vendor/lld/lld-release_39-r276489

1 files changed, 563 insertions, 212 deletions

diff --git a/ELF/InputFiles.cpp b/ELF/InputFiles.cpp
index 6a908d450f60..57e556395937 100644
--- a/ELF/InputFiles.cpp
+++ b/ELF/InputFiles.cpp
@@ -8,10 +8,17 @@
 //===----------------------------------------------------------------------===//
 
 #include "InputFiles.h"
-#include "InputSection.h"
+#include "Driver.h"
 #include "Error.h"
+#include "InputSection.h"
+#include "SymbolTable.h"
 #include "Symbols.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/Bitcode/ReaderWriter.h"
+#include "llvm/CodeGen/Analysis.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
 using namespace llvm::ELF;
@@ -19,43 +26,52 @@ using namespace llvm::object;
 using namespace llvm::sys::fs;
 
 using namespace lld;
-using namespace lld::elf2;
-
-namespace {
-class ECRAII {
-  std::error_code EC;
-
-public:
-  std::error_code &getEC() { return EC; }
-  ~ECRAII() { error(EC); }
-};
+using namespace lld::elf;
+
+// Returns "(internal)", "foo.a(bar.o)" or "baz.o".
+std::string elf::getFilename(const InputFile *F) {
+  if (!F)
+    return "(internal)";
+  if (!F->ArchiveName.empty())
+    return (F->ArchiveName + "(" + F->getName() + ")").str();
+  return F->getName();
 }
 
 template <class ELFT>
-ELFFileBase<ELFT>::ELFFileBase(Kind K, MemoryBufferRef M)
-    : InputFile(K, M), ELFObj(MB.getBuffer(), ECRAII().getEC()) {}
+static ELFFile<ELFT> createELFObj(MemoryBufferRef MB) {
+  std::error_code EC;
+  ELFFile<ELFT> F(MB.getBuffer(), EC);
+  if (EC)
+    error(EC, "failed to read " + MB.getBufferIdentifier());
+  return F;
+}
 
-template <class ELFT>
-ELFKind ELFFileBase<ELFT>::getELFKind() {
+template <class ELFT> static ELFKind getELFKind() {
   if (ELFT::TargetEndianness == support::little)
     return ELFT::Is64Bits ? ELF64LEKind : ELF32LEKind;
   return ELFT::Is64Bits ? ELF64BEKind : ELF32BEKind;
 }
 
 template <class ELFT>
-typename ELFFileBase<ELFT>::Elf_Sym_Range
-ELFFileBase<ELFT>::getSymbolsHelper(bool Local) {
+ELFFileBase<ELFT>::ELFFileBase(Kind K, MemoryBufferRef MB)
+    : InputFile(K, MB), ELFObj(createELFObj<ELFT>(MB)) {
+  EKind = getELFKind<ELFT>();
+  EMachine = ELFObj.getHeader()->e_machine;
+}
+
+template <class ELFT>
+typename ELFT::SymRange ELFFileBase<ELFT>::getElfSymbols(bool OnlyGlobals) {
   if (!Symtab)
     return Elf_Sym_Range(nullptr, nullptr);
   Elf_Sym_Range Syms = ELFObj.symbols(Symtab);
   uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
   uint32_t FirstNonLocal = Symtab->sh_info;
   if (FirstNonLocal > NumSymbols)
-    error("Invalid sh_info in symbol table");
-  if (!Local)
-    return make_range(Syms.begin() + FirstNonLocal, Syms.end());
-  // +1 to skip over dummy symbol.
-  return make_range(Syms.begin() + 1, Syms.begin() + FirstNonLocal);
+    fatal(getFilename(this) + ": invalid sh_info in symbol table");
+
+  if (OnlyGlobals)
+    return makeArrayRef(Syms.begin() + FirstNonLocal, Syms.end());
+  return makeArrayRef(Syms.begin(), Syms.end());
 }
 
 template <class ELFT>
@@ -63,7 +79,7 @@ uint32_t ELFFileBase<ELFT>::getSectionIndex(const Elf_Sym &Sym) const {
   uint32_t I = Sym.st_shndx;
   if (I == ELF::SHN_XINDEX)
     return ELFObj.getExtendedSymbolTableIndex(&Sym, Symtab, SymtabSHNDX);
-  if (I >= ELF::SHN_LORESERVE || I == ELF::SHN_ABS)
+  if (I >= ELF::SHN_LORESERVE)
     return 0;
   return I;
 }
@@ -71,44 +87,46 @@ uint32_t ELFFileBase<ELFT>::getSectionIndex(const Elf_Sym &Sym) const {
 template <class ELFT> void ELFFileBase<ELFT>::initStringTable() {
   if (!Symtab)
     return;
-  ErrorOr<StringRef> StringTableOrErr = ELFObj.getStringTableForSymtab(*Symtab);
-  error(StringTableOrErr);
-  StringTable = *StringTableOrErr;
+  StringTable = check(ELFObj.getStringTableForSymtab(*Symtab));
 }
 
 template <class ELFT>
-typename ELFFileBase<ELFT>::Elf_Sym_Range
-ELFFileBase<ELFT>::getNonLocalSymbols() {
-  return getSymbolsHelper(false);
+elf::ObjectFile<ELFT>::ObjectFile(MemoryBufferRef M)
+    : ELFFileBase<ELFT>(Base::ObjectKind, M) {}
+
+template <class ELFT>
+ArrayRef<SymbolBody *> elf::ObjectFile<ELFT>::getNonLocalSymbols() {
+  if (!this->Symtab)
+    return this->SymbolBodies;
+  uint32_t FirstNonLocal = this->Symtab->sh_info;
+  return makeArrayRef(this->SymbolBodies).slice(FirstNonLocal);
 }
 
 template <class ELFT>
-ObjectFile<ELFT>::ObjectFile(MemoryBufferRef M)
-    : ELFFileBase<ELFT>(Base::ObjectKind, M) {}
+ArrayRef<SymbolBody *> elf::ObjectFile<ELFT>::getLocalSymbols() {
+  if (!this->Symtab)
+    return this->SymbolBodies;
+  uint32_t FirstNonLocal = this->Symtab->sh_info;
+  return makeArrayRef(this->SymbolBodies).slice(1, FirstNonLocal - 1);
+}
 
 template <class ELFT>
-typename ObjectFile<ELFT>::Elf_Sym_Range ObjectFile<ELFT>::getLocalSymbols() {
-  return this->getSymbolsHelper(true);
+ArrayRef<SymbolBody *> elf::ObjectFile<ELFT>::getSymbols() {
+  if (!this->Symtab)
+    return this->SymbolBodies;
+  return makeArrayRef(this->SymbolBodies).slice(1);
 }
 
-template <class ELFT> uint32_t ObjectFile<ELFT>::getMipsGp0() const {
-  if (MipsReginfo)
+template <class ELFT> uint32_t elf::ObjectFile<ELFT>::getMipsGp0() const {
+  if (ELFT::Is64Bits && MipsOptions && MipsOptions->Reginfo)
+    return MipsOptions->Reginfo->ri_gp_value;
+  if (!ELFT::Is64Bits && MipsReginfo && MipsReginfo->Reginfo)
     return MipsReginfo->Reginfo->ri_gp_value;
   return 0;
 }
 
 template <class ELFT>
-const typename ObjectFile<ELFT>::Elf_Sym *
-ObjectFile<ELFT>::getLocalSymbol(uintX_t SymIndex) {
-  uint32_t FirstNonLocal = this->Symtab->sh_info;
-  if (SymIndex >= FirstNonLocal)
-    return nullptr;
-  Elf_Sym_Range Syms = this->ELFObj.symbols(this->Symtab);
-  return Syms.begin() + SymIndex;
-}
-
-template <class ELFT>
-void ObjectFile<ELFT>::parse(DenseSet<StringRef> &ComdatGroups) {
+void elf::ObjectFile<ELFT>::parse(DenseSet<StringRef> &ComdatGroups) {
   // Read section and symbol tables.
   initializeSections(ComdatGroups);
   initializeSymbols();
@@ -118,63 +136,57 @@ void ObjectFile<ELFT>::parse(DenseSet<StringRef> &ComdatGroups) {
 // They are identified and deduplicated by group name. This function
 // returns a group name.
 template <class ELFT>
-StringRef ObjectFile<ELFT>::getShtGroupSignature(const Elf_Shdr &Sec) {
+StringRef elf::ObjectFile<ELFT>::getShtGroupSignature(const Elf_Shdr &Sec) {
   const ELFFile<ELFT> &Obj = this->ELFObj;
-  uint32_t SymtabdSectionIndex = Sec.sh_link;
-  ErrorOr<const Elf_Shdr *> SecOrErr = Obj.getSection(SymtabdSectionIndex);
-  error(SecOrErr);
-  const Elf_Shdr *SymtabSec = *SecOrErr;
-  uint32_t SymIndex = Sec.sh_info;
-  const Elf_Sym *Sym = Obj.getSymbol(SymtabSec, SymIndex);
-  ErrorOr<StringRef> StringTableOrErr = Obj.getStringTableForSymtab(*SymtabSec);
-  error(StringTableOrErr);
-  ErrorOr<StringRef> SignatureOrErr = Sym->getName(*StringTableOrErr);
-  error(SignatureOrErr);
-  return *SignatureOrErr;
+  const Elf_Shdr *Symtab = check(Obj.getSection(Sec.sh_link));
+  const Elf_Sym *Sym = Obj.getSymbol(Symtab, Sec.sh_info);
+  StringRef Strtab = check(Obj.getStringTableForSymtab(*Symtab));
+  return check(Sym->getName(Strtab));
 }
 
 template <class ELFT>
-ArrayRef<typename ObjectFile<ELFT>::uint32_X>
-ObjectFile<ELFT>::getShtGroupEntries(const Elf_Shdr &Sec) {
+ArrayRef<typename elf::ObjectFile<ELFT>::Elf_Word>
+elf::ObjectFile<ELFT>::getShtGroupEntries(const Elf_Shdr &Sec) {
   const ELFFile<ELFT> &Obj = this->ELFObj;
-  ErrorOr<ArrayRef<uint32_X>> EntriesOrErr =
-      Obj.template getSectionContentsAsArray<uint32_X>(&Sec);
-  error(EntriesOrErr);
-  ArrayRef<uint32_X> Entries = *EntriesOrErr;
+  ArrayRef<Elf_Word> Entries =
+      check(Obj.template getSectionContentsAsArray<Elf_Word>(&Sec));
   if (Entries.empty() || Entries[0] != GRP_COMDAT)
-    error("Unsupported SHT_GROUP format");
+    fatal(getFilename(this) + ": unsupported SHT_GROUP format");
   return Entries.slice(1);
 }
 
 template <class ELFT>
-static bool shouldMerge(const typename ELFFile<ELFT>::Elf_Shdr &Sec) {
-  typedef typename ELFFile<ELFT>::uintX_t uintX_t;
+bool elf::ObjectFile<ELFT>::shouldMerge(const Elf_Shdr &Sec) {
+  // We don't merge sections if -O0 (default is -O1). This makes sometimes
+  // the linker significantly faster, although the output will be bigger.
+  if (Config->Optimize == 0)
+    return false;
+
   uintX_t Flags = Sec.sh_flags;
   if (!(Flags & SHF_MERGE))
     return false;
   if (Flags & SHF_WRITE)
-    error("Writable SHF_MERGE sections are not supported");
+    fatal(getFilename(this) + ": writable SHF_MERGE section is not supported");
   uintX_t EntSize = Sec.sh_entsize;
   if (!EntSize || Sec.sh_size % EntSize)
-    error("SHF_MERGE section size must be a multiple of sh_entsize");
+    fatal(getFilename(this) +
+          ": SHF_MERGE section size must be a multiple of sh_entsize");
 
-  // Don't try to merge if the aligment is larger than the sh_entsize.
+  // Don't try to merge if the alignment is larger than the sh_entsize and this
+  // is not SHF_STRINGS.
   //
-  // If this is not a SHF_STRINGS, we would need to pad after every entity. It
-  // would be equivalent for the producer of the .o to just set a larger
+  // Since this is not a SHF_STRINGS, we would need to pad after every entity.
+  // It would be equivalent for the producer of the .o to just set a larger
   // sh_entsize.
-  //
-  // If this is a SHF_STRINGS, the larger alignment makes sense. Unfortunately
-  // it would complicate tail merging. This doesn't seem that common to
-  // justify the effort.
-  if (Sec.sh_addralign > EntSize)
-    return false;
+  if (Flags & SHF_STRINGS)
+    return true;
 
-  return true;
+  return Sec.sh_addralign <= EntSize;
 }
 
 template <class ELFT>
-void ObjectFile<ELFT>::initializeSections(DenseSet<StringRef> &ComdatGroups) {
+void elf::ObjectFile<ELFT>::initializeSections(
+    DenseSet<StringRef> &ComdatGroups) {
   uint64_t Size = this->ELFObj.getNumSections();
   Sections.resize(Size);
   unsigned I = -1;
@@ -191,53 +203,85 @@ void ObjectFile<ELFT>::initializeSections(DenseSet<StringRef> &ComdatGroups) {
         continue;
       for (uint32_t SecIndex : getShtGroupEntries(Sec)) {
         if (SecIndex >= Size)
-          error("Invalid section index in group");
+          fatal(getFilename(this) + ": invalid section index in group: " +
+                Twine(SecIndex));
         Sections[SecIndex] = &InputSection<ELFT>::Discarded;
       }
       break;
     case SHT_SYMTAB:
       this->Symtab = &Sec;
       break;
-    case SHT_SYMTAB_SHNDX: {
-      ErrorOr<ArrayRef<Elf_Word>> ErrorOrTable = Obj.getSHNDXTable(Sec);
-      error(ErrorOrTable);
-      this->SymtabSHNDX = *ErrorOrTable;
+    case SHT_SYMTAB_SHNDX:
+      this->SymtabSHNDX = check(Obj.getSHNDXTable(Sec));
       break;
-    }
     case SHT_STRTAB:
     case SHT_NULL:
       break;
     case SHT_RELA:
     case SHT_REL: {
-      uint32_t RelocatedSectionIndex = Sec.sh_info;
-      if (RelocatedSectionIndex >= Size)
-        error("Invalid relocated section index");
-      InputSectionBase<ELFT> *RelocatedSection =
-          Sections[RelocatedSectionIndex];
-      if (!RelocatedSection)
-        error("Unsupported relocation reference");
-      if (auto *S = dyn_cast<InputSection<ELFT>>(RelocatedSection)) {
+      // This section contains relocation information.
+      // If -r is given, we do not interpret or apply relocation
+      // but just copy relocation sections to output.
+      if (Config->Relocatable) {
+        Sections[I] = new (IAlloc.Allocate()) InputSection<ELFT>(this, &Sec);
+        break;
+      }
+
+      // Find the relocation target section and associate this
+      // section with it.
+      InputSectionBase<ELFT> *Target = getRelocTarget(Sec);
+      if (!Target)
+        break;
+      if (auto *S = dyn_cast<InputSection<ELFT>>(Target)) {
         S->RelocSections.push_back(&Sec);
-      } else if (auto *S = dyn_cast<EHInputSection<ELFT>>(RelocatedSection)) {
+        break;
+      }
+      if (auto *S = dyn_cast<EhInputSection<ELFT>>(Target)) {
         if (S->RelocSection)
-          error("Multiple relocation sections to .eh_frame are not supported");
+          fatal(
+              getFilename(this) +
+              ": multiple relocation sections to .eh_frame are not supported");
         S->RelocSection = &Sec;
-      } else {
-        error("Relocations pointing to SHF_MERGE are not supported");
+        break;
       }
-      break;
+      fatal(getFilename(this) +
+            ": relocations pointing to SHF_MERGE are not supported");
     }
+    case SHT_ARM_ATTRIBUTES:
+      // FIXME: ARM meta-data section. At present attributes are ignored,
+      // they can be used to reason about object compatibility.
+      Sections[I] = &InputSection<ELFT>::Discarded;
+      break;
     default:
       Sections[I] = createInputSection(Sec);
     }
   }
 }
 
-template <class ELFT> InputSectionBase<ELFT> *
-ObjectFile<ELFT>::createInputSection(const Elf_Shdr &Sec) {
-  ErrorOr<StringRef> NameOrErr = this->ELFObj.getSectionName(&Sec);
-  error(NameOrErr);
-  StringRef Name = *NameOrErr;
+template <class ELFT>
+InputSectionBase<ELFT> *
+elf::ObjectFile<ELFT>::getRelocTarget(const Elf_Shdr &Sec) {
+  uint32_t Idx = Sec.sh_info;
+  if (Idx >= Sections.size())
+    fatal(getFilename(this) + ": invalid relocated section index: " +
+          Twine(Idx));
+  InputSectionBase<ELFT> *Target = Sections[Idx];
+
+  // Strictly speaking, a relocation section must be included in the
+  // group of the section it relocates. However, LLVM 3.3 and earlier
+  // would fail to do so, so we gracefully handle that case.
+  if (Target == &InputSection<ELFT>::Discarded)
+    return nullptr;
+
+  if (!Target)
+    fatal(getFilename(this) + ": unsupported relocation reference");
+  return Target;
+}
+
+template <class ELFT>
+InputSectionBase<ELFT> *
+elf::ObjectFile<ELFT>::createInputSection(const Elf_Shdr &Sec) {
+  StringRef Name = check(this->ELFObj.getSectionName(&Sec));
 
   // .note.GNU-stack is a marker section to control the presence of
   // PT_GNU_STACK segment in outputs. Since the presence of the segment
@@ -246,98 +290,129 @@ ObjectFile<ELFT>::createInputSection(const Elf_Shdr &Sec) {
   if (Name == ".note.GNU-stack")
     return &InputSection<ELFT>::Discarded;
 
-  // A MIPS object file has a special section that contains register
-  // usage info, which needs to be handled by the linker specially.
-  if (Config->EMachine == EM_MIPS && Name == ".reginfo") {
-    MipsReginfo = new (Alloc) MipsReginfoInputSection<ELFT>(this, &Sec);
-    return MipsReginfo;
+  if (Name == ".note.GNU-split-stack") {
+    error("objects using splitstacks are not supported");
+    return &InputSection<ELFT>::Discarded;
   }
 
-  if (Name == ".eh_frame")
-    return new (EHAlloc.Allocate()) EHInputSection<ELFT>(this, &Sec);
-  if (shouldMerge<ELFT>(Sec))
+  if (Config->StripDebug && Name.startswith(".debug"))
+    return &InputSection<ELFT>::Discarded;
+
+  // A MIPS object file has a special sections that contain register
+  // usage info, which need to be handled by the linker specially.
+  if (Config->EMachine == EM_MIPS) {
+    if (Name == ".reginfo") {
+      MipsReginfo.reset(new MipsReginfoInputSection<ELFT>(this, &Sec));
+      return MipsReginfo.get();
+    }
+    if (Name == ".MIPS.options") {
+      MipsOptions.reset(new MipsOptionsInputSection<ELFT>(this, &Sec));
+      return MipsOptions.get();
+    }
+  }
+
+  // The linker merges EH (exception handling) frames and creates a
+  // .eh_frame_hdr section for runtime. So we handle them with a special
+  // class. For relocatable outputs, they are just passed through.
+  if (Name == ".eh_frame" && !Config->Relocatable)
+    return new (EHAlloc.Allocate()) EhInputSection<ELFT>(this, &Sec);
+
+  if (shouldMerge(Sec))
     return new (MAlloc.Allocate()) MergeInputSection<ELFT>(this, &Sec);
-  return new (Alloc) InputSection<ELFT>(this, &Sec);
+  return new (IAlloc.Allocate()) InputSection<ELFT>(this, &Sec);
 }
 
-template <class ELFT> void ObjectFile<ELFT>::initializeSymbols() {
+template <class ELFT> void elf::ObjectFile<ELFT>::initializeSymbols() {
   this->initStringTable();
-  Elf_Sym_Range Syms = this->getNonLocalSymbols();
+  Elf_Sym_Range Syms = this->getElfSymbols(false);
   uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
   SymbolBodies.reserve(NumSymbols);
   for (const Elf_Sym &Sym : Syms)
-    SymbolBodies.push_back(createSymbolBody(this->StringTable, &Sym));
+    SymbolBodies.push_back(createSymbolBody(&Sym));
 }
 
 template <class ELFT>
 InputSectionBase<ELFT> *
-ObjectFile<ELFT>::getSection(const Elf_Sym &Sym) const {
+elf::ObjectFile<ELFT>::getSection(const Elf_Sym &Sym) const {
   uint32_t Index = this->getSectionIndex(Sym);
   if (Index == 0)
     return nullptr;
   if (Index >= Sections.size() || !Sections[Index])
-    error("Invalid section index");
-  return Sections[Index];
+    fatal(getFilename(this) + ": invalid section index: " + Twine(Index));
+  InputSectionBase<ELFT> *S = Sections[Index];
+  if (S == &InputSectionBase<ELFT>::Discarded)
+    return S;
+  return S->Repl;
 }
 
 template <class ELFT>
-SymbolBody *ObjectFile<ELFT>::createSymbolBody(StringRef StringTable,
-                                                     const Elf_Sym *Sym) {
-  ErrorOr<StringRef> NameOrErr = Sym->getName(StringTable);
-  error(NameOrErr);
-  StringRef Name = *NameOrErr;
+SymbolBody *elf::ObjectFile<ELFT>::createSymbolBody(const Elf_Sym *Sym) {
+  int Binding = Sym->getBinding();
+  InputSectionBase<ELFT> *Sec = getSection(*Sym);
+  if (Binding == STB_LOCAL) {
+    if (Sym->st_shndx == SHN_UNDEF)
+      return new (this->Alloc)
+          Undefined(Sym->st_name, Sym->st_other, Sym->getType(), this);
+    return new (this->Alloc) DefinedRegular<ELFT>(*Sym, Sec);
+  }
+
+  StringRef Name = check(Sym->getName(this->StringTable));
 
   switch (Sym->st_shndx) {
   case SHN_UNDEF:
-    return new (Alloc) UndefinedElf<ELFT>(Name, *Sym);
+    return elf::Symtab<ELFT>::X
+        ->addUndefined(Name, Binding, Sym->st_other, Sym->getType(),
+                       /*CanOmitFromDynSym*/ false, this)
+        ->body();
   case SHN_COMMON:
-    return new (Alloc) DefinedCommon(Name, Sym->st_size, Sym->st_value,
-                                     Sym->getBinding() == llvm::ELF::STB_WEAK,
-                                     Sym->getVisibility());
+    return elf::Symtab<ELFT>::X
+        ->addCommon(Name, Sym->st_size, Sym->st_value, Binding, Sym->st_other,
+                    Sym->getType(), this)
+        ->body();
   }
 
-  switch (Sym->getBinding()) {
+  switch (Binding) {
   default:
-    error("unexpected binding");
+    fatal(getFilename(this) + ": unexpected binding: " + Twine(Binding));
   case STB_GLOBAL:
   case STB_WEAK:
-  case STB_GNU_UNIQUE: {
-    InputSectionBase<ELFT> *Sec = getSection(*Sym);
+  case STB_GNU_UNIQUE:
     if (Sec == &InputSection<ELFT>::Discarded)
-      return new (Alloc) UndefinedElf<ELFT>(Name, *Sym);
-    return new (Alloc) DefinedRegular<ELFT>(Name, *Sym, Sec);
-  }
+      return elf::Symtab<ELFT>::X
+          ->addUndefined(Name, Binding, Sym->st_other, Sym->getType(),
+                         /*CanOmitFromDynSym*/ false, this)
+          ->body();
+    return elf::Symtab<ELFT>::X->addRegular(Name, *Sym, Sec)->body();
   }
 }
 
-void ArchiveFile::parse() {
-  ErrorOr<std::unique_ptr<Archive>> FileOrErr = Archive::create(MB);
-  error(FileOrErr, "Failed to parse archive");
-  File = std::move(*FileOrErr);
-
-  // Allocate a buffer for Lazy objects.
-  size_t NumSyms = File->getNumberOfSymbols();
-  LazySymbols.reserve(NumSyms);
+template <class ELFT> void ArchiveFile::parse() {
+  File = check(Archive::create(MB), "failed to parse archive");
 
   // Read the symbol table to construct Lazy objects.
   for (const Archive::Symbol &Sym : File->symbols())
-    LazySymbols.emplace_back(this, Sym);
+    Symtab<ELFT>::X->addLazyArchive(this, Sym);
 }
 
 // Returns a buffer pointing to a member file containing a given symbol.
 MemoryBufferRef ArchiveFile::getMember(const Archive::Symbol *Sym) {
-  ErrorOr<Archive::Child> COrErr = Sym->getMember();
-  error(COrErr, "Could not get the member for symbol " + Sym->getName());
-  const Archive::Child &C = *COrErr;
+  Archive::Child C =
+      check(Sym->getMember(),
+            "could not get the member for symbol " + Sym->getName());
 
   if (!Seen.insert(C.getChildOffset()).second)
     return MemoryBufferRef();
 
-  ErrorOr<MemoryBufferRef> RefOrErr = C.getMemoryBufferRef();
-  if (!RefOrErr)
-    error(RefOrErr, "Could not get the buffer for the member defining symbol " +
-          Sym->getName());
-  return *RefOrErr;
+  MemoryBufferRef Ret =
+      check(C.getMemoryBufferRef(),
+            "could not get the buffer for the member defining symbol " +
+                Sym->getName());
+
+  if (C.getParent()->isThin() && Driver->Cpio)
+    Driver->Cpio->append(relativeToRoot(check(C.getFullName())),
+                         Ret.getBuffer());
+
+  return Ret;
 }
 
 template <class ELFT>
@@ -345,21 +420,19 @@ SharedFile<ELFT>::SharedFile(MemoryBufferRef M)
     : ELFFileBase<ELFT>(Base::SharedKind, M), AsNeeded(Config->AsNeeded) {}
 
 template <class ELFT>
-const typename ELFFile<ELFT>::Elf_Shdr *
+const typename ELFT::Shdr *
 SharedFile<ELFT>::getSection(const Elf_Sym &Sym) const {
   uint32_t Index = this->getSectionIndex(Sym);
   if (Index == 0)
     return nullptr;
-  ErrorOr<const Elf_Shdr *> Ret = this->ELFObj.getSection(Index);
-  error(Ret);
-  return *Ret;
+  return check(this->ELFObj.getSection(Index));
 }
 
 // Partially parse the shared object file so that we can call
 // getSoName on this object.
 template <class ELFT> void SharedFile<ELFT>::parseSoName() {
-  typedef typename ELFFile<ELFT>::Elf_Dyn Elf_Dyn;
-  typedef typename ELFFile<ELFT>::uintX_t uintX_t;
+  typedef typename ELFT::Dyn Elf_Dyn;
+  typedef typename ELFT::uint uintX_t;
   const Elf_Shdr *DynamicSec = nullptr;
 
   const ELFFile<ELFT> Obj = this->ELFObj;
@@ -373,12 +446,15 @@ template <class ELFT> void SharedFile<ELFT>::parseSoName() {
     case SHT_DYNAMIC:
       DynamicSec = &Sec;
       break;
-    case SHT_SYMTAB_SHNDX: {
-      ErrorOr<ArrayRef<Elf_Word>> ErrorOrTable = Obj.getSHNDXTable(Sec);
-      error(ErrorOrTable);
-      this->SymtabSHNDX = *ErrorOrTable;
+    case SHT_SYMTAB_SHNDX:
+      this->SymtabSHNDX = check(Obj.getSHNDXTable(Sec));
+      break;
+    case SHT_GNU_versym:
+      this->VersymSec = &Sec;
+      break;
+    case SHT_GNU_verdef:
+      this->VerdefSec = &Sec;
       break;
-    }
     }
   }
 
@@ -395,83 +471,358 @@ template <class ELFT> void SharedFile<ELFT>::parseSoName() {
     if (Dyn.d_tag == DT_SONAME) {
       uintX_t Val = Dyn.getVal();
       if (Val >= this->StringTable.size())
-        error("Invalid DT_SONAME entry");
+        fatal(getFilename(this) + ": invalid DT_SONAME entry");
       SoName = StringRef(this->StringTable.data() + Val);
       return;
     }
   }
 }
 
+// Parse the version definitions in the object file if present. Returns a vector
+// whose nth element contains a pointer to the Elf_Verdef for version identifier
+// n. Version identifiers that are not definitions map to nullptr. The array
+// always has at least length 1.
+template <class ELFT>
+std::vector<const typename ELFT::Verdef *>
+SharedFile<ELFT>::parseVerdefs(const Elf_Versym *&Versym) {
+  std::vector<const Elf_Verdef *> Verdefs(1);
+  // We only need to process symbol versions for this DSO if it has both a
+  // versym and a verdef section, which indicates that the DSO contains symbol
+  // version definitions.
+  if (!VersymSec || !VerdefSec)
+    return Verdefs;
+
+  // The location of the first global versym entry.
+  Versym = reinterpret_cast<const Elf_Versym *>(this->ELFObj.base() +
+                                                VersymSec->sh_offset) +
+           this->Symtab->sh_info;
+
+  // We cannot determine the largest verdef identifier without inspecting
+  // every Elf_Verdef, but both bfd and gold assign verdef identifiers
+  // sequentially starting from 1, so we predict that the largest identifier
+  // will be VerdefCount.
+  unsigned VerdefCount = VerdefSec->sh_info;
+  Verdefs.resize(VerdefCount + 1);
+
+  // Build the Verdefs array by following the chain of Elf_Verdef objects
+  // from the start of the .gnu.version_d section.
+  const uint8_t *Verdef = this->ELFObj.base() + VerdefSec->sh_offset;
+  for (unsigned I = 0; I != VerdefCount; ++I) {
+    auto *CurVerdef = reinterpret_cast<const Elf_Verdef *>(Verdef);
+    Verdef += CurVerdef->vd_next;
+    unsigned VerdefIndex = CurVerdef->vd_ndx;
+    if (Verdefs.size() <= VerdefIndex)
+      Verdefs.resize(VerdefIndex + 1);
+    Verdefs[VerdefIndex] = CurVerdef;
+  }
+
+  return Verdefs;
+}
+
 // Fully parse the shared object file. This must be called after parseSoName().
 template <class ELFT> void SharedFile<ELFT>::parseRest() {
-  Elf_Sym_Range Syms = this->getNonLocalSymbols();
-  uint32_t NumSymbols = std::distance(Syms.begin(), Syms.end());
-  SymbolBodies.reserve(NumSymbols);
+  // Create mapping from version identifiers to Elf_Verdef entries.
+  const Elf_Versym *Versym = nullptr;
+  std::vector<const Elf_Verdef *> Verdefs = parseVerdefs(Versym);
+
+  Elf_Sym_Range Syms = this->getElfSymbols(true);
   for (const Elf_Sym &Sym : Syms) {
-    ErrorOr<StringRef> NameOrErr = Sym.getName(this->StringTable);
-    error(NameOrErr.getError());
-    StringRef Name = *NameOrErr;
+    unsigned VersymIndex = 0;
+    if (Versym) {
+      VersymIndex = Versym->vs_index;
+      ++Versym;
+    }
 
-    if (Sym.isUndefined())
+    StringRef Name = check(Sym.getName(this->StringTable));
+    if (Sym.isUndefined()) {
       Undefs.push_back(Name);
-    else
-      SymbolBodies.emplace_back(this, Name, Sym);
+      continue;
+    }
+
+    if (Versym) {
+      // Ignore local symbols and non-default versions.
+      if (VersymIndex == VER_NDX_LOCAL || (VersymIndex & VERSYM_HIDDEN))
+        continue;
+    }
+
+    const Elf_Verdef *V =
+        VersymIndex == VER_NDX_GLOBAL ? nullptr : Verdefs[VersymIndex];
+    elf::Symtab<ELFT>::X->addShared(this, Name, Sym, V);
   }
 }
 
-template <typename T>
-static std::unique_ptr<InputFile> createELFFileAux(MemoryBufferRef MB) {
-  std::unique_ptr<T> Ret = llvm::make_unique<T>(MB);
+static ELFKind getELFKind(MemoryBufferRef MB) {
+  std::string TripleStr = getBitcodeTargetTriple(MB, Driver->Context);
+  Triple TheTriple(TripleStr);
+  bool Is64Bits = TheTriple.isArch64Bit();
+  if (TheTriple.isLittleEndian())
+    return Is64Bits ? ELF64LEKind : ELF32LEKind;
+  return Is64Bits ? ELF64BEKind : ELF32BEKind;
+}
 
-  if (!Config->FirstElf)
-    Config->FirstElf = Ret.get();
+static uint8_t getMachineKind(MemoryBufferRef MB) {
+  std::string TripleStr = getBitcodeTargetTriple(MB, Driver->Context);
+  switch (Triple(TripleStr).getArch()) {
+  case Triple::aarch64:
+    return EM_AARCH64;
+  case Triple::arm:
+    return EM_ARM;
+  case Triple::mips:
+  case Triple::mipsel:
+  case Triple::mips64:
+  case Triple::mips64el:
+    return EM_MIPS;
+  case Triple::ppc:
+    return EM_PPC;
+  case Triple::ppc64:
+    return EM_PPC64;
+  case Triple::x86:
+    return EM_386;
+  case Triple::x86_64:
+    return EM_X86_64;
+  default:
+    fatal(MB.getBufferIdentifier() +
+          ": could not infer e_machine from bitcode target triple " +
+          TripleStr);
+  }
+}
+
+BitcodeFile::BitcodeFile(MemoryBufferRef MB) : InputFile(BitcodeKind, MB) {
+  EKind = getELFKind(MB);
+  EMachine = getMachineKind(MB);
+}
 
-  if (Config->EKind == ELFNoneKind) {
-    Config->EKind = Ret->getELFKind();
-    Config->EMachine = Ret->getEMachine();
+static uint8_t getGvVisibility(const GlobalValue *GV) {
+  switch (GV->getVisibility()) {
+  case GlobalValue::DefaultVisibility:
+    return STV_DEFAULT;
+  case GlobalValue::HiddenVisibility:
+    return STV_HIDDEN;
+  case GlobalValue::ProtectedVisibility:
+    return STV_PROTECTED;
   }
+  llvm_unreachable("unknown visibility");
+}
+
+template <class ELFT>
+Symbol *BitcodeFile::createSymbol(const DenseSet<const Comdat *> &KeptComdats,
+                                  const IRObjectFile &Obj,
+                                  const BasicSymbolRef &Sym) {
+  const GlobalValue *GV = Obj.getSymbolGV(Sym.getRawDataRefImpl());
+
+  SmallString<64> Name;
+  raw_svector_ostream OS(Name);
+  Sym.printName(OS);
+  StringRef NameRef = Saver.save(StringRef(Name));
+
+  uint32_t Flags = Sym.getFlags();
+  bool IsWeak = Flags & BasicSymbolRef::SF_Weak;
+  uint32_t Binding = IsWeak ? STB_WEAK : STB_GLOBAL;
+
+  uint8_t Type = STT_NOTYPE;
+  bool CanOmitFromDynSym = false;
+  // FIXME: Expose a thread-local flag for module asm symbols.
+  if (GV) {
+    if (GV->isThreadLocal())
+      Type = STT_TLS;
+    CanOmitFromDynSym = canBeOmittedFromSymbolTable(GV);
+  }
+
+  uint8_t Visibility;
+  if (GV)
+    Visibility = getGvVisibility(GV);
+  else
+    // FIXME: Set SF_Hidden flag correctly for module asm symbols, and expose
+    // protected visibility.
+    Visibility = STV_DEFAULT;
+
+  if (GV)
+    if (const Comdat *C = GV->getComdat())
+      if (!KeptComdats.count(C))
+        return Symtab<ELFT>::X->addUndefined(NameRef, Binding, Visibility, Type,
+                                             CanOmitFromDynSym, this);
+
+  const Module &M = Obj.getModule();
+  if (Flags & BasicSymbolRef::SF_Undefined)
+    return Symtab<ELFT>::X->addUndefined(NameRef, Binding, Visibility, Type,
+                                         CanOmitFromDynSym, this);
+  if (Flags & BasicSymbolRef::SF_Common) {
+    // FIXME: Set SF_Common flag correctly for module asm symbols, and expose
+    // size and alignment.
+    assert(GV);
+    const DataLayout &DL = M.getDataLayout();
+    uint64_t Size = DL.getTypeAllocSize(GV->getValueType());
+    return Symtab<ELFT>::X->addCommon(NameRef, Size, GV->getAlignment(),
+                                      Binding, Visibility, STT_OBJECT, this);
+  }
+  return Symtab<ELFT>::X->addBitcode(NameRef, IsWeak, Visibility, Type,
+                                     CanOmitFromDynSym, this);
+}
 
-  return std::move(Ret);
+bool BitcodeFile::shouldSkip(uint32_t Flags) {
+  return !(Flags & BasicSymbolRef::SF_Global) ||
+         (Flags & BasicSymbolRef::SF_FormatSpecific);
+}
+
+template <class ELFT>
+void BitcodeFile::parse(DenseSet<StringRef> &ComdatGroups) {
+  Obj = check(IRObjectFile::create(MB, Driver->Context));
+  const Module &M = Obj->getModule();
+
+  DenseSet<const Comdat *> KeptComdats;
+  for (const auto &P : M.getComdatSymbolTable()) {
+    StringRef N = Saver.save(P.first());
+    if (ComdatGroups.insert(N).second)
+      KeptComdats.insert(&P.second);
+  }
+
+  for (const BasicSymbolRef &Sym : Obj->symbols())
+    if (!shouldSkip(Sym.getFlags()))
+      Symbols.push_back(createSymbol<ELFT>(KeptComdats, *Obj, Sym));
 }
 
 template <template <class> class T>
 static std::unique_ptr<InputFile> createELFFile(MemoryBufferRef MB) {
-  std::pair<unsigned char, unsigned char> Type = getElfArchType(MB.getBuffer());
-  if (Type.second != ELF::ELFDATA2LSB && Type.second != ELF::ELFDATA2MSB)
-    error("Invalid data encoding: " + MB.getBufferIdentifier());
-
-  if (Type.first == ELF::ELFCLASS32) {
-    if (Type.second == ELF::ELFDATA2LSB)
-      return createELFFileAux<T<ELF32LE>>(MB);
-    return createELFFileAux<T<ELF32BE>>(MB);
-  }
-  if (Type.first == ELF::ELFCLASS64) {
-    if (Type.second == ELF::ELFDATA2LSB)
-      return createELFFileAux<T<ELF64LE>>(MB);
-    return createELFFileAux<T<ELF64BE>>(MB);
-  }
-  error("Invalid file class: " + MB.getBufferIdentifier());
+  unsigned char Size;
+  unsigned char Endian;
+  std::tie(Size, Endian) = getElfArchType(MB.getBuffer());
+  if (Endian != ELFDATA2LSB && Endian != ELFDATA2MSB)
+    fatal("invalid data encoding: " + MB.getBufferIdentifier());
+
+  std::unique_ptr<InputFile> Obj;
+  if (Size == ELFCLASS32 && Endian == ELFDATA2LSB)
+    Obj.reset(new T<ELF32LE>(MB));
+  else if (Size == ELFCLASS32 && Endian == ELFDATA2MSB)
+    Obj.reset(new T<ELF32BE>(MB));
+  else if (Size == ELFCLASS64 && Endian == ELFDATA2LSB)
+    Obj.reset(new T<ELF64LE>(MB));
+  else if (Size == ELFCLASS64 && Endian == ELFDATA2MSB)
+    Obj.reset(new T<ELF64BE>(MB));
+  else
+    fatal("invalid file class: " + MB.getBufferIdentifier());
+
+  if (!Config->FirstElf)
+    Config->FirstElf = Obj.get();
+  return Obj;
+}
+
+static bool isBitcode(MemoryBufferRef MB) {
+  using namespace sys::fs;
+  return identify_magic(MB.getBuffer()) == file_magic::bitcode;
 }
 
-std::unique_ptr<InputFile> elf2::createObjectFile(MemoryBufferRef MB) {
-  return createELFFile<ObjectFile>(MB);
+std::unique_ptr<InputFile> elf::createObjectFile(MemoryBufferRef MB,
+                                                 StringRef ArchiveName) {
+  std::unique_ptr<InputFile> F;
+  if (isBitcode(MB))
+    F.reset(new BitcodeFile(MB));
+  else
+    F = createELFFile<ObjectFile>(MB);
+  F->ArchiveName = ArchiveName;
+  return F;
 }
 
-std::unique_ptr<InputFile> elf2::createSharedFile(MemoryBufferRef MB) {
+std::unique_ptr<InputFile> elf::createSharedFile(MemoryBufferRef MB) {
   return createELFFile<SharedFile>(MB);
 }
 
-template class elf2::ELFFileBase<ELF32LE>;
-template class elf2::ELFFileBase<ELF32BE>;
-template class elf2::ELFFileBase<ELF64LE>;
-template class elf2::ELFFileBase<ELF64BE>;
+MemoryBufferRef LazyObjectFile::getBuffer() {
+  if (Seen)
+    return MemoryBufferRef();
+  Seen = true;
+  return MB;
+}
 
-template class elf2::ObjectFile<ELF32LE>;
-template class elf2::ObjectFile<ELF32BE>;
-template class elf2::ObjectFile<ELF64LE>;
-template class elf2::ObjectFile<ELF64BE>;
+template <class ELFT>
+void LazyObjectFile::parse() {
+  for (StringRef Sym : getSymbols())
+    Symtab<ELFT>::X->addLazyObject(Sym, *this);
+}
+
+template <class ELFT> std::vector<StringRef> LazyObjectFile::getElfSymbols() {
+  typedef typename ELFT::Shdr Elf_Shdr;
+  typedef typename ELFT::Sym Elf_Sym;
+  typedef typename ELFT::SymRange Elf_Sym_Range;
+
+  const ELFFile<ELFT> Obj = createELFObj<ELFT>(this->MB);
+  for (const Elf_Shdr &Sec : Obj.sections()) {
+    if (Sec.sh_type != SHT_SYMTAB)
+      continue;
+    Elf_Sym_Range Syms = Obj.symbols(&Sec);
+    uint32_t FirstNonLocal = Sec.sh_info;
+    StringRef StringTable = check(Obj.getStringTableForSymtab(Sec));
+    std::vector<StringRef> V;
+    for (const Elf_Sym &Sym : Syms.slice(FirstNonLocal))
+      if (Sym.st_shndx != SHN_UNDEF)
+        V.push_back(check(Sym.getName(StringTable)));
+    return V;
+  }
+  return {};
+}
+
+std::vector<StringRef> LazyObjectFile::getBitcodeSymbols() {
+  LLVMContext Context;
+  std::unique_ptr<IRObjectFile> Obj =
+      check(IRObjectFile::create(this->MB, Context));
+  std::vector<StringRef> V;
+  for (const BasicSymbolRef &Sym : Obj->symbols()) {
+    uint32_t Flags = Sym.getFlags();
+    if (BitcodeFile::shouldSkip(Flags))
+      continue;
+    if (Flags & BasicSymbolRef::SF_Undefined)
+      continue;
+    SmallString<64> Name;
+    raw_svector_ostream OS(Name);
+    Sym.printName(OS);
+    V.push_back(Saver.save(StringRef(Name)));
+  }
+  return V;
+}
+
+// Returns a vector of globally-visible defined symbol names.
+std::vector<StringRef> LazyObjectFile::getSymbols() {
+  if (isBitcode(this->MB))
+    return getBitcodeSymbols();
+
+  unsigned char Size;
+  unsigned char Endian;
+  std::tie(Size, Endian) = getElfArchType(this->MB.getBuffer());
+  if (Size == ELFCLASS32) {
+    if (Endian == ELFDATA2LSB)
+      return getElfSymbols<ELF32LE>();
+    return getElfSymbols<ELF32BE>();
+  }
+  if (Endian == ELFDATA2LSB)
+    return getElfSymbols<ELF64LE>();
+  return getElfSymbols<ELF64BE>();
+}
 
-template class elf2::SharedFile<ELF32LE>;
-template class elf2::SharedFile<ELF32BE>;
-template class elf2::SharedFile<ELF64LE>;
-template class elf2::SharedFile<ELF64BE>;
+template void ArchiveFile::parse<ELF32LE>();
+template void ArchiveFile::parse<ELF32BE>();
+template void ArchiveFile::parse<ELF64LE>();
+template void ArchiveFile::parse<ELF64BE>();
+
+template void BitcodeFile::parse<ELF32LE>(DenseSet<StringRef> &);
+template void BitcodeFile::parse<ELF32BE>(DenseSet<StringRef> &);
+template void BitcodeFile::parse<ELF64LE>(DenseSet<StringRef> &);
+template void BitcodeFile::parse<ELF64BE>(DenseSet<StringRef> &);
+
+template void LazyObjectFile::parse<ELF32LE>();
+template void LazyObjectFile::parse<ELF32BE>();
+template void LazyObjectFile::parse<ELF64LE>();
+template void LazyObjectFile::parse<ELF64BE>();
+
+template class elf::ELFFileBase<ELF32LE>;
+template class elf::ELFFileBase<ELF32BE>;
+template class elf::ELFFileBase<ELF64LE>;
+template class elf::ELFFileBase<ELF64BE>;
+
+template class elf::ObjectFile<ELF32LE>;
+template class elf::ObjectFile<ELF32BE>;
+template class elf::ObjectFile<ELF64LE>;
+template class elf::ObjectFile<ELF64BE>;
+
+template class elf::SharedFile<ELF32LE>;
+template class elf::SharedFile<ELF32BE>;
+template class elf::SharedFile<ELF64LE>;
+template class elf::SharedFile<ELF64BE>;