0 (default is -O1). This
   // sometimes makes the linker significantly faster, although the output will
   // be bigger.
@@ -344,14 +497,14 @@ template <class ELFT> bool ObjFile<ELFT>::shouldMerge(const Elf_Shdr &Sec) {
   // SHF_MERGE sections based both on their name and sh_entsize, but that seems
   // to be more trouble than it is worth. Instead, we just use the regular (-O1)
   // logic for -r.
-  if (Config->Optimize == 0 && !Config->Relocatable)
+  if (config->optimize == 0 && !config->relocatable)
     return false;
 
   // A mergeable section with size 0 is useless because they don't have
   // any data to merge. A mergeable string section with size 0 can be
   // argued as invalid because it doesn't end with a null character.
   // We'll avoid a mess by handling them as if they were non-mergeable.
-  if (Sec.sh_size == 0)
+  if (sec.sh_size == 0)
     return false;
 
   // Check for sh_entsize. The ELF spec is not clear about the zero
@@ -359,17 +512,17 @@ template <class ELFT> bool ObjFile<ELFT>::shouldMerge(const Elf_Shdr &Sec) {
   // the section does not hold a table of fixed-size entries". We know
   // that Rust 1.13 produces a string mergeable section with a zero
   // sh_entsize. Here we just accept it rather than being picky about it.
-  uint64_t EntSize = Sec.sh_entsize;
-  if (EntSize == 0)
+  uint64_t entSize = sec.sh_entsize;
+  if (entSize == 0)
     return false;
-  if (Sec.sh_size % EntSize)
+  if (sec.sh_size % entSize)
     fatal(toString(this) +
           ": SHF_MERGE section size must be a multiple of sh_entsize");
 
-  uint64_t Flags = Sec.sh_flags;
-  if (!(Flags & SHF_MERGE))
+  uint64_t flags = sec.sh_flags;
+  if (!(flags & SHF_MERGE))
     return false;
-  if (Flags & SHF_WRITE)
+  if (flags & SHF_WRITE)
     fatal(toString(this) + ": writable SHF_MERGE section is not supported");
 
   return true;
@@ -385,118 +538,138 @@ template <class ELFT> bool ObjFile<ELFT>::shouldMerge(const Elf_Shdr &Sec) {
 // When the option is given, we link "just symbols". The section table is
 // initialized with null pointers.
 template <class ELFT> void ObjFile<ELFT>::initializeJustSymbols() {
-  ArrayRef<Elf_Shdr> ObjSections = CHECK(this->getObj().sections(), this);
-  this->Sections.resize(ObjSections.size());
+  ArrayRef<Elf_Shdr> sections = CHECK(this->getObj().sections(), this);
+  this->sections.resize(sections.size());
+}
 
-  for (const Elf_Shdr &Sec : ObjSections) {
-    if (Sec.sh_type != SHT_SYMTAB)
-      continue;
-    this->initSymtab(ObjSections, &Sec);
+// An ELF object file may contain a `.deplibs` section. If it exists, the
+// section contains a list of library specifiers such as `m` for libm. This
+// function resolves a given name by finding the first matching library checking
+// the various ways that a library can be specified to LLD. This ELF extension
+// is a form of autolinking and is called `dependent libraries`. It is currently
+// unique to LLVM and lld.
+static void addDependentLibrary(StringRef specifier, const InputFile *f) {
+  if (!config->dependentLibraries)
     return;
-  }
+  if (fs::exists(specifier))
+    driver->addFile(specifier, /*withLOption=*/false);
+  else if (Optional<std::string> s = findFromSearchPaths(specifier))
+    driver->addFile(*s, /*withLOption=*/true);
+  else if (Optional<std::string> s = searchLibraryBaseName(specifier))
+    driver->addFile(*s, /*withLOption=*/true);
+  else
+    error(toString(f) +
+          ": unable to find library from dependent library specifier: " +
+          specifier);
 }
 
 template <class ELFT>
-void ObjFile<ELFT>::initializeSections(
-    DenseSet<CachedHashStringRef> &ComdatGroups) {
-  const ELFFile<ELFT> &Obj = this->getObj();
-
-  ArrayRef<Elf_Shdr> ObjSections = CHECK(Obj.sections(), this);
-  uint64_t Size = ObjSections.size();
-  this->Sections.resize(Size);
-  this->SectionStringTable =
-      CHECK(Obj.getSectionStringTable(ObjSections), this);
-
-  for (size_t I = 0, E = ObjSections.size(); I < E; I++) {
-    if (this->Sections[I] == &InputSection::Discarded)
+void ObjFile<ELFT>::initializeSections(bool ignoreComdats) {
+  const ELFFile<ELFT> &obj = this->getObj();
+
+  ArrayRef<Elf_Shdr> objSections = CHECK(obj.sections(), this);
+  uint64_t size = objSections.size();
+  this->sections.resize(size);
+  this->sectionStringTable =
+      CHECK(obj.getSectionStringTable(objSections), this);
+
+  for (size_t i = 0, e = objSections.size(); i < e; i++) {
+    if (this->sections[i] == &InputSection::discarded)
       continue;
-    const Elf_Shdr &Sec = ObjSections[I];
+    const Elf_Shdr &sec = objSections[i];
 
-    if (Sec.sh_type == ELF::SHT_LLVM_CALL_GRAPH_PROFILE)
-      CGProfile = check(
-          this->getObj().template getSectionContentsAsArray<Elf_CGProfile>(
-              &Sec));
+    if (sec.sh_type == ELF::SHT_LLVM_CALL_GRAPH_PROFILE)
+      cgProfile =
+          check(obj.template getSectionContentsAsArray<Elf_CGProfile>(&sec));
 
     // SHF_EXCLUDE'ed sections are discarded by the linker. However,
     // if -r is given, we'll let the final link discard such sections.
     // This is compatible with GNU.
-    if ((Sec.sh_flags & SHF_EXCLUDE) && !Config->Relocatable) {
-      if (Sec.sh_type == SHT_LLVM_ADDRSIG) {
+    if ((sec.sh_flags & SHF_EXCLUDE) && !config->relocatable) {
+      if (sec.sh_type == SHT_LLVM_ADDRSIG) {
         // We ignore the address-significance table if we know that the object
         // file was created by objcopy or ld -r. This is because these tools
         // will reorder the symbols in the symbol table, invalidating the data
         // in the address-significance table, which refers to symbols by index.
-        if (Sec.sh_link != 0)
-          this->AddrsigSec = &Sec;
-        else if (Config->ICF == ICFLevel::Safe)
+        if (sec.sh_link != 0)
+          this->addrsigSec = &sec;
+        else if (config->icf == ICFLevel::Safe)
           warn(toString(this) + ": --icf=safe is incompatible with object "
                                 "files created using objcopy or ld -r");
       }
-      this->Sections[I] = &InputSection::Discarded;
+      this->sections[i] = &InputSection::discarded;
       continue;
     }
 
-    switch (Sec.sh_type) {
+    switch (sec.sh_type) {
     case SHT_GROUP: {
       // De-duplicate section groups by their signatures.
-      StringRef Signature = getShtGroupSignature(ObjSections, Sec);
-      bool IsNew = ComdatGroups.insert(CachedHashStringRef(Signature)).second;
-      this->Sections[I] = &InputSection::Discarded;
-
-      // We only support GRP_COMDAT type of group. Get the all entries of the
-      // section here to let getShtGroupEntries to check the type early for us.
-      ArrayRef<Elf_Word> Entries = getShtGroupEntries(Sec);
-
-      // If it is a new section group, we want to keep group members.
-      // Group leader sections, which contain indices of group members, are
-      // discarded because they are useless beyond this point. The only
-      // exception is the -r option because in order to produce re-linkable
-      // object files, we want to pass through basically everything.
-      if (IsNew) {
-        if (Config->Relocatable)
-          this->Sections[I] = createInputSection(Sec);
+      StringRef signature = getShtGroupSignature(objSections, sec);
+      this->sections[i] = &InputSection::discarded;
+
+
+      ArrayRef<Elf_Word> entries =
+          CHECK(obj.template getSectionContentsAsArray<Elf_Word>(&sec), this);
+      if (entries.empty())
+        fatal(toString(this) + ": empty SHT_GROUP");
+
+      // The first word of a SHT_GROUP section contains flags. Currently,
+      // the standard defines only "GRP_COMDAT" flag for the COMDAT group.
+      // An group with the empty flag doesn't define anything; such sections
+      // are just skipped.
+      if (entries[0] == 0)
+        continue;
+
+      if (entries[0] != GRP_COMDAT)
+        fatal(toString(this) + ": unsupported SHT_GROUP format");
+
+      bool isNew =
+          ignoreComdats ||
+          symtab->comdatGroups.try_emplace(CachedHashStringRef(signature), this)
+              .second;
+      if (isNew) {
+        if (config->relocatable)
+          this->sections[i] = createInputSection(sec);
         continue;
       }
 
       // Otherwise, discard group members.
-      for (uint32_t SecIndex : Entries) {
-        if (SecIndex >= Size)
+      for (uint32_t secIndex : entries.slice(1)) {
+        if (secIndex >= size)
           fatal(toString(this) +
-                ": invalid section index in group: " + Twine(SecIndex));
-        this->Sections[SecIndex] = &InputSection::Discarded;
+                ": invalid section index in group: " + Twine(secIndex));
+        this->sections[secIndex] = &InputSection::discarded;
       }
       break;
     }
-    case SHT_SYMTAB:
-      this->initSymtab(ObjSections, &Sec);
-      break;
     case SHT_SYMTAB_SHNDX:
-      this->SymtabSHNDX = CHECK(Obj.getSHNDXTable(Sec, ObjSections), this);
+      shndxTable = CHECK(obj.getSHNDXTable(sec, objSections), this);
       break;
+    case SHT_SYMTAB:
     case SHT_STRTAB:
     case SHT_NULL:
       break;
     default:
-      this->Sections[I] = createInputSection(Sec);
+      this->sections[i] = createInputSection(sec);
     }
 
     // .ARM.exidx sections have a reverse dependency on the InputSection they
     // have a SHF_LINK_ORDER dependency, this is identified by the sh_link.
-    if (Sec.sh_flags & SHF_LINK_ORDER) {
-      InputSectionBase *LinkSec = nullptr;
-      if (Sec.sh_link < this->Sections.size())
-        LinkSec = this->Sections[Sec.sh_link];
-      if (!LinkSec)
+    if (sec.sh_flags & SHF_LINK_ORDER) {
+      InputSectionBase *linkSec = nullptr;
+      if (sec.sh_link < this->sections.size())
+        linkSec = this->sections[sec.sh_link];
+      if (!linkSec)
         fatal(toString(this) +
-              ": invalid sh_link index: " + Twine(Sec.sh_link));
+              ": invalid sh_link index: " + Twine(sec.sh_link));
 
-      InputSection *IS = cast<InputSection>(this->Sections[I]);
-      LinkSec->DependentSections.push_back(IS);
-      if (!isa<InputSection>(LinkSec))
-        error("a section " + IS->Name +
+      InputSection *isec = cast<InputSection>(this->sections[i]);
+      linkSec->dependentSections.push_back(isec);
+      if (!isa<InputSection>(linkSec))
+        error("a section " + isec->name +
               " with SHF_LINK_ORDER should not refer a non-regular "
               "section: " +
-              toString(LinkSec));
+              toString(linkSec));
     }
   }
 }
@@ -504,9 +677,9 @@ void ObjFile<ELFT>::initializeSections(
 // For ARM only, to set the EF_ARM_ABI_FLOAT_SOFT or EF_ARM_ABI_FLOAT_HARD
 // flag in the ELF Header we need to look at Tag_ABI_VFP_args to find out how
 // the input objects have been compiled.
-static void updateARMVFPArgs(const ARMAttributeParser &Attributes,
-                             const InputFile *F) {
-  if (!Attributes.hasAttribute(ARMBuildAttrs::ABI_VFP_args))
+static void updateARMVFPArgs(const ARMAttributeParser &attributes,
+                             const InputFile *f) {
+  if (!attributes.hasAttribute(ARMBuildAttrs::ABI_VFP_args))
     // If an ABI tag isn't present then it is implicitly given the value of 0
     // which maps to ARMBuildAttrs::BaseAAPCS. However many assembler files,
     // including some in glibc that don't use FP args (and should have value 3)
@@ -514,31 +687,31 @@ static void updateARMVFPArgs(const ARMAttributeParser &Attributes,
     // as a clash.
     return;
 
-  unsigned VFPArgs = Attributes.getAttributeValue(ARMBuildAttrs::ABI_VFP_args);
-  ARMVFPArgKind Arg;
-  switch (VFPArgs) {
+  unsigned vfpArgs = attributes.getAttributeValue(ARMBuildAttrs::ABI_VFP_args);
+  ARMVFPArgKind arg;
+  switch (vfpArgs) {
   case ARMBuildAttrs::BaseAAPCS:
-    Arg = ARMVFPArgKind::Base;
+    arg = ARMVFPArgKind::Base;
     break;
   case ARMBuildAttrs::HardFPAAPCS:
-    Arg = ARMVFPArgKind::VFP;
+    arg = ARMVFPArgKind::VFP;
     break;
   case ARMBuildAttrs::ToolChainFPPCS:
     // Tool chain specific convention that conforms to neither AAPCS variant.
-    Arg = ARMVFPArgKind::ToolChain;
+    arg = ARMVFPArgKind::ToolChain;
     break;
   case ARMBuildAttrs::CompatibleFPAAPCS:
     // Object compatible with all conventions.
     return;
   default:
-    error(toString(F) + ": unknown Tag_ABI_VFP_args value: " + Twine(VFPArgs));
+    error(toString(f) + ": unknown Tag_ABI_VFP_args value: " + Twine(vfpArgs));
     return;
   }
   // Follow ld.bfd and error if there is a mix of calling conventions.
-  if (Config->ARMVFPArgs != Arg && Config->ARMVFPArgs != ARMVFPArgKind::Default)
-    error(toString(F) + ": incompatible Tag_ABI_VFP_args");
+  if (config->armVFPArgs != arg && config->armVFPArgs != ARMVFPArgKind::Default)
+    error(toString(f) + ": incompatible Tag_ABI_VFP_args");
   else
-    Config->ARMVFPArgs = Arg;
+    config->armVFPArgs = arg;
 }
 
 // The ARM support in lld makes some use of instructions that are not available
@@ -550,11 +723,11 @@ static void updateARMVFPArgs(const ARMAttributeParser &Attributes,
 // at compile time. We follow the convention that if at least one input object
 // is compiled with an architecture that supports these features then lld is
 // permitted to use them.
-static void updateSupportedARMFeatures(const ARMAttributeParser &Attributes) {
-  if (!Attributes.hasAttribute(ARMBuildAttrs::CPU_arch))
+static void updateSupportedARMFeatures(const ARMAttributeParser &attributes) {
+  if (!attributes.hasAttribute(ARMBuildAttrs::CPU_arch))
     return;
-  auto Arch = Attributes.getAttributeValue(ARMBuildAttrs::CPU_arch);
-  switch (Arch) {
+  auto arch = attributes.getAttributeValue(ARMBuildAttrs::CPU_arch);
+  switch (arch) {
   case ARMBuildAttrs::Pre_v4:
   case ARMBuildAttrs::v4:
   case ARMBuildAttrs::v4T:
@@ -566,70 +739,156 @@ static void updateSupportedARMFeatures(const ARMAttributeParser &Attributes) {
   case ARMBuildAttrs::v6:
   case ARMBuildAttrs::v6KZ:
   case ARMBuildAttrs::v6K:
-    Config->ARMHasBlx = true;
+    config->armHasBlx = true;
     // Architectures used in pre-Cortex processors do not support
     // The J1 = 1 J2 = 1 Thumb branch range extension, with the exception
     // of Architecture v6T2 (arm1156t2-s and arm1156t2f-s) that do.
     break;
   default:
     // All other Architectures have BLX and extended branch encoding
-    Config->ARMHasBlx = true;
-    Config->ARMJ1J2BranchEncoding = true;
-    if (Arch != ARMBuildAttrs::v6_M && Arch != ARMBuildAttrs::v6S_M)
+    config->armHasBlx = true;
+    config->armJ1J2BranchEncoding = true;
+    if (arch != ARMBuildAttrs::v6_M && arch != ARMBuildAttrs::v6S_M)
       // All Architectures used in Cortex processors with the exception
       // of v6-M and v6S-M have the MOVT and MOVW instructions.
-      Config->ARMHasMovtMovw = true;
+      config->armHasMovtMovw = true;
     break;
   }
 }
 
+// If a source file is compiled with x86 hardware-assisted call flow control
+// enabled, the generated object file contains feature flags indicating that
+// fact. This function reads the feature flags and returns it.
+//
+// Essentially we want to read a single 32-bit value in this function, but this
+// function is rather complicated because the value is buried deep inside a
+// .note.gnu.property section.
+//
+// The section consists of one or more NOTE records. Each NOTE record consists
+// of zero or more type-length-value fields. We want to find a field of a
+// certain type. It seems a bit too much to just store a 32-bit value, perhaps
+// the ABI is unnecessarily complicated.
+template <class ELFT>
+static uint32_t readAndFeatures(ObjFile<ELFT> *obj, ArrayRef<uint8_t> data) {
+  using Elf_Nhdr = typename ELFT::Nhdr;
+  using Elf_Note = typename ELFT::Note;
+
+  uint32_t featuresSet = 0;
+  while (!data.empty()) {
+    // Read one NOTE record.
+    if (data.size() < sizeof(Elf_Nhdr))
+      fatal(toString(obj) + ": .note.gnu.property: section too short");
+
+    auto *nhdr = reinterpret_cast<const Elf_Nhdr *>(data.data());
+    if (data.size() < nhdr->getSize())
+      fatal(toString(obj) + ": .note.gnu.property: section too short");
+
+    Elf_Note note(*nhdr);
+    if (nhdr->n_type != NT_GNU_PROPERTY_TYPE_0 || note.getName() != "GNU") {
+      data = data.slice(nhdr->getSize());
+      continue;
+    }
+
+    uint32_t featureAndType = config->emachine == EM_AARCH64
+                                  ? GNU_PROPERTY_AARCH64_FEATURE_1_AND
+                                  : GNU_PROPERTY_X86_FEATURE_1_AND;
+
+    // Read a body of a NOTE record, which consists of type-length-value fields.
+    ArrayRef<uint8_t> desc = note.getDesc();
+    while (!desc.empty()) {
+      if (desc.size() < 8)
+        fatal(toString(obj) + ": .note.gnu.property: section too short");
+
+      uint32_t type = read32le(desc.data());
+      uint32_t size = read32le(desc.data() + 4);
+
+      if (type == featureAndType) {
+        // We found a FEATURE_1_AND field. There may be more than one of these
+        // in a .note.gnu.propery section, for a relocatable object we
+        // accumulate the bits set.
+        featuresSet |= read32le(desc.data() + 8);
+      }
+
+      // On 64-bit, a payload may be followed by a 4-byte padding to make its
+      // size a multiple of 8.
+      if (ELFT::Is64Bits)
+        size = alignTo(size, 8);
+
+      desc = desc.slice(size + 8); // +8 for Type and Size
+    }
+
+    // Go to next NOTE record to look for more FEATURE_1_AND descriptions.
+    data = data.slice(nhdr->getSize());
+  }
+
+  return featuresSet;
+}
+
 template <class ELFT>
-InputSectionBase *ObjFile<ELFT>::getRelocTarget(const Elf_Shdr &Sec) {
-  uint32_t Idx = Sec.sh_info;
-  if (Idx >= this->Sections.size())
-    fatal(toString(this) + ": invalid relocated section index: " + Twine(Idx));
-  InputSectionBase *Target = this->Sections[Idx];
+InputSectionBase *ObjFile<ELFT>::getRelocTarget(const Elf_Shdr &sec) {
+  uint32_t idx = sec.sh_info;
+  if (idx >= this->sections.size())
+    fatal(toString(this) + ": invalid relocated section index: " + Twine(idx));
+  InputSectionBase *target = this->sections[idx];
 
   // Strictly speaking, a relocation section must be included in the
   // group of the section it relocates. However, LLVM 3.3 and earlier
   // would fail to do so, so we gracefully handle that case.
-  if (Target == &InputSection::Discarded)
+  if (target == &InputSection::discarded)
     return nullptr;
 
-  if (!Target)
+  if (!target)
     fatal(toString(this) + ": unsupported relocation reference");
-  return Target;
+  return target;
 }
 
 // Create a regular InputSection class that has the same contents
 // as a given section.
-static InputSection *toRegularSection(MergeInputSection *Sec) {
-  return make<InputSection>(Sec->File, Sec->Flags, Sec->Type, Sec->Alignment,
-                            Sec->data(), Sec->Name);
+static InputSection *toRegularSection(MergeInputSection *sec) {
+  return make<InputSection>(sec->file, sec->flags, sec->type, sec->alignment,
+                            sec->data(), sec->name);
 }
 
 template <class ELFT>
-InputSectionBase *ObjFile<ELFT>::createInputSection(const Elf_Shdr &Sec) {
-  StringRef Name = getSectionName(Sec);
+InputSectionBase *ObjFile<ELFT>::createInputSection(const Elf_Shdr &sec) {
+  StringRef name = getSectionName(sec);
 
-  switch (Sec.sh_type) {
+  switch (sec.sh_type) {
   case SHT_ARM_ATTRIBUTES: {
-    if (Config->EMachine != EM_ARM)
+    if (config->emachine != EM_ARM)
       break;
-    ARMAttributeParser Attributes;
-    ArrayRef<uint8_t> Contents = check(this->getObj().getSectionContents(&Sec));
-    Attributes.Parse(Contents, /*isLittle*/ Config->EKind == ELF32LEKind);
-    updateSupportedARMFeatures(Attributes);
-    updateARMVFPArgs(Attributes, this);
+    ARMAttributeParser attributes;
+    ArrayRef<uint8_t> contents = check(this->getObj().getSectionContents(&sec));
+    attributes.Parse(contents, /*isLittle*/ config->ekind == ELF32LEKind);
+    updateSupportedARMFeatures(attributes);
+    updateARMVFPArgs(attributes, this);
 
     // FIXME: Retain the first attribute section we see. The eglibc ARM
     // dynamic loaders require the presence of an attribute section for dlopen
     // to work. In a full implementation we would merge all attribute sections.
-    if (In.ARMAttributes == nullptr) {
-      In.ARMAttributes = make<InputSection>(*this, Sec, Name);
-      return In.ARMAttributes;
+    if (in.armAttributes == nullptr) {
+      in.armAttributes = make<InputSection>(*this, sec, name);
+      return in.armAttributes;
     }
-    return &InputSection::Discarded;
+    return &InputSection::discarded;
+  }
+  case SHT_LLVM_DEPENDENT_LIBRARIES: {
+    if (config->relocatable)
+      break;
+    ArrayRef<char> data =
+        CHECK(this->getObj().template getSectionContentsAsArray<char>(&sec), this);
+    if (!data.empty() && data.back() != '\0') {
+      error(toString(this) +
+            ": corrupted dependent libraries section (unterminated string): " +
+            name);
+      return &InputSection::discarded;
+    }
+    for (const char *d = data.begin(), *e = data.end(); d < e;) {
+      StringRef s(d);
+      addDependentLibrary(s, this);
+      d += s.size() + 1;
+    }
+    return &InputSection::discarded;
   }
   case SHT_RELA:
   case SHT_REL: {
@@ -638,25 +897,25 @@ InputSectionBase *ObjFile<ELFT>::createInputSection(const Elf_Shdr &Sec) {
     // and the group is discarded, even though it's a violation of the
     // spec. We handle that situation gracefully by discarding dangling
     // relocation sections.
-    InputSectionBase *Target = getRelocTarget(Sec);
-    if (!Target)
+    InputSectionBase *target = getRelocTarget(sec);
+    if (!target)
       return nullptr;
 
     // This section contains relocation information.
     // If -r is given, we do not interpret or apply relocation
     // but just copy relocation sections to output.
-    if (Config->Relocatable) {
-      InputSection *RelocSec = make<InputSection>(*this, Sec, Name);
+    if (config->relocatable) {
+      InputSection *relocSec = make<InputSection>(*this, sec, name);
       // We want to add a dependency to target, similar like we do for
       // -emit-relocs below. This is useful for the case when linker script
       // contains the "/DISCARD/". It is perhaps uncommon to use a script with
       // -r, but we faced it in the Linux kernel and have to handle such case
       // and not to crash.
-      Target->DependentSections.push_back(RelocSec);
-      return RelocSec;
+      target->dependentSections.push_back(relocSec);
+      return relocSec;
     }
 
-    if (Target->FirstRelocation)
+    if (target->firstRelocation)
       fatal(toString(this) +
             ": multiple relocation sections to one section are not supported");
 
@@ -665,33 +924,33 @@ InputSectionBase *ObjFile<ELFT>::createInputSection(const Elf_Shdr &Sec) {
     // because applying relocations at end of linking changes section
     // contents. So, we simply handle such sections as non-mergeable ones.
     // Degrading like this is acceptable because section merging is optional.
-    if (auto *MS = dyn_cast<MergeInputSection>(Target)) {
-      Target = toRegularSection(MS);
-      this->Sections[Sec.sh_info] = Target;
+    if (auto *ms = dyn_cast<MergeInputSection>(target)) {
+      target = toRegularSection(ms);
+      this->sections[sec.sh_info] = target;
     }
 
-    if (Sec.sh_type == SHT_RELA) {
-      ArrayRef<Elf_Rela> Rels = CHECK(this->getObj().relas(&Sec), this);
-      Target->FirstRelocation = Rels.begin();
-      Target->NumRelocations = Rels.size();
-      Target->AreRelocsRela = true;
+    if (sec.sh_type == SHT_RELA) {
+      ArrayRef<Elf_Rela> rels = CHECK(getObj().relas(&sec), this);
+      target->firstRelocation = rels.begin();
+      target->numRelocations = rels.size();
+      target->areRelocsRela = true;
     } else {
-      ArrayRef<Elf_Rel> Rels = CHECK(this->getObj().rels(&Sec), this);
-      Target->FirstRelocation = Rels.begin();
-      Target->NumRelocations = Rels.size();
-      Target->AreRelocsRela = false;
+      ArrayRef<Elf_Rel> rels = CHECK(getObj().rels(&sec), this);
+      target->firstRelocation = rels.begin();
+      target->numRelocations = rels.size();
+      target->areRelocsRela = false;
     }
-    assert(isUInt<31>(Target->NumRelocations));
+    assert(isUInt<31>(target->numRelocations));
 
     // Relocation sections processed by the linker are usually removed
     // from the output, so returning `nullptr` for the normal case.
     // However, if -emit-relocs is given, we need to leave them in the output.
     // (Some post link analysis tools need this information.)
-    if (Config->EmitRelocs) {
-      InputSection *RelocSec = make<InputSection>(*this, Sec, Name);
+    if (config->emitRelocs) {
+      InputSection *relocSec = make<InputSection>(*this, sec, name);
       // We will not emit relocation section if target was discarded.
-      Target->DependentSections.push_back(RelocSec);
-      return RelocSec;
+      target->dependentSections.push_back(relocSec);
+      return relocSec;
     }
     return nullptr;
   }
@@ -710,28 +969,42 @@ InputSectionBase *ObjFile<ELFT>::createInputSection(const Elf_Shdr &Sec) {
   // explicitly told to do otherwise (by -z execstack). Because the stack
   // executable-ness is controlled solely by command line options,
   // .note.GNU-stack sections are simply ignored.
-  if (Name == ".note.GNU-stack")
-    return &InputSection::Discarded;
+  if (name == ".note.GNU-stack")
+    return &InputSection::discarded;
+
+  // Object files that use processor features such as Intel Control-Flow
+  // Enforcement (CET) or AArch64 Branch Target Identification BTI, use a
+  // .note.gnu.property section containing a bitfield of feature bits like the
+  // GNU_PROPERTY_X86_FEATURE_1_IBT flag. Read a bitmap containing the flag.
+  //
+  // Since we merge bitmaps from multiple object files to create a new
+  // .note.gnu.property containing a single AND'ed bitmap, we discard an input
+  // file's .note.gnu.property section.
+  if (name == ".note.gnu.property") {
+    ArrayRef<uint8_t> contents = check(this->getObj().getSectionContents(&sec));
+    this->andFeatures = readAndFeatures(this, contents);
+    return &InputSection::discarded;
+  }
 
   // Split stacks is a feature to support a discontiguous stack,
   // commonly used in the programming language Go. For the details,
   // see https://gcc.gnu.org/wiki/SplitStacks. An object file compiled
   // for split stack will include a .note.GNU-split-stack section.
-  if (Name == ".note.GNU-split-stack") {
-    if (Config->Relocatable) {
+  if (name == ".note.GNU-split-stack") {
+    if (config->relocatable) {
       error("cannot mix split-stack and non-split-stack in a relocatable link");
-      return &InputSection::Discarded;
+      return &InputSection::discarded;
     }
-    this->SplitStack = true;
-    return &InputSection::Discarded;
+    this->splitStack = true;
+    return &InputSection::discarded;
   }
 
   // An object file cmpiled for split stack, but where some of the
   // functions were compiled with the no_split_stack_attribute will
   // include a .note.GNU-no-split-stack section.
-  if (Name == ".note.GNU-no-split-stack") {
-    this->SomeNoSplitStack = true;
-    return &InputSection::Discarded;
+  if (name == ".note.GNU-no-split-stack") {
+    this->someNoSplitStack = true;
+    return &InputSection::discarded;
   }
 
   // The linkonce feature is a sort of proto-comdat. Some glibc i386 object
@@ -739,245 +1012,205 @@ InputSectionBase *ObjFile<ELFT>::createInputSection(const Elf_Shdr &Sec) {
   // sections. Drop those sections to avoid duplicate symbol errors.
   // FIXME: This is glibc PR20543, we should remove this hack once that has been
   // fixed for a while.
-  if (Name.startswith(".gnu.linkonce."))
-    return &InputSection::Discarded;
+  if (name == ".gnu.linkonce.t.__x86.get_pc_thunk.bx" ||
+      name == ".gnu.linkonce.t.__i686.get_pc_thunk.bx")
+    return &InputSection::discarded;
 
   // If we are creating a new .build-id section, strip existing .build-id
   // sections so that the output won't have more than one .build-id.
   // This is not usually a problem because input object files normally don't
   // have .build-id sections, but you can create such files by
   // "ld.{bfd,gold,lld} -r --build-id", and we want to guard against it.
-  if (Name == ".note.gnu.build-id" && Config->BuildId != BuildIdKind::None)
-    return &InputSection::Discarded;
+  if (name == ".note.gnu.build-id" && config->buildId != BuildIdKind::None)
+    return &InputSection::discarded;
 
   // The linker merges EH (exception handling) frames and creates a
   // .eh_frame_hdr section for runtime. So we handle them with a special
   // class. For relocatable outputs, they are just passed through.
-  if (Name == ".eh_frame" && !Config->Relocatable)
-    return make<EhInputSection>(*this, Sec, Name);
+  if (name == ".eh_frame" && !config->relocatable)
+    return make<EhInputSection>(*this, sec, name);
 
-  if (shouldMerge(Sec))
-    return make<MergeInputSection>(*this, Sec, Name);
-  return make<InputSection>(*this, Sec, Name);
+  if (shouldMerge(sec))
+    return make<MergeInputSection>(*this, sec, name);
+  return make<InputSection>(*this, sec, name);
 }
 
 template <class ELFT>
-StringRef ObjFile<ELFT>::getSectionName(const Elf_Shdr &Sec) {
-  return CHECK(this->getObj().getSectionName(&Sec, SectionStringTable), this);
+StringRef ObjFile<ELFT>::getSectionName(const Elf_Shdr &sec) {
+  return CHECK(getObj().getSectionName(&sec, sectionStringTable), this);
 }
 
+// Initialize this->Symbols. this->Symbols is a parallel array as
+// its corresponding ELF symbol table.
 template <class ELFT> void ObjFile<ELFT>::initializeSymbols() {
-  this->Symbols.reserve(this->ELFSyms.size());
-  for (const Elf_Sym &Sym : this->ELFSyms)
-    this->Symbols.push_back(createSymbol(&Sym));
-}
-
-template <class ELFT> Symbol *ObjFile<ELFT>::createSymbol(const Elf_Sym *Sym) {
-  int Binding = Sym->getBinding();
-
-  uint32_t SecIdx = this->getSectionIndex(*Sym);
-  if (SecIdx >= this->Sections.size())
-    fatal(toString(this) + ": invalid section index: " + Twine(SecIdx));
-
-  InputSectionBase *Sec = this->Sections[SecIdx];
-  uint8_t StOther = Sym->st_other;
-  uint8_t Type = Sym->getType();
-  uint64_t Value = Sym->st_value;
-  uint64_t Size = Sym->st_size;
-
-  if (Binding == STB_LOCAL) {
-    if (Sym->getType() == STT_FILE)
-      SourceFile = CHECK(Sym->getName(this->StringTable), this);
+  ArrayRef<Elf_Sym> eSyms = this->getELFSyms<ELFT>();
+  this->symbols.resize(eSyms.size());
+
+  // Our symbol table may have already been partially initialized
+  // because of LazyObjFile.
+  for (size_t i = 0, end = eSyms.size(); i != end; ++i)
+    if (!this->symbols[i] && eSyms[i].getBinding() != STB_LOCAL)
+      this->symbols[i] =
+          symtab->insert(CHECK(eSyms[i].getName(this->stringTable), this));
+
+  // Fill this->Symbols. A symbol is either local or global.
+  for (size_t i = 0, end = eSyms.size(); i != end; ++i) {
+    const Elf_Sym &eSym = eSyms[i];
+
+    // Read symbol attributes.
+    uint32_t secIdx = getSectionIndex(eSym);
+    if (secIdx >= this->sections.size())
+      fatal(toString(this) + ": invalid section index: " + Twine(secIdx));
+
+    InputSectionBase *sec = this->sections[secIdx];
+    uint8_t binding = eSym.getBinding();
+    uint8_t stOther = eSym.st_other;
+    uint8_t type = eSym.getType();
+    uint64_t value = eSym.st_value;
+    uint64_t size = eSym.st_size;
+    StringRefZ name = this->stringTable.data() + eSym.st_name;
+
+    // Handle local symbols. Local symbols are not added to the symbol
+    // table because they are not visible from other object files. We
+    // allocate symbol instances and add their pointers to Symbols.
+    if (binding == STB_LOCAL) {
+      if (eSym.getType() == STT_FILE)
+        sourceFile = CHECK(eSym.getName(this->stringTable), this);
+
+      if (this->stringTable.size() <= eSym.st_name)
+        fatal(toString(this) + ": invalid symbol name offset");
+
+      if (eSym.st_shndx == SHN_UNDEF)
+        this->symbols[i] = make<Undefined>(this, name, binding, stOther, type);
+      else if (sec == &InputSection::discarded)
+        this->symbols[i] = make<Undefined>(this, name, binding, stOther, type,
+                                           /*DiscardedSecIdx=*/secIdx);
+      else
+        this->symbols[i] =
+            make<Defined>(this, name, binding, stOther, type, value, size, sec);
+      continue;
+    }
 
-    if (this->StringTable.size() <= Sym->st_name)
-      fatal(toString(this) + ": invalid symbol name offset");
+    // Handle global undefined symbols.
+    if (eSym.st_shndx == SHN_UNDEF) {
+      this->symbols[i]->resolve(Undefined{this, name, binding, stOther, type});
+      continue;
+    }
 
-    StringRefZ Name = this->StringTable.data() + Sym->st_name;
-    if (Sym->st_shndx == SHN_UNDEF)
-      return make<Undefined>(this, Name, Binding, StOther, Type);
+    // Handle global common symbols.
+    if (eSym.st_shndx == SHN_COMMON) {
+      if (value == 0 || value >= UINT32_MAX)
+        fatal(toString(this) + ": common symbol '" + StringRef(name.data) +
+              "' has invalid alignment: " + Twine(value));
+      this->symbols[i]->resolve(
+          CommonSymbol{this, name, binding, stOther, type, value, size});
+      continue;
+    }
 
-    return make<Defined>(this, Name, Binding, StOther, Type, Value, Size, Sec);
-  }
+    // If a defined symbol is in a discarded section, handle it as if it
+    // were an undefined symbol. Such symbol doesn't comply with the
+    // standard, but in practice, a .eh_frame often directly refer
+    // COMDAT member sections, and if a comdat group is discarded, some
+    // defined symbol in a .eh_frame becomes dangling symbols.
+    if (sec == &InputSection::discarded) {
+      this->symbols[i]->resolve(
+          Undefined{this, name, binding, stOther, type, secIdx});
+      continue;
+    }
 
-  StringRef Name = CHECK(Sym->getName(this->StringTable), this);
-
-  switch (Sym->st_shndx) {
-  case SHN_UNDEF:
-    return Symtab->addUndefined<ELFT>(Name, Binding, StOther, Type,
-                                      /*CanOmitFromDynSym=*/false, this);
-  case SHN_COMMON:
-    if (Value == 0 || Value >= UINT32_MAX)
-      fatal(toString(this) + ": common symbol '" + Name +
-            "' has invalid alignment: " + Twine(Value));
-    return Symtab->addCommon(Name, Size, Value, Binding, StOther, Type, *this);
-  }
+    // Handle global defined symbols.
+    if (binding == STB_GLOBAL || binding == STB_WEAK ||
+        binding == STB_GNU_UNIQUE) {
+      this->symbols[i]->resolve(
+          Defined{this, name, binding, stOther, type, value, size, sec});
+      continue;
+    }
 
-  switch (Binding) {
-  default:
-    fatal(toString(this) + ": unexpected binding: " + Twine(Binding));
-  case STB_GLOBAL:
-  case STB_WEAK:
-  case STB_GNU_UNIQUE:
-    if (Sec == &InputSection::Discarded)
-      return Symtab->addUndefined<ELFT>(Name, Binding, StOther, Type,
-                                        /*CanOmitFromDynSym=*/false, this);
-    return Symtab->addDefined(Name, StOther, Type, Value, Size, Binding, Sec,
-                              this);
+    fatal(toString(this) + ": unexpected binding: " + Twine((int)binding));
   }
 }
 
-ArchiveFile::ArchiveFile(std::unique_ptr<Archive> &&File)
-    : InputFile(ArchiveKind, File->getMemoryBufferRef()),
-      File(std::move(File)) {}
+ArchiveFile::ArchiveFile(std::unique_ptr<Archive> &&file)
+    : InputFile(ArchiveKind, file->getMemoryBufferRef()),
+      file(std::move(file)) {}
 
-template <class ELFT> void ArchiveFile::parse() {
-  for (const Archive::Symbol &Sym : File->symbols())
-    Symtab->addLazyArchive<ELFT>(Sym.getName(), *this, Sym);
+void ArchiveFile::parse() {
+  for (const Archive::Symbol &sym : file->symbols())
+    symtab->addSymbol(LazyArchive{*this, sym});
 }
 
 // Returns a buffer pointing to a member file containing a given symbol.
-InputFile *ArchiveFile::fetch(const Archive::Symbol &Sym) {
-  Archive::Child C =
-      CHECK(Sym.getMember(), toString(this) +
+void ArchiveFile::fetch(const Archive::Symbol &sym) {
+  Archive::Child c =
+      CHECK(sym.getMember(), toString(this) +
                                  ": could not get the member for symbol " +
-                                 Sym.getName());
+                                 sym.getName());
 
-  if (!Seen.insert(C.getChildOffset()).second)
-    return nullptr;
+  if (!seen.insert(c.getChildOffset()).second)
+    return;
 
-  MemoryBufferRef MB =
-      CHECK(C.getMemoryBufferRef(),
+  MemoryBufferRef mb =
+      CHECK(c.getMemoryBufferRef(),
             toString(this) +
                 ": could not get the buffer for the member defining symbol " +
-                Sym.getName());
+                sym.getName());
 
-  if (Tar && C.getParent()->isThin())
-    Tar->append(relativeToRoot(CHECK(C.getFullName(), this)), MB.getBuffer());
+  if (tar && c.getParent()->isThin())
+    tar->append(relativeToRoot(CHECK(c.getFullName(), this)), mb.getBuffer());
 
-  InputFile *File = createObjectFile(
-      MB, getName(), C.getParent()->isThin() ? 0 : C.getChildOffset());
-  File->GroupId = GroupId;
-  return File;
+  InputFile *file = createObjectFile(
+      mb, getName(), c.getParent()->isThin() ? 0 : c.getChildOffset());
+  file->groupId = groupId;
+  parseFile(file);
 }
 
-template <class ELFT>
-SharedFile<ELFT>::SharedFile(MemoryBufferRef M, StringRef DefaultSoName)
-    : ELFFileBase<ELFT>(Base::SharedKind, M), SoName(DefaultSoName),
-      IsNeeded(!Config->AsNeeded) {}
-
-// Partially parse the shared object file so that we can call
-// getSoName on this object.
-template <class ELFT> void SharedFile<ELFT>::parseSoName() {
-  const Elf_Shdr *DynamicSec = nullptr;
-  const ELFFile<ELFT> Obj = this->getObj();
-  ArrayRef<Elf_Shdr> Sections = CHECK(Obj.sections(), this);
-
-  // Search for .dynsym, .dynamic, .symtab, .gnu.version and .gnu.version_d.
-  for (const Elf_Shdr &Sec : Sections) {
-    switch (Sec.sh_type) {
-    default:
-      continue;
-    case SHT_DYNSYM:
-      this->initSymtab(Sections, &Sec);
-      break;
-    case SHT_DYNAMIC:
-      DynamicSec = &Sec;
-      break;
-    case SHT_SYMTAB_SHNDX:
-      this->SymtabSHNDX = CHECK(Obj.getSHNDXTable(Sec, Sections), this);
-      break;
-    case SHT_GNU_versym:
-      this->VersymSec = &Sec;
-      break;
-    case SHT_GNU_verdef:
-      this->VerdefSec = &Sec;
-      break;
-    }
-  }
-
-  if (this->VersymSec && this->ELFSyms.empty())
-    error("SHT_GNU_versym should be associated with symbol table");
-
-  // Search for a DT_SONAME tag to initialize this->SoName.
-  if (!DynamicSec)
-    return;
-  ArrayRef<Elf_Dyn> Arr =
-      CHECK(Obj.template getSectionContentsAsArray<Elf_Dyn>(DynamicSec), this);
-  for (const Elf_Dyn &Dyn : Arr) {
-    if (Dyn.d_tag == DT_SONAME) {
-      uint64_t Val = Dyn.getVal();
-      if (Val >= this->StringTable.size())
-        fatal(toString(this) + ": invalid DT_SONAME entry");
-      SoName = this->StringTable.data() + Val;
-      return;
-    }
-  }
-}
-
-// Parses ".gnu.version" section which is a parallel array for the symbol table.
-// If a given file doesn't have ".gnu.version" section, returns VER_NDX_GLOBAL.
-template <class ELFT> std::vector<uint32_t> SharedFile<ELFT>::parseVersyms() {
-  size_t Size = this->ELFSyms.size() - this->FirstGlobal;
-  if (!VersymSec)
-    return std::vector<uint32_t>(Size, VER_NDX_GLOBAL);
-
-  const char *Base = this->MB.getBuffer().data();
-  const Elf_Versym *Versym =
-      reinterpret_cast<const Elf_Versym *>(Base + VersymSec->sh_offset) +
-      this->FirstGlobal;
-
-  std::vector<uint32_t> Ret(Size);
-  for (size_t I = 0; I < Size; ++I)
-    Ret[I] = Versym[I].vs_index;
-  return Ret;
-}
+unsigned SharedFile::vernauxNum;
 
-// Parse the version definitions in the object file if present. Returns a vector
-// whose nth element contains a pointer to the Elf_Verdef for version identifier
-// n. Version identifiers that are not definitions map to nullptr.
-template <class ELFT>
-std::vector<const typename ELFT::Verdef *> SharedFile<ELFT>::parseVerdefs() {
-  if (!VerdefSec)
+// Parse the version definitions in the object file if present, and return a
+// vector whose nth element contains a pointer to the Elf_Verdef for version
+// identifier n. Version identifiers that are not definitions map to nullptr.
+template <typename ELFT>
+static std::vector<const void *> parseVerdefs(const uint8_t *base,
+                                              const typename ELFT::Shdr *sec) {
+  if (!sec)
     return {};
 
   // We cannot determine the largest verdef identifier without inspecting
   // every Elf_Verdef, but both bfd and gold assign verdef identifiers
   // sequentially starting from 1, so we predict that the largest identifier
-  // will be VerdefCount.
-  unsigned VerdefCount = VerdefSec->sh_info;
-  std::vector<const Elf_Verdef *> Verdefs(VerdefCount + 1);
+  // will be verdefCount.
+  unsigned verdefCount = sec->sh_info;
+  std::vector<const void *> verdefs(verdefCount + 1);
 
   // Build the Verdefs array by following the chain of Elf_Verdef objects
   // from the start of the .gnu.version_d section.
-  const char *Base = this->MB.getBuffer().data();
-  const char *Verdef = Base + VerdefSec->sh_offset;
-  for (unsigned I = 0; I != VerdefCount; ++I) {
-    auto *CurVerdef = reinterpret_cast<const Elf_Verdef *>(Verdef);
-    Verdef += CurVerdef->vd_next;
-    unsigned VerdefIndex = CurVerdef->vd_ndx;
-    Verdefs.resize(VerdefIndex + 1);
-    Verdefs[VerdefIndex] = CurVerdef;
+  const uint8_t *verdef = base + sec->sh_offset;
+  for (unsigned i = 0; i != verdefCount; ++i) {
+    auto *curVerdef = reinterpret_cast<const typename ELFT::Verdef *>(verdef);
+    verdef += curVerdef->vd_next;
+    unsigned verdefIndex = curVerdef->vd_ndx;
+    verdefs.resize(verdefIndex + 1);
+    verdefs[verdefIndex] = curVerdef;
   }
-
-  return Verdefs;
+  return verdefs;
 }
 
 // We do not usually care about alignments of data in shared object
 // files because the loader takes care of it. However, if we promote a
 // DSO symbol to point to .bss due to copy relocation, we need to keep
 // the original alignment requirements. We infer it in this function.
-template <class ELFT>
-uint32_t SharedFile<ELFT>::getAlignment(ArrayRef<Elf_Shdr> Sections,
-                                        const Elf_Sym &Sym) {
-  uint64_t Ret = UINT64_MAX;
-  if (Sym.st_value)
-    Ret = 1ULL << countTrailingZeros((uint64_t)Sym.st_value);
-  if (0 < Sym.st_shndx && Sym.st_shndx < Sections.size())
-    Ret = std::min<uint64_t>(Ret, Sections[Sym.st_shndx].sh_addralign);
-  return (Ret > UINT32_MAX) ? 0 : Ret;
+template <typename ELFT>
+static uint64_t getAlignment(ArrayRef<typename ELFT::Shdr> sections,
+                             const typename ELFT::Sym &sym) {
+  uint64_t ret = UINT64_MAX;
+  if (sym.st_value)
+    ret = 1ULL << countTrailingZeros((uint64_t)sym.st_value);
+  if (0 < sym.st_shndx && sym.st_shndx < sections.size())
+    ret = std::min<uint64_t>(ret, sections[sym.st_shndx].sh_addralign);
+  return (ret > UINT32_MAX) ? 0 : ret;
 }
 
-// Fully parse the shared object file. This must be called after parseSoName().
+// Fully parse the shared object file.
 //
 // This function parses symbol versions. If a DSO has version information,
 // the file has a ".gnu.version_d" section which contains symbol version
@@ -992,80 +1225,163 @@ uint32_t SharedFile<ELFT>::getAlignment(ArrayRef<Elf_Shdr> Sections,
 // The file format for symbol versioning is perhaps a bit more complicated
 // than necessary, but you can easily understand the code if you wrap your
 // head around the data structure described above.
-template <class ELFT> void SharedFile<ELFT>::parseRest() {
-  Verdefs = parseVerdefs();                       // parse .gnu.version_d
-  std::vector<uint32_t> Versyms = parseVersyms(); // parse .gnu.version
-  ArrayRef<Elf_Shdr> Sections = CHECK(this->getObj().sections(), this);
+template <class ELFT> void SharedFile::parse() {
+  using Elf_Dyn = typename ELFT::Dyn;
+  using Elf_Shdr = typename ELFT::Shdr;
+  using Elf_Sym = typename ELFT::Sym;
+  using Elf_Verdef = typename ELFT::Verdef;
+  using Elf_Versym = typename ELFT::Versym;
+
+  ArrayRef<Elf_Dyn> dynamicTags;
+  const ELFFile<ELFT> obj = this->getObj<ELFT>();
+  ArrayRef<Elf_Shdr> sections = CHECK(obj.sections(), this);
+
+  const Elf_Shdr *versymSec = nullptr;
+  const Elf_Shdr *verdefSec = nullptr;
+
+  // Search for .dynsym, .dynamic, .symtab, .gnu.version and .gnu.version_d.
+  for (const Elf_Shdr &sec : sections) {
+    switch (sec.sh_type) {
+    default:
+      continue;
+    case SHT_DYNAMIC:
+      dynamicTags =
+          CHECK(obj.template getSectionContentsAsArray<Elf_Dyn>(&sec), this);
+      break;
+    case SHT_GNU_versym:
+      versymSec = &sec;
+      break;
+    case SHT_GNU_verdef:
+      verdefSec = &sec;
+      break;
+    }
+  }
+
+  if (versymSec && numELFSyms == 0) {
+    error("SHT_GNU_versym should be associated with symbol table");
+    return;
+  }
+
+  // Search for a DT_SONAME tag to initialize this->soName.
+  for (const Elf_Dyn &dyn : dynamicTags) {
+    if (dyn.d_tag == DT_NEEDED) {
+      uint64_t val = dyn.getVal();
+      if (val >= this->stringTable.size())
+        fatal(toString(this) + ": invalid DT_NEEDED entry");
+      dtNeeded.push_back(this->stringTable.data() + val);
+    } else if (dyn.d_tag == DT_SONAME) {
+      uint64_t val = dyn.getVal();
+      if (val >= this->stringTable.size())
+        fatal(toString(this) + ": invalid DT_SONAME entry");
+      soName = this->stringTable.data() + val;
+    }
+  }
+
+  // DSOs are uniquified not by filename but by soname.
+  DenseMap<StringRef, SharedFile *>::iterator it;
+  bool wasInserted;
+  std::tie(it, wasInserted) = symtab->soNames.try_emplace(soName, this);
+
+  // If a DSO appears more than once on the command line with and without
+  // --as-needed, --no-as-needed takes precedence over --as-needed because a
+  // user can add an extra DSO with --no-as-needed to force it to be added to
+  // the dependency list.
+  it->second->isNeeded |= isNeeded;
+  if (!wasInserted)
+    return;
+
+  sharedFiles.push_back(this);
+
+  verdefs = parseVerdefs<ELFT>(obj.base(), verdefSec);
+
+  // Parse ".gnu.version" section which is a parallel array for the symbol
+  // table. If a given file doesn't have a ".gnu.version" section, we use
+  // VER_NDX_GLOBAL.
+  size_t size = numELFSyms - firstGlobal;
+  std::vector<uint32_t> versyms(size, VER_NDX_GLOBAL);
+  if (versymSec) {
+    ArrayRef<Elf_Versym> versym =
+        CHECK(obj.template getSectionContentsAsArray<Elf_Versym>(versymSec),
+              this)
+            .slice(firstGlobal);
+    for (size_t i = 0; i < size; ++i)
+      versyms[i] = versym[i].vs_index;
+  }
 
   // System libraries can have a lot of symbols with versions. Using a
   // fixed buffer for computing the versions name (foo@ver) can save a
   // lot of allocations.
-  SmallString<0> VersionedNameBuffer;
+  SmallString<0> versionedNameBuffer;
 
   // Add symbols to the symbol table.
-  ArrayRef<Elf_Sym> Syms = this->getGlobalELFSyms();
-  for (size_t I = 0; I < Syms.size(); ++I) {
-    const Elf_Sym &Sym = Syms[I];
+  ArrayRef<Elf_Sym> syms = this->getGlobalELFSyms<ELFT>();
+  for (size_t i = 0; i < syms.size(); ++i) {
+    const Elf_Sym &sym = syms[i];
 
     // ELF spec requires that all local symbols precede weak or global
     // symbols in each symbol table, and the index of first non-local symbol
     // is stored to sh_info. If a local symbol appears after some non-local
     // symbol, that's a violation of the spec.
-    StringRef Name = CHECK(Sym.getName(this->StringTable), this);
-    if (Sym.getBinding() == STB_LOCAL) {
-      warn("found local symbol '" + Name +
+    StringRef name = CHECK(sym.getName(this->stringTable), this);
+    if (sym.getBinding() == STB_LOCAL) {
+      warn("found local symbol '" + name +
            "' in global part of symbol table in file " + toString(this));
       continue;
     }
 
-    if (Sym.isUndefined()) {
-      Symbol *S = Symtab->addUndefined<ELFT>(Name, Sym.getBinding(),
-                                             Sym.st_other, Sym.getType(),
-                                             /*CanOmitFromDynSym=*/false, this);
-      S->ExportDynamic = true;
+    if (sym.isUndefined()) {
+      Symbol *s = symtab->addSymbol(
+          Undefined{this, name, sym.getBinding(), sym.st_other, sym.getType()});
+      s->exportDynamic = true;
       continue;
     }
 
     // MIPS BFD linker puts _gp_disp symbol into DSO files and incorrectly
     // assigns VER_NDX_LOCAL to this section global symbol. Here is a
     // workaround for this bug.
-    uint32_t Idx = Versyms[I] & ~VERSYM_HIDDEN;
-    if (Config->EMachine == EM_MIPS && Idx == VER_NDX_LOCAL &&
-        Name == "_gp_disp")
+    uint32_t idx = versyms[i] & ~VERSYM_HIDDEN;
+    if (config->emachine == EM_MIPS && idx == VER_NDX_LOCAL &&
+        name == "_gp_disp")
       continue;
 
-    uint64_t Alignment = getAlignment(Sections, Sym);
-    if (!(Versyms[I] & VERSYM_HIDDEN))
-      Symtab->addShared(Name, *this, Sym, Alignment, Idx);
+    uint32_t alignment = getAlignment<ELFT>(sections, sym);
+    if (!(versyms[i] & VERSYM_HIDDEN)) {
+      symtab->addSymbol(SharedSymbol{*this, name, sym.getBinding(),
+                                     sym.st_other, sym.getType(), sym.st_value,
+                                     sym.st_size, alignment, idx});
+    }
 
     // Also add the symbol with the versioned name to handle undefined symbols
     // with explicit versions.
-    if (Idx == VER_NDX_GLOBAL)
+    if (idx == VER_NDX_GLOBAL)
       continue;
 
-    if (Idx >= Verdefs.size() || Idx == VER_NDX_LOCAL) {
-      error("corrupt input file: version definition index " + Twine(Idx) +
-            " for symbol " + Name + " is out of bounds\n>>> defined in " +
+    if (idx >= verdefs.size() || idx == VER_NDX_LOCAL) {
+      error("corrupt input file: version definition index " + Twine(idx) +
+            " for symbol " + name + " is out of bounds\n>>> defined in " +
             toString(this));
       continue;
     }
 
-    StringRef VerName =
-        this->StringTable.data() + Verdefs[Idx]->getAux()->vda_name;
-    VersionedNameBuffer.clear();
-    Name = (Name + "@" + VerName).toStringRef(VersionedNameBuffer);
-    Symtab->addShared(Saver.save(Name), *this, Sym, Alignment, Idx);
+    StringRef verName =
+        this->stringTable.data() +
+        reinterpret_cast<const Elf_Verdef *>(verdefs[idx])->getAux()->vda_name;
+    versionedNameBuffer.clear();
+    name = (name + "@" + verName).toStringRef(versionedNameBuffer);
+    symtab->addSymbol(SharedSymbol{*this, saver.save(name), sym.getBinding(),
+                                   sym.st_other, sym.getType(), sym.st_value,
+                                   sym.st_size, alignment, idx});
   }
 }
 
-static ELFKind getBitcodeELFKind(const Triple &T) {
-  if (T.isLittleEndian())
-    return T.isArch64Bit() ? ELF64LEKind : ELF32LEKind;
-  return T.isArch64Bit() ? ELF64BEKind : ELF32BEKind;
+static ELFKind getBitcodeELFKind(const Triple &t) {
+  if (t.isLittleEndian())
+    return t.isArch64Bit() ? ELF64LEKind : ELF32LEKind;
+  return t.isArch64Bit() ? ELF64BEKind : ELF32BEKind;
 }
 
-static uint8_t getBitcodeMachineKind(StringRef Path, const Triple &T) {
-  switch (T.getArch()) {
+static uint8_t getBitcodeMachineKind(StringRef path, const Triple &t) {
+  switch (t.getArch()) {
   case Triple::aarch64:
     return EM_AARCH64;
   case Triple::amdgcn:
@@ -1088,25 +1404,28 @@ static uint8_t getBitcodeMachineKind(StringRef Path, const Triple &T) {
   case Triple::ppc64:
   case Triple::ppc64le:
     return EM_PPC64;
+  case Triple::riscv32:
+  case Triple::riscv64:
+    return EM_RISCV;
   case Triple::x86:
-    return T.isOSIAMCU() ? EM_IAMCU : EM_386;
+    return t.isOSIAMCU() ? EM_IAMCU : EM_386;
   case Triple::x86_64:
     return EM_X86_64;
   default:
-    error(Path + ": could not infer e_machine from bitcode target triple " +
-          T.str());
+    error(path + ": could not infer e_machine from bitcode target triple " +
+          t.str());
     return EM_NONE;
   }
 }
 
-BitcodeFile::BitcodeFile(MemoryBufferRef MB, StringRef ArchiveName,
-                         uint64_t OffsetInArchive)
-    : InputFile(BitcodeKind, MB) {
-  this->ArchiveName = ArchiveName;
+BitcodeFile::BitcodeFile(MemoryBufferRef mb, StringRef archiveName,
+                         uint64_t offsetInArchive)
+    : InputFile(BitcodeKind, mb) {
+  this->archiveName = archiveName;
 
-  std::string Path = MB.getBufferIdentifier().str();
-  if (Config->ThinLTOIndexOnly)
-    Path = replaceThinLTOSuffix(MB.getBufferIdentifier());
+  std::string path = mb.getBufferIdentifier().str();
+  if (config->thinLTOIndexOnly)
+    path = replaceThinLTOSuffix(mb.getBufferIdentifier());
 
   // ThinLTO assumes that all MemoryBufferRefs given to it have a unique
   // name. If two archives define two members with the same name, this
@@ -1114,20 +1433,21 @@ BitcodeFile::BitcodeFile(MemoryBufferRef MB, StringRef ArchiveName,
   // into consideration at LTO time (which very likely causes undefined
   // symbols later in the link stage). So we append file offset to make
   // filename unique.
-  MemoryBufferRef MBRef(
-      MB.getBuffer(),
-      Saver.save(ArchiveName + Path +
-                 (ArchiveName.empty() ? "" : utostr(OffsetInArchive))));
+  StringRef name = archiveName.empty()
+                       ? saver.save(path)
+                       : saver.save(archiveName + "(" + path + " at " +
+                                    utostr(offsetInArchive) + ")");
+  MemoryBufferRef mbref(mb.getBuffer(), name);
 
-  Obj = CHECK(lto::InputFile::create(MBRef), this);
+  obj = CHECK(lto::InputFile::create(mbref), this);
 
-  Triple T(Obj->getTargetTriple());
-  EKind = getBitcodeELFKind(T);
-  EMachine = getBitcodeMachineKind(MB.getBufferIdentifier(), T);
+  Triple t(obj->getTargetTriple());
+  ekind = getBitcodeELFKind(t);
+  emachine = getBitcodeMachineKind(mb.getBufferIdentifier(), t);
 }
 
-static uint8_t mapVisibility(GlobalValue::VisibilityTypes GvVisibility) {
-  switch (GvVisibility) {
+static uint8_t mapVisibility(GlobalValue::VisibilityTypes gvVisibility) {
+  switch (gvVisibility) {
   case GlobalValue::DefaultVisibility:
     return STV_DEFAULT;
   case GlobalValue::HiddenVisibility:
@@ -1139,209 +1459,187 @@ static uint8_t mapVisibility(GlobalValue::VisibilityTypes GvVisibility) {
 }
 
 template <class ELFT>
-static Symbol *createBitcodeSymbol(const std::vector<bool> &KeptComdats,
-                                   const lto::InputFile::Symbol &ObjSym,
-                                   BitcodeFile &F) {
-  StringRef Name = Saver.save(ObjSym.getName());
-  uint32_t Binding = ObjSym.isWeak() ? STB_WEAK : STB_GLOBAL;
-
-  uint8_t Type = ObjSym.isTLS() ? STT_TLS : STT_NOTYPE;
-  uint8_t Visibility = mapVisibility(ObjSym.getVisibility());
-  bool CanOmitFromDynSym = ObjSym.canBeOmittedFromSymbolTable();
-
-  int C = ObjSym.getComdatIndex();
-  if (C != -1 && !KeptComdats[C])
-    return Symtab->addUndefined<ELFT>(Name, Binding, Visibility, Type,
-                                      CanOmitFromDynSym, &F);
-
-  if (ObjSym.isUndefined())
-    return Symtab->addUndefined<ELFT>(Name, Binding, Visibility, Type,
-                                      CanOmitFromDynSym, &F);
-
-  if (ObjSym.isCommon())
-    return Symtab->addCommon(Name, ObjSym.getCommonSize(),
-                             ObjSym.getCommonAlignment(), Binding, Visibility,
-                             STT_OBJECT, F);
-
-  return Symtab->addBitcode(Name, Binding, Visibility, Type, CanOmitFromDynSym,
-                            F);
-}
+static Symbol *createBitcodeSymbol(const std::vector<bool> &keptComdats,
+                                   const lto::InputFile::Symbol &objSym,
+                                   BitcodeFile &f) {
+  StringRef name = saver.save(objSym.getName());
+  uint8_t binding = objSym.isWeak() ? STB_WEAK : STB_GLOBAL;
+  uint8_t type = objSym.isTLS() ? STT_TLS : STT_NOTYPE;
+  uint8_t visibility = mapVisibility(objSym.getVisibility());
+  bool canOmitFromDynSym = objSym.canBeOmittedFromSymbolTable();
+
+  int c = objSym.getComdatIndex();
+  if (objSym.isUndefined() || (c != -1 && !keptComdats[c])) {
+    Undefined New(&f, name, binding, visibility, type);
+    if (canOmitFromDynSym)
+      New.exportDynamic = false;
+    return symtab->addSymbol(New);
+  }
 
-template <class ELFT>
-void BitcodeFile::parse(DenseSet<CachedHashStringRef> &ComdatGroups) {
-  std::vector<bool> KeptComdats;
-  for (StringRef S : Obj->getComdatTable())
-    KeptComdats.push_back(ComdatGroups.insert(CachedHashStringRef(S)).second);
+  if (objSym.isCommon())
+    return symtab->addSymbol(
+        CommonSymbol{&f, name, binding, visibility, STT_OBJECT,
+                     objSym.getCommonAlignment(), objSym.getCommonSize()});
 
-  for (const lto::InputFile::Symbol &ObjSym : Obj->symbols())
-    Symbols.push_back(createBitcodeSymbol<ELFT>(KeptComdats, ObjSym, *this));
+  Defined New(&f, name, binding, visibility, type, 0, 0, nullptr);
+  if (canOmitFromDynSym)
+    New.exportDynamic = false;
+  return symtab->addSymbol(New);
 }
 
-static ELFKind getELFKind(MemoryBufferRef MB) {
-  unsigned char Size;
-  unsigned char Endian;
-  std::tie(Size, Endian) = getElfArchType(MB.getBuffer());
-
-  if (Endian != ELFDATA2LSB && Endian != ELFDATA2MSB)
-    fatal(MB.getBufferIdentifier() + ": invalid data encoding");
-  if (Size != ELFCLASS32 && Size != ELFCLASS64)
-    fatal(MB.getBufferIdentifier() + ": invalid file class");
+template <class ELFT> void BitcodeFile::parse() {
+  std::vector<bool> keptComdats;
+  for (StringRef s : obj->getComdatTable())
+    keptComdats.push_back(
+        symtab->comdatGroups.try_emplace(CachedHashStringRef(s), this).second);
 
-  size_t BufSize = MB.getBuffer().size();
-  if ((Size == ELFCLASS32 && BufSize < sizeof(Elf32_Ehdr)) ||
-      (Size == ELFCLASS64 && BufSize < sizeof(Elf64_Ehdr)))
-    fatal(MB.getBufferIdentifier() + ": file is too short");
+  for (const lto::InputFile::Symbol &objSym : obj->symbols())
+    symbols.push_back(createBitcodeSymbol<ELFT>(keptComdats, objSym, *this));
 
-  if (Size == ELFCLASS32)
-    return (Endian == ELFDATA2LSB) ? ELF32LEKind : ELF32BEKind;
-  return (Endian == ELFDATA2LSB) ? ELF64LEKind : ELF64BEKind;
+  for (auto l : obj->getDependentLibraries())
+    addDependentLibrary(l, this);
 }
 
 void BinaryFile::parse() {
-  ArrayRef<uint8_t> Data = arrayRefFromStringRef(MB.getBuffer());
-  auto *Section = make<InputSection>(this, SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
-                                     8, Data, ".data");
-  Sections.push_back(Section);
+  ArrayRef<uint8_t> data = arrayRefFromStringRef(mb.getBuffer());
+  auto *section = make<InputSection>(this, SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
+                                     8, data, ".data");
+  sections.push_back(section);
 
   // For each input file foo that is embedded to a result as a binary
   // blob, we define _binary_foo_{start,end,size} symbols, so that
   // user programs can access blobs by name. Non-alphanumeric
   // characters in a filename are replaced with underscore.
-  std::string S = "_binary_" + MB.getBufferIdentifier().str();
-  for (size_t I = 0; I < S.size(); ++I)
-    if (!isAlnum(S[I]))
-      S[I] = '_';
-
-  Symtab->addDefined(Saver.save(S + "_start"), STV_DEFAULT, STT_OBJECT, 0, 0,
-                     STB_GLOBAL, Section, nullptr);
-  Symtab->addDefined(Saver.save(S + "_end"), STV_DEFAULT, STT_OBJECT,
-                     Data.size(), 0, STB_GLOBAL, Section, nullptr);
-  Symtab->addDefined(Saver.save(S + "_size"), STV_DEFAULT, STT_OBJECT,
-                     Data.size(), 0, STB_GLOBAL, nullptr, nullptr);
+  std::string s = "_binary_" + mb.getBufferIdentifier().str();
+  for (size_t i = 0; i < s.size(); ++i)
+    if (!isAlnum(s[i]))
+      s[i] = '_';
+
+  symtab->addSymbol(Defined{nullptr, saver.save(s + "_start"), STB_GLOBAL,
+                            STV_DEFAULT, STT_OBJECT, 0, 0, section});
+  symtab->addSymbol(Defined{nullptr, saver.save(s + "_end"), STB_GLOBAL,
+                            STV_DEFAULT, STT_OBJECT, data.size(), 0, section});
+  symtab->addSymbol(Defined{nullptr, saver.save(s + "_size"), STB_GLOBAL,
+                            STV_DEFAULT, STT_OBJECT, data.size(), 0, nullptr});
 }
 
-InputFile *elf::createObjectFile(MemoryBufferRef MB, StringRef ArchiveName,
-                                 uint64_t OffsetInArchive) {
-  if (isBitcode(MB))
-    return make<BitcodeFile>(MB, ArchiveName, OffsetInArchive);
+InputFile *elf::createObjectFile(MemoryBufferRef mb, StringRef archiveName,
+                                 uint64_t offsetInArchive) {
+  if (isBitcode(mb))
+    return make<BitcodeFile>(mb, archiveName, offsetInArchive);
 
-  switch (getELFKind(MB)) {
+  switch (getELFKind(mb, archiveName)) {
   case ELF32LEKind:
-    return make<ObjFile<ELF32LE>>(MB, ArchiveName);
+    return make<ObjFile<ELF32LE>>(mb, archiveName);
   case ELF32BEKind:
-    return make<ObjFile<ELF32BE>>(MB, ArchiveName);
+    return make<ObjFile<ELF32BE>>(mb, archiveName);
   case ELF64LEKind:
-    return make<ObjFile<ELF64LE>>(MB, ArchiveName);
+    return make<ObjFile<ELF64LE>>(mb, archiveName);
   case ELF64BEKind:
-    return make<ObjFile<ELF64BE>>(MB, ArchiveName);
+    return make<ObjFile<ELF64BE>>(mb, archiveName);
   default:
     llvm_unreachable("getELFKind");
   }
 }
 
-InputFile *elf::createSharedFile(MemoryBufferRef MB, StringRef DefaultSoName) {
-  switch (getELFKind(MB)) {
-  case ELF32LEKind:
-    return make<SharedFile<ELF32LE>>(MB, DefaultSoName);
-  case ELF32BEKind:
-    return make<SharedFile<ELF32BE>>(MB, DefaultSoName);
-  case ELF64LEKind:
-    return make<SharedFile<ELF64LE>>(MB, DefaultSoName);
-  case ELF64BEKind:
-    return make<SharedFile<ELF64BE>>(MB, DefaultSoName);
-  default:
-    llvm_unreachable("getELFKind");
-  }
-}
+void LazyObjFile::fetch() {
+  if (mb.getBuffer().empty())
+    return;
 
-MemoryBufferRef LazyObjFile::getBuffer() {
-  if (AddedToLink)
-    return MemoryBufferRef();
-  AddedToLink = true;
-  return MB;
-}
+  InputFile *file = createObjectFile(mb, archiveName, offsetInArchive);
+  file->groupId = groupId;
 
-InputFile *LazyObjFile::fetch() {
-  MemoryBufferRef MBRef = getBuffer();
-  if (MBRef.getBuffer().empty())
-    return nullptr;
+  mb = {};
+
+  // Copy symbol vector so that the new InputFile doesn't have to
+  // insert the same defined symbols to the symbol table again.
+  file->symbols = std::move(symbols);
 
-  InputFile *File = createObjectFile(MBRef, ArchiveName, OffsetInArchive);
-  File->GroupId = GroupId;
-  return File;
+  parseFile(file);
 }
 
 template <class ELFT> void LazyObjFile::parse() {
+  using Elf_Sym = typename ELFT::Sym;
+
   // A lazy object file wraps either a bitcode file or an ELF file.
-  if (isBitcode(this->MB)) {
-    std::unique_ptr<lto::InputFile> Obj =
-        CHECK(lto::InputFile::create(this->MB), this);
-    for (const lto::InputFile::Symbol &Sym : Obj->symbols())
-      if (!Sym.isUndefined())
-        Symtab->addLazyObject<ELFT>(Saver.save(Sym.getName()), *this);
+  if (isBitcode(this->mb)) {
+    std::unique_ptr<lto::InputFile> obj =
+        CHECK(lto::InputFile::create(this->mb), this);
+    for (const lto::InputFile::Symbol &sym : obj->symbols()) {
+      if (sym.isUndefined())
+        continue;
+      symtab->addSymbol(LazyObject{*this, saver.save(sym.getName())});
+    }
     return;
   }
 
-  if (getELFKind(this->MB) != Config->EKind) {
-    error("incompatible file: " + this->MB.getBufferIdentifier());
+  if (getELFKind(this->mb, archiveName) != config->ekind) {
+    error("incompatible file: " + this->mb.getBufferIdentifier());
     return;
   }
 
-  ELFFile<ELFT> Obj = check(ELFFile<ELFT>::create(MB.getBuffer()));
-  ArrayRef<typename ELFT::Shdr> Sections = CHECK(Obj.sections(), this);
+  // Find a symbol table.
+  ELFFile<ELFT> obj = check(ELFFile<ELFT>::create(mb.getBuffer()));
+  ArrayRef<typename ELFT::Shdr> sections = CHECK(obj.sections(), this);
 
-  for (const typename ELFT::Shdr &Sec : Sections) {
-    if (Sec.sh_type != SHT_SYMTAB)
+  for (const typename ELFT::Shdr &sec : sections) {
+    if (sec.sh_type != SHT_SYMTAB)
       continue;
 
-    typename ELFT::SymRange Syms = CHECK(Obj.symbols(&Sec), this);
-    uint32_t FirstGlobal = Sec.sh_info;
-    StringRef StringTable =
-        CHECK(Obj.getStringTableForSymtab(Sec, Sections), this);
+    // A symbol table is found.
+    ArrayRef<Elf_Sym> eSyms = CHECK(obj.symbols(&sec), this);
+    uint32_t firstGlobal = sec.sh_info;
+    StringRef strtab = CHECK(obj.getStringTableForSymtab(sec, sections), this);
+    this->symbols.resize(eSyms.size());
+
+    // Get existing symbols or insert placeholder symbols.
+    for (size_t i = firstGlobal, end = eSyms.size(); i != end; ++i)
+      if (eSyms[i].st_shndx != SHN_UNDEF)
+        this->symbols[i] = symtab->insert(CHECK(eSyms[i].getName(strtab), this));
+
+    // Replace existing symbols with LazyObject symbols.
+    //
+    // resolve() may trigger this->fetch() if an existing symbol is an
+    // undefined symbol. If that happens, this LazyObjFile has served
+    // its purpose, and we can exit from the loop early.
+    for (Symbol *sym : this->symbols) {
+      if (!sym)
+        continue;
+      sym->resolve(LazyObject{*this, sym->getName()});
 
-    for (const typename ELFT::Sym &Sym : Syms.slice(FirstGlobal))
-      if (Sym.st_shndx != SHN_UNDEF)
-        Symtab->addLazyObject<ELFT>(CHECK(Sym.getName(StringTable), this),
-                                    *this);
+      // MemoryBuffer is emptied if this file is instantiated as ObjFile.
+      if (mb.getBuffer().empty())
+        return;
+    }
     return;
   }
 }
 
-std::string elf::replaceThinLTOSuffix(StringRef Path) {
-  StringRef Suffix = Config->ThinLTOObjectSuffixReplace.first;
-  StringRef Repl = Config->ThinLTOObjectSuffixReplace.second;
+std::string elf::replaceThinLTOSuffix(StringRef path) {
+  StringRef suffix = config->thinLTOObjectSuffixReplace.first;
+  StringRef repl = config->thinLTOObjectSuffixReplace.second;
 
-  if (Path.consume_back(Suffix))
-    return (Path + Repl).str();
-  return Path;
+  if (path.consume_back(suffix))
+    return (path + repl).str();
+  return path;
 }
 
-template void ArchiveFile::parse<ELF32LE>();
-template void ArchiveFile::parse<ELF32BE>();
-template void ArchiveFile::parse<ELF64LE>();
-template void ArchiveFile::parse<ELF64BE>();
-
-template void BitcodeFile::parse<ELF32LE>(DenseSet<CachedHashStringRef> &);
-template void BitcodeFile::parse<ELF32BE>(DenseSet<CachedHashStringRef> &);
-template void BitcodeFile::parse<ELF64LE>(DenseSet<CachedHashStringRef> &);
-template void BitcodeFile::parse<ELF64BE>(DenseSet<CachedHashStringRef> &);
+template void BitcodeFile::parse<ELF32LE>();
+template void BitcodeFile::parse<ELF32BE>();
+template void BitcodeFile::parse<ELF64LE>();
+template void BitcodeFile::parse<ELF64BE>();
 
 template void LazyObjFile::parse<ELF32LE>();
 template void LazyObjFile::parse<ELF32BE>();
 template void LazyObjFile::parse<ELF64LE>();
 template void LazyObjFile::parse<ELF64BE>();
 
-template class elf::ELFFileBase<ELF32LE>;
-template class elf::ELFFileBase<ELF32BE>;
-template class elf::ELFFileBase<ELF64LE>;
-template class elf::ELFFileBase<ELF64BE>;
-
 template class elf::ObjFile<ELF32LE>;
 template class elf::ObjFile<ELF32BE>;
 template class elf::ObjFile<ELF64LE>;
 template class elf::ObjFile<ELF64BE>;
 
-template class elf::SharedFile<ELF32LE>;
-template class elf::SharedFile<ELF32BE>;
-template class elf::SharedFile<ELF64LE>;
-template class elf::SharedFile<ELF64BE>;
+template void SharedFile::parse<ELF32LE>();
+template void SharedFile::parse<ELF32BE>();
+template void SharedFile::parse<ELF64LE>();
+template void SharedFile::parse<ELF64BE>();