Import LLVM 3.9.1 including clang and lld.

1 files changed, 1965 insertions, 0 deletions

diff --git a/gnu/llvm/tools/lld/ELF/OutputSections.cpp b/gnu/llvm/tools/lld/ELF/OutputSections.cpp
new file mode 100644
index 00000000000..50b94015f22
--- /dev/null
+++ b/gnu/llvm/tools/lld/ELF/OutputSections.cpp
@@ -0,0 +1,1965 @@
+//===- OutputSections.cpp -------------------------------------------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "OutputSections.h"
+#include "Config.h"
+#include "EhFrame.h"
+#include "LinkerScript.h"
+#include "Strings.h"
+#include "SymbolTable.h"
+#include "Target.h"
+#include "lld/Core/Parallel.h"
+#include "llvm/Support/Dwarf.h"
+#include "llvm/Support/MD5.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/SHA1.h"
+#include <map>
+
+using namespace llvm;
+using namespace llvm::dwarf;
+using namespace llvm::object;
+using namespace llvm::support::endian;
+using namespace llvm::ELF;
+
+using namespace lld;
+using namespace lld::elf;
+
+template <class ELFT>
+OutputSectionBase<ELFT>::OutputSectionBase(StringRef Name, uint32_t Type,
+                                           uintX_t Flags)
+    : Name(Name) {
+  memset(&Header, 0, sizeof(Elf_Shdr));
+  Header.sh_type = Type;
+  Header.sh_flags = Flags;
+  Header.sh_addralign = 1;
+}
+
+template <class ELFT>
+void OutputSectionBase<ELFT>::writeHeaderTo(Elf_Shdr *Shdr) {
+  *Shdr = Header;
+}
+
+template <class ELFT>
+GotPltSection<ELFT>::GotPltSection()
+    : OutputSectionBase<ELFT>(".got.plt", SHT_PROGBITS, SHF_ALLOC | SHF_WRITE) {
+  this->Header.sh_addralign = Target->GotPltEntrySize;
+}
+
+template <class ELFT> void GotPltSection<ELFT>::addEntry(SymbolBody &Sym) {
+  Sym.GotPltIndex = Target->GotPltHeaderEntriesNum + Entries.size();
+  Entries.push_back(&Sym);
+}
+
+template <class ELFT> bool GotPltSection<ELFT>::empty() const {
+  return Entries.empty();
+}
+
+template <class ELFT> void GotPltSection<ELFT>::finalize() {
+  this->Header.sh_size = (Target->GotPltHeaderEntriesNum + Entries.size()) *
+                         Target->GotPltEntrySize;
+}
+
+template <class ELFT> void GotPltSection<ELFT>::writeTo(uint8_t *Buf) {
+  Target->writeGotPltHeader(Buf);
+  Buf += Target->GotPltHeaderEntriesNum * Target->GotPltEntrySize;
+  for (const SymbolBody *B : Entries) {
+    Target->writeGotPlt(Buf, *B);
+    Buf += sizeof(uintX_t);
+  }
+}
+
+template <class ELFT>
+GotSection<ELFT>::GotSection()
+    : OutputSectionBase<ELFT>(".got", SHT_PROGBITS, SHF_ALLOC | SHF_WRITE) {
+  if (Config->EMachine == EM_MIPS)
+    this->Header.sh_flags |= SHF_MIPS_GPREL;
+  this->Header.sh_addralign = Target->GotEntrySize;
+}
+
+template <class ELFT>
+void GotSection<ELFT>::addEntry(SymbolBody &Sym) {
+  Sym.GotIndex = Entries.size();
+  Entries.push_back(&Sym);
+}
+
+template <class ELFT>
+void GotSection<ELFT>::addMipsEntry(SymbolBody &Sym, uintX_t Addend,
+                                    RelExpr Expr) {
+  // For "true" local symbols which can be referenced from the same module
+  // only compiler creates two instructions for address loading:
+  //
+  // lw   $8, 0($gp) # R_MIPS_GOT16
+  // addi $8, $8, 0  # R_MIPS_LO16
+  //
+  // The first instruction loads high 16 bits of the symbol address while
+  // the second adds an offset. That allows to reduce number of required
+  // GOT entries because only one global offset table entry is necessary
+  // for every 64 KBytes of local data. So for local symbols we need to
+  // allocate number of GOT entries to hold all required "page" addresses.
+  //
+  // All global symbols (hidden and regular) considered by compiler uniformly.
+  // It always generates a single `lw` instruction and R_MIPS_GOT16 relocation
+  // to load address of the symbol. So for each such symbol we need to
+  // allocate dedicated GOT entry to store its address.
+  //
+  // If a symbol is preemptible we need help of dynamic linker to get its
+  // final address. The corresponding GOT entries are allocated in the
+  // "global" part of GOT. Entries for non preemptible global symbol allocated
+  // in the "local" part of GOT.
+  //
+  // See "Global Offset Table" in Chapter 5:
+  // ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
+  if (Expr == R_MIPS_GOT_LOCAL_PAGE) {
+    // At this point we do not know final symbol value so to reduce number
+    // of allocated GOT entries do the following trick. Save all output
+    // sections referenced by GOT relocations. Then later in the `finalize`
+    // method calculate number of "pages" required to cover all saved output
+    // section and allocate appropriate number of GOT entries.
+    auto *OutSec = cast<DefinedRegular<ELFT>>(&Sym)->Section->OutSec;
+    MipsOutSections.insert(OutSec);
+    return;
+  }
+  if (Sym.isTls()) {
+    // GOT entries created for MIPS TLS relocations behave like
+    // almost GOT entries from other ABIs. They go to the end
+    // of the global offset table.
+    Sym.GotIndex = Entries.size();
+    Entries.push_back(&Sym);
+    return;
+  }
+  auto AddEntry = [&](SymbolBody &S, uintX_t A, MipsGotEntries &Items) {
+    if (S.isInGot() && !A)
+      return;
+    size_t NewIndex = Items.size();
+    if (!MipsGotMap.insert({{&S, A}, NewIndex}).second)
+      return;
+    Items.emplace_back(&S, A);
+    if (!A)
+      S.GotIndex = NewIndex;
+  };
+  if (Sym.isPreemptible()) {
+    // Ignore addends for preemptible symbols. They got single GOT entry anyway.
+    AddEntry(Sym, 0, MipsGlobal);
+    Sym.IsInGlobalMipsGot = true;
+  } else
+    AddEntry(Sym, Addend, MipsLocal);
+}
+
+template <class ELFT> bool GotSection<ELFT>::addDynTlsEntry(SymbolBody &Sym) {
+  if (Sym.GlobalDynIndex != -1U)
+    return false;
+  Sym.GlobalDynIndex = Entries.size();
+  // Global Dynamic TLS entries take two GOT slots.
+  Entries.push_back(nullptr);
+  Entries.push_back(&Sym);
+  return true;
+}
+
+// Reserves TLS entries for a TLS module ID and a TLS block offset.
+// In total it takes two GOT slots.
+template <class ELFT> bool GotSection<ELFT>::addTlsIndex() {
+  if (TlsIndexOff != uint32_t(-1))
+    return false;
+  TlsIndexOff = Entries.size() * sizeof(uintX_t);
+  Entries.push_back(nullptr);
+  Entries.push_back(nullptr);
+  return true;
+}
+
+template <class ELFT>
+typename GotSection<ELFT>::uintX_t
+GotSection<ELFT>::getMipsLocalPageOffset(uintX_t EntryValue) {
+  // Initialize the entry by the %hi(EntryValue) expression
+  // but without right-shifting.
+  EntryValue = (EntryValue + 0x8000) & ~0xffff;
+  // Take into account MIPS GOT header.
+  // See comment in the GotSection::writeTo.
+  size_t NewIndex = MipsLocalGotPos.size() + 2;
+  auto P = MipsLocalGotPos.insert(std::make_pair(EntryValue, NewIndex));
+  assert(!P.second || MipsLocalGotPos.size() <= MipsPageEntries);
+  return (uintX_t)P.first->second * sizeof(uintX_t) - MipsGPOffset;
+}
+
+template <class ELFT>
+typename GotSection<ELFT>::uintX_t
+GotSection<ELFT>::getMipsGotOffset(const SymbolBody &B, uintX_t Addend) const {
+  uintX_t Off = MipsPageEntries;
+  if (B.isTls())
+    Off += MipsLocal.size() + MipsGlobal.size() + B.GotIndex;
+  else if (B.IsInGlobalMipsGot)
+    Off += MipsLocal.size() + B.GotIndex;
+  else if (B.isInGot())
+    Off += B.GotIndex;
+  else {
+    auto It = MipsGotMap.find({&B, Addend});
+    assert(It != MipsGotMap.end());
+    Off += It->second;
+  }
+  return Off * sizeof(uintX_t) - MipsGPOffset;
+}
+
+template <class ELFT>
+typename GotSection<ELFT>::uintX_t GotSection<ELFT>::getMipsTlsOffset() {
+  return (MipsPageEntries + MipsLocal.size() + MipsGlobal.size()) *
+         sizeof(uintX_t);
+}
+
+template <class ELFT>
+typename GotSection<ELFT>::uintX_t
+GotSection<ELFT>::getGlobalDynAddr(const SymbolBody &B) const {
+  return this->getVA() + B.GlobalDynIndex * sizeof(uintX_t);
+}
+
+template <class ELFT>
+typename GotSection<ELFT>::uintX_t
+GotSection<ELFT>::getGlobalDynOffset(const SymbolBody &B) const {
+  return B.GlobalDynIndex * sizeof(uintX_t);
+}
+
+template <class ELFT>
+const SymbolBody *GotSection<ELFT>::getMipsFirstGlobalEntry() const {
+  return MipsGlobal.empty() ? nullptr : MipsGlobal.front().first;
+}
+
+template <class ELFT>
+unsigned GotSection<ELFT>::getMipsLocalEntriesNum() const {
+  return MipsPageEntries + MipsLocal.size();
+}
+
+template <class ELFT> void GotSection<ELFT>::finalize() {
+  size_t EntriesNum = Entries.size();
+  if (Config->EMachine == EM_MIPS) {
+    // Take into account MIPS GOT header.
+    // See comment in the GotSection::writeTo.
+    MipsPageEntries += 2;
+    for (const OutputSectionBase<ELFT> *OutSec : MipsOutSections) {
+      // Calculate an upper bound of MIPS GOT entries required to store page
+      // addresses of local symbols. We assume the worst case - each 64kb
+      // page of the output section has at least one GOT relocation against it.
+      // Add 0x8000 to the section's size because the page address stored
+      // in the GOT entry is calculated as (value + 0x8000) & ~0xffff.
+      MipsPageEntries += (OutSec->getSize() + 0x8000 + 0xfffe) / 0xffff;
+    }
+    EntriesNum += MipsPageEntries + MipsLocal.size() + MipsGlobal.size();
+  }
+  this->Header.sh_size = EntriesNum * sizeof(uintX_t);
+}
+
+template <class ELFT> void GotSection<ELFT>::writeMipsGot(uint8_t *&Buf) {
+  // Set the MSB of the second GOT slot. This is not required by any
+  // MIPS ABI documentation, though.
+  //
+  // There is a comment in glibc saying that "The MSB of got[1] of a
+  // gnu object is set to identify gnu objects," and in GNU gold it
+  // says "the second entry will be used by some runtime loaders".
+  // But how this field is being used is unclear.
+  //
+  // We are not really willing to mimic other linkers behaviors
+  // without understanding why they do that, but because all files
+  // generated by GNU tools have this special GOT value, and because
+  // we've been doing this for years, it is probably a safe bet to
+  // keep doing this for now. We really need to revisit this to see
+  // if we had to do this.
+  auto *P = reinterpret_cast<typename ELFT::Off *>(Buf);
+  P[1] = uintX_t(1) << (ELFT::Is64Bits ? 63 : 31);
+  // Write 'page address' entries to the local part of the GOT.
+  for (std::pair<uintX_t, size_t> &L : MipsLocalGotPos) {
+    uint8_t *Entry = Buf + L.second * sizeof(uintX_t);
+    write<uintX_t, ELFT::TargetEndianness, sizeof(uintX_t)>(Entry, L.first);
+  }
+  Buf += MipsPageEntries * sizeof(uintX_t);
+  auto AddEntry = [&](const MipsGotEntry &SA) {
+    uint8_t *Entry = Buf;
+    Buf += sizeof(uintX_t);
+    const SymbolBody* Body = SA.first;
+    uintX_t VA = Body->template getVA<ELFT>(SA.second);
+    write<uintX_t, ELFT::TargetEndianness, sizeof(uintX_t)>(Entry, VA);
+  };
+  std::for_each(std::begin(MipsLocal), std::end(MipsLocal), AddEntry);
+  std::for_each(std::begin(MipsGlobal), std::end(MipsGlobal), AddEntry);
+}
+
+template <class ELFT> void GotSection<ELFT>::writeTo(uint8_t *Buf) {
+  if (Config->EMachine == EM_MIPS)
+    writeMipsGot(Buf);
+  for (const SymbolBody *B : Entries) {
+    uint8_t *Entry = Buf;
+    Buf += sizeof(uintX_t);
+    if (!B)
+      continue;
+    if (B->isPreemptible())
+      continue; // The dynamic linker will take care of it.
+    uintX_t VA = B->getVA<ELFT>();
+    write<uintX_t, ELFT::TargetEndianness, sizeof(uintX_t)>(Entry, VA);
+  }
+}
+
+template <class ELFT>
+PltSection<ELFT>::PltSection()
+    : OutputSectionBase<ELFT>(".plt", SHT_PROGBITS, SHF_ALLOC | SHF_EXECINSTR) {
+  this->Header.sh_addralign = 16;
+}
+
+template <class ELFT> void PltSection<ELFT>::writeTo(uint8_t *Buf) {
+  // At beginning of PLT, we have code to call the dynamic linker
+  // to resolve dynsyms at runtime. Write such code.
+  Target->writePltHeader(Buf);
+  size_t Off = Target->PltHeaderSize;
+
+  for (auto &I : Entries) {
+    const SymbolBody *B = I.first;
+    unsigned RelOff = I.second;
+    uint64_t Got = B->getGotPltVA<ELFT>();
+    uint64_t Plt = this->getVA() + Off;
+    Target->writePlt(Buf + Off, Got, Plt, B->PltIndex, RelOff);
+    Off += Target->PltEntrySize;
+  }
+}
+
+template <class ELFT> void PltSection<ELFT>::addEntry(SymbolBody &Sym) {
+  Sym.PltIndex = Entries.size();
+  unsigned RelOff = Out<ELFT>::RelaPlt->getRelocOffset();
+  Entries.push_back(std::make_pair(&Sym, RelOff));
+}
+
+template <class ELFT> void PltSection<ELFT>::finalize() {
+  this->Header.sh_size =
+      Target->PltHeaderSize + Entries.size() * Target->PltEntrySize;
+}
+
+template <class ELFT>
+RelocationSection<ELFT>::RelocationSection(StringRef Name, bool Sort)
+    : OutputSectionBase<ELFT>(Name, Config->Rela ? SHT_RELA : SHT_REL,
+                              SHF_ALLOC),
+      Sort(Sort) {
+  this->Header.sh_entsize = Config->Rela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
+  this->Header.sh_addralign = sizeof(uintX_t);
+}
+
+template <class ELFT>
+void RelocationSection<ELFT>::addReloc(const DynamicReloc<ELFT> &Reloc) {
+  Relocs.push_back(Reloc);
+}
+
+template <class ELFT, class RelTy>
+static bool compRelocations(const RelTy &A, const RelTy &B) {
+  return A.getSymbol(Config->Mips64EL) < B.getSymbol(Config->Mips64EL);
+}
+
+template <class ELFT> void RelocationSection<ELFT>::writeTo(uint8_t *Buf) {
+  uint8_t *BufBegin = Buf;
+  for (const DynamicReloc<ELFT> &Rel : Relocs) {
+    auto *P = reinterpret_cast<Elf_Rela *>(Buf);
+    Buf += Config->Rela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
+
+    if (Config->Rela)
+      P->r_addend = Rel.getAddend();
+    P->r_offset = Rel.getOffset();
+    if (Config->EMachine == EM_MIPS && Rel.getOutputSec() == Out<ELFT>::Got)
+      // Dynamic relocation against MIPS GOT section make deal TLS entries
+      // allocated in the end of the GOT. We need to adjust the offset to take
+      // in account 'local' and 'global' GOT entries.
+      P->r_offset += Out<ELFT>::Got->getMipsTlsOffset();
+    P->setSymbolAndType(Rel.getSymIndex(), Rel.Type, Config->Mips64EL);
+  }
+
+  if (Sort) {
+    if (Config->Rela)
+      std::stable_sort((Elf_Rela *)BufBegin,
+                       (Elf_Rela *)BufBegin + Relocs.size(),
+                       compRelocations<ELFT, Elf_Rela>);
+    else
+      std::stable_sort((Elf_Rel *)BufBegin, (Elf_Rel *)BufBegin + Relocs.size(),
+                       compRelocations<ELFT, Elf_Rel>);
+  }
+}
+
+template <class ELFT> unsigned RelocationSection<ELFT>::getRelocOffset() {
+  return this->Header.sh_entsize * Relocs.size();
+}
+
+template <class ELFT> void RelocationSection<ELFT>::finalize() {
+  this->Header.sh_link = Static ? Out<ELFT>::SymTab->SectionIndex
+                                : Out<ELFT>::DynSymTab->SectionIndex;
+  this->Header.sh_size = Relocs.size() * this->Header.sh_entsize;
+}
+
+template <class ELFT>
+InterpSection<ELFT>::InterpSection()
+    : OutputSectionBase<ELFT>(".interp", SHT_PROGBITS, SHF_ALLOC) {
+  this->Header.sh_size = Config->DynamicLinker.size() + 1;
+}
+
+template <class ELFT> void InterpSection<ELFT>::writeTo(uint8_t *Buf) {
+  StringRef S = Config->DynamicLinker;
+  memcpy(Buf, S.data(), S.size());
+}
+
+template <class ELFT>
+HashTableSection<ELFT>::HashTableSection()
+    : OutputSectionBase<ELFT>(".hash", SHT_HASH, SHF_ALLOC) {
+  this->Header.sh_entsize = sizeof(Elf_Word);
+  this->Header.sh_addralign = sizeof(Elf_Word);
+}
+
+static uint32_t hashSysv(StringRef Name) {
+  uint32_t H = 0;
+  for (char C : Name) {
+    H = (H << 4) + C;
+    uint32_t G = H & 0xf0000000;
+    if (G)
+      H ^= G >> 24;
+    H &= ~G;
+  }
+  return H;
+}
+
+template <class ELFT> void HashTableSection<ELFT>::finalize() {
+  this->Header.sh_link = Out<ELFT>::DynSymTab->SectionIndex;
+
+  unsigned NumEntries = 2;                             // nbucket and nchain.
+  NumEntries += Out<ELFT>::DynSymTab->getNumSymbols(); // The chain entries.
+
+  // Create as many buckets as there are symbols.
+  // FIXME: This is simplistic. We can try to optimize it, but implementing
+  // support for SHT_GNU_HASH is probably even more profitable.
+  NumEntries += Out<ELFT>::DynSymTab->getNumSymbols();
+  this->Header.sh_size = NumEntries * sizeof(Elf_Word);
+}
+
+template <class ELFT> void HashTableSection<ELFT>::writeTo(uint8_t *Buf) {
+  unsigned NumSymbols = Out<ELFT>::DynSymTab->getNumSymbols();
+  auto *P = reinterpret_cast<Elf_Word *>(Buf);
+  *P++ = NumSymbols; // nbucket
+  *P++ = NumSymbols; // nchain
+
+  Elf_Word *Buckets = P;
+  Elf_Word *Chains = P + NumSymbols;
+
+  for (const std::pair<SymbolBody *, unsigned> &P :
+       Out<ELFT>::DynSymTab->getSymbols()) {
+    SymbolBody *Body = P.first;
+    StringRef Name = Body->getName();
+    unsigned I = Body->DynsymIndex;
+    uint32_t Hash = hashSysv(Name) % NumSymbols;
+    Chains[I] = Buckets[Hash];
+    Buckets[Hash] = I;
+  }
+}
+
+static uint32_t hashGnu(StringRef Name) {
+  uint32_t H = 5381;
+  for (uint8_t C : Name)
+    H = (H << 5) + H + C;
+  return H;
+}
+
+template <class ELFT>
+GnuHashTableSection<ELFT>::GnuHashTableSection()
+    : OutputSectionBase<ELFT>(".gnu.hash", SHT_GNU_HASH, SHF_ALLOC) {
+  this->Header.sh_entsize = ELFT::Is64Bits ? 0 : 4;
+  this->Header.sh_addralign = sizeof(uintX_t);
+}
+
+template <class ELFT>
+unsigned GnuHashTableSection<ELFT>::calcNBuckets(unsigned NumHashed) {
+  if (!NumHashed)
+    return 0;
+
+  // These values are prime numbers which are not greater than 2^(N-1) + 1.
+  // In result, for any particular NumHashed we return a prime number
+  // which is not greater than NumHashed.
+  static const unsigned Primes[] = {
+      1,   1,    3,    3,    7,    13,    31,    61,    127,   251,
+      509, 1021, 2039, 4093, 8191, 16381, 32749, 65521, 131071};
+
+  return Primes[std::min<unsigned>(Log2_32_Ceil(NumHashed),
+                                   array_lengthof(Primes) - 1)];
+}
+
+// Bloom filter estimation: at least 8 bits for each hashed symbol.
+// GNU Hash table requirement: it should be a power of 2,
+//   the minimum value is 1, even for an empty table.
+// Expected results for a 32-bit target:
+//   calcMaskWords(0..4)   = 1
+//   calcMaskWords(5..8)   = 2
+//   calcMaskWords(9..16)  = 4
+// For a 64-bit target:
+//   calcMaskWords(0..8)   = 1
+//   calcMaskWords(9..16)  = 2
+//   calcMaskWords(17..32) = 4
+template <class ELFT>
+unsigned GnuHashTableSection<ELFT>::calcMaskWords(unsigned NumHashed) {
+  if (!NumHashed)
+    return 1;
+  return NextPowerOf2((NumHashed - 1) / sizeof(Elf_Off));
+}
+
+template <class ELFT> void GnuHashTableSection<ELFT>::finalize() {
+  unsigned NumHashed = Symbols.size();
+  NBuckets = calcNBuckets(NumHashed);
+  MaskWords = calcMaskWords(NumHashed);
+  // Second hash shift estimation: just predefined values.
+  Shift2 = ELFT::Is64Bits ? 6 : 5;
+
+  this->Header.sh_link = Out<ELFT>::DynSymTab->SectionIndex;
+  this->Header.sh_size = sizeof(Elf_Word) * 4            // Header
+                         + sizeof(Elf_Off) * MaskWords   // Bloom Filter
+                         + sizeof(Elf_Word) * NBuckets   // Hash Buckets
+                         + sizeof(Elf_Word) * NumHashed; // Hash Values
+}
+
+template <class ELFT> void GnuHashTableSection<ELFT>::writeTo(uint8_t *Buf) {
+  writeHeader(Buf);
+  if (Symbols.empty())
+    return;
+  writeBloomFilter(Buf);
+  writeHashTable(Buf);
+}
+
+template <class ELFT>
+void GnuHashTableSection<ELFT>::writeHeader(uint8_t *&Buf) {
+  auto *P = reinterpret_cast<Elf_Word *>(Buf);
+  *P++ = NBuckets;
+  *P++ = Out<ELFT>::DynSymTab->getNumSymbols() - Symbols.size();
+  *P++ = MaskWords;
+  *P++ = Shift2;
+  Buf = reinterpret_cast<uint8_t *>(P);
+}
+
+template <class ELFT>
+void GnuHashTableSection<ELFT>::writeBloomFilter(uint8_t *&Buf) {
+  unsigned C = sizeof(Elf_Off) * 8;
+
+  auto *Masks = reinterpret_cast<Elf_Off *>(Buf);
+  for (const SymbolData &Sym : Symbols) {
+    size_t Pos = (Sym.Hash / C) & (MaskWords - 1);
+    uintX_t V = (uintX_t(1) << (Sym.Hash % C)) |
+                (uintX_t(1) << ((Sym.Hash >> Shift2) % C));
+    Masks[Pos] |= V;
+  }
+  Buf += sizeof(Elf_Off) * MaskWords;
+}
+
+template <class ELFT>
+void GnuHashTableSection<ELFT>::writeHashTable(uint8_t *Buf) {
+  Elf_Word *Buckets = reinterpret_cast<Elf_Word *>(Buf);
+  Elf_Word *Values = Buckets + NBuckets;
+
+  int PrevBucket = -1;
+  int I = 0;
+  for (const SymbolData &Sym : Symbols) {
+    int Bucket = Sym.Hash % NBuckets;
+    assert(PrevBucket <= Bucket);
+    if (Bucket != PrevBucket) {
+      Buckets[Bucket] = Sym.Body->DynsymIndex;
+      PrevBucket = Bucket;
+      if (I > 0)
+        Values[I - 1] |= 1;
+    }
+    Values[I] = Sym.Hash & ~1;
+    ++I;
+  }
+  if (I > 0)
+    Values[I - 1] |= 1;
+}
+
+// Add symbols to this symbol hash table. Note that this function
+// destructively sort a given vector -- which is needed because
+// GNU-style hash table places some sorting requirements.
+template <class ELFT>
+void GnuHashTableSection<ELFT>::addSymbols(
+    std::vector<std::pair<SymbolBody *, size_t>> &V) {
+  // Ideally this will just be 'auto' but GCC 6.1 is not able
+  // to deduce it correctly.
+  std::vector<std::pair<SymbolBody *, size_t>>::iterator Mid =
+      std::stable_partition(V.begin(), V.end(),
+                            [](std::pair<SymbolBody *, size_t> &P) {
+                              return P.first->isUndefined();
+                            });
+  if (Mid == V.end())
+    return;
+  for (auto I = Mid, E = V.end(); I != E; ++I) {
+    SymbolBody *B = I->first;
+    size_t StrOff = I->second;
+    Symbols.push_back({B, StrOff, hashGnu(B->getName())});
+  }
+
+  unsigned NBuckets = calcNBuckets(Symbols.size());
+  std::stable_sort(Symbols.begin(), Symbols.end(),
+                   [&](const SymbolData &L, const SymbolData &R) {
+                     return L.Hash % NBuckets < R.Hash % NBuckets;
+                   });
+
+  V.erase(Mid, V.end());
+  for (const SymbolData &Sym : Symbols)
+    V.push_back({Sym.Body, Sym.STName});
+}
+
+// Returns the number of version definition entries. Because the first entry
+// is for the version definition itself, it is the number of versioned symbols
+// plus one. Note that we don't support multiple versions yet.
+static unsigned getVerDefNum() { return Config->VersionDefinitions.size() + 1; }
+
+template <class ELFT>
+DynamicSection<ELFT>::DynamicSection()
+    : OutputSectionBase<ELFT>(".dynamic", SHT_DYNAMIC, SHF_ALLOC | SHF_WRITE) {
+  Elf_Shdr &Header = this->Header;
+  Header.sh_addralign = sizeof(uintX_t);
+  Header.sh_entsize = ELFT::Is64Bits ? 16 : 8;
+
+  // .dynamic section is not writable on MIPS.
+  // See "Special Section" in Chapter 4 in the following document:
+  // ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
+  if (Config->EMachine == EM_MIPS)
+    Header.sh_flags = SHF_ALLOC;
+}
+
+template <class ELFT> void DynamicSection<ELFT>::finalize() {
+  if (this->Header.sh_size)
+    return; // Already finalized.
+
+  Elf_Shdr &Header = this->Header;
+  Header.sh_link = Out<ELFT>::DynStrTab->SectionIndex;
+
+  auto Add = [=](Entry E) { Entries.push_back(E); };
+
+  // Add strings. We know that these are the last strings to be added to
+  // DynStrTab and doing this here allows this function to set DT_STRSZ.
+  if (!Config->RPath.empty())
+    Add({Config->EnableNewDtags ? DT_RUNPATH : DT_RPATH,
+         Out<ELFT>::DynStrTab->addString(Config->RPath)});
+  for (const std::unique_ptr<SharedFile<ELFT>> &F :
+       Symtab<ELFT>::X->getSharedFiles())
+    if (F->isNeeded())
+      Add({DT_NEEDED, Out<ELFT>::DynStrTab->addString(F->getSoName())});
+  if (!Config->SoName.empty())
+    Add({DT_SONAME, Out<ELFT>::DynStrTab->addString(Config->SoName)});
+
+  Out<ELFT>::DynStrTab->finalize();
+
+  if (Out<ELFT>::RelaDyn->hasRelocs()) {
+    bool IsRela = Config->Rela;
+    Add({IsRela ? DT_RELA : DT_REL, Out<ELFT>::RelaDyn});
+    Add({IsRela ? DT_RELASZ : DT_RELSZ, Out<ELFT>::RelaDyn->getSize()});
+    Add({IsRela ? DT_RELAENT : DT_RELENT,
+         uintX_t(IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel))});
+  }
+  if (Out<ELFT>::RelaPlt && Out<ELFT>::RelaPlt->hasRelocs()) {
+    Add({DT_JMPREL, Out<ELFT>::RelaPlt});
+    Add({DT_PLTRELSZ, Out<ELFT>::RelaPlt->getSize()});
+    Add({Config->EMachine == EM_MIPS ? DT_MIPS_PLTGOT : DT_PLTGOT,
+         Out<ELFT>::GotPlt});
+    Add({DT_PLTREL, uint64_t(Config->Rela ? DT_RELA : DT_REL)});
+  }
+
+  Add({DT_SYMTAB, Out<ELFT>::DynSymTab});
+  Add({DT_SYMENT, sizeof(Elf_Sym)});
+  Add({DT_STRTAB, Out<ELFT>::DynStrTab});
+  Add({DT_STRSZ, Out<ELFT>::DynStrTab->getSize()});
+  if (Out<ELFT>::GnuHashTab)
+    Add({DT_GNU_HASH, Out<ELFT>::GnuHashTab});
+  if (Out<ELFT>::HashTab)
+    Add({DT_HASH, Out<ELFT>::HashTab});
+
+  if (PreInitArraySec) {
+    Add({DT_PREINIT_ARRAY, PreInitArraySec});
+    Add({DT_PREINIT_ARRAYSZ, PreInitArraySec->getSize()});
+  }
+  if (InitArraySec) {
+    Add({DT_INIT_ARRAY, InitArraySec});
+    Add({DT_INIT_ARRAYSZ, (uintX_t)InitArraySec->getSize()});
+  }
+  if (FiniArraySec) {
+    Add({DT_FINI_ARRAY, FiniArraySec});
+    Add({DT_FINI_ARRAYSZ, (uintX_t)FiniArraySec->getSize()});
+  }
+
+  if (SymbolBody *B = Symtab<ELFT>::X->find(Config->Init))
+    Add({DT_INIT, B});
+  if (SymbolBody *B = Symtab<ELFT>::X->find(Config->Fini))
+    Add({DT_FINI, B});
+
+  uint32_t DtFlags = 0;
+  uint32_t DtFlags1 = 0;
+  if (Config->Bsymbolic)
+    DtFlags |= DF_SYMBOLIC;
+  if (Config->ZNodelete)
+    DtFlags1 |= DF_1_NODELETE;
+  if (Config->ZNow) {
+    DtFlags |= DF_BIND_NOW;
+    DtFlags1 |= DF_1_NOW;
+  }
+  if (Config->ZOrigin) {
+    DtFlags |= DF_ORIGIN;
+    DtFlags1 |= DF_1_ORIGIN;
+  }
+
+  if (DtFlags)
+    Add({DT_FLAGS, DtFlags});
+  if (DtFlags1)
+    Add({DT_FLAGS_1, DtFlags1});
+
+  if (!Config->Entry.empty())
+    Add({DT_DEBUG, (uint64_t)0});
+
+  bool HasVerNeed = Out<ELFT>::VerNeed->getNeedNum() != 0;
+  if (HasVerNeed || Out<ELFT>::VerDef)
+    Add({DT_VERSYM, Out<ELFT>::VerSym});
+  if (Out<ELFT>::VerDef) {
+    Add({DT_VERDEF, Out<ELFT>::VerDef});
+    Add({DT_VERDEFNUM, getVerDefNum()});
+  }
+  if (HasVerNeed) {
+    Add({DT_VERNEED, Out<ELFT>::VerNeed});
+    Add({DT_VERNEEDNUM, Out<ELFT>::VerNeed->getNeedNum()});
+  }
+
+  if (Config->EMachine == EM_MIPS) {
+    Add({DT_MIPS_RLD_VERSION, 1});
+    Add({DT_MIPS_FLAGS, RHF_NOTPOT});
+    Add({DT_MIPS_BASE_ADDRESS, Config->ImageBase});
+    Add({DT_MIPS_SYMTABNO, Out<ELFT>::DynSymTab->getNumSymbols()});
+    Add({DT_MIPS_LOCAL_GOTNO, Out<ELFT>::Got->getMipsLocalEntriesNum()});
+    if (const SymbolBody *B = Out<ELFT>::Got->getMipsFirstGlobalEntry())
+      Add({DT_MIPS_GOTSYM, B->DynsymIndex});
+    else
+      Add({DT_MIPS_GOTSYM, Out<ELFT>::DynSymTab->getNumSymbols()});
+    Add({DT_PLTGOT, Out<ELFT>::Got});
+    if (Out<ELFT>::MipsRldMap)
+      Add({DT_MIPS_RLD_MAP, Out<ELFT>::MipsRldMap});
+  }
+
+  // +1 for DT_NULL
+  Header.sh_size = (Entries.size() + 1) * Header.sh_entsize;
+}
+
+template <class ELFT> void DynamicSection<ELFT>::writeTo(uint8_t *Buf) {
+  auto *P = reinterpret_cast<Elf_Dyn *>(Buf);
+
+  for (const Entry &E : Entries) {
+    P->d_tag = E.Tag;
+    switch (E.Kind) {
+    case Entry::SecAddr:
+      P->d_un.d_ptr = E.OutSec->getVA();
+      break;
+    case Entry::SymAddr:
+      P->d_un.d_ptr = E.Sym->template getVA<ELFT>();
+      break;
+    case Entry::PlainInt:
+      P->d_un.d_val = E.Val;
+      break;
+    }
+    ++P;
+  }
+}
+
+template <class ELFT>
+EhFrameHeader<ELFT>::EhFrameHeader()
+    : OutputSectionBase<ELFT>(".eh_frame_hdr", SHT_PROGBITS, SHF_ALLOC) {}
+
+// .eh_frame_hdr contains a binary search table of pointers to FDEs.
+// Each entry of the search table consists of two values,
+// the starting PC from where FDEs covers, and the FDE's address.
+// It is sorted by PC.
+template <class ELFT> void EhFrameHeader<ELFT>::writeTo(uint8_t *Buf) {
+  const endianness E = ELFT::TargetEndianness;
+
+  // Sort the FDE list by their PC and uniqueify. Usually there is only
+  // one FDE for a PC (i.e. function), but if ICF merges two functions
+  // into one, there can be more than one FDEs pointing to the address.
+  auto Less = [](const FdeData &A, const FdeData &B) { return A.Pc < B.Pc; };
+  std::stable_sort(Fdes.begin(), Fdes.end(), Less);
+  auto Eq = [](const FdeData &A, const FdeData &B) { return A.Pc == B.Pc; };
+  Fdes.erase(std::unique(Fdes.begin(), Fdes.end(), Eq), Fdes.end());
+
+  Buf[0] = 1;
+  Buf[1] = DW_EH_PE_pcrel | DW_EH_PE_sdata4;
+  Buf[2] = DW_EH_PE_udata4;
+  Buf[3] = DW_EH_PE_datarel | DW_EH_PE_sdata4;
+  write32<E>(Buf + 4, Out<ELFT>::EhFrame->getVA() - this->getVA() - 4);
+  write32<E>(Buf + 8, Fdes.size());
+  Buf += 12;
+
+  uintX_t VA = this->getVA();
+  for (FdeData &Fde : Fdes) {
+    write32<E>(Buf, Fde.Pc - VA);
+    write32<E>(Buf + 4, Fde.FdeVA - VA);
+    Buf += 8;
+  }
+}
+
+template <class ELFT> void EhFrameHeader<ELFT>::finalize() {
+  // .eh_frame_hdr has a 12 bytes header followed by an array of FDEs.
+  this->Header.sh_size = 12 + Out<ELFT>::EhFrame->NumFdes * 8;
+}
+
+template <class ELFT>
+void EhFrameHeader<ELFT>::addFde(uint32_t Pc, uint32_t FdeVA) {
+  Fdes.push_back({Pc, FdeVA});
+}
+
+template <class ELFT>
+OutputSection<ELFT>::OutputSection(StringRef Name, uint32_t Type, uintX_t Flags)
+    : OutputSectionBase<ELFT>(Name, Type, Flags) {
+  if (Type == SHT_RELA)
+    this->Header.sh_entsize = sizeof(Elf_Rela);
+  else if (Type == SHT_REL)
+    this->Header.sh_entsize = sizeof(Elf_Rel);
+}
+
+template <class ELFT> void OutputSection<ELFT>::finalize() {
+  uint32_t Type = this->Header.sh_type;
+  if (Type != SHT_RELA && Type != SHT_REL)
+    return;
+  this->Header.sh_link = Out<ELFT>::SymTab->SectionIndex;
+  // sh_info for SHT_REL[A] sections should contain the section header index of
+  // the section to which the relocation applies.
+  InputSectionBase<ELFT> *S = Sections[0]->getRelocatedSection();
+  this->Header.sh_info = S->OutSec->SectionIndex;
+}
+
+template <class ELFT>
+void OutputSection<ELFT>::addSection(InputSectionBase<ELFT> *C) {
+  assert(C->Live);
+  auto *S = cast<InputSection<ELFT>>(C);
+  Sections.push_back(S);
+  S->OutSec = this;
+  this->updateAlignment(S->Alignment);
+}
+
+// If an input string is in the form of "foo.N" where N is a number,
+// return N. Otherwise, returns 65536, which is one greater than the
+// lowest priority.
+static int getPriority(StringRef S) {
+  size_t Pos = S.rfind('.');
+  if (Pos == StringRef::npos)
+    return 65536;
+  int V;
+  if (S.substr(Pos + 1).getAsInteger(10, V))
+    return 65536;
+  return V;
+}
+
+// This function is called after we sort input sections
+// and scan relocations to setup sections' offsets.
+template <class ELFT> void OutputSection<ELFT>::assignOffsets() {
+  uintX_t Off = this->Header.sh_size;
+  for (InputSection<ELFT> *S : Sections) {
+    Off = alignTo(Off, S->Alignment);
+    S->OutSecOff = Off;
+    Off += S->getSize();
+  }
+  this->Header.sh_size = Off;
+}
+
+// Sorts input sections by section name suffixes, so that .foo.N comes
+// before .foo.M if N < M. Used to sort .{init,fini}_array.N sections.
+// We want to keep the original order if the priorities are the same
+// because the compiler keeps the original initialization order in a
+// translation unit and we need to respect that.
+// For more detail, read the section of the GCC's manual about init_priority.
+template <class ELFT> void OutputSection<ELFT>::sortInitFini() {
+  // Sort sections by priority.
+  typedef std::pair<int, InputSection<ELFT> *> Pair;
+  auto Comp = [](const Pair &A, const Pair &B) { return A.first < B.first; };
+
+  std::vector<Pair> V;
+  for (InputSection<ELFT> *S : Sections)
+    V.push_back({getPriority(S->getSectionName()), S});
+  std::stable_sort(V.begin(), V.end(), Comp);
+  Sections.clear();
+  for (Pair &P : V)
+    Sections.push_back(P.second);
+}
+
+// Returns true if S matches /Filename.?\.o$/.
+static bool isCrtBeginEnd(StringRef S, StringRef Filename) {
+  if (!S.endswith(".o"))
+    return false;
+  S = S.drop_back(2);
+  if (S.endswith(Filename))
+    return true;
+  return !S.empty() && S.drop_back().endswith(Filename);
+}
+
+static bool isCrtbegin(StringRef S) { return isCrtBeginEnd(S, "crtbegin"); }
+static bool isCrtend(StringRef S) { return isCrtBeginEnd(S, "crtend"); }
+
+// .ctors and .dtors are sorted by this priority from highest to lowest.
+//
+//  1. The section was contained in crtbegin (crtbegin contains
+//     some sentinel value in its .ctors and .dtors so that the runtime
+//     can find the beginning of the sections.)
+//
+//  2. The section has an optional priority value in the form of ".ctors.N"
+//     or ".dtors.N" where N is a number. Unlike .{init,fini}_array,
+//     they are compared as string rather than number.
+//
+//  3. The section is just ".ctors" or ".dtors".
+//
+//  4. The section was contained in crtend, which contains an end marker.
+//
+// In an ideal world, we don't need this function because .init_array and
+// .ctors are duplicate features (and .init_array is newer.) However, there
+// are too many real-world use cases of .ctors, so we had no choice to
+// support that with this rather ad-hoc semantics.
+template <class ELFT>
+static bool compCtors(const InputSection<ELFT> *A,
+                      const InputSection<ELFT> *B) {
+  bool BeginA = isCrtbegin(A->getFile()->getName());
+  bool BeginB = isCrtbegin(B->getFile()->getName());
+  if (BeginA != BeginB)
+    return BeginA;
+  bool EndA = isCrtend(A->getFile()->getName());
+  bool EndB = isCrtend(B->getFile()->getName());
+  if (EndA != EndB)
+    return EndB;
+  StringRef X = A->getSectionName();
+  StringRef Y = B->getSectionName();
+  assert(X.startswith(".ctors") || X.startswith(".dtors"));
+  assert(Y.startswith(".ctors") || Y.startswith(".dtors"));
+  X = X.substr(6);
+  Y = Y.substr(6);
+  if (X.empty() && Y.empty())
+    return false;
+  return X < Y;
+}
+
+// Sorts input sections by the special rules for .ctors and .dtors.
+// Unfortunately, the rules are different from the one for .{init,fini}_array.
+// Read the comment above.
+template <class ELFT> void OutputSection<ELFT>::sortCtorsDtors() {
+  std::stable_sort(Sections.begin(), Sections.end(), compCtors<ELFT>);
+}
+
+static void fill(uint8_t *Buf, size_t Size, ArrayRef<uint8_t> A) {
+  size_t I = 0;
+  for (; I + A.size() < Size; I += A.size())
+    memcpy(Buf + I, A.data(), A.size());
+  memcpy(Buf + I, A.data(), Size - I);
+}
+
+template <class ELFT> void OutputSection<ELFT>::writeTo(uint8_t *Buf) {
+  ArrayRef<uint8_t> Filler = Script<ELFT>::X->getFiller(this->Name);
+  if (!Filler.empty())
+    fill(Buf, this->getSize(), Filler);
+  if (Config->Threads) {
+    parallel_for_each(Sections.begin(), Sections.end(),
+                      [=](InputSection<ELFT> *C) { C->writeTo(Buf); });
+  } else {
+    for (InputSection<ELFT> *C : Sections)
+      C->writeTo(Buf);
+  }
+}
+
+template <class ELFT>
+EhOutputSection<ELFT>::EhOutputSection()
+    : OutputSectionBase<ELFT>(".eh_frame", SHT_PROGBITS, SHF_ALLOC) {}
+
+// Returns the first relocation that points to a region
+// between Begin and Begin+Size.
+template <class IntTy, class RelTy>
+static const RelTy *getReloc(IntTy Begin, IntTy Size, ArrayRef<RelTy> &Rels) {
+  for (auto I = Rels.begin(), E = Rels.end(); I != E; ++I) {
+    if (I->r_offset < Begin)
+      continue;
+
+    // Truncate Rels for fast access. That means we expect that the
+    // relocations are sorted and we are looking up symbols in
+    // sequential order. It is naturally satisfied for .eh_frame.
+    Rels = Rels.slice(I - Rels.begin());
+    if (I->r_offset < Begin + Size)
+      return I;
+    return nullptr;
+  }
+  Rels = ArrayRef<RelTy>();
+  return nullptr;
+}
+
+// Search for an existing CIE record or create a new one.
+// CIE records from input object files are uniquified by their contents
+// and where their relocations point to.
+template <class ELFT>
+template <class RelTy>
+CieRecord *EhOutputSection<ELFT>::addCie(SectionPiece &Piece,
+                                         EhInputSection<ELFT> *Sec,
+                                         ArrayRef<RelTy> &Rels) {
+  const endianness E = ELFT::TargetEndianness;
+  if (read32<E>(Piece.data().data() + 4) != 0)
+    fatal("CIE expected at beginning of .eh_frame: " + Sec->getSectionName());
+
+  SymbolBody *Personality = nullptr;
+  if (const RelTy *Rel = getReloc(Piece.InputOff, Piece.size(), Rels))
+    Personality = &Sec->getFile()->getRelocTargetSym(*Rel);
+
+  // Search for an existing CIE by CIE contents/relocation target pair.
+  CieRecord *Cie = &CieMap[{Piece.data(), Personality}];
+
+  // If not found, create a new one.
+  if (Cie->Piece == nullptr) {
+    Cie->Piece = &Piece;
+    Cies.push_back(Cie);
+  }
+  return Cie;
+}
+
+// There is one FDE per function. Returns true if a given FDE
+// points to a live function.
+template <class ELFT>
+template <class RelTy>
+bool EhOutputSection<ELFT>::isFdeLive(SectionPiece &Piece,
+                                      EhInputSection<ELFT> *Sec,
+                                      ArrayRef<RelTy> &Rels) {
+  const RelTy *Rel = getReloc(Piece.InputOff, Piece.size(), Rels);
+  if (!Rel)
+    fatal("FDE doesn't reference another section");
+  SymbolBody &B = Sec->getFile()->getRelocTargetSym(*Rel);
+  auto *D = dyn_cast<DefinedRegular<ELFT>>(&B);
+  if (!D || !D->Section)
+    return false;
+  InputSectionBase<ELFT> *Target = D->Section->Repl;
+  return Target && Target->Live;
+}
+
+// .eh_frame is a sequence of CIE or FDE records. In general, there
+// is one CIE record per input object file which is followed by
+// a list of FDEs. This function searches an existing CIE or create a new
+// one and associates FDEs to the CIE.
+template <class ELFT>
+template <class RelTy>
+void EhOutputSection<ELFT>::addSectionAux(EhInputSection<ELFT> *Sec,
+                                          ArrayRef<RelTy> Rels) {
+  const endianness E = ELFT::TargetEndianness;
+
+  DenseMap<size_t, CieRecord *> OffsetToCie;
+  for (SectionPiece &Piece : Sec->Pieces) {
+    // The empty record is the end marker.
+    if (Piece.size() == 4)
+      return;
+
+    size_t Offset = Piece.InputOff;
+    uint32_t ID = read32<E>(Piece.data().data() + 4);
+    if (ID == 0) {
+      OffsetToCie[Offset] = addCie(Piece, Sec, Rels);
+      continue;
+    }
+
+    uint32_t CieOffset = Offset + 4 - ID;
+    CieRecord *Cie = OffsetToCie[CieOffset];
+    if (!Cie)
+      fatal("invalid CIE reference");
+
+    if (!isFdeLive(Piece, Sec, Rels))
+      continue;
+    Cie->FdePieces.push_back(&Piece);
+    NumFdes++;
+  }
+}
+
+template <class ELFT>
+void EhOutputSection<ELFT>::addSection(InputSectionBase<ELFT> *C) {
+  auto *Sec = cast<EhInputSection<ELFT>>(C);
+  Sec->OutSec = this;
+  this->updateAlignment(Sec->Alignment);
+  Sections.push_back(Sec);
+
+  // .eh_frame is a sequence of CIE or FDE records. This function
+  // splits it into pieces so that we can call
+  // SplitInputSection::getSectionPiece on the section.
+  Sec->split();
+  if (Sec->Pieces.empty())
+    return;
+
+  if (const Elf_Shdr *RelSec = Sec->RelocSection) {
+    ELFFile<ELFT> &Obj = Sec->getFile()->getObj();
+    if (RelSec->sh_type == SHT_RELA)
+      addSectionAux(Sec, Obj.relas(RelSec));
+    else
+      addSectionAux(Sec, Obj.rels(RelSec));
+    return;
+  }
+  addSectionAux(Sec, makeArrayRef<Elf_Rela>(nullptr, nullptr));
+}
+
+template <class ELFT>
+static void writeCieFde(uint8_t *Buf, ArrayRef<uint8_t> D) {
+  memcpy(Buf, D.data(), D.size());
+
+  // Fix the size field. -4 since size does not include the size field itself.
+  const endianness E = ELFT::TargetEndianness;
+  write32<E>(Buf, alignTo(D.size(), sizeof(typename ELFT::uint)) - 4);
+}
+
+template <class ELFT> void EhOutputSection<ELFT>::finalize() {
+  if (this->Header.sh_size)
+    return; // Already finalized.
+
+  size_t Off = 0;
+  for (CieRecord *Cie : Cies) {
+    Cie->Piece->OutputOff = Off;
+    Off += alignTo(Cie->Piece->size(), sizeof(uintX_t));
+
+    for (SectionPiece *Fde : Cie->FdePieces) {
+      Fde->OutputOff = Off;
+      Off += alignTo(Fde->size(), sizeof(uintX_t));
+    }
+  }
+  this->Header.sh_size = Off;
+}
+
+template <class ELFT> static uint64_t readFdeAddr(uint8_t *Buf, int Size) {
+  const endianness E = ELFT::TargetEndianness;
+  switch (Size) {
+  case DW_EH_PE_udata2:
+    return read16<E>(Buf);
+  case DW_EH_PE_udata4:
+    return read32<E>(Buf);
+  case DW_EH_PE_udata8:
+    return read64<E>(Buf);
+  case DW_EH_PE_absptr:
+    if (ELFT::Is64Bits)
+      return read64<E>(Buf);
+    return read32<E>(Buf);
+  }
+  fatal("unknown FDE size encoding");
+}
+
+// Returns the VA to which a given FDE (on a mmap'ed buffer) is applied to.
+// We need it to create .eh_frame_hdr section.
+template <class ELFT>
+typename ELFT::uint EhOutputSection<ELFT>::getFdePc(uint8_t *Buf, size_t FdeOff,
+                                                    uint8_t Enc) {
+  // The starting address to which this FDE applies is
+  // stored at FDE + 8 byte.
+  size_t Off = FdeOff + 8;
+  uint64_t Addr = readFdeAddr<ELFT>(Buf + Off, Enc & 0x7);
+  if ((Enc & 0x70) == DW_EH_PE_absptr)
+    return Addr;
+  if ((Enc & 0x70) == DW_EH_PE_pcrel)
+    return Addr + this->getVA() + Off;
+  fatal("unknown FDE size relative encoding");
+}
+
+template <class ELFT> void EhOutputSection<ELFT>::writeTo(uint8_t *Buf) {
+  const endianness E = ELFT::TargetEndianness;
+  for (CieRecord *Cie : Cies) {
+    size_t CieOffset = Cie->Piece->OutputOff;
+    writeCieFde<ELFT>(Buf + CieOffset, Cie->Piece->data());
+
+    for (SectionPiece *Fde : Cie->FdePieces) {
+      size_t Off = Fde->OutputOff;
+      writeCieFde<ELFT>(Buf + Off, Fde->data());
+
+      // FDE's second word should have the offset to an associated CIE.
+      // Write it.
+      write32<E>(Buf + Off + 4, Off + 4 - CieOffset);
+    }
+  }
+
+  for (EhInputSection<ELFT> *S : Sections)
+    S->relocate(Buf, nullptr);
+
+  // Construct .eh_frame_hdr. .eh_frame_hdr is a binary search table
+  // to get a FDE from an address to which FDE is applied. So here
+  // we obtain two addresses and pass them to EhFrameHdr object.
+  if (Out<ELFT>::EhFrameHdr) {
+    for (CieRecord *Cie : Cies) {
+      uint8_t Enc = getFdeEncoding<ELFT>(Cie->Piece->data());
+      for (SectionPiece *Fde : Cie->FdePieces) {
+        uintX_t Pc = getFdePc(Buf, Fde->OutputOff, Enc);
+        uintX_t FdeVA = this->getVA() + Fde->OutputOff;
+        Out<ELFT>::EhFrameHdr->addFde(Pc, FdeVA);
+      }
+    }
+  }
+}
+
+template <class ELFT>
+MergeOutputSection<ELFT>::MergeOutputSection(StringRef Name, uint32_t Type,
+                                             uintX_t Flags, uintX_t Alignment)
+    : OutputSectionBase<ELFT>(Name, Type, Flags),
+      Builder(StringTableBuilder::RAW, Alignment) {}
+
+template <class ELFT> void MergeOutputSection<ELFT>::writeTo(uint8_t *Buf) {
+  if (shouldTailMerge()) {
+    StringRef Data = Builder.data();
+    memcpy(Buf, Data.data(), Data.size());
+    return;
+  }
+  for (const std::pair<CachedHash<StringRef>, size_t> &P : Builder.getMap()) {
+    StringRef Data = P.first.Val;
+    memcpy(Buf + P.second, Data.data(), Data.size());
+  }
+}
+
+static StringRef toStringRef(ArrayRef<uint8_t> A) {
+  return {(const char *)A.data(), A.size()};
+}
+
+template <class ELFT>
+void MergeOutputSection<ELFT>::addSection(InputSectionBase<ELFT> *C) {
+  auto *Sec = cast<MergeInputSection<ELFT>>(C);
+  Sec->OutSec = this;
+  this->updateAlignment(Sec->Alignment);
+  this->Header.sh_entsize = Sec->getSectionHdr()->sh_entsize;
+  Sections.push_back(Sec);
+
+  bool IsString = this->Header.sh_flags & SHF_STRINGS;
+
+  for (SectionPiece &Piece : Sec->Pieces) {
+    if (!Piece.Live)
+      continue;
+    uintX_t OutputOffset = Builder.add(toStringRef(Piece.data()));
+    if (!IsString || !shouldTailMerge())
+      Piece.OutputOff = OutputOffset;
+  }
+}
+
+template <class ELFT>
+unsigned MergeOutputSection<ELFT>::getOffset(StringRef Val) {
+  return Builder.getOffset(Val);
+}
+
+template <class ELFT> bool MergeOutputSection<ELFT>::shouldTailMerge() const {
+  return Config->Optimize >= 2 && this->Header.sh_flags & SHF_STRINGS;
+}
+
+template <class ELFT> void MergeOutputSection<ELFT>::finalize() {
+  if (shouldTailMerge())
+    Builder.finalize();
+  this->Header.sh_size = Builder.getSize();
+}
+
+template <class ELFT> void MergeOutputSection<ELFT>::finalizePieces() {
+  for (MergeInputSection<ELFT> *Sec : Sections)
+    Sec->finalizePieces();
+}
+
+template <class ELFT>
+StringTableSection<ELFT>::StringTableSection(StringRef Name, bool Dynamic)
+    : OutputSectionBase<ELFT>(Name, SHT_STRTAB,
+                              Dynamic ? (uintX_t)SHF_ALLOC : 0),
+      Dynamic(Dynamic) {}
+
+// Adds a string to the string table. If HashIt is true we hash and check for
+// duplicates. It is optional because the name of global symbols are already
+// uniqued and hashing them again has a big cost for a small value: uniquing
+// them with some other string that happens to be the same.
+template <class ELFT>
+unsigned StringTableSection<ELFT>::addString(StringRef S, bool HashIt) {
+  if (HashIt) {
+    auto R = StringMap.insert(std::make_pair(S, Size));
+    if (!R.second)
+      return R.first->second;
+  }
+  unsigned Ret = Size;
+  Size += S.size() + 1;
+  Strings.push_back(S);
+  return Ret;
+}
+
+template <class ELFT> void StringTableSection<ELFT>::writeTo(uint8_t *Buf) {
+  // ELF string tables start with NUL byte, so advance the pointer by one.
+  ++Buf;
+  for (StringRef S : Strings) {
+    memcpy(Buf, S.data(), S.size());
+    Buf += S.size() + 1;
+  }
+}
+
+template <class ELFT>
+typename ELFT::uint DynamicReloc<ELFT>::getOffset() const {
+  if (OutputSec)
+    return OutputSec->getVA() + OffsetInSec;
+  return InputSec->OutSec->getVA() + InputSec->getOffset(OffsetInSec);
+}
+
+template <class ELFT>
+typename ELFT::uint DynamicReloc<ELFT>::getAddend() const {
+  if (UseSymVA)
+    return Sym->getVA<ELFT>(Addend);
+  return Addend;
+}
+
+template <class ELFT> uint32_t DynamicReloc<ELFT>::getSymIndex() const {
+  if (Sym && !UseSymVA)
+    return Sym->DynsymIndex;
+  return 0;
+}
+
+template <class ELFT>
+SymbolTableSection<ELFT>::SymbolTableSection(
+    StringTableSection<ELFT> &StrTabSec)
+    : OutputSectionBase<ELFT>(StrTabSec.isDynamic() ? ".dynsym" : ".symtab",
+                              StrTabSec.isDynamic() ? SHT_DYNSYM : SHT_SYMTAB,
+                              StrTabSec.isDynamic() ? (uintX_t)SHF_ALLOC : 0),
+      StrTabSec(StrTabSec) {
+  this->Header.sh_entsize = sizeof(Elf_Sym);
+  this->Header.sh_addralign = sizeof(uintX_t);
+}
+
+// Orders symbols according to their positions in the GOT,
+// in compliance with MIPS ABI rules.
+// See "Global Offset Table" in Chapter 5 in the following document
+// for detailed description:
+// ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
+static bool sortMipsSymbols(const std::pair<SymbolBody *, unsigned> &L,
+                            const std::pair<SymbolBody *, unsigned> &R) {
+  // Sort entries related to non-local preemptible symbols by GOT indexes.
+  // All other entries go to the first part of GOT in arbitrary order.
+  bool LIsInLocalGot = !L.first->IsInGlobalMipsGot;
+  bool RIsInLocalGot = !R.first->IsInGlobalMipsGot;
+  if (LIsInLocalGot || RIsInLocalGot)
+    return !RIsInLocalGot;
+  return L.first->GotIndex < R.first->GotIndex;
+}
+
+static uint8_t getSymbolBinding(SymbolBody *Body) {
+  Symbol *S = Body->symbol();
+  uint8_t Visibility = S->Visibility;
+  if (Visibility != STV_DEFAULT && Visibility != STV_PROTECTED)
+    return STB_LOCAL;
+  if (Config->NoGnuUnique && S->Binding == STB_GNU_UNIQUE)
+    return STB_GLOBAL;
+  return S->Binding;
+}
+
+template <class ELFT> void SymbolTableSection<ELFT>::finalize() {
+  if (this->Header.sh_size)
+    return; // Already finalized.
+
+  this->Header.sh_size = getNumSymbols() * sizeof(Elf_Sym);
+  this->Header.sh_link = StrTabSec.SectionIndex;
+  this->Header.sh_info = NumLocals + 1;
+
+  if (Config->Relocatable) {
+    size_t I = NumLocals;
+    for (const std::pair<SymbolBody *, size_t> &P : Symbols)
+      P.first->DynsymIndex = ++I;
+    return;
+  }
+
+  if (!StrTabSec.isDynamic()) {
+    std::stable_sort(Symbols.begin(), Symbols.end(),
+                     [](const std::pair<SymbolBody *, unsigned> &L,
+                        const std::pair<SymbolBody *, unsigned> &R) {
+                       return getSymbolBinding(L.first) == STB_LOCAL &&
+                              getSymbolBinding(R.first) != STB_LOCAL;
+                     });
+    return;
+  }
+  if (Out<ELFT>::GnuHashTab)
+    // NB: It also sorts Symbols to meet the GNU hash table requirements.
+    Out<ELFT>::GnuHashTab->addSymbols(Symbols);
+  else if (Config->EMachine == EM_MIPS)
+    std::stable_sort(Symbols.begin(), Symbols.end(), sortMipsSymbols);
+  size_t I = 0;
+  for (const std::pair<SymbolBody *, size_t> &P : Symbols)
+    P.first->DynsymIndex = ++I;
+}
+
+template <class ELFT>
+void SymbolTableSection<ELFT>::addSymbol(SymbolBody *B) {
+  Symbols.push_back({B, StrTabSec.addString(B->getName(), false)});
+}
+
+template <class ELFT> void SymbolTableSection<ELFT>::writeTo(uint8_t *Buf) {
+  Buf += sizeof(Elf_Sym);
+
+  // All symbols with STB_LOCAL binding precede the weak and global symbols.
+  // .dynsym only contains global symbols.
+  if (!Config->DiscardAll && !StrTabSec.isDynamic())
+    writeLocalSymbols(Buf);
+
+  writeGlobalSymbols(Buf);
+}
+
+template <class ELFT>
+void SymbolTableSection<ELFT>::writeLocalSymbols(uint8_t *&Buf) {
+  // Iterate over all input object files to copy their local symbols
+  // to the output symbol table pointed by Buf.
+  for (const std::unique_ptr<ObjectFile<ELFT>> &File :
+       Symtab<ELFT>::X->getObjectFiles()) {
+    for (const std::pair<const DefinedRegular<ELFT> *, size_t> &P :
+         File->KeptLocalSyms) {
+      const DefinedRegular<ELFT> &Body = *P.first;
+      InputSectionBase<ELFT> *Section = Body.Section;
+      auto *ESym = reinterpret_cast<Elf_Sym *>(Buf);
+
+      if (!Section) {
+        ESym->st_shndx = SHN_ABS;
+        ESym->st_value = Body.Value;
+      } else {
+        const OutputSectionBase<ELFT> *OutSec = Section->OutSec;
+        ESym->st_shndx = OutSec->SectionIndex;
+        ESym->st_value = OutSec->getVA() + Section->getOffset(Body);
+      }
+      ESym->st_name = P.second;
+      ESym->st_size = Body.template getSize<ELFT>();
+      ESym->setBindingAndType(STB_LOCAL, Body.Type);
+      Buf += sizeof(*ESym);
+    }
+  }
+}
+
+template <class ELFT>
+void SymbolTableSection<ELFT>::writeGlobalSymbols(uint8_t *Buf) {
+  // Write the internal symbol table contents to the output symbol table
+  // pointed by Buf.
+  auto *ESym = reinterpret_cast<Elf_Sym *>(Buf);
+  for (const std::pair<SymbolBody *, size_t> &P : Symbols) {
+    SymbolBody *Body = P.first;
+    size_t StrOff = P.second;
+
+    uint8_t Type = Body->Type;
+    uintX_t Size = Body->getSize<ELFT>();
+
+    ESym->setBindingAndType(getSymbolBinding(Body), Type);
+    ESym->st_size = Size;
+    ESym->st_name = StrOff;
+    ESym->setVisibility(Body->symbol()->Visibility);
+    ESym->st_value = Body->getVA<ELFT>();
+
+    if (const OutputSectionBase<ELFT> *OutSec = getOutputSection(Body))
+      ESym->st_shndx = OutSec->SectionIndex;
+    else if (isa<DefinedRegular<ELFT>>(Body))
+      ESym->st_shndx = SHN_ABS;
+
+    // On MIPS we need to mark symbol which has a PLT entry and requires pointer
+    // equality by STO_MIPS_PLT flag. That is necessary to help dynamic linker
+    // distinguish such symbols and MIPS lazy-binding stubs.
+    // https://sourceware.org/ml/binutils/2008-07/txt00000.txt
+    if (Config->EMachine == EM_MIPS && Body->isInPlt() &&
+        Body->NeedsCopyOrPltAddr)
+      ESym->st_other |= STO_MIPS_PLT;
+    ++ESym;
+  }
+}
+
+template <class ELFT>
+const OutputSectionBase<ELFT> *
+SymbolTableSection<ELFT>::getOutputSection(SymbolBody *Sym) {
+  switch (Sym->kind()) {
+  case SymbolBody::DefinedSyntheticKind:
+    return cast<DefinedSynthetic<ELFT>>(Sym)->Section;
+  case SymbolBody::DefinedRegularKind: {
+    auto &D = cast<DefinedRegular<ELFT>>(*Sym);
+    if (D.Section)
+      return D.Section->OutSec;
+    break;
+  }
+  case SymbolBody::DefinedCommonKind:
+    return Out<ELFT>::Bss;
+  case SymbolBody::SharedKind:
+    if (cast<SharedSymbol<ELFT>>(Sym)->needsCopy())
+      return Out<ELFT>::Bss;
+    break;
+  case SymbolBody::UndefinedKind:
+  case SymbolBody::LazyArchiveKind:
+  case SymbolBody::LazyObjectKind:
+    break;
+  case SymbolBody::DefinedBitcodeKind:
+    llvm_unreachable("should have been replaced");
+  }
+  return nullptr;
+}
+
+template <class ELFT>
+VersionDefinitionSection<ELFT>::VersionDefinitionSection()
+    : OutputSectionBase<ELFT>(".gnu.version_d", SHT_GNU_verdef, SHF_ALLOC) {
+  this->Header.sh_addralign = sizeof(uint32_t);
+}
+
+static StringRef getFileDefName() {
+  if (!Config->SoName.empty())
+    return Config->SoName;
+  return Config->OutputFile;
+}
+
+template <class ELFT> void VersionDefinitionSection<ELFT>::finalize() {
+  FileDefNameOff = Out<ELFT>::DynStrTab->addString(getFileDefName());
+  for (VersionDefinition &V : Config->VersionDefinitions)
+    V.NameOff = Out<ELFT>::DynStrTab->addString(V.Name);
+
+  this->Header.sh_size =
+      (sizeof(Elf_Verdef) + sizeof(Elf_Verdaux)) * getVerDefNum();
+  this->Header.sh_link = Out<ELFT>::DynStrTab->SectionIndex;
+
+  // sh_info should be set to the number of definitions. This fact is missed in
+  // documentation, but confirmed by binutils community:
+  // https://sourceware.org/ml/binutils/2014-11/msg00355.html
+  this->Header.sh_info = getVerDefNum();
+}
+
+template <class ELFT>
+void VersionDefinitionSection<ELFT>::writeOne(uint8_t *Buf, uint32_t Index,
+                                              StringRef Name, size_t NameOff) {
+  auto *Verdef = reinterpret_cast<Elf_Verdef *>(Buf);
+  Verdef->vd_version = 1;
+  Verdef->vd_cnt = 1;
+  Verdef->vd_aux = sizeof(Elf_Verdef);
+  Verdef->vd_next = sizeof(Elf_Verdef) + sizeof(Elf_Verdaux);
+  Verdef->vd_flags = (Index == 1 ? VER_FLG_BASE : 0);
+  Verdef->vd_ndx = Index;
+  Verdef->vd_hash = hashSysv(Name);
+
+  auto *Verdaux = reinterpret_cast<Elf_Verdaux *>(Buf + sizeof(Elf_Verdef));
+  Verdaux->vda_name = NameOff;
+  Verdaux->vda_next = 0;
+}
+
+template <class ELFT>
+void VersionDefinitionSection<ELFT>::writeTo(uint8_t *Buf) {
+  writeOne(Buf, 1, getFileDefName(), FileDefNameOff);
+
+  for (VersionDefinition &V : Config->VersionDefinitions) {
+    Buf += sizeof(Elf_Verdef) + sizeof(Elf_Verdaux);
+    writeOne(Buf, V.Id, V.Name, V.NameOff);
+  }
+
+  // Need to terminate the last version definition.
+  Elf_Verdef *Verdef = reinterpret_cast<Elf_Verdef *>(Buf);
+  Verdef->vd_next = 0;
+}
+
+template <class ELFT>
+VersionTableSection<ELFT>::VersionTableSection()
+    : OutputSectionBase<ELFT>(".gnu.version", SHT_GNU_versym, SHF_ALLOC) {
+  this->Header.sh_addralign = sizeof(uint16_t);
+}
+
+template <class ELFT> void VersionTableSection<ELFT>::finalize() {
+  this->Header.sh_size =
+      sizeof(Elf_Versym) * (Out<ELFT>::DynSymTab->getSymbols().size() + 1);
+  this->Header.sh_entsize = sizeof(Elf_Versym);
+  // At the moment of june 2016 GNU docs does not mention that sh_link field
+  // should be set, but Sun docs do. Also readelf relies on this field.
+  this->Header.sh_link = Out<ELFT>::DynSymTab->SectionIndex;
+}
+
+template <class ELFT> void VersionTableSection<ELFT>::writeTo(uint8_t *Buf) {
+  auto *OutVersym = reinterpret_cast<Elf_Versym *>(Buf) + 1;
+  for (const std::pair<SymbolBody *, size_t> &P :
+       Out<ELFT>::DynSymTab->getSymbols()) {
+    OutVersym->vs_index = P.first->symbol()->VersionId;
+    ++OutVersym;
+  }
+}
+
+template <class ELFT>
+VersionNeedSection<ELFT>::VersionNeedSection()
+    : OutputSectionBase<ELFT>(".gnu.version_r", SHT_GNU_verneed, SHF_ALLOC) {
+  this->Header.sh_addralign = sizeof(uint32_t);
+
+  // Identifiers in verneed section start at 2 because 0 and 1 are reserved
+  // for VER_NDX_LOCAL and VER_NDX_GLOBAL.
+  // First identifiers are reserved by verdef section if it exist.
+  NextIndex = getVerDefNum() + 1;
+}
+
+template <class ELFT>
+void VersionNeedSection<ELFT>::addSymbol(SharedSymbol<ELFT> *SS) {
+  if (!SS->Verdef) {
+    SS->symbol()->VersionId = VER_NDX_GLOBAL;
+    return;
+  }
+  SharedFile<ELFT> *F = SS->file();
+  // If we don't already know that we need an Elf_Verneed for this DSO, prepare
+  // to create one by adding it to our needed list and creating a dynstr entry
+  // for the soname.
+  if (F->VerdefMap.empty())
+    Needed.push_back({F, Out<ELFT>::DynStrTab->addString(F->getSoName())});
+  typename SharedFile<ELFT>::NeededVer &NV = F->VerdefMap[SS->Verdef];
+  // If we don't already know that we need an Elf_Vernaux for this Elf_Verdef,
+  // prepare to create one by allocating a version identifier and creating a
+  // dynstr entry for the version name.
+  if (NV.Index == 0) {
+    NV.StrTab = Out<ELFT>::DynStrTab->addString(
+        SS->file()->getStringTable().data() + SS->Verdef->getAux()->vda_name);
+    NV.Index = NextIndex++;
+  }
+  SS->symbol()->VersionId = NV.Index;
+}
+
+template <class ELFT> void VersionNeedSection<ELFT>::writeTo(uint8_t *Buf) {
+  // The Elf_Verneeds need to appear first, followed by the Elf_Vernauxs.
+  auto *Verneed = reinterpret_cast<Elf_Verneed *>(Buf);
+  auto *Vernaux = reinterpret_cast<Elf_Vernaux *>(Verneed + Needed.size());
+
+  for (std::pair<SharedFile<ELFT> *, size_t> &P : Needed) {
+    // Create an Elf_Verneed for this DSO.
+    Verneed->vn_version = 1;
+    Verneed->vn_cnt = P.first->VerdefMap.size();
+    Verneed->vn_file = P.second;
+    Verneed->vn_aux =
+        reinterpret_cast<char *>(Vernaux) - reinterpret_cast<char *>(Verneed);
+    Verneed->vn_next = sizeof(Elf_Verneed);
+    ++Verneed;
+
+    // Create the Elf_Vernauxs for this Elf_Verneed. The loop iterates over
+    // VerdefMap, which will only contain references to needed version
+    // definitions. Each Elf_Vernaux is based on the information contained in
+    // the Elf_Verdef in the source DSO. This loop iterates over a std::map of
+    // pointers, but is deterministic because the pointers refer to Elf_Verdef
+    // data structures within a single input file.
+    for (auto &NV : P.first->VerdefMap) {
+      Vernaux->vna_hash = NV.first->vd_hash;
+      Vernaux->vna_flags = 0;
+      Vernaux->vna_other = NV.second.Index;
+      Vernaux->vna_name = NV.second.StrTab;
+      Vernaux->vna_next = sizeof(Elf_Vernaux);
+      ++Vernaux;
+    }
+
+    Vernaux[-1].vna_next = 0;
+  }
+  Verneed[-1].vn_next = 0;
+}
+
+template <class ELFT> void VersionNeedSection<ELFT>::finalize() {
+  this->Header.sh_link = Out<ELFT>::DynStrTab->SectionIndex;
+  this->Header.sh_info = Needed.size();
+  unsigned Size = Needed.size() * sizeof(Elf_Verneed);
+  for (std::pair<SharedFile<ELFT> *, size_t> &P : Needed)
+    Size += P.first->VerdefMap.size() * sizeof(Elf_Vernaux);
+  this->Header.sh_size = Size;
+}
+
+template <class ELFT>
+BuildIdSection<ELFT>::BuildIdSection(size_t HashSize)
+    : OutputSectionBase<ELFT>(".note.gnu.build-id", SHT_NOTE, SHF_ALLOC),
+      HashSize(HashSize) {
+  // 16 bytes for the note section header.
+  this->Header.sh_size = 16 + HashSize;
+}
+
+template <class ELFT> void BuildIdSection<ELFT>::writeTo(uint8_t *Buf) {
+  const endianness E = ELFT::TargetEndianness;
+  write32<E>(Buf, 4);                   // Name size
+  write32<E>(Buf + 4, HashSize);        // Content size
+  write32<E>(Buf + 8, NT_GNU_BUILD_ID); // Type
+  memcpy(Buf + 12, "GNU", 4);           // Name string
+  HashBuf = Buf + 16;
+}
+
+template <class ELFT>
+void BuildIdFnv1<ELFT>::writeBuildId(ArrayRef<ArrayRef<uint8_t>> Bufs) {
+  const endianness E = ELFT::TargetEndianness;
+
+  // 64-bit FNV-1 hash
+  uint64_t Hash = 0xcbf29ce484222325;
+  for (ArrayRef<uint8_t> Buf : Bufs) {
+    for (uint8_t B : Buf) {
+      Hash *= 0x100000001b3;
+      Hash ^= B;
+    }
+  }
+  write64<E>(this->HashBuf, Hash);
+}
+
+template <class ELFT>
+void BuildIdMd5<ELFT>::writeBuildId(ArrayRef<ArrayRef<uint8_t>> Bufs) {
+  MD5 Hash;
+  for (ArrayRef<uint8_t> Buf : Bufs)
+    Hash.update(Buf);
+  MD5::MD5Result Res;
+  Hash.final(Res);
+  memcpy(this->HashBuf, Res, 16);
+}
+
+template <class ELFT>
+void BuildIdSha1<ELFT>::writeBuildId(ArrayRef<ArrayRef<uint8_t>> Bufs) {
+  SHA1 Hash;
+  for (ArrayRef<uint8_t> Buf : Bufs)
+    Hash.update(Buf);
+  memcpy(this->HashBuf, Hash.final().data(), 20);
+}
+
+template <class ELFT>
+BuildIdHexstring<ELFT>::BuildIdHexstring()
+    : BuildIdSection<ELFT>(Config->BuildIdVector.size()) {}
+
+template <class ELFT>
+void BuildIdHexstring<ELFT>::writeBuildId(ArrayRef<ArrayRef<uint8_t>> Bufs) {
+  memcpy(this->HashBuf, Config->BuildIdVector.data(),
+         Config->BuildIdVector.size());
+}
+
+template <class ELFT>
+MipsReginfoOutputSection<ELFT>::MipsReginfoOutputSection()
+    : OutputSectionBase<ELFT>(".reginfo", SHT_MIPS_REGINFO, SHF_ALLOC) {
+  this->Header.sh_addralign = 4;
+  this->Header.sh_entsize = sizeof(Elf_Mips_RegInfo);
+  this->Header.sh_size = sizeof(Elf_Mips_RegInfo);
+}
+
+template <class ELFT>
+void MipsReginfoOutputSection<ELFT>::writeTo(uint8_t *Buf) {
+  auto *R = reinterpret_cast<Elf_Mips_RegInfo *>(Buf);
+  R->ri_gp_value = Out<ELFT>::Got->getVA() + MipsGPOffset;
+  R->ri_gprmask = GprMask;
+}
+
+template <class ELFT>
+void MipsReginfoOutputSection<ELFT>::addSection(InputSectionBase<ELFT> *C) {
+  // Copy input object file's .reginfo gprmask to output.
+  auto *S = cast<MipsReginfoInputSection<ELFT>>(C);
+  GprMask |= S->Reginfo->ri_gprmask;
+  S->OutSec = this;
+}
+
+template <class ELFT>
+MipsOptionsOutputSection<ELFT>::MipsOptionsOutputSection()
+    : OutputSectionBase<ELFT>(".MIPS.options", SHT_MIPS_OPTIONS,
+                              SHF_ALLOC | SHF_MIPS_NOSTRIP) {
+  this->Header.sh_addralign = 8;
+  this->Header.sh_entsize = 1;
+  this->Header.sh_size = sizeof(Elf_Mips_Options) + sizeof(Elf_Mips_RegInfo);
+}
+
+template <class ELFT>
+void MipsOptionsOutputSection<ELFT>::writeTo(uint8_t *Buf) {
+  auto *Opt = reinterpret_cast<Elf_Mips_Options *>(Buf);
+  Opt->kind = ODK_REGINFO;
+  Opt->size = this->Header.sh_size;
+  Opt->section = 0;
+  Opt->info = 0;
+  auto *Reg = reinterpret_cast<Elf_Mips_RegInfo *>(Buf + sizeof(*Opt));
+  Reg->ri_gp_value = Out<ELFT>::Got->getVA() + MipsGPOffset;
+  Reg->ri_gprmask = GprMask;
+}
+
+template <class ELFT>
+void MipsOptionsOutputSection<ELFT>::addSection(InputSectionBase<ELFT> *C) {
+  auto *S = cast<MipsOptionsInputSection<ELFT>>(C);
+  if (S->Reginfo)
+    GprMask |= S->Reginfo->ri_gprmask;
+  S->OutSec = this;
+}
+
+template <class ELFT>
+std::pair<OutputSectionBase<ELFT> *, bool>
+OutputSectionFactory<ELFT>::create(InputSectionBase<ELFT> *C,
+                                   StringRef OutsecName) {
+  SectionKey<ELFT::Is64Bits> Key = createKey(C, OutsecName);
+  OutputSectionBase<ELFT> *&Sec = Map[Key];
+  if (Sec)
+    return {Sec, false};
+
+  switch (C->SectionKind) {
+  case InputSectionBase<ELFT>::Regular:
+    Sec = new OutputSection<ELFT>(Key.Name, Key.Type, Key.Flags);
+    break;
+  case InputSectionBase<ELFT>::EHFrame:
+    return {Out<ELFT>::EhFrame, false};
+  case InputSectionBase<ELFT>::Merge:
+    Sec = new MergeOutputSection<ELFT>(Key.Name, Key.Type, Key.Flags,
+                                       Key.Alignment);
+    break;
+  case InputSectionBase<ELFT>::MipsReginfo:
+    Sec = new MipsReginfoOutputSection<ELFT>();
+    break;
+  case InputSectionBase<ELFT>::MipsOptions:
+    Sec = new MipsOptionsOutputSection<ELFT>();
+    break;
+  }
+  return {Sec, true};
+}
+
+template <class ELFT>
+OutputSectionBase<ELFT> *OutputSectionFactory<ELFT>::lookup(StringRef Name,
+                                                            uint32_t Type,
+                                                            uintX_t Flags) {
+  return Map.lookup({Name, Type, Flags, 0});
+}
+
+template <class ELFT>
+SectionKey<ELFT::Is64Bits>
+OutputSectionFactory<ELFT>::createKey(InputSectionBase<ELFT> *C,
+                                      StringRef OutsecName) {
+  const Elf_Shdr *H = C->getSectionHdr();
+  uintX_t Flags = H->sh_flags & ~SHF_GROUP & ~SHF_COMPRESSED;
+
+  // For SHF_MERGE we create different output sections for each alignment.
+  // This makes each output section simple and keeps a single level mapping from
+  // input to output.
+  uintX_t Alignment = 0;
+  if (isa<MergeInputSection<ELFT>>(C))
+    Alignment = std::max(H->sh_addralign, H->sh_entsize);
+
+  uint32_t Type = H->sh_type;
+  return SectionKey<ELFT::Is64Bits>{OutsecName, Type, Flags, Alignment};
+}
+
+template <bool Is64Bits>
+typename lld::elf::SectionKey<Is64Bits>
+DenseMapInfo<lld::elf::SectionKey<Is64Bits>>::getEmptyKey() {
+  return SectionKey<Is64Bits>{DenseMapInfo<StringRef>::getEmptyKey(), 0, 0, 0};
+}
+
+template <bool Is64Bits>
+typename lld::elf::SectionKey<Is64Bits>
+DenseMapInfo<lld::elf::SectionKey<Is64Bits>>::getTombstoneKey() {
+  return SectionKey<Is64Bits>{DenseMapInfo<StringRef>::getTombstoneKey(), 0, 0,
+                              0};
+}
+
+template <bool Is64Bits>
+unsigned
+DenseMapInfo<lld::elf::SectionKey<Is64Bits>>::getHashValue(const Key &Val) {
+  return hash_combine(Val.Name, Val.Type, Val.Flags, Val.Alignment);
+}
+
+template <bool Is64Bits>
+bool DenseMapInfo<lld::elf::SectionKey<Is64Bits>>::isEqual(const Key &LHS,
+                                                           const Key &RHS) {
+  return DenseMapInfo<StringRef>::isEqual(LHS.Name, RHS.Name) &&
+         LHS.Type == RHS.Type && LHS.Flags == RHS.Flags &&
+         LHS.Alignment == RHS.Alignment;
+}
+
+namespace llvm {
+template struct DenseMapInfo<SectionKey<true>>;
+template struct DenseMapInfo<SectionKey<false>>;
+}
+
+namespace lld {
+namespace elf {
+template class OutputSectionBase<ELF32LE>;
+template class OutputSectionBase<ELF32BE>;
+template class OutputSectionBase<ELF64LE>;
+template class OutputSectionBase<ELF64BE>;
+
+template class EhFrameHeader<ELF32LE>;
+template class EhFrameHeader<ELF32BE>;
+template class EhFrameHeader<ELF64LE>;
+template class EhFrameHeader<ELF64BE>;
+
+template class GotPltSection<ELF32LE>;
+template class GotPltSection<ELF32BE>;
+template class GotPltSection<ELF64LE>;
+template class GotPltSection<ELF64BE>;
+
+template class GotSection<ELF32LE>;
+template class GotSection<ELF32BE>;
+template class GotSection<ELF64LE>;
+template class GotSection<ELF64BE>;
+
+template class PltSection<ELF32LE>;
+template class PltSection<ELF32BE>;
+template class PltSection<ELF64LE>;
+template class PltSection<ELF64BE>;
+
+template class RelocationSection<ELF32LE>;
+template class RelocationSection<ELF32BE>;
+template class RelocationSection<ELF64LE>;
+template class RelocationSection<ELF64BE>;
+
+template class InterpSection<ELF32LE>;
+template class InterpSection<ELF32BE>;
+template class InterpSection<ELF64LE>;
+template class InterpSection<ELF64BE>;
+
+template class GnuHashTableSection<ELF32LE>;
+template class GnuHashTableSection<ELF32BE>;
+template class GnuHashTableSection<ELF64LE>;
+template class GnuHashTableSection<ELF64BE>;
+
+template class HashTableSection<ELF32LE>;
+template class HashTableSection<ELF32BE>;
+template class HashTableSection<ELF64LE>;
+template class HashTableSection<ELF64BE>;
+
+template class DynamicSection<ELF32LE>;
+template class DynamicSection<ELF32BE>;
+template class DynamicSection<ELF64LE>;
+template class DynamicSection<ELF64BE>;
+
+template class OutputSection<ELF32LE>;
+template class OutputSection<ELF32BE>;
+template class OutputSection<ELF64LE>;
+template class OutputSection<ELF64BE>;
+
+template class EhOutputSection<ELF32LE>;
+template class EhOutputSection<ELF32BE>;
+template class EhOutputSection<ELF64LE>;
+template class EhOutputSection<ELF64BE>;
+
+template class MipsReginfoOutputSection<ELF32LE>;
+template class MipsReginfoOutputSection<ELF32BE>;
+template class MipsReginfoOutputSection<ELF64LE>;
+template class MipsReginfoOutputSection<ELF64BE>;
+
+template class MipsOptionsOutputSection<ELF32LE>;
+template class MipsOptionsOutputSection<ELF32BE>;
+template class MipsOptionsOutputSection<ELF64LE>;
+template class MipsOptionsOutputSection<ELF64BE>;
+
+template class MergeOutputSection<ELF32LE>;
+template class MergeOutputSection<ELF32BE>;
+template class MergeOutputSection<ELF64LE>;
+template class MergeOutputSection<ELF64BE>;
+
+template class StringTableSection<ELF32LE>;
+template class StringTableSection<ELF32BE>;
+template class StringTableSection<ELF64LE>;
+template class StringTableSection<ELF64BE>;
+
+template class SymbolTableSection<ELF32LE>;
+template class SymbolTableSection<ELF32BE>;
+template class SymbolTableSection<ELF64LE>;
+template class SymbolTableSection<ELF64BE>;
+
+template class VersionTableSection<ELF32LE>;
+template class VersionTableSection<ELF32BE>;
+template class VersionTableSection<ELF64LE>;
+template class VersionTableSection<ELF64BE>;
+
+template class VersionNeedSection<ELF32LE>;
+template class VersionNeedSection<ELF32BE>;
+template class VersionNeedSection<ELF64LE>;
+template class VersionNeedSection<ELF64BE>;
+
+template class VersionDefinitionSection<ELF32LE>;
+template class VersionDefinitionSection<ELF32BE>;
+template class VersionDefinitionSection<ELF64LE>;
+template class VersionDefinitionSection<ELF64BE>;
+
+template class BuildIdSection<ELF32LE>;
+template class BuildIdSection<ELF32BE>;
+template class BuildIdSection<ELF64LE>;
+template class BuildIdSection<ELF64BE>;
+
+template class BuildIdFnv1<ELF32LE>;
+template class BuildIdFnv1<ELF32BE>;
+template class BuildIdFnv1<ELF64LE>;
+template class BuildIdFnv1<ELF64BE>;
+
+template class BuildIdMd5<ELF32LE>;
+template class BuildIdMd5<ELF32BE>;
+template class BuildIdMd5<ELF64LE>;
+template class BuildIdMd5<ELF64BE>;
+
+template class BuildIdSha1<ELF32LE>;
+template class BuildIdSha1<ELF32BE>;
+template class BuildIdSha1<ELF64LE>;
+template class BuildIdSha1<ELF64BE>;
+
+template class BuildIdHexstring<ELF32LE>;
+template class BuildIdHexstring<ELF32BE>;
+template class BuildIdHexstring<ELF64LE>;
+template class BuildIdHexstring<ELF64BE>;
+
+template class OutputSectionFactory<ELF32LE>;
+template class OutputSectionFactory<ELF32BE>;
+template class OutputSectionFactory<ELF64LE>;
+template class OutputSectionFactory<ELF64BE>;
+}
+}