vendor/lld/lld-release_39-r276489

1 files changed, 577 insertions, 138 deletions

diff --git a/ELF/SymbolTable.cpp b/ELF/SymbolTable.cpp
index 65f5dff9d7a3..78c1298df427 100644
--- a/ELF/SymbolTable.cpp
+++ b/ELF/SymbolTable.cpp
@@ -17,7 +17,11 @@
 #include "SymbolTable.h"
 #include "Config.h"
 #include "Error.h"
+#include "LinkerScript.h"
+#include "Strings.h"
+#include "SymbolListFile.h"
 #include "Symbols.h"
+#include "llvm/Bitcode/ReaderWriter.h"
 #include "llvm/Support/StringSaver.h"
 
 using namespace llvm;
@@ -25,40 +29,48 @@ using namespace llvm::object;
 using namespace llvm::ELF;
 
 using namespace lld;
-using namespace lld::elf2;
+using namespace lld::elf;
 
 // All input object files must be for the same architecture
 // (e.g. it does not make sense to link x86 object files with
 // MIPS object files.) This function checks for that error.
-template <class ELFT>
-static void checkCompatibility(InputFile *FileP) {
-  auto *F = dyn_cast<ELFFileBase<ELFT>>(FileP);
-  if (!F)
-    return;
-  if (F->getELFKind() == Config->EKind && F->getEMachine() == Config->EMachine)
-    return;
+template <class ELFT> static bool isCompatible(InputFile *F) {
+  if (!isa<ELFFileBase<ELFT>>(F) && !isa<BitcodeFile>(F))
+    return true;
+  if (F->EKind == Config->EKind && F->EMachine == Config->EMachine)
+    return true;
   StringRef A = F->getName();
   StringRef B = Config->Emulation;
   if (B.empty())
     B = Config->FirstElf->getName();
   error(A + " is incompatible with " + B);
+  return false;
 }
 
 // Add symbols in File to the symbol table.
 template <class ELFT>
 void SymbolTable<ELFT>::addFile(std::unique_ptr<InputFile> File) {
   InputFile *FileP = File.get();
-  checkCompatibility<ELFT>(FileP);
+  if (!isCompatible<ELFT>(FileP))
+    return;
 
   // .a file
   if (auto *F = dyn_cast<ArchiveFile>(FileP)) {
     ArchiveFiles.emplace_back(cast<ArchiveFile>(File.release()));
-    F->parse();
-    for (Lazy &Sym : F->getLazySymbols())
-      addLazy(&Sym);
+    F->parse<ELFT>();
     return;
   }
 
+  // Lazy object file
+  if (auto *F = dyn_cast<LazyObjectFile>(FileP)) {
+    LazyObjectFiles.emplace_back(cast<LazyObjectFile>(File.release()));
+    F->parse<ELFT>();
+    return;
+  }
+
+  if (Config->Trace)
+    outs() << getFilename(FileP) << "\n";
+
   // .so file
   if (auto *F = dyn_cast<SharedFile<ELFT>>(FileP)) {
     // DSOs are uniquified not by filename but by soname.
@@ -68,189 +80,443 @@ void SymbolTable<ELFT>::addFile(std::unique_ptr<InputFile> File) {
 
     SharedFiles.emplace_back(cast<SharedFile<ELFT>>(File.release()));
     F->parseRest();
-    for (SharedSymbol<ELFT> &B : F->getSharedSymbols())
-      resolve(&B);
     return;
   }
 
-  // .o file
+  // LLVM bitcode file
+  if (auto *F = dyn_cast<BitcodeFile>(FileP)) {
+    BitcodeFiles.emplace_back(cast<BitcodeFile>(File.release()));
+    F->parse<ELFT>(ComdatGroups);
+    return;
+  }
+
+  // Regular object file
   auto *F = cast<ObjectFile<ELFT>>(FileP);
   ObjectFiles.emplace_back(cast<ObjectFile<ELFT>>(File.release()));
   F->parse(ComdatGroups);
-  for (SymbolBody *B : F->getSymbols())
-    resolve(B);
 }
 
-// Add an undefined symbol.
-template <class ELFT>
-SymbolBody *SymbolTable<ELFT>::addUndefined(StringRef Name) {
-  auto *Sym = new (Alloc) Undefined(Name, false, STV_DEFAULT, false);
-  resolve(Sym);
-  return Sym;
-}
+// This function is where all the optimizations of link-time
+// optimization happens. When LTO is in use, some input files are
+// not in native object file format but in the LLVM bitcode format.
+// This function compiles bitcode files into a few big native files
+// using LLVM functions and replaces bitcode symbols with the results.
+// Because all bitcode files that consist of a program are passed
+// to the compiler at once, it can do whole-program optimization.
+template <class ELFT> void SymbolTable<ELFT>::addCombinedLtoObject() {
+  if (BitcodeFiles.empty())
+    return;
 
-// Add an undefined symbol. Unlike addUndefined, that symbol
-// doesn't have to be resolved, thus "opt" (optional).
-template <class ELFT>
-SymbolBody *SymbolTable<ELFT>::addUndefinedOpt(StringRef Name) {
-  auto *Sym = new (Alloc) Undefined(Name, false, STV_HIDDEN, true);
-  resolve(Sym);
-  return Sym;
-}
+  // Compile bitcode files.
+  Lto.reset(new BitcodeCompiler);
+  for (const std::unique_ptr<BitcodeFile> &F : BitcodeFiles)
+    Lto->add(*F);
+  std::vector<std::unique_ptr<InputFile>> IFs = Lto->compile();
 
-template <class ELFT>
-SymbolBody *SymbolTable<ELFT>::addAbsolute(StringRef Name, Elf_Sym &ESym) {
-  // Pass nullptr because absolute symbols have no corresponding input sections.
-  auto *Sym = new (Alloc) DefinedRegular<ELFT>(Name, ESym, nullptr);
-  resolve(Sym);
-  return Sym;
+  // Replace bitcode symbols.
+  for (auto &IF : IFs) {
+    ObjectFile<ELFT> *Obj = cast<ObjectFile<ELFT>>(IF.release());
+
+    DenseSet<StringRef> DummyGroups;
+    Obj->parse(DummyGroups);
+    ObjectFiles.emplace_back(Obj);
+  }
 }
 
 template <class ELFT>
-SymbolBody *SymbolTable<ELFT>::addSynthetic(StringRef Name,
-                                            OutputSectionBase<ELFT> &Section,
-                                            uintX_t Value) {
-  auto *Sym = new (Alloc) DefinedSynthetic<ELFT>(Name, Value, Section);
-  resolve(Sym);
-  return Sym;
+DefinedRegular<ELFT> *SymbolTable<ELFT>::addAbsolute(StringRef Name,
+                                                     uint8_t Visibility) {
+  return cast<DefinedRegular<ELFT>>(
+      addRegular(Name, STB_GLOBAL, Visibility)->body());
 }
 
 // Add Name as an "ignored" symbol. An ignored symbol is a regular
-// linker-synthesized defined symbol, but it is not recorded to the output
-// file's symbol table. Such symbols are useful for some linker-defined symbols.
+// linker-synthesized defined symbol, but is only defined if needed.
 template <class ELFT>
-SymbolBody *SymbolTable<ELFT>::addIgnored(StringRef Name) {
-  return addAbsolute(Name, ElfSym<ELFT>::IgnoredWeak);
+DefinedRegular<ELFT> *SymbolTable<ELFT>::addIgnored(StringRef Name,
+                                                    uint8_t Visibility) {
+  if (!find(Name))
+    return nullptr;
+  return addAbsolute(Name, Visibility);
 }
 
-// The 'strong' variant of the addIgnored. Adds symbol which has a global
-// binding and cannot be substituted.
-template <class ELFT>
-SymbolBody *SymbolTable<ELFT>::addIgnoredStrong(StringRef Name) {
-  return addAbsolute(Name, ElfSym<ELFT>::Ignored);
+// Set a flag for --trace-symbol so that we can print out a log message
+// if a new symbol with the same name is inserted into the symbol table.
+template <class ELFT> void SymbolTable<ELFT>::trace(StringRef Name) {
+  Symtab.insert({Name, {-1, true}});
 }
 
 // Rename SYM as __wrap_SYM. The original symbol is preserved as __real_SYM.
 // Used to implement --wrap.
 template <class ELFT> void SymbolTable<ELFT>::wrap(StringRef Name) {
-  if (Symtab.count(Name) == 0)
+  SymbolBody *B = find(Name);
+  if (!B)
     return;
   StringSaver Saver(Alloc);
-  Symbol *Sym = addUndefined(Name)->getSymbol();
-  Symbol *Real = addUndefined(Saver.save("__real_" + Name))->getSymbol();
-  Symbol *Wrap = addUndefined(Saver.save("__wrap_" + Name))->getSymbol();
-  Real->Body = Sym->Body;
-  Sym->Body = Wrap->Body;
+  Symbol *Sym = B->symbol();
+  Symbol *Real = addUndefined(Saver.save("__real_" + Name));
+  Symbol *Wrap = addUndefined(Saver.save("__wrap_" + Name));
+  // We rename symbols by replacing the old symbol's SymbolBody with the new
+  // symbol's SymbolBody. This causes all SymbolBody pointers referring to the
+  // old symbol to instead refer to the new symbol.
+  memcpy(Real->Body.buffer, Sym->Body.buffer, sizeof(Sym->Body));
+  memcpy(Sym->Body.buffer, Wrap->Body.buffer, sizeof(Wrap->Body));
+}
+
+static uint8_t getMinVisibility(uint8_t VA, uint8_t VB) {
+  if (VA == STV_DEFAULT)
+    return VB;
+  if (VB == STV_DEFAULT)
+    return VA;
+  return std::min(VA, VB);
 }
 
-// Returns a file from which symbol B was created.
-// If B does not belong to any file, returns a nullptr.
+// Find an existing symbol or create and insert a new one.
 template <class ELFT>
-ELFFileBase<ELFT> *SymbolTable<ELFT>::findFile(SymbolBody *B) {
-  for (const std::unique_ptr<ObjectFile<ELFT>> &F : ObjectFiles) {
-    ArrayRef<SymbolBody *> Syms = F->getSymbols();
-    if (std::find(Syms.begin(), Syms.end(), B) != Syms.end())
-      return F.get();
+std::pair<Symbol *, bool> SymbolTable<ELFT>::insert(StringRef Name) {
+  auto P = Symtab.insert({Name, {(int)SymVector.size(), false}});
+  SymIndex &V = P.first->second;
+  bool IsNew = P.second;
+
+  if (V.Idx == -1) {
+    IsNew = true;
+    V = {(int)SymVector.size(), true};
+  }
+
+  Symbol *Sym;
+  if (IsNew) {
+    Sym = new (Alloc) Symbol;
+    Sym->Binding = STB_WEAK;
+    Sym->Visibility = STV_DEFAULT;
+    Sym->IsUsedInRegularObj = false;
+    Sym->ExportDynamic = false;
+    Sym->VersionId = Config->DefaultSymbolVersion;
+    Sym->Traced = V.Traced;
+    SymVector.push_back(Sym);
+  } else {
+    Sym = SymVector[V.Idx];
   }
-  return nullptr;
+  return {Sym, IsNew};
+}
+
+// Find an existing symbol or create and insert a new one, then apply the given
+// attributes.
+template <class ELFT>
+std::pair<Symbol *, bool>
+SymbolTable<ELFT>::insert(StringRef Name, uint8_t Type, uint8_t Visibility,
+                          bool CanOmitFromDynSym, bool IsUsedInRegularObj,
+                          InputFile *File) {
+  Symbol *S;
+  bool WasInserted;
+  std::tie(S, WasInserted) = insert(Name);
+
+  // Merge in the new symbol's visibility.
+  S->Visibility = getMinVisibility(S->Visibility, Visibility);
+  if (!CanOmitFromDynSym && (Config->Shared || Config->ExportDynamic))
+    S->ExportDynamic = true;
+  if (IsUsedInRegularObj)
+    S->IsUsedInRegularObj = true;
+  if (!WasInserted && S->body()->Type != SymbolBody::UnknownType &&
+      ((Type == STT_TLS) != S->body()->isTls()))
+    error("TLS attribute mismatch for symbol: " +
+          conflictMsg(S->body(), File));
+
+  return {S, WasInserted};
 }
 
 // Construct a string in the form of "Sym in File1 and File2".
 // Used to construct an error message.
-template <class ELFT>
-std::string SymbolTable<ELFT>::conflictMsg(SymbolBody *Old, SymbolBody *New) {
-  ELFFileBase<ELFT> *OldFile = findFile(Old);
-  ELFFileBase<ELFT> *NewFile = findFile(New);
+template <typename ELFT>
+std::string SymbolTable<ELFT>::conflictMsg(SymbolBody *Existing,
+                                           InputFile *NewFile) {
+  std::string Sym = Existing->getName();
+  if (Config->Demangle)
+    Sym = demangle(Sym);
+  return Sym + " in " + getFilename(Existing->File) + " and " +
+         getFilename(NewFile);
+}
 
-  StringRef Sym = Old->getName();
-  StringRef F1 = OldFile ? OldFile->getName() : "(internal)";
-  StringRef F2 = NewFile ? NewFile->getName() : "(internal)";
-  return (Sym + " in " + F1 + " and " + F2).str();
+template <class ELFT> Symbol *SymbolTable<ELFT>::addUndefined(StringRef Name) {
+  return addUndefined(Name, STB_GLOBAL, STV_DEFAULT, /*Type*/ 0,
+                      /*CanOmitFromDynSym*/ false, /*File*/ nullptr);
 }
 
-// This function resolves conflicts if there's an existing symbol with
-// the same name. Decisions are made based on symbol type.
-template <class ELFT> void SymbolTable<ELFT>::resolve(SymbolBody *New) {
-  Symbol *Sym = insert(New);
-  if (Sym->Body == New)
-    return;
+template <class ELFT>
+Symbol *SymbolTable<ELFT>::addUndefined(StringRef Name, uint8_t Binding,
+                                        uint8_t StOther, uint8_t Type,
+                                        bool CanOmitFromDynSym,
+                                        InputFile *File) {
+  Symbol *S;
+  bool WasInserted;
+  std::tie(S, WasInserted) =
+      insert(Name, Type, StOther & 3, CanOmitFromDynSym,
+             /*IsUsedInRegularObj*/ !File || !isa<BitcodeFile>(File), File);
+  if (WasInserted) {
+    S->Binding = Binding;
+    replaceBody<Undefined>(S, Name, StOther, Type, File);
+    return S;
+  }
+  if (Binding != STB_WEAK) {
+    if (S->body()->isShared() || S->body()->isLazy())
+      S->Binding = Binding;
+    if (auto *SS = dyn_cast<SharedSymbol<ELFT>>(S->body()))
+      SS->file()->IsUsed = true;
+  }
+  if (auto *L = dyn_cast<Lazy>(S->body())) {
+    // An undefined weak will not fetch archive members, but we have to remember
+    // its type. See also comment in addLazyArchive.
+    if (S->isWeak())
+      L->Type = Type;
+    else if (auto F = L->fetch())
+      addFile(std::move(F));
+  }
+  return S;
+}
 
-  SymbolBody *Existing = Sym->Body;
+// We have a new defined symbol with the specified binding. Return 1 if the new
+// symbol should win, -1 if the new symbol should lose, or 0 if both symbols are
+// strong defined symbols.
+static int compareDefined(Symbol *S, bool WasInserted, uint8_t Binding) {
+  if (WasInserted)
+    return 1;
+  SymbolBody *Body = S->body();
+  if (Body->isLazy() || Body->isUndefined() || Body->isShared())
+    return 1;
+  if (Binding == STB_WEAK)
+    return -1;
+  if (S->isWeak())
+    return 1;
+  return 0;
+}
 
-  if (Lazy *L = dyn_cast<Lazy>(Existing)) {
-    if (auto *Undef = dyn_cast<Undefined>(New)) {
-      addMemberFile(Undef, L);
-      return;
+// We have a new non-common defined symbol with the specified binding. Return 1
+// if the new symbol should win, -1 if the new symbol should lose, or 0 if there
+// is a conflict. If the new symbol wins, also update the binding.
+static int compareDefinedNonCommon(Symbol *S, bool WasInserted, uint8_t Binding) {
+  if (int Cmp = compareDefined(S, WasInserted, Binding)) {
+    if (Cmp > 0)
+      S->Binding = Binding;
+    return Cmp;
+  }
+  if (isa<DefinedCommon>(S->body())) {
+    // Non-common symbols take precedence over common symbols.
+    if (Config->WarnCommon)
+      warning("common " + S->body()->getName() + " is overridden");
+    return 1;
+  }
+  return 0;
+}
+
+template <class ELFT>
+Symbol *SymbolTable<ELFT>::addCommon(StringRef N, uint64_t Size,
+                                     uint64_t Alignment, uint8_t Binding,
+                                     uint8_t StOther, uint8_t Type,
+                                     InputFile *File) {
+  Symbol *S;
+  bool WasInserted;
+  std::tie(S, WasInserted) =
+      insert(N, Type, StOther & 3, /*CanOmitFromDynSym*/ false,
+             /*IsUsedInRegularObj*/ true, File);
+  int Cmp = compareDefined(S, WasInserted, Binding);
+  if (Cmp > 0) {
+    S->Binding = Binding;
+    replaceBody<DefinedCommon>(S, N, Size, Alignment, StOther, Type, File);
+  } else if (Cmp == 0) {
+    auto *C = dyn_cast<DefinedCommon>(S->body());
+    if (!C) {
+      // Non-common symbols take precedence over common symbols.
+      if (Config->WarnCommon)
+        warning("common " + S->body()->getName() + " is overridden");
+      return S;
     }
-    // Found a definition for something also in an archive.
-    // Ignore the archive definition.
-    Sym->Body = New;
-    return;
+
+    if (Config->WarnCommon)
+      warning("multiple common of " + S->body()->getName());
+
+    C->Size = std::max(C->Size, Size);
+    C->Alignment = std::max(C->Alignment, Alignment);
   }
+  return S;
+}
 
-  if (New->isTls() != Existing->isTls())
-    error("TLS attribute mismatch for symbol: " + conflictMsg(Existing, New));
+template <class ELFT>
+void SymbolTable<ELFT>::reportDuplicate(SymbolBody *Existing,
+                                        InputFile *NewFile) {
+  std::string Msg = "duplicate symbol: " + conflictMsg(Existing, NewFile);
+  if (Config->AllowMultipleDefinition)
+    warning(Msg);
+  else
+    error(Msg);
+}
 
-  // compare() returns -1, 0, or 1 if the lhs symbol is less preferable,
-  // equivalent (conflicting), or more preferable, respectively.
-  int Comp = Existing->compare<ELFT>(New);
-  if (Comp == 0) {
-    std::string S = "duplicate symbol: " + conflictMsg(Existing, New);
-    if (!Config->AllowMultipleDefinition)
-      error(S);
-    warning(S);
-    return;
+template <typename ELFT>
+Symbol *SymbolTable<ELFT>::addRegular(StringRef Name, const Elf_Sym &Sym,
+                                      InputSectionBase<ELFT> *Section) {
+  Symbol *S;
+  bool WasInserted;
+  std::tie(S, WasInserted) =
+      insert(Name, Sym.getType(), Sym.getVisibility(),
+             /*CanOmitFromDynSym*/ false, /*IsUsedInRegularObj*/ true,
+             Section ? Section->getFile() : nullptr);
+  int Cmp = compareDefinedNonCommon(S, WasInserted, Sym.getBinding());
+  if (Cmp > 0)
+    replaceBody<DefinedRegular<ELFT>>(S, Name, Sym, Section);
+  else if (Cmp == 0)
+    reportDuplicate(S->body(), Section->getFile());
+  return S;
+}
+
+template <typename ELFT>
+Symbol *SymbolTable<ELFT>::addRegular(StringRef Name, uint8_t Binding,
+                                      uint8_t StOther) {
+  Symbol *S;
+  bool WasInserted;
+  std::tie(S, WasInserted) =
+      insert(Name, STT_NOTYPE, StOther & 3, /*CanOmitFromDynSym*/ false,
+             /*IsUsedInRegularObj*/ true, nullptr);
+  int Cmp = compareDefinedNonCommon(S, WasInserted, Binding);
+  if (Cmp > 0)
+    replaceBody<DefinedRegular<ELFT>>(S, Name, StOther);
+  else if (Cmp == 0)
+    reportDuplicate(S->body(), nullptr);
+  return S;
+}
+
+template <typename ELFT>
+Symbol *SymbolTable<ELFT>::addSynthetic(StringRef N,
+                                        OutputSectionBase<ELFT> *Section,
+                                        uintX_t Value) {
+  Symbol *S;
+  bool WasInserted;
+  std::tie(S, WasInserted) =
+      insert(N, STT_NOTYPE, STV_HIDDEN, /*CanOmitFromDynSym*/ false,
+             /*IsUsedInRegularObj*/ true, nullptr);
+  int Cmp = compareDefinedNonCommon(S, WasInserted, STB_GLOBAL);
+  if (Cmp > 0)
+    replaceBody<DefinedSynthetic<ELFT>>(S, N, Value, Section);
+  else if (Cmp == 0)
+    reportDuplicate(S->body(), nullptr);
+  return S;
+}
+
+template <typename ELFT>
+void SymbolTable<ELFT>::addShared(SharedFile<ELFT> *F, StringRef Name,
+                                  const Elf_Sym &Sym,
+                                  const typename ELFT::Verdef *Verdef) {
+  // DSO symbols do not affect visibility in the output, so we pass STV_DEFAULT
+  // as the visibility, which will leave the visibility in the symbol table
+  // unchanged.
+  Symbol *S;
+  bool WasInserted;
+  std::tie(S, WasInserted) =
+      insert(Name, Sym.getType(), STV_DEFAULT, /*CanOmitFromDynSym*/ true,
+             /*IsUsedInRegularObj*/ false, F);
+  // Make sure we preempt DSO symbols with default visibility.
+  if (Sym.getVisibility() == STV_DEFAULT)
+    S->ExportDynamic = true;
+  if (WasInserted || isa<Undefined>(S->body())) {
+    replaceBody<SharedSymbol<ELFT>>(S, F, Name, Sym, Verdef);
+    if (!S->isWeak())
+      F->IsUsed = true;
   }
-  if (Comp < 0)
-    Sym->Body = New;
 }
 
-// Find an existing symbol or create and insert a new one.
-template <class ELFT> Symbol *SymbolTable<ELFT>::insert(SymbolBody *New) {
-  StringRef Name = New->getName();
-  Symbol *&Sym = Symtab[Name];
-  if (!Sym)
-    Sym = new (Alloc) Symbol{New};
-  New->setBackref(Sym);
-  return Sym;
+template <class ELFT>
+Symbol *SymbolTable<ELFT>::addBitcode(StringRef Name, bool IsWeak,
+                                      uint8_t StOther, uint8_t Type,
+                                      bool CanOmitFromDynSym, BitcodeFile *F) {
+  Symbol *S;
+  bool WasInserted;
+  std::tie(S, WasInserted) = insert(Name, Type, StOther & 3, CanOmitFromDynSym,
+                                    /*IsUsedInRegularObj*/ false, F);
+  int Cmp =
+      compareDefinedNonCommon(S, WasInserted, IsWeak ? STB_WEAK : STB_GLOBAL);
+  if (Cmp > 0)
+    replaceBody<DefinedBitcode>(S, Name, StOther, Type, F);
+  else if (Cmp == 0)
+    reportDuplicate(S->body(), F);
+  return S;
 }
 
 template <class ELFT> SymbolBody *SymbolTable<ELFT>::find(StringRef Name) {
   auto It = Symtab.find(Name);
   if (It == Symtab.end())
     return nullptr;
-  return It->second->Body;
+  SymIndex V = It->second;
+  if (V.Idx == -1)
+    return nullptr;
+  return SymVector[V.Idx]->body();
+}
+
+// Returns a list of defined symbols that match with a given glob pattern.
+template <class ELFT>
+std::vector<SymbolBody *> SymbolTable<ELFT>::findAll(StringRef Pattern) {
+  std::vector<SymbolBody *> Res;
+  for (Symbol *Sym : SymVector) {
+    SymbolBody *B = Sym->body();
+    if (!B->isUndefined() && globMatch(Pattern, B->getName()))
+      Res.push_back(B);
+  }
+  return Res;
 }
 
-template <class ELFT> void SymbolTable<ELFT>::addLazy(Lazy *L) {
-  Symbol *Sym = insert(L);
-  if (Sym->Body == L)
+template <class ELFT>
+void SymbolTable<ELFT>::addLazyArchive(ArchiveFile *F,
+                                       const object::Archive::Symbol Sym) {
+  Symbol *S;
+  bool WasInserted;
+  std::tie(S, WasInserted) = insert(Sym.getName());
+  if (WasInserted) {
+    replaceBody<LazyArchive>(S, *F, Sym, SymbolBody::UnknownType);
     return;
-  if (auto *Undef = dyn_cast<Undefined>(Sym->Body)) {
-    Sym->Body = L;
-    addMemberFile(Undef, L);
   }
+  if (!S->body()->isUndefined())
+    return;
+
+  // Weak undefined symbols should not fetch members from archives. If we were
+  // to keep old symbol we would not know that an archive member was available
+  // if a strong undefined symbol shows up afterwards in the link. If a strong
+  // undefined symbol never shows up, this lazy symbol will get to the end of
+  // the link and must be treated as the weak undefined one. We already marked
+  // this symbol as used when we added it to the symbol table, but we also need
+  // to preserve its type. FIXME: Move the Type field to Symbol.
+  if (S->isWeak()) {
+    replaceBody<LazyArchive>(S, *F, Sym, S->body()->Type);
+    return;
+  }
+  MemoryBufferRef MBRef = F->getMember(&Sym);
+  if (!MBRef.getBuffer().empty())
+    addFile(createObjectFile(MBRef, F->getName()));
 }
 
 template <class ELFT>
-void SymbolTable<ELFT>::addMemberFile(Undefined *Undef, Lazy *L) {
-  // Weak undefined symbols should not fetch members from archives.
-  // If we were to keep old symbol we would not know that an archive member was
-  // available if a strong undefined symbol shows up afterwards in the link.
-  // If a strong undefined symbol never shows up, this lazy symbol will
-  // get to the end of the link and must be treated as the weak undefined one.
-  // We set UsedInRegularObj in a similar way to what is done with shared
-  // symbols and mark it as weak to reduce how many special cases are needed.
-  if (Undef->isWeak()) {
-    L->setUsedInRegularObj();
-    L->setWeak();
+void SymbolTable<ELFT>::addLazyObject(StringRef Name, LazyObjectFile &Obj) {
+  Symbol *S;
+  bool WasInserted;
+  std::tie(S, WasInserted) = insert(Name);
+  if (WasInserted) {
+    replaceBody<LazyObject>(S, Name, Obj, SymbolBody::UnknownType);
     return;
   }
+  if (!S->body()->isUndefined())
+    return;
+
+  // See comment for addLazyArchive above.
+  if (S->isWeak()) {
+    replaceBody<LazyObject>(S, Name, Obj, S->body()->Type);
+  } else {
+    MemoryBufferRef MBRef = Obj.getBuffer();
+    if (!MBRef.getBuffer().empty())
+      addFile(createObjectFile(MBRef));
+  }
+}
 
-  // Fetch a member file that has the definition for L.
-  // getMember returns nullptr if the member was already read from the library.
-  if (std::unique_ptr<InputFile> File = L->getMember())
-    addFile(std::move(File));
+// Process undefined (-u) flags by loading lazy symbols named by those flags.
+template <class ELFT> void SymbolTable<ELFT>::scanUndefinedFlags() {
+  for (StringRef S : Config->Undefined)
+    if (auto *L = dyn_cast_or_null<Lazy>(find(S)))
+      if (std::unique_ptr<InputFile> File = L->fetch())
+        addFile(std::move(File));
 }
 
 // This function takes care of the case in which shared libraries depend on
@@ -265,10 +531,183 @@ template <class ELFT> void SymbolTable<ELFT>::scanShlibUndefined() {
     for (StringRef U : File->getUndefinedSymbols())
       if (SymbolBody *Sym = find(U))
         if (Sym->isDefined())
-          Sym->setUsedInDynamicReloc();
+          Sym->symbol()->ExportDynamic = true;
+}
+
+// This function process the dynamic list option by marking all the symbols
+// to be exported in the dynamic table.
+template <class ELFT> void SymbolTable<ELFT>::scanDynamicList() {
+  for (StringRef S : Config->DynamicList)
+    if (SymbolBody *B = find(S))
+      B->symbol()->ExportDynamic = true;
+}
+
+static bool hasWildcard(StringRef S) {
+  return S.find_first_of("?*") != StringRef::npos;
+}
+
+static void setVersionId(SymbolBody *Body, StringRef VersionName,
+                         StringRef Name, uint16_t Version) {
+  if (!Body || Body->isUndefined()) {
+    if (Config->NoUndefinedVersion)
+      error("version script assignment of " + VersionName + " to symbol " +
+            Name + " failed: symbol not defined");
+    return;
+  }
+
+  Symbol *Sym = Body->symbol();
+  if (Sym->VersionId != Config->DefaultSymbolVersion)
+    warning("duplicate symbol " + Name + " in version script");
+  Sym->VersionId = Version;
+}
+
+template <class ELFT>
+std::map<std::string, SymbolBody *> SymbolTable<ELFT>::getDemangledSyms() {
+  std::map<std::string, SymbolBody *> Result;
+  for (Symbol *Sym : SymVector) {
+    SymbolBody *B = Sym->body();
+    Result[demangle(B->getName())] = B;
+  }
+  return Result;
+}
+
+static bool hasExternCpp() {
+  for (VersionDefinition &V : Config->VersionDefinitions)
+    for (SymbolVersion Sym : V.Globals)
+      if (Sym.IsExternCpp)
+        return true;
+  return false;
+}
+
+// This function processes the --version-script option by marking all global
+// symbols with the VersionScriptGlobal flag, which acts as a filter on the
+// dynamic symbol table.
+template <class ELFT> void SymbolTable<ELFT>::scanVersionScript() {
+  // If version script does not contain versions declarations,
+  // we just should mark global symbols.
+  if (!Config->VersionScriptGlobals.empty()) {
+    for (SymbolVersion &Sym : Config->VersionScriptGlobals)
+      if (SymbolBody *B = find(Sym.Name))
+        B->symbol()->VersionId = VER_NDX_GLOBAL;
+    return;
+  }
+
+  if (Config->VersionDefinitions.empty())
+    return;
+
+  // If we have symbols version declarations, we should
+  // assign version references for each symbol.
+  // Current rules are:
+  // * If there is an exact match for the mangled name or we have extern C++
+  //   exact match, then we use it.
+  // * Otherwise, we look through the wildcard patterns. We look through the
+  //   version tags in reverse order. We use the first match we find (the last
+  //   matching version tag in the file).
+  // Handle exact matches and build a map of demangled externs for
+  // quick search during next step.
+  std::map<std::string, SymbolBody *> Demangled;
+  if (hasExternCpp())
+    Demangled = getDemangledSyms();
+
+  for (VersionDefinition &V : Config->VersionDefinitions) {
+    for (SymbolVersion Sym : V.Globals) {
+      if (hasWildcard(Sym.Name))
+        continue;
+      SymbolBody *B = Sym.IsExternCpp ? Demangled[Sym.Name] : find(Sym.Name);
+      setVersionId(B, V.Name, Sym.Name, V.Id);
+    }
+  }
+
+  // Handle wildcards.
+  for (size_t I = Config->VersionDefinitions.size() - 1; I != (size_t)-1; --I) {
+    VersionDefinition &V = Config->VersionDefinitions[I];
+    for (SymbolVersion &Sym : V.Globals)
+      if (hasWildcard(Sym.Name))
+        for (SymbolBody *B : findAll(Sym.Name))
+          if (B->symbol()->VersionId == Config->DefaultSymbolVersion)
+            B->symbol()->VersionId = V.Id;
+  }
+}
+
+// Returns the size of the longest version name.
+static int getMaxVersionLen() {
+  size_t Len = 0;
+  for (VersionDefinition &V : Config->VersionDefinitions)
+    Len = std::max(Len, V.Name.size());
+  return Len;
+}
+
+// Parses a symbol name in the form of <name>@<version> or <name>@@<version>.
+static std::pair<StringRef, uint16_t>
+getSymbolVersion(SymbolBody *B, int MaxVersionLen) {
+  StringRef S = B->getName();
+
+  // MaxVersionLen was passed so that we don't need to scan
+  // all characters in a symbol name. It is effective because
+  // versions are usually short and symbol names can be very long.
+  size_t Pos = S.find('@', std::max(0, int(S.size()) - MaxVersionLen - 2));
+  if (Pos == 0 || Pos == StringRef::npos)
+    return {"", 0};
+
+  StringRef Name = S.substr(0, Pos);
+  StringRef Verstr = S.substr(Pos + 1);
+  if (Verstr.empty())
+    return {"", 0};
+
+  // '@@' in a symbol name means the default version.
+  // It is usually the most recent one.
+  bool IsDefault = (Verstr[0] == '@');
+  if (IsDefault)
+    Verstr = Verstr.substr(1);
+
+  for (VersionDefinition &V : Config->VersionDefinitions) {
+    if (V.Name == Verstr)
+      return {Name, IsDefault ? V.Id : (V.Id | VERSYM_HIDDEN)};
+  }
+
+  // It is an error if the specified version was not defined.
+  error("symbol " + S + " has undefined version " + Verstr);
+  return {"", 0};
+}
+
+// Versions are usually assigned to symbols using version scripts,
+// but there's another way to assign versions to symbols.
+// If a symbol name contains '@', the string after it is not
+// actually a part of the symbol name but specifies a version.
+// This function takes care of it.
+template <class ELFT> void SymbolTable<ELFT>::scanSymbolVersions() {
+  if (Config->VersionDefinitions.empty())
+    return;
+
+  int MaxVersionLen = getMaxVersionLen();
+
+  // Unfortunately there's no way other than iterating over all
+  // symbols to look for '@' characters in symbol names.
+  // So this is inherently slow. A good news is that we do this
+  // only when versions have been defined.
+  for (Symbol *Sym : SymVector) {
+    // Symbol versions for exported symbols are by nature
+    // only for defined global symbols.
+    SymbolBody *B = Sym->body();
+    if (!B->isDefined())
+      continue;
+    uint8_t Visibility = B->getVisibility();
+    if (Visibility != STV_DEFAULT && Visibility != STV_PROTECTED)
+      continue;
+
+    // Look for '@' in the symbol name.
+    StringRef Name;
+    uint16_t Version;
+    std::tie(Name, Version) = getSymbolVersion(B, MaxVersionLen);
+    if (Name.empty())
+      continue;
+
+    B->setName(Name);
+    Sym->VersionId = Version;
+  }
 }
 
-template class elf2::SymbolTable<ELF32LE>;
-template class elf2::SymbolTable<ELF32BE>;
-template class elf2::SymbolTable<ELF64LE>;
-template class elf2::SymbolTable<ELF64BE>;
+template class elf::SymbolTable<ELF32LE>;
+template class elf::SymbolTable<ELF32BE>;
+template class elf::SymbolTable<ELF64LE>;
+template class elf::SymbolTable<ELF64BE>;