Convert EhOutputSection to be a synthetic section.

With this we complete the transition out of special output sections,
and with the previous patches it should be possible to merge
OutputSectionBase and OuputSection.

llvm-svn: 296023

9 files changed, 282 insertions, 278 deletions

diff --git a/lld/ELF/InputSection.cpp b/lld/ELF/InputSection.cpp
index 0d40c198676..6e9a7d78401 100644
--- a/lld/ELF/InputSection.cpp
+++ b/lld/ELF/InputSection.cpp
@@ -121,6 +121,8 @@ template <class ELFT>
 OutputSectionBase *InputSectionBase::getOutputSection() const {
   if (auto *MS = dyn_cast<MergeInputSection<ELFT>>(this))
     return MS->MergeSec ? MS->MergeSec->OutSec : nullptr;
+  if (auto *EH = dyn_cast<EhInputSection<ELFT>>(this))
+    return EH->EHSec->OutSec;
   return OutSec;
 }
 
@@ -499,7 +501,7 @@ void InputSectionBase::relocate(uint8_t *Buf, uint8_t *BufEnd) {
     uint8_t *BufLoc = Buf + Offset;
     uint32_t Type = Rel.Type;
 
-    uintX_t AddrLoc = OutSec->Addr + Offset;
+    uintX_t AddrLoc = getOutputSection<ELFT>()->Addr + Offset;
     RelExpr Expr = Rel.Expr;
     uint64_t TargetVA = SignExtend64<Bits>(
         getRelocTargetVA<ELFT>(Type, Rel.Addend, AddrLoc, *Rel.Sym, Expr));
diff --git a/lld/ELF/InputSection.h b/lld/ELF/InputSection.h
index 49733fc5fa2..0ad9ceba363 100644
--- a/lld/ELF/InputSection.h
+++ b/lld/ELF/InputSection.h
@@ -28,6 +28,7 @@ class SymbolBody;
 struct SectionPiece;
 
 template <class ELFT> class DefinedRegular;
+template <class ELFT> class EhFrameSection;
 template <class ELFT> class MergeSyntheticSection;
 template <class ELFT> class ObjectFile;
 template <class ELFT> class OutputSection;
@@ -244,6 +245,7 @@ public:
   // Splittable sections are handled as a sequence of data
   // rather than a single large blob of data.
   std::vector<EhSectionPiece> Pieces;
+  EhFrameSection<ELFT> *EHSec = nullptr;
 };
 
 // This corresponds to a non SHF_MERGE section of an input file.
diff --git a/lld/ELF/OutputSections.cpp b/lld/ELF/OutputSections.cpp
index 10aeca5a5bb..7de2be2dc16 100644
--- a/lld/ELF/OutputSections.cpp
+++ b/lld/ELF/OutputSections.cpp
@@ -9,7 +9,6 @@
 
 #include "OutputSections.h"
 #include "Config.h"
-#include "EhFrame.h"
 #include "LinkerScript.h"
 #include "Memory.h"
 #include "Strings.h"
@@ -270,217 +269,6 @@ template <class ELFT> void OutputSection<ELFT>::writeTo(uint8_t *Buf) {
 }
 
 template <class ELFT>
-EhOutputSection<ELFT>::EhOutputSection()
-    : OutputSectionBase(".eh_frame", SHT_PROGBITS, SHF_ALLOC) {}
-
-template <class ELFT>
-void EhOutputSection<ELFT>::forEachInputSection(
-    std::function<void(InputSectionBase *)> F) {
-  for (EhInputSection<ELFT> *S : Sections)
-    F(S);
-}
-
-// 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(EhSectionPiece &Piece,
-                                         ArrayRef<RelTy> Rels) {
-  auto *Sec = cast<EhInputSection<ELFT>>(Piece.ID);
-  const endianness E = ELFT::TargetEndianness;
-  if (read32<E>(Piece.data().data() + 4) != 0)
-    fatal(toString(Sec) + ": CIE expected at beginning of .eh_frame");
-
-  SymbolBody *Personality = nullptr;
-  unsigned FirstRelI = Piece.FirstRelocation;
-  if (FirstRelI != (unsigned)-1)
-    Personality =
-        &Sec->template getFile<ELFT>()->getRelocTargetSym(Rels[FirstRelI]);
-
-  // 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(EhSectionPiece &Piece,
-                                      ArrayRef<RelTy> Rels) {
-  auto *Sec = cast<EhInputSection<ELFT>>(Piece.ID);
-  unsigned FirstRelI = Piece.FirstRelocation;
-  if (FirstRelI == (unsigned)-1)
-    return false;
-  const RelTy &Rel = Rels[FirstRelI];
-  SymbolBody &B = Sec->template getFile<ELFT>()->getRelocTargetSym(Rel);
-  auto *D = dyn_cast<DefinedRegular<ELFT>>(&B);
-  if (!D || !D->Section)
-    return false;
-  InputSectionBase *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 (EhSectionPiece &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, Rels);
-      continue;
-    }
-
-    uint32_t CieOffset = Offset + 4 - ID;
-    CieRecord *Cie = OffsetToCie[CieOffset];
-    if (!Cie)
-      fatal(toString(Sec) + ": invalid CIE reference");
-
-    if (!isFdeLive(Piece, Rels))
-      continue;
-    Cie->FdePieces.push_back(&Piece);
-    NumFdes++;
-  }
-}
-
-template <class ELFT>
-void EhOutputSection<ELFT>::addSection(InputSectionBase *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 (Sec->NumRelocations) {
-    if (Sec->AreRelocsRela)
-      addSectionAux(Sec, Sec->template relas<ELFT>());
-    else
-      addSectionAux(Sec, Sec->template rels<ELFT>());
-    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->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 (EhSectionPiece *Fde : Cie->FdePieces) {
-      Fde->OutputOff = Off;
-      Off += alignTo(Fde->size(), sizeof(uintX_t));
-    }
-  }
-  this->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->Addr + 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 (EhSectionPiece *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->template relocate<ELFT>(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 (In<ELFT>::EhFrameHdr) {
-    for (CieRecord *Cie : Cies) {
-      uint8_t Enc = getFdeEncoding<ELFT>(Cie->Piece);
-      for (SectionPiece *Fde : Cie->FdePieces) {
-        uintX_t Pc = getFdePc(Buf, Fde->OutputOff, Enc);
-        uintX_t FdeVA = this->Addr + Fde->OutputOff;
-        In<ELFT>::EhFrameHdr->addFde(Pc, FdeVA);
-      }
-    }
-  }
-}
-
-template <class ELFT>
 static typename ELFT::uint getOutFlags(InputSectionBase *S) {
   return S->Flags & ~SHF_GROUP & ~SHF_COMPRESSED;
 }
@@ -596,7 +384,7 @@ void OutputSectionFactory<ELFT>::addInputSec(InputSectionBase *IS,
   } else {
     uint32_t Type = IS->Type;
     if (IS->kind() == InputSectionBase::EHFrame) {
-      Out<ELFT>::EhFrame->addSection(IS);
+      In<ELFT>::EhFrame->addSection(IS);
       return;
     }
     Sec = make<OutputSection<ELFT>>(Key.Name, Type, Flags);
@@ -639,11 +427,6 @@ 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 OutputSectionFactory<ELF32LE>;
 template class OutputSectionFactory<ELF32BE>;
 template class OutputSectionFactory<ELF64LE>;
diff --git a/lld/ELF/OutputSections.h b/lld/ELF/OutputSections.h
index f1f45dda58e..bdd032015ad 100644
--- a/lld/ELF/OutputSections.h
+++ b/lld/ELF/OutputSections.h
@@ -129,52 +129,6 @@ public:
   uint8_t *Loc = nullptr;
 };
 
-struct CieRecord {
-  EhSectionPiece *Piece = nullptr;
-  std::vector<EhSectionPiece *> FdePieces;
-};
-
-// Output section for .eh_frame.
-template <class ELFT> class EhOutputSection final : public OutputSectionBase {
-  typedef typename ELFT::uint uintX_t;
-  typedef typename ELFT::Shdr Elf_Shdr;
-  typedef typename ELFT::Rel Elf_Rel;
-  typedef typename ELFT::Rela Elf_Rela;
-
-public:
-  EhOutputSection();
-  void writeTo(uint8_t *Buf) override;
-  void finalize() override;
-  bool empty() const { return Sections.empty(); }
-  void forEachInputSection(std::function<void(InputSectionBase *)> F) override;
-
-  void addSection(InputSectionBase *S) override;
-  Kind getKind() const override { return EHFrame; }
-  static bool classof(const OutputSectionBase *B) {
-    return B->getKind() == EHFrame;
-  }
-
-  size_t NumFdes = 0;
-
-private:
-  template <class RelTy>
-  void addSectionAux(EhInputSection<ELFT> *S, llvm::ArrayRef<RelTy> Rels);
-
-  template <class RelTy>
-  CieRecord *addCie(EhSectionPiece &Piece, ArrayRef<RelTy> Rels);
-
-  template <class RelTy>
-  bool isFdeLive(EhSectionPiece &Piece, ArrayRef<RelTy> Rels);
-
-  uintX_t getFdePc(uint8_t *Buf, size_t Off, uint8_t Enc);
-
-  std::vector<EhInputSection<ELFT> *> Sections;
-  std::vector<CieRecord *> Cies;
-
-  // CIE records are uniquified by their contents and personality functions.
-  llvm::DenseMap<std::pair<ArrayRef<uint8_t>, SymbolBody *>, CieRecord> CieMap;
-};
-
 // All output sections that are hadnled by the linker specially are
 // globally accessible. Writer initializes them, so don't use them
 // until Writer is initialized.
@@ -183,7 +137,6 @@ template <class ELFT> struct Out {
   typedef typename ELFT::Phdr Elf_Phdr;
 
   static uint8_t First;
-  static EhOutputSection<ELFT> *EhFrame;
   static OutputSection<ELFT> *Bss;
   static OutputSection<ELFT> *BssRelRo;
   static OutputSectionBase *Opd;
@@ -241,7 +194,6 @@ template <class ELFT> uint64_t getHeaderSize() {
 }
 
 template <class ELFT> uint8_t Out<ELFT>::First;
-template <class ELFT> EhOutputSection<ELFT> *Out<ELFT>::EhFrame;
 template <class ELFT> OutputSection<ELFT> *Out<ELFT>::Bss;
 template <class ELFT> OutputSection<ELFT> *Out<ELFT>::BssRelRo;
 template <class ELFT> OutputSectionBase *Out<ELFT>::Opd;
diff --git a/lld/ELF/Relocations.h b/lld/ELF/Relocations.h
index f07f74efb05..d1420cf37ac 100644
--- a/lld/ELF/Relocations.h
+++ b/lld/ELF/Relocations.h
@@ -15,7 +15,6 @@
 namespace lld {
 namespace elf {
 class SymbolBody;
-class InputSectionData;
 class InputSection;
 class InputSectionBase;
 class OutputSectionBase;
diff --git a/lld/ELF/SyntheticSections.cpp b/lld/ELF/SyntheticSections.cpp
index 0398249016e..d3575a1fb29 100644
--- a/lld/ELF/SyntheticSections.cpp
+++ b/lld/ELF/SyntheticSections.cpp
@@ -401,6 +401,210 @@ void BuildIdSection<ELFT>::writeBuildId(ArrayRef<uint8_t> Buf) {
 }
 
 template <class ELFT>
+EhFrameSection<ELFT>::EhFrameSection()
+    : SyntheticSection<ELFT>(SHF_ALLOC, SHT_PROGBITS, 1, ".eh_frame") {}
+
+// 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 *EhFrameSection<ELFT>::addCie(EhSectionPiece &Piece,
+                                        ArrayRef<RelTy> Rels) {
+  auto *Sec = cast<EhInputSection<ELFT>>(Piece.ID);
+  const endianness E = ELFT::TargetEndianness;
+  if (read32<E>(Piece.data().data() + 4) != 0)
+    fatal(toString(Sec) + ": CIE expected at beginning of .eh_frame");
+
+  SymbolBody *Personality = nullptr;
+  unsigned FirstRelI = Piece.FirstRelocation;
+  if (FirstRelI != (unsigned)-1)
+    Personality =
+        &Sec->template getFile<ELFT>()->getRelocTargetSym(Rels[FirstRelI]);
+
+  // 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 EhFrameSection<ELFT>::isFdeLive(EhSectionPiece &Piece,
+                                     ArrayRef<RelTy> Rels) {
+  auto *Sec = cast<EhInputSection<ELFT>>(Piece.ID);
+  unsigned FirstRelI = Piece.FirstRelocation;
+  if (FirstRelI == (unsigned)-1)
+    return false;
+  const RelTy &Rel = Rels[FirstRelI];
+  SymbolBody &B = Sec->template getFile<ELFT>()->getRelocTargetSym(Rel);
+  auto *D = dyn_cast<DefinedRegular<ELFT>>(&B);
+  if (!D || !D->Section)
+    return false;
+  InputSectionBase *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 EhFrameSection<ELFT>::addSectionAux(EhInputSection<ELFT> *Sec,
+                                         ArrayRef<RelTy> Rels) {
+  const endianness E = ELFT::TargetEndianness;
+
+  DenseMap<size_t, CieRecord *> OffsetToCie;
+  for (EhSectionPiece &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, Rels);
+      continue;
+    }
+
+    uint32_t CieOffset = Offset + 4 - ID;
+    CieRecord *Cie = OffsetToCie[CieOffset];
+    if (!Cie)
+      fatal(toString(Sec) + ": invalid CIE reference");
+
+    if (!isFdeLive(Piece, Rels))
+      continue;
+    Cie->FdePieces.push_back(&Piece);
+    NumFdes++;
+  }
+}
+
+template <class ELFT>
+void EhFrameSection<ELFT>::addSection(InputSectionBase *C) {
+  auto *Sec = cast<EhInputSection<ELFT>>(C);
+  Sec->EHSec = 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 (Sec->NumRelocations) {
+    if (Sec->AreRelocsRela)
+      addSectionAux(Sec, Sec->template relas<ELFT>());
+    else
+      addSectionAux(Sec, Sec->template rels<ELFT>());
+    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 EhFrameSection<ELFT>::finalize() {
+  if (this->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 (EhSectionPiece *Fde : Cie->FdePieces) {
+      Fde->OutputOff = Off;
+      Off += alignTo(Fde->size(), sizeof(uintX_t));
+    }
+  }
+  this->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 EhFrameSection<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->OutSec->Addr + Off;
+  fatal("unknown FDE size relative encoding");
+}
+
+template <class ELFT> void EhFrameSection<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 (EhSectionPiece *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->template relocate<ELFT>(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 (In<ELFT>::EhFrameHdr) {
+    for (CieRecord *Cie : Cies) {
+      uint8_t Enc = getFdeEncoding<ELFT>(Cie->Piece);
+      for (SectionPiece *Fde : Cie->FdePieces) {
+        uintX_t Pc = getFdePc(Buf, Fde->OutputOff, Enc);
+        uintX_t FdeVA = this->OutSec->Addr + Fde->OutputOff;
+        In<ELFT>::EhFrameHdr->addFde(Pc, FdeVA);
+      }
+    }
+  }
+}
+
+template <class ELFT>
 GotSection<ELFT>::GotSection()
     : SyntheticSection<ELFT>(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
                              Target->GotEntrySize, ".got") {}
@@ -1675,7 +1879,7 @@ template <class ELFT> void EhFrameHeader<ELFT>::writeTo(uint8_t *Buf) {
   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->Addr - this->getVA() - 4);
+  write32<E>(Buf + 4, In<ELFT>::EhFrame->OutSec->Addr - this->getVA() - 4);
   write32<E>(Buf + 8, Fdes.size());
   Buf += 12;
 
@@ -1689,7 +1893,7 @@ template <class ELFT> void EhFrameHeader<ELFT>::writeTo(uint8_t *Buf) {
 
 template <class ELFT> size_t EhFrameHeader<ELFT>::getSize() const {
   // .eh_frame_hdr has a 12 bytes header followed by an array of FDEs.
-  return 12 + Out<ELFT>::EhFrame->NumFdes * 8;
+  return 12 + In<ELFT>::EhFrame->NumFdes * 8;
 }
 
 template <class ELFT>
@@ -1698,7 +1902,7 @@ void EhFrameHeader<ELFT>::addFde(uint32_t Pc, uint32_t FdeVA) {
 }
 
 template <class ELFT> bool EhFrameHeader<ELFT>::empty() const {
-  return Out<ELFT>::EhFrame->empty();
+  return In<ELFT>::EhFrame->empty();
 }
 
 template <class ELFT>
@@ -2158,3 +2362,8 @@ template class elf::ThunkSection<ELF32LE>;
 template class elf::ThunkSection<ELF32BE>;
 template class elf::ThunkSection<ELF64LE>;
 template class elf::ThunkSection<ELF64BE>;
+
+template class elf::EhFrameSection<ELF32LE>;
+template class elf::EhFrameSection<ELF32BE>;
+template class elf::EhFrameSection<ELF64LE>;
+template class elf::EhFrameSection<ELF64BE>;
diff --git a/lld/ELF/SyntheticSections.h b/lld/ELF/SyntheticSections.h
index 43f3ee96dbb..98b6c8beeb1 100644
--- a/lld/ELF/SyntheticSections.h
+++ b/lld/ELF/SyntheticSections.h
@@ -25,6 +25,7 @@
 #ifndef LLD_ELF_SYNTHETIC_SECTION_H
 #define LLD_ELF_SYNTHETIC_SECTION_H
 
+#include "EhFrame.h"
 #include "GdbIndex.h"
 #include "InputSection.h"
 #include "llvm/ADT/MapVector.h"
@@ -59,6 +60,55 @@ public:
   }
 };
 
+struct CieRecord {
+  EhSectionPiece *Piece = nullptr;
+  std::vector<EhSectionPiece *> FdePieces;
+};
+
+// Section for .eh_frame.
+template <class ELFT>
+class EhFrameSection final : public SyntheticSection<ELFT> {
+  typedef typename ELFT::uint uintX_t;
+  typedef typename ELFT::Shdr Elf_Shdr;
+  typedef typename ELFT::Rel Elf_Rel;
+  typedef typename ELFT::Rela Elf_Rela;
+
+  void updateAlignment(uint64_t Val) {
+    if (Val > this->Alignment)
+      this->Alignment = Val;
+  }
+
+public:
+  EhFrameSection();
+  void writeTo(uint8_t *Buf) override;
+  void finalize() override;
+  bool empty() const override { return Sections.empty(); }
+  size_t getSize() const override { return Size; }
+
+  void addSection(InputSectionBase *S);
+
+  size_t NumFdes = 0;
+
+private:
+  uint64_t Size = 0;
+  template <class RelTy>
+  void addSectionAux(EhInputSection<ELFT> *S, llvm::ArrayRef<RelTy> Rels);
+
+  template <class RelTy>
+  CieRecord *addCie(EhSectionPiece &Piece, ArrayRef<RelTy> Rels);
+
+  template <class RelTy>
+  bool isFdeLive(EhSectionPiece &Piece, ArrayRef<RelTy> Rels);
+
+  uintX_t getFdePc(uint8_t *Buf, size_t Off, uint8_t Enc);
+
+  std::vector<EhInputSection<ELFT> *> Sections;
+  std::vector<CieRecord *> Cies;
+
+  // CIE records are uniquified by their contents and personality functions.
+  llvm::DenseMap<std::pair<ArrayRef<uint8_t>, SymbolBody *>, CieRecord> CieMap;
+};
+
 template <class ELFT> class GotSection final : public SyntheticSection<ELFT> {
   typedef typename ELFT::uint uintX_t;
 
@@ -762,6 +812,7 @@ template <class ELFT> struct In {
   static GnuHashTableSection<ELFT> *GnuHashTab;
   static GdbIndexSection<ELFT> *GdbIndex;
   static GotSection<ELFT> *Got;
+  static EhFrameSection<ELFT> *EhFrame;
   static MipsGotSection<ELFT> *MipsGot;
   static GotPltSection<ELFT> *GotPlt;
   static IgotPltSection<ELFT> *IgotPlt;
@@ -791,6 +842,7 @@ template <class ELFT> EhFrameHeader<ELFT> *In<ELFT>::EhFrameHdr;
 template <class ELFT> GdbIndexSection<ELFT> *In<ELFT>::GdbIndex;
 template <class ELFT> GnuHashTableSection<ELFT> *In<ELFT>::GnuHashTab;
 template <class ELFT> GotSection<ELFT> *In<ELFT>::Got;
+template <class ELFT> EhFrameSection<ELFT> *In<ELFT>::EhFrame;
 template <class ELFT> MipsGotSection<ELFT> *In<ELFT>::MipsGot;
 template <class ELFT> GotPltSection<ELFT> *In<ELFT>::GotPlt;
 template <class ELFT> IgotPltSection<ELFT> *In<ELFT>::IgotPlt;
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index 35d9759565a..835f4d0bcde 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -318,7 +318,6 @@ template <class ELFT> void Writer<ELFT>::createSyntheticSections() {
                                                   SHF_ALLOC | SHF_WRITE);
   In<ELFT>::DynStrTab = make<StringTableSection<ELFT>>(".dynstr", true);
   In<ELFT>::Dynamic = make<DynamicSection<ELFT>>();
-  Out<ELFT>::EhFrame = make<EhOutputSection<ELFT>>();
   In<ELFT>::RelaDyn = make<RelocationSection<ELFT>>(
       Config->Rela ? ".rela.dyn" : ".rel.dyn", Config->ZCombreloc);
   In<ELFT>::ShStrTab = make<StringTableSection<ELFT>>(".shstrtab", false);
@@ -444,6 +443,11 @@ template <class ELFT> void Writer<ELFT>::createSyntheticSections() {
     Add(In<ELFT>::EhFrameHdr);
   }
 
+  if (!Config->Relocatable) {
+    In<ELFT>::EhFrame = make<EhFrameSection<ELFT>>();
+    Add(In<ELFT>::EhFrame);
+  }
+
   if (In<ELFT>::SymTab)
     Add(In<ELFT>::SymTab);
   Add(In<ELFT>::ShStrTab);
@@ -1088,10 +1092,10 @@ template <class ELFT> void Writer<ELFT>::finalizeSections() {
   // Define __rel[a]_iplt_{start,end} symbols if needed.
   addRelIpltSymbols();
 
-  if (!Out<ELFT>::EhFrame->empty()) {
-    OutputSections.push_back(Out<ELFT>::EhFrame);
-    Out<ELFT>::EhFrame->finalize();
-  }
+  // This responsible for splitting up .eh_frame section into
+  // pieces. The relocation scan uses those peaces, so this has to be
+  // earlier.
+  finalizeSynthetic<ELFT>({In<ELFT>::EhFrame});
 
   // Scan relocations. This must be done after every symbol is declared so that
   // we can correctly decide if a dynamic relocation is needed.
@@ -1323,7 +1327,7 @@ template <class ELFT> std::vector<PhdrEntry> Writer<ELFT>::createPhdrs() {
     Ret.push_back(std::move(RelRo));
 
   // PT_GNU_EH_FRAME is a special section pointing on .eh_frame_hdr.
-  if (!Out<ELFT>::EhFrame->empty() && In<ELFT>::EhFrameHdr)
+  if (!In<ELFT>::EhFrame->empty() && In<ELFT>::EhFrameHdr)
     AddHdr(PT_GNU_EH_FRAME, In<ELFT>::EhFrameHdr->OutSec->getPhdrFlags())
         ->add(In<ELFT>::EhFrameHdr->OutSec);
 
@@ -1827,7 +1831,7 @@ template <class ELFT> void Writer<ELFT>::writeSections() {
 
   // The .eh_frame_hdr depends on .eh_frame section contents, therefore
   // it should be written after .eh_frame is written.
-  if (!Out<ELFT>::EhFrame->empty() && EhFrameHdr)
+  if (EhFrameHdr)
     EhFrameHdr->writeTo(Buf + EhFrameHdr->Offset);
 }
 
diff --git a/lld/test/ELF/map-file.s b/lld/test/ELF/map-file.s
index e94937c5939..4b02aecd8de 100644
--- a/lld/test/ELF/map-file.s
+++ b/lld/test/ELF/map-file.s
@@ -28,6 +28,7 @@ local:
 
 // CHECK:      Address          Size             Align Out     In      File    Symbol
 // CHECK-NEXT: 0000000000200158 0000000000000030     8 .eh_frame
+// CHECK-NEXT: 0000000000200158 0000000000000030     8         .eh_frame
 // CHECK-NEXT: 0000000000201000 0000000000000015     4 .text
 // CHECK-NEXT: 0000000000201000 000000000000000e     4         .text
 // CHECK-NEXT: 0000000000201000 000000000000000e     4                 {{.*}}{{/|\\}}map-file.s.tmp1.o