Remove more superfluous .str() and replace std::string concatenation with Twine.
[oota-llvm.git] / lib / MC / WinCOFFObjectWriter.cpp
index e98777894a714152ea4e8b0d78ae692d62f1d04e..ff90b7c2cefa4ef88f7b257a77b51cade29e5f78 100644 (file)
 //
 //===----------------------------------------------------------------------===//
 
-#define DEBUG_TYPE "WinCOFFObjectWriter"
-
 #include "llvm/MC/MCWinCOFFObjectWriter.h"
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
-#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/MC/MCAsmLayout.h"
 #include "llvm/MC/MCAssembler.h"
 #include "llvm/MC/MCSectionCOFF.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/MC/MCValue.h"
+#include "llvm/MC/StringTableBuilder.h"
 #include "llvm/Support/COFF.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/Endian.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/TimeValue.h"
 #include <cstdio>
 
 using namespace llvm;
 
+#define DEBUG_TYPE "WinCOFFObjectWriter"
+
 namespace {
 typedef SmallString<COFF::NameSize> name;
 
@@ -71,7 +73,6 @@ public:
   MCSymbolData const *MCData;
 
   COFFSymbol(StringRef name);
-  size_t size() const;
   void set_name_offset(uint32_t Offset);
 
   bool should_keep() const;
@@ -102,20 +103,6 @@ public:
   static size_t size();
 };
 
-// This class holds the COFF string table.
-class StringTable {
-  typedef StringMap<size_t> map;
-  map Map;
-
-  void update_length();
-public:
-  std::vector<char> Data;
-
-  StringTable();
-  size_t size() const;
-  size_t insert(StringRef String);
-};
-
 class WinCOFFObjectWriter : public MCObjectWriter {
 public:
 
@@ -131,13 +118,26 @@ public:
   COFF::header Header;
   sections     Sections;
   symbols      Symbols;
-  StringTable  Strings;
+  StringTableBuilder Strings;
 
   // Maps used during object file creation.
   section_map SectionMap;
   symbol_map  SymbolMap;
 
+  bool UseBigObj;
+
   WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW, raw_ostream &OS);
+  
+  void reset() override {
+    memset(&Header, 0, sizeof(Header));
+    Header.Machine = TargetObjectWriter->getMachine();
+    Sections.clear();
+    Symbols.clear();
+    Strings.clear();
+    SectionMap.clear();
+    SymbolMap.clear();
+    MCObjectWriter::reset();
+  }
 
   COFFSymbol *createSymbol(StringRef Name);
   COFFSymbol *GetOrCreateCOFFSymbol(const MCSymbol * Symbol);
@@ -150,10 +150,10 @@ public:
   void DefineSymbol(MCSymbolData const &SymbolData, MCAssembler &Assembler,
                     const MCAsmLayout &Layout);
 
-  void MakeSymbolReal(COFFSymbol &S, size_t Index);
-  void MakeSectionReal(COFFSection &S, size_t Number);
+  void SetSymbolName(COFFSymbol &S);
+  void SetSectionName(COFFSection &S);
 
-  bool ExportSymbol(MCSymbolData const &SymbolData, MCAssembler &Asm);
+  bool ExportSymbol(const MCSymbol &Symbol, MCAssembler &Asm);
 
   bool IsPhysicalSection(COFFSection *S);
 
@@ -170,7 +170,14 @@ public:
   void ExecutePostLayoutBinding(MCAssembler &Asm,
                                 const MCAsmLayout &Layout) override;
 
-  void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
+  bool IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
+                                              const MCSymbolData &DataA,
+                                              const MCFragment &FB, bool InSet,
+                                              bool IsPCRel) const override;
+
+  bool isWeak(const MCSymbolData &SD) const override;
+
+  void RecordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
                         const MCFragment *Fragment, const MCFixup &Fixup,
                         MCValue Target, bool &IsPCRel,
                         uint64_t &FixedValue) override;
@@ -179,12 +186,9 @@ public:
 };
 }
 
-static inline void write_uint32_le(void *Data, uint32_t const &Value) {
-  uint8_t *Ptr = reinterpret_cast<uint8_t *>(Data);
-  Ptr[0] = (Value & 0x000000FF) >>  0;
-  Ptr[1] = (Value & 0x0000FF00) >>  8;
-  Ptr[2] = (Value & 0x00FF0000) >> 16;
-  Ptr[3] = (Value & 0xFF000000) >> 24;
+static inline void write_uint32_le(void *Data, uint32_t Value) {
+  support::endian::write<uint32_t, support::little, support::unaligned>(Data,
+                                                                        Value);
 }
 
 //------------------------------------------------------------------------------
@@ -199,10 +203,6 @@ COFFSymbol::COFFSymbol(StringRef name)
   memset(&Data, 0, sizeof(Data));
 }
 
-size_t COFFSymbol::size() const {
-  return COFF::SymbolSize + (Data.NumberOfAuxSymbols * COFF::SymbolSize);
-}
-
 // In the case that the name does not fit within 8 bytes, the offset
 // into the string table is stored in the last 4 bytes instead, leaving
 // the first 4 bytes as 0.
@@ -253,56 +253,12 @@ size_t COFFSection::size() {
   return COFF::SectionSize;
 }
 
-//------------------------------------------------------------------------------
-// StringTable class implementation
-
-/// Write the length of the string table into Data.
-/// The length of the string table includes uint32 length header.
-void StringTable::update_length() {
-  write_uint32_le(&Data.front(), Data.size());
-}
-
-StringTable::StringTable() {
-  // The string table data begins with the length of the entire string table
-  // including the length header. Allocate space for this header.
-  Data.resize(4);
-  update_length();
-}
-
-size_t StringTable::size() const {
-  return Data.size();
-}
-
-/// Add String to the table iff it is not already there.
-/// @returns the index into the string table where the string is now located.
-size_t StringTable::insert(StringRef String) {
-  map::iterator i = Map.find(String);
-
-  if (i != Map.end())
-    return i->second;
-
-  size_t Offset = Data.size();
-
-  // Insert string data into string table.
-  Data.insert(Data.end(), String.begin(), String.end());
-  Data.push_back('\0');
-
-  // Put a reference to it in the map.
-  Map[String] = Offset;
-
-  // Update the internal length field.
-  update_length();
-
-  return Offset;
-}
-
 //------------------------------------------------------------------------------
 // WinCOFFObjectWriter class implementation
 
 WinCOFFObjectWriter::WinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
                                          raw_ostream &OS)
-  : MCObjectWriter(OS, true)
-  , TargetObjectWriter(MOTW) {
+    : MCObjectWriter(OS, true), TargetObjectWriter(MOTW) {
   memset(&Header, 0, sizeof(Header));
 
   Header.Machine = TargetObjectWriter->getMachine();
@@ -312,12 +268,12 @@ COFFSymbol *WinCOFFObjectWriter::createSymbol(StringRef Name) {
   return createCOFFEntity<COFFSymbol>(Name, Symbols);
 }
 
-COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol * Symbol){
+COFFSymbol *WinCOFFObjectWriter::GetOrCreateCOFFSymbol(const MCSymbol *Symbol) {
   symbol_map::iterator i = SymbolMap.find(Symbol);
   if (i != SymbolMap.end())
     return i->second;
-  COFFSymbol *RetSymbol
-    = createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols);
+  COFFSymbol *RetSymbol =
+      createCOFFEntity<COFFSymbol>(Symbol->getName(), Symbols);
   SymbolMap[Symbol] = RetSymbol;
   return RetSymbol;
 }
@@ -347,6 +303,14 @@ void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
 
   COFFSection *coff_section = createSection(Sec.getSectionName());
   COFFSymbol  *coff_symbol = createSymbol(Sec.getSectionName());
+  if (Sec.getSelection() != COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
+    if (const MCSymbol *S = Sec.getCOMDATSymbol()) {
+      COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(S);
+      if (COMDATSymbol->Section)
+        report_fatal_error("two sections have the same comdat");
+      COMDATSymbol->Section = coff_section;
+    }
+  }
 
   coff_section->Symbol = coff_symbol;
   coff_symbol->Section = coff_section;
@@ -385,6 +349,18 @@ void WinCOFFObjectWriter::DefineSection(MCSectionData const &SectionData) {
   SectionMap[&SectionData.getSection()] = coff_section;
 }
 
+static uint64_t getSymbolValue(const MCSymbolData &Data,
+                               const MCAsmLayout &Layout) {
+  if (Data.isCommon() && Data.isExternal())
+    return Data.getCommonSize();
+
+  uint64_t Res;
+  if (!Layout.getSymbolOffset(&Data, Res))
+    return 0;
+
+  return Res;
+}
+
 /// This function takes a symbol data object from the assembler
 /// and creates the associated COFF symbol staging object.
 void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
@@ -406,9 +382,7 @@ void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
 
       coff_symbol->Other = GetOrCreateCOFFSymbol(&SymRef->getSymbol());
     } else {
-      std::string WeakName = std::string(".weak.")
-                           +  Symbol.getName().str()
-                           + ".default";
+      std::string WeakName = (".weak." + Symbol.getName() + ".default").str();
       COFFSymbol *WeakDefault = createSymbol(WeakName);
       WeakDefault->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
       WeakDefault->Data.StorageClass  = COFF::IMAGE_SYM_CLASS_EXTERNAL;
@@ -427,33 +401,38 @@ void WinCOFFObjectWriter::DefineSymbol(MCSymbolData const &SymbolData,
 
     coff_symbol->MCData = &SymbolData;
   } else {
-    const MCSymbolData &ResSymData =
-      Assembler.getSymbolData(Symbol.AliasedSymbol());
-
-    if (Symbol.isVariable()) {
-      int64_t Addr;
-      if (Symbol.getVariableValue()->EvaluateAsAbsolute(Addr, Layout))
-        coff_symbol->Data.Value = Addr;
-    } else if (SymbolData.isExternal() && SymbolData.isCommon()) {
-      coff_symbol->Data.Value = SymbolData.getCommonSize();
-    }
+    const MCSymbolData &ResSymData = Assembler.getSymbolData(Symbol);
+    const MCSymbol *Base = Layout.getBaseSymbol(Symbol);
+    coff_symbol->Data.Value = getSymbolValue(ResSymData, Layout);
 
     coff_symbol->Data.Type         = (ResSymData.getFlags() & 0x0000FFFF) >>  0;
     coff_symbol->Data.StorageClass = (ResSymData.getFlags() & 0x00FF0000) >> 16;
 
     // If no storage class was specified in the streamer, define it here.
     if (coff_symbol->Data.StorageClass == 0) {
-      bool external = ResSymData.isExternal() || !ResSymData.Fragment;
+      bool IsExternal =
+          ResSymData.isExternal() ||
+          (!ResSymData.getFragment() && !ResSymData.getSymbol().isVariable());
 
-      coff_symbol->Data.StorageClass =
-       external ? COFF::IMAGE_SYM_CLASS_EXTERNAL : COFF::IMAGE_SYM_CLASS_STATIC;
+      coff_symbol->Data.StorageClass = IsExternal
+                                           ? COFF::IMAGE_SYM_CLASS_EXTERNAL
+                                           : COFF::IMAGE_SYM_CLASS_STATIC;
     }
 
-    if (Symbol.isAbsolute() || Symbol.AliasedSymbol().isVariable())
+    if (!Base) {
       coff_symbol->Data.SectionNumber = COFF::IMAGE_SYM_ABSOLUTE;
-    else if (ResSymData.Fragment)
-      coff_symbol->Section =
-        SectionMap[&ResSymData.Fragment->getParent()->getSection()];
+    } else {
+      const MCSymbolData &BaseData = Assembler.getSymbolData(*Base);
+      if (BaseData.getFragment()) {
+        COFFSection *Sec =
+            SectionMap[&BaseData.getFragment()->getParent()->getSection()];
+
+        if (coff_symbol->Section && coff_symbol->Section != Sec)
+          report_fatal_error("conflicting sections for symbol");
+
+        coff_symbol->Section = Sec;
+      }
+    }
 
     coff_symbol->MCData = &ResSymData;
   }
@@ -486,11 +465,9 @@ static void encodeBase64StringEntry(char* Buffer, uint64_t Value) {
   }
 }
 
-/// making a section real involves assigned it a number and putting
-/// name into the string table if needed
-void WinCOFFObjectWriter::MakeSectionReal(COFFSection &S, size_t Number) {
+void WinCOFFObjectWriter::SetSectionName(COFFSection &S) {
   if (S.Name.size() > COFF::NameSize) {
-    uint64_t StringTableEntry = Strings.insert(S.Name.c_str());
+    uint64_t StringTableEntry = Strings.getOffset(S.Name);
 
     if (StringTableEntry <= Max6DecimalOffset) {
       std::sprintf(S.Header.Name, "/%d", unsigned(StringTableEntry));
@@ -508,32 +485,33 @@ void WinCOFFObjectWriter::MakeSectionReal(COFFSection &S, size_t Number) {
     }
   } else
     std::memcpy(S.Header.Name, S.Name.c_str(), S.Name.size());
-
-  S.Number = Number;
-  S.Symbol->Data.SectionNumber = S.Number;
-  S.Symbol->Aux[0].Aux.SectionDefinition.Number = S.Number;
 }
 
-void WinCOFFObjectWriter::MakeSymbolReal(COFFSymbol &S, size_t Index) {
-  if (S.Name.size() > COFF::NameSize) {
-    size_t StringTableEntry = Strings.insert(S.Name.c_str());
-
-    S.set_name_offset(StringTableEntry);
-  } else
+void WinCOFFObjectWriter::SetSymbolName(COFFSymbol &S) {
+  if (S.Name.size() > COFF::NameSize)
+    S.set_name_offset(Strings.getOffset(S.Name));
+  else
     std::memcpy(S.Data.Name, S.Name.c_str(), S.Name.size());
-  S.Index = Index;
 }
 
-bool WinCOFFObjectWriter::ExportSymbol(MCSymbolData const &SymbolData,
+bool WinCOFFObjectWriter::ExportSymbol(const MCSymbol &Symbol,
                                        MCAssembler &Asm) {
   // This doesn't seem to be right. Strings referred to from the .data section
   // need symbols so they can be linked to code in the .text section right?
 
-  // return Asm.isSymbolLinkerVisible (&SymbolData);
+  // return Asm.isSymbolLinkerVisible(Symbol);
+
+  // Non-temporary labels should always be visible to the linker.
+  if (!Symbol.isTemporary())
+    return true;
+
+  // Absolute temporary labels are never visible.
+  if (!Symbol.isInSection())
+    return false;
 
   // For now, all non-variable symbols are exported,
   // the linker will sort the rest out for us.
-  return SymbolData.isExternal() || !SymbolData.getSymbol().isVariable();
+  return !Symbol.isVariable();
 }
 
 bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
@@ -545,19 +523,39 @@ bool WinCOFFObjectWriter::IsPhysicalSection(COFFSection *S) {
 // entity writing methods
 
 void WinCOFFObjectWriter::WriteFileHeader(const COFF::header &Header) {
-  WriteLE16(Header.Machine);
-  WriteLE16(Header.NumberOfSections);
-  WriteLE32(Header.TimeDateStamp);
-  WriteLE32(Header.PointerToSymbolTable);
-  WriteLE32(Header.NumberOfSymbols);
-  WriteLE16(Header.SizeOfOptionalHeader);
-  WriteLE16(Header.Characteristics);
+  if (UseBigObj) {
+    WriteLE16(COFF::IMAGE_FILE_MACHINE_UNKNOWN);
+    WriteLE16(0xFFFF);
+    WriteLE16(COFF::BigObjHeader::MinBigObjectVersion);
+    WriteLE16(Header.Machine);
+    WriteLE32(Header.TimeDateStamp);
+    for (uint8_t MagicChar : COFF::BigObjMagic)
+      Write8(MagicChar);
+    WriteLE32(0);
+    WriteLE32(0);
+    WriteLE32(0);
+    WriteLE32(0);
+    WriteLE32(Header.NumberOfSections);
+    WriteLE32(Header.PointerToSymbolTable);
+    WriteLE32(Header.NumberOfSymbols);
+  } else {
+    WriteLE16(Header.Machine);
+    WriteLE16(static_cast<int16_t>(Header.NumberOfSections));
+    WriteLE32(Header.TimeDateStamp);
+    WriteLE32(Header.PointerToSymbolTable);
+    WriteLE32(Header.NumberOfSymbols);
+    WriteLE16(Header.SizeOfOptionalHeader);
+    WriteLE16(Header.Characteristics);
+  }
 }
 
 void WinCOFFObjectWriter::WriteSymbol(const COFFSymbol &S) {
   WriteBytes(StringRef(S.Data.Name, COFF::NameSize));
   WriteLE32(S.Data.Value);
-  WriteLE16(S.Data.SectionNumber);
+  if (UseBigObj)
+    WriteLE32(S.Data.SectionNumber);
+  else
+    WriteLE16(static_cast<int16_t>(S.Data.SectionNumber));
   WriteLE16(S.Data.Type);
   Write8(S.Data.StorageClass);
   Write8(S.Data.NumberOfAuxSymbols);
@@ -575,6 +573,8 @@ void WinCOFFObjectWriter::WriteAuxiliarySymbols(
       WriteLE32(i->Aux.FunctionDefinition.PointerToLinenumber);
       WriteLE32(i->Aux.FunctionDefinition.PointerToNextFunction);
       WriteZeros(sizeof(i->Aux.FunctionDefinition.unused));
+      if (UseBigObj)
+        WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
       break;
     case ATbfAndefSymbol:
       WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused1));
@@ -582,24 +582,32 @@ void WinCOFFObjectWriter::WriteAuxiliarySymbols(
       WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused2));
       WriteLE32(i->Aux.bfAndefSymbol.PointerToNextFunction);
       WriteZeros(sizeof(i->Aux.bfAndefSymbol.unused3));
+      if (UseBigObj)
+        WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
       break;
     case ATWeakExternal:
       WriteLE32(i->Aux.WeakExternal.TagIndex);
       WriteLE32(i->Aux.WeakExternal.Characteristics);
       WriteZeros(sizeof(i->Aux.WeakExternal.unused));
+      if (UseBigObj)
+        WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
       break;
     case ATFile:
-      WriteBytes(StringRef(reinterpret_cast<const char *>(i->Aux.File.FileName),
-                 sizeof(i->Aux.File.FileName)));
+      WriteBytes(
+          StringRef(reinterpret_cast<const char *>(&i->Aux),
+                    UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size));
       break;
     case ATSectionDefinition:
       WriteLE32(i->Aux.SectionDefinition.Length);
       WriteLE16(i->Aux.SectionDefinition.NumberOfRelocations);
       WriteLE16(i->Aux.SectionDefinition.NumberOfLinenumbers);
       WriteLE32(i->Aux.SectionDefinition.CheckSum);
-      WriteLE16(i->Aux.SectionDefinition.Number);
+      WriteLE16(static_cast<int16_t>(i->Aux.SectionDefinition.Number));
       Write8(i->Aux.SectionDefinition.Selection);
       WriteZeros(sizeof(i->Aux.SectionDefinition.unused));
+      WriteLE16(static_cast<int16_t>(i->Aux.SectionDefinition.Number >> 16));
+      if (UseBigObj)
+        WriteZeros(COFF::Symbol32Size - COFF::Symbol16Size);
       break;
     }
   }
@@ -632,55 +640,36 @@ void WinCOFFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
                                                    const MCAsmLayout &Layout) {
   // "Define" each section & symbol. This creates section & symbol
   // entries in the staging area.
+  for (const auto &Section : Asm)
+    DefineSection(Section);
 
-  static_assert(sizeof(COFF::AuxiliaryFile::FileName) == COFF::SymbolSize,
-                "size mismatch for COFF::AuxiliaryFile::FileName");
-  for (auto FI = Asm.file_names_begin(), FE = Asm.file_names_end();
-       FI != FE; ++FI) {
-    // round up to calculate the number of auxiliary symbols required
-    unsigned Count = (FI->size() + COFF::SymbolSize) / COFF::SymbolSize;
-
-    COFFSymbol *file = createSymbol(".file");
-    file->Data.StorageClass = COFF::IMAGE_SYM_CLASS_FILE;
-    file->Aux.resize(Count);
-
-    unsigned Offset = 0;
-    unsigned Length = FI->size();
-    for (auto & Aux : file->Aux) {
-      Aux.AuxType = ATFile;
-
-      if (Length > COFF::SymbolSize) {
-        memcpy(Aux.Aux.File.FileName, FI->c_str() + Offset, COFF::SymbolSize);
-        Length = Length - COFF::SymbolSize;
-      } else {
-        memcpy(Aux.Aux.File.FileName, FI->c_str() + Offset, Length);
-        memset(&Aux.Aux.File.FileName[Length], 0, COFF::SymbolSize - Length);
-        Length = 0;
-      }
-
-      Offset = Offset + COFF::SymbolSize;
-    }
-  }
+  for (MCSymbolData &SD : Asm.symbols())
+    if (ExportSymbol(SD.getSymbol(), Asm))
+      DefineSymbol(SD, Asm, Layout);
+}
 
-  for (MCAssembler::const_iterator i = Asm.begin(), e = Asm.end(); i != e; i++)
-    DefineSection(*i);
+bool WinCOFFObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(
+    const MCAssembler &Asm, const MCSymbolData &DataA, const MCFragment &FB,
+    bool InSet, bool IsPCRel) const {
+  // MS LINK expects to be able to replace all references to a function with a
+  // thunk to implement their /INCREMENTAL feature.  Make sure we don't optimize
+  // away any relocations to functions.
+  if ((((DataA.getFlags() & COFF::SF_TypeMask) >> COFF::SF_TypeShift) >>
+       COFF::SCT_COMPLEX_TYPE_SHIFT) == COFF::IMAGE_SYM_DTYPE_FUNCTION)
+    return false;
+  return MCObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(Asm, DataA, FB,
+                                                                InSet, IsPCRel);
+}
 
-  for (MCAssembler::const_symbol_iterator i = Asm.symbol_begin(),
-                                          e = Asm.symbol_end();
-       i != e; i++) {
-    if (ExportSymbol(*i, Asm)) {
-      DefineSymbol(*i, Asm, Layout);
-    }
-  }
+bool WinCOFFObjectWriter::isWeak(const MCSymbolData &SD) const {
+  // FIXME: this is for PR23025. Write a good description on
+  // why this is needed.
+  return SD.isExternal();
 }
 
-void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
-                                           const MCAsmLayout &Layout,
-                                           const MCFragment *Fragment,
-                                           const MCFixup &Fixup,
-                                           MCValue Target,
-                                           bool &IsPCRel,
-                                           uint64_t &FixedValue) {
+void WinCOFFObjectWriter::RecordRelocation(
+    MCAssembler &Asm, const MCAsmLayout &Layout, const MCFragment *Fragment,
+    const MCFixup &Fixup, MCValue Target, bool &IsPCRel, uint64_t &FixedValue) {
   assert(Target.getSymA() && "Relocation must reference a symbol!");
 
   const MCSymbol &Symbol = Target.getSymA()->getSymbol();
@@ -690,7 +679,7 @@ void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
         Fixup.getLoc(),
         Twine("symbol '") + A.getName() + "' can not be undefined");
 
-  MCSymbolData &A_SD = Asm.getSymbolData(A);
+  const MCSymbolData &A_SD = Asm.getSymbolData(A);
 
   MCSectionData const *SectionData = Fragment->getParent();
 
@@ -707,7 +696,7 @@ void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
 
   if (SymB) {
     const MCSymbol *B = &SymB->getSymbol();
-    MCSymbolData &B_SD = Asm.getSymbolData(*B);
+    const MCSymbolData &B_SD = Asm.getSymbolData(*B);
     if (!B_SD.getFragment())
       Asm.getContext().FatalError(
           Fixup.getLoc(),
@@ -723,17 +712,22 @@ void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
     CrossSection = &Symbol.getSection() != &B->getSection();
 
     // Offset of the symbol in the section
-    int64_t a = Layout.getSymbolOffset(&B_SD);
-
-    // Ofeset of the relocation in the section
-    int64_t b = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
+    int64_t OffsetOfB = Layout.getSymbolOffset(&B_SD);
 
-    FixedValue = b - a;
     // In the case where we have SymbA and SymB, we just need to store the delta
     // between the two symbols.  Update FixedValue to account for the delta, and
     // skip recording the relocation.
-    if (!CrossSection)
+    if (!CrossSection) {
+      int64_t OffsetOfA = Layout.getSymbolOffset(&A_SD);
+      FixedValue = (OffsetOfA - OffsetOfB) + Target.getConstant();
       return;
+    }
+
+    // Offset of the relocation in the section
+    int64_t OffsetOfRelocation =
+        Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
+
+    FixedValue = OffsetOfRelocation - OffsetOfB;
   } else {
     FixedValue = Target.getConstant();
   }
@@ -746,16 +740,17 @@ void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
   // Turn relocations for temporary symbols into section relocations.
   if (coff_symbol->MCData->getSymbol().isTemporary() || CrossSection) {
     Reloc.Symb = coff_symbol->Section->Symbol;
-    FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->Fragment)
-                + coff_symbol->MCData->getOffset();
+    FixedValue += Layout.getFragmentOffset(coff_symbol->MCData->getFragment()) +
+                  coff_symbol->MCData->getOffset();
   } else
     Reloc.Symb = coff_symbol;
 
   ++Reloc.Symb->Relocations;
 
   Reloc.Data.VirtualAddress += Fixup.getOffset();
-  Reloc.Data.Type = TargetObjectWriter->getRelocType(Target, Fixup,
-                                                     CrossSection);
+  Reloc.Data.Type =
+      TargetObjectWriter->getRelocType(Target, Fixup, CrossSection,
+                                       Asm.getBackend());
 
   // FIXME: Can anyone explain what this does other than adjust for the size
   // of the offset?
@@ -765,86 +760,169 @@ void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
        Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32))
     FixedValue += 4;
 
-  coff_section->Relocations.push_back(Reloc);
+  if (Header.Machine == COFF::IMAGE_FILE_MACHINE_ARMNT) {
+    switch (Reloc.Data.Type) {
+    case COFF::IMAGE_REL_ARM_ABSOLUTE:
+    case COFF::IMAGE_REL_ARM_ADDR32:
+    case COFF::IMAGE_REL_ARM_ADDR32NB:
+    case COFF::IMAGE_REL_ARM_TOKEN:
+    case COFF::IMAGE_REL_ARM_SECTION:
+    case COFF::IMAGE_REL_ARM_SECREL:
+      break;
+    case COFF::IMAGE_REL_ARM_BRANCH11:
+    case COFF::IMAGE_REL_ARM_BLX11:
+      // IMAGE_REL_ARM_BRANCH11 and IMAGE_REL_ARM_BLX11 are only used for
+      // pre-ARMv7, which implicitly rules it out of ARMNT (it would be valid
+      // for Windows CE).
+    case COFF::IMAGE_REL_ARM_BRANCH24:
+    case COFF::IMAGE_REL_ARM_BLX24:
+    case COFF::IMAGE_REL_ARM_MOV32A:
+      // IMAGE_REL_ARM_BRANCH24, IMAGE_REL_ARM_BLX24, IMAGE_REL_ARM_MOV32A are
+      // only used for ARM mode code, which is documented as being unsupported
+      // by Windows on ARM.  Empirical proof indicates that masm is able to
+      // generate the relocations however the rest of the MSVC toolchain is
+      // unable to handle it.
+      llvm_unreachable("unsupported relocation");
+      break;
+    case COFF::IMAGE_REL_ARM_MOV32T:
+      break;
+    case COFF::IMAGE_REL_ARM_BRANCH20T:
+    case COFF::IMAGE_REL_ARM_BRANCH24T:
+    case COFF::IMAGE_REL_ARM_BLX23T:
+      // IMAGE_REL_BRANCH20T, IMAGE_REL_ARM_BRANCH24T, IMAGE_REL_ARM_BLX23T all
+      // perform a 4 byte adjustment to the relocation.  Relative branches are
+      // offset by 4 on ARM, however, because there is no RELA relocations, all
+      // branches are offset by 4.
+      FixedValue = FixedValue + 4;
+      break;
+    }
+  }
+
+  if (TargetObjectWriter->recordRelocation(Fixup))
+    coff_section->Relocations.push_back(Reloc);
 }
 
 void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
                                       const MCAsmLayout &Layout) {
+  size_t SectionsSize = Sections.size();
+  if (SectionsSize > static_cast<size_t>(INT32_MAX))
+    report_fatal_error(
+        "PE COFF object files can't have more than 2147483647 sections");
+
   // Assign symbol and section indexes and offsets.
-  Header.NumberOfSections = 0;
-
-  DenseMap<COFFSection *, uint16_t> SectionIndices;
-  for (sections::iterator i = Sections.begin(),
-                          e = Sections.end(); i != e; i++) {
-    if (Layout.getSectionAddressSize((*i)->MCData) > 0) {
-      size_t Number = ++Header.NumberOfSections;
-      SectionIndices[i->get()] = Number;
-      MakeSectionReal(**i, Number);
-    } else {
-      (*i)->Number = -1;
-    }
+  int32_t NumberOfSections = static_cast<int32_t>(SectionsSize);
+
+  UseBigObj = NumberOfSections > COFF::MaxNumberOfSections16;
+
+  DenseMap<COFFSection *, int32_t> SectionIndices(
+      NextPowerOf2(NumberOfSections));
+
+  // Assign section numbers.
+  size_t Number = 1;
+  for (const auto &Section : Sections) {
+    SectionIndices[Section.get()] = Number;
+    Section->Number = Number;
+    Section->Symbol->Data.SectionNumber = Number;
+    Section->Symbol->Aux[0].Aux.SectionDefinition.Number = Number;
+    ++Number;
   }
 
+  Header.NumberOfSections = NumberOfSections;
   Header.NumberOfSymbols = 0;
 
-  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
-    COFFSymbol &coff_symbol = **i;
-    MCSymbolData const *SymbolData = coff_symbol.MCData;
+  for (auto FI = Asm.file_names_begin(), FE = Asm.file_names_end();
+       FI != FE; ++FI) {
+    // round up to calculate the number of auxiliary symbols required
+    unsigned SymbolSize = UseBigObj ? COFF::Symbol32Size : COFF::Symbol16Size;
+    unsigned Count = (FI->size() + SymbolSize - 1) / SymbolSize;
 
-    // Update section number & offset for symbols that have them.
-    if (SymbolData && SymbolData->Fragment) {
-      assert(coff_symbol.Section != nullptr);
+    COFFSymbol *file = createSymbol(".file");
+    file->Data.SectionNumber = COFF::IMAGE_SYM_DEBUG;
+    file->Data.StorageClass = COFF::IMAGE_SYM_CLASS_FILE;
+    file->Aux.resize(Count);
 
-      coff_symbol.Data.SectionNumber = coff_symbol.Section->Number;
-      coff_symbol.Data.Value = Layout.getFragmentOffset(SymbolData->Fragment)
-                              + SymbolData->Offset;
-    }
+    unsigned Offset = 0;
+    unsigned Length = FI->size();
+    for (auto &Aux : file->Aux) {
+      Aux.AuxType = ATFile;
+
+      if (Length > SymbolSize) {
+        memcpy(&Aux.Aux, FI->c_str() + Offset, SymbolSize);
+        Length = Length - SymbolSize;
+      } else {
+        memcpy(&Aux.Aux, FI->c_str() + Offset, Length);
+        memset((char *)&Aux.Aux + Length, 0, SymbolSize - Length);
+        break;
+      }
 
-    if (coff_symbol.should_keep()) {
-      MakeSymbolReal(coff_symbol, Header.NumberOfSymbols++);
+      Offset += SymbolSize;
+    }
+  }
 
+  for (auto &Symbol : Symbols) {
+    // Update section number & offset for symbols that have them.
+    if (Symbol->Section)
+      Symbol->Data.SectionNumber = Symbol->Section->Number;
+    if (Symbol->should_keep()) {
+      Symbol->Index = Header.NumberOfSymbols++;
       // Update auxiliary symbol info.
-      coff_symbol.Data.NumberOfAuxSymbols = coff_symbol.Aux.size();
-      Header.NumberOfSymbols += coff_symbol.Data.NumberOfAuxSymbols;
+      Symbol->Data.NumberOfAuxSymbols = Symbol->Aux.size();
+      Header.NumberOfSymbols += Symbol->Data.NumberOfAuxSymbols;
     } else
-      coff_symbol.Index = -1;
+      Symbol->Index = -1;
   }
 
+  // Build string table.
+  for (const auto &S : Sections)
+    if (S->Name.size() > COFF::NameSize)
+      Strings.add(S->Name);
+  for (const auto &S : Symbols)
+    if (S->should_keep() && S->Name.size() > COFF::NameSize)
+      Strings.add(S->Name);
+  Strings.finalize(StringTableBuilder::WinCOFF);
+
+  // Set names.
+  for (const auto &S : Sections)
+    SetSectionName(*S);
+  for (auto &S : Symbols)
+    if (S->should_keep())
+      SetSymbolName(*S);
+
   // Fixup weak external references.
-  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++) {
-    COFFSymbol &coff_symbol = **i;
-    if (coff_symbol.Other) {
-      assert(coff_symbol.Index != -1);
-      assert(coff_symbol.Aux.size() == 1 &&
-             "Symbol must contain one aux symbol!");
-      assert(coff_symbol.Aux[0].AuxType == ATWeakExternal &&
+  for (auto &Symbol : Symbols) {
+    if (Symbol->Other) {
+      assert(Symbol->Index != -1);
+      assert(Symbol->Aux.size() == 1 && "Symbol must contain one aux symbol!");
+      assert(Symbol->Aux[0].AuxType == ATWeakExternal &&
              "Symbol's aux symbol must be a Weak External!");
-      coff_symbol.Aux[0].Aux.WeakExternal.TagIndex = coff_symbol.Other->Index;
+      Symbol->Aux[0].Aux.WeakExternal.TagIndex = Symbol->Other->Index;
     }
   }
 
   // Fixup associative COMDAT sections.
-  for (sections::iterator i = Sections.begin(),
-                          e = Sections.end(); i != e; i++) {
-    if ((*i)->Symbol->Aux[0].Aux.SectionDefinition.Selection !=
+  for (auto &Section : Sections) {
+    if (Section->Symbol->Aux[0].Aux.SectionDefinition.Selection !=
         COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE)
       continue;
 
-    const MCSectionCOFF &MCSec = static_cast<const MCSectionCOFF &>(
-                                                    (*i)->MCData->getSection());
+    const MCSectionCOFF &MCSec =
+      static_cast<const MCSectionCOFF &>(Section->MCData->getSection());
 
-    COFFSection *Assoc = SectionMap.lookup(MCSec.getAssocSection());
-    if (!Assoc) {
-      report_fatal_error(Twine("Missing associated COMDAT section ") +
-                         MCSec.getAssocSection()->getSectionName() +
-                         " for section " + MCSec.getSectionName());
-    }
+    const MCSymbol *COMDAT = MCSec.getCOMDATSymbol();
+    assert(COMDAT);
+    COFFSymbol *COMDATSymbol = GetOrCreateCOFFSymbol(COMDAT);
+    assert(COMDATSymbol);
+    COFFSection *Assoc = COMDATSymbol->Section;
+    if (!Assoc)
+      report_fatal_error(
+          Twine("Missing associated COMDAT section for section ") +
+          MCSec.getSectionName());
 
     // Skip this section if the associated section is unused.
     if (Assoc->Number == -1)
       continue;
 
-    (*i)->Symbol->Aux[0].Aux.SectionDefinition.Number = SectionIndices[Assoc];
+    Section->Symbol->Aux[0].Aux.SectionDefinition.Number = SectionIndices[Assoc];
   }
 
 
@@ -852,20 +930,23 @@ void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
 
   unsigned offset = 0;
 
-  offset += COFF::HeaderSize;
+  if (UseBigObj)
+    offset += COFF::Header32Size;
+  else
+    offset += COFF::Header16Size;
   offset += COFF::SectionSize * Header.NumberOfSections;
 
-  for (MCAssembler::const_iterator i = Asm.begin(),
-                                   e = Asm.end();
-                                   i != e; i++) {
-    COFFSection *Sec = SectionMap[&i->getSection()];
+  for (const auto &Section : Asm) {
+    COFFSection *Sec = SectionMap[&Section.getSection()];
 
     if (Sec->Number == -1)
       continue;
 
-    Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(i);
+    Sec->Header.SizeOfRawData = Layout.getSectionAddressSize(&Section);
 
     if (IsPhysicalSection(Sec)) {
+      // Align the section data to a four byte boundary.
+      offset = RoundUpToAlignment(offset, 4);
       Sec->Header.PointerToRawData = offset;
 
       offset += Sec->Header.SizeOfRawData;
@@ -875,7 +956,7 @@ void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
       bool RelocationsOverflow = Sec->Relocations.size() >= 0xffff;
 
       if (RelocationsOverflow) {
-        // Signal overflow by setting NumberOfSections to max value. Actual
+        // Signal overflow by setting NumberOfRelocations to max value. Actual
         // size is found in reloc #0. Microsoft tools understand this.
         Sec->Header.NumberOfRelocations = 0xffff;
       } else {
@@ -890,16 +971,14 @@ void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
 
       offset += COFF::RelocationSize * Sec->Relocations.size();
 
-      for (relocations::iterator cr = Sec->Relocations.begin(),
-                                 er = Sec->Relocations.end();
-                                 cr != er; ++cr) {
-        assert((*cr).Symb->Index != -1);
-        (*cr).Data.SymbolTableIndex = (*cr).Symb->Index;
+      for (auto &Relocation : Sec->Relocations) {
+        assert(Relocation.Symb->Index != -1);
+        Relocation.Data.SymbolTableIndex = Relocation.Symb->Index;
       }
     }
 
-    assert(Sec->Symbol->Aux.size() == 1
-      && "Section's symbol must have one aux!");
+    assert(Sec->Symbol->Aux.size() == 1 &&
+           "Section's symbol must have one aux!");
     AuxSymbol &Aux = Sec->Symbol->Aux[0];
     assert(Aux.AuxType == ATSectionDefinition &&
            "Section's symbol's aux symbol must be a Section Definition!");
@@ -922,13 +1001,13 @@ void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
     sections::iterator i, ie;
     MCAssembler::const_iterator j, je;
 
-    for (i = Sections.begin(), ie = Sections.end(); i != ie; i++)
-      if ((*i)->Number != -1) {
-        if ((*i)->Relocations.size() >= 0xffff) {
-          (*i)->Header.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
-        }
-        WriteSectionHeader((*i)->Header);
+    for (auto &Section : Sections) {
+      if (Section->Number != -1) {
+        if (Section->Relocations.size() >= 0xffff)
+          Section->Header.Characteristics |= COFF::IMAGE_SCN_LNK_NRELOC_OVFL;
+        WriteSectionHeader(Section->Header);
       }
+    }
 
     for (i = Sections.begin(), ie = Sections.end(),
          j = Asm.begin(), je = Asm.end();
@@ -938,9 +1017,15 @@ void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
         continue;
 
       if ((*i)->Header.PointerToRawData != 0) {
-        assert(OS.tell() == (*i)->Header.PointerToRawData &&
+        assert(OS.tell() <= (*i)->Header.PointerToRawData &&
                "Section::PointerToRawData is insane!");
 
+        unsigned SectionDataPadding = (*i)->Header.PointerToRawData - OS.tell();
+        assert(SectionDataPadding < 4 &&
+               "Should only need at most three bytes of padding!");
+
+        WriteZeros(SectionDataPadding);
+
         Asm.writeSectionData(j, Layout);
       }
 
@@ -958,11 +1043,8 @@ void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
           WriteRelocation(r);
         }
 
-        for (relocations::const_iterator k = (*i)->Relocations.begin(),
-                                               ke = (*i)->Relocations.end();
-                                               k != ke; k++) {
-          WriteRelocation(k->Data);
-        }
+        for (const auto &Relocation : (*i)->Relocations)
+          WriteRelocation(Relocation.Data);
       } else
         assert((*i)->Header.PointerToRelocations == 0 &&
                "Section::PointerToRelocations is insane!");
@@ -972,11 +1054,11 @@ void WinCOFFObjectWriter::WriteObject(MCAssembler &Asm,
   assert(OS.tell() == Header.PointerToSymbolTable &&
          "Header::PointerToSymbolTable is insane!");
 
-  for (symbols::iterator i = Symbols.begin(), e = Symbols.end(); i != e; i++)
-    if ((*i)->Index != -1)
-      WriteSymbol(**i);
+  for (auto &Symbol : Symbols)
+    if (Symbol->Index != -1)
+      WriteSymbol(*Symbol);
 
-  OS.write((char const *)&Strings.Data.front(), Strings.Data.size());
+  OS.write(Strings.data().data(), Strings.data().size());
 }
 
 MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_) :