[MC] Allow MCObjectWriter's output stream to be swapped out

[majnemer]

Summary

There are occasions where it is useful to consider the entirety of the
contents of a section. For example, compressed debug info needs the
entire section available before it can compress it and write it out.
The compressed debug info scenario was previously implemented by
mirroring the implementation of writeSectionData in the ELFObjectWriter.

Instead, allow the output stream to be swapped on demand. This lets
callers redirect the output stream to a more convenient location before
it hits the object file.

No functionality change is intended.

[• rafael]

Nice!

llvm/trunk/include/llvm/MC/MCObjectWriter.h

 /// should be emitted as part of writeObject().
 ///
 /// The object writer also contains a number of helper methods for writing
 /// binary data to the output stream.
 class MCObjectWriter {
   MCObjectWriter(const MCObjectWriter &) = delete;
   void operator=(const MCObjectWriter &) = delete;
 
-protected:
-  raw_pwrite_stream &OS;
+  raw_pwrite_stream *OS;
 
+protected:
   unsigned IsLittleEndian : 1;
 
 protected: // Can only create subclasses.
   MCObjectWriter(raw_pwrite_stream &OS, bool IsLittleEndian)
-      : OS(OS), IsLittleEndian(IsLittleEndian) {}
+      : OS(&OS), IsLittleEndian(IsLittleEndian) {}
 
 public:
   virtual ~MCObjectWriter();
 
   /// lifetime management
   virtual void reset() {}
 
   bool isLittleEndian() const { return IsLittleEndian; }
 
-  raw_ostream &getStream() { return OS; }
+  raw_pwrite_stream &getStream() { return *OS; }
+  void setStream(raw_pwrite_stream &NewOS) { OS = &NewOS; }
 
   /// \name High-Level API
   /// @{
 
   /// Perform any late binding of symbols (for example, to assign symbol
   /// indices for use when generating relocations).
   ///
   /// This routine is called by the assembler after layout and relaxation is
public:
   /// complete, fixups have been evaluated and applied, and relocations
   /// generated.
   virtual void writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) = 0;
 
   /// @}
   /// \name Binary Output
   /// @{
 
-  void write8(uint8_t Value) { OS << char(Value); }
+  void write8(uint8_t Value) { *OS << char(Value); }
 
   void writeLE16(uint16_t Value) {
-    support::endian::Writer<support::little>(OS).write(Value);
+    support::endian::Writer<support::little>(*OS).write(Value);
   }
 
   void writeLE32(uint32_t Value) {
-    support::endian::Writer<support::little>(OS).write(Value);
+    support::endian::Writer<support::little>(*OS).write(Value);
   }
 
   void writeLE64(uint64_t Value) {
-    support::endian::Writer<support::little>(OS).write(Value);
+    support::endian::Writer<support::little>(*OS).write(Value);
   }
 
   void writeBE16(uint16_t Value) {
-    support::endian::Writer<support::big>(OS).write(Value);
+    support::endian::Writer<support::big>(*OS).write(Value);
   }
 
   void writeBE32(uint32_t Value) {
-    support::endian::Writer<support::big>(OS).write(Value);
+    support::endian::Writer<support::big>(*OS).write(Value);
   }
 
   void writeBE64(uint64_t Value) {
-    support::endian::Writer<support::big>(OS).write(Value);
+    support::endian::Writer<support::big>(*OS).write(Value);
   }
 
   void write16(uint16_t Value) {
     if (IsLittleEndian)
       writeLE16(Value);
     else
       writeBE16(Value);
   }
void write64(uint64_t Value) {
     else
       writeBE64(Value);
   }
 
   void WriteZeros(unsigned N) {
     const char Zeros[16] = {0};
 
     for (unsigned i = 0, e = N / 16; i != e; ++i)
-      OS << StringRef(Zeros, 16);
+      *OS << StringRef(Zeros, 16);
 
-    OS << StringRef(Zeros, N % 16);
+    *OS << StringRef(Zeros, N % 16);
   }
 
   void writeBytes(const SmallVectorImpl<char> &ByteVec,
                   unsigned ZeroFillSize = 0) {
     writeBytes(StringRef(ByteVec.data(), ByteVec.size()), ZeroFillSize);
   }
 
   void writeBytes(StringRef Str, unsigned ZeroFillSize = 0) {
     // TODO: this version may need to go away once all fragment contents are
     // converted to SmallVector<char, N>
     assert(
         (ZeroFillSize == 0 || Str.size() <= ZeroFillSize) &&
         "data size greater than fill size, unexpected large write will occur");
-    OS << Str;
+    *OS << Str;
     if (ZeroFillSize)
       WriteZeros(ZeroFillSize - Str.size());
   }
 
   /// @}
 };
 
 } // End llvm namespace
 
 #endif

llvm/trunk/lib/MC/ELFObjectWriter.cpp

void WriteWord(uint64_t W) {
       if (is64Bit())
         write64(W);
       else
         write32(W);
     }
 
     template <typename T> void write(T Val) {
       if (IsLittleEndian)
-        support::endian::Writer<support::little>(OS).write(Val);
+        support::endian::Writer<support::little>(getStream()).write(Val);
       else
-        support::endian::Writer<support::big>(OS).write(Val);
+        support::endian::Writer<support::big>(getStream()).write(Val);
     }
 
     void writeHeader(const MCAssembler &Asm);
 
     void writeSymbol(SymbolTableWriter &Writer, uint32_t StringIndex,
                      ELFSymbolData &MSD, const MCAsmLayout &Layout);
 
     // Start and end offset of each section
public:
     void writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
     void writeSection(const SectionIndexMapTy &SectionIndexMap,
                       uint32_t GroupSymbolIndex, uint64_t Offset, uint64_t Size,
                       const MCSectionELF &Section);
   };
 }
 
 void ELFObjectWriter::align(unsigned Alignment) {
-  uint64_t Padding = OffsetToAlignment(OS.tell(), Alignment);
+  uint64_t Padding = OffsetToAlignment(getStream().tell(), Alignment);
   WriteZeros(Padding);
 }
 
 unsigned ELFObjectWriter::addToSectionTable(const MCSectionELF *Sec) {
   SectionTable.push_back(Sec);
   StrTabBuilder.add(Sec->getSectionName());
   return SectionTable.size();
 }
void ELFObjectWriter::computeSymbolTable(
   // Symbol table
   unsigned EntrySize = is64Bit() ? ELF::SYMENTRY_SIZE64 : ELF::SYMENTRY_SIZE32;
   MCSectionELF *SymtabSection =
       Ctx.getELFSection(".symtab", ELF::SHT_SYMTAB, 0, EntrySize, "");
   SymtabSection->setAlignment(is64Bit() ? 8 : 4);
   SymbolTableIndex = addToSectionTable(SymtabSection);
 
   align(SymtabSection->getAlignment());
-  uint64_t SecStart = OS.tell();
+  uint64_t SecStart = getStream().tell();
 
   // The first entry is the undefined symbol entry.
   Writer.writeSymbol(0, 0, 0, 0, 0, 0, false);
 
   std::vector<ELFSymbolData> LocalSymbolData;
   std::vector<ELFSymbolData> ExternalSymbolData;
 
   // Add the data for the symbols.
void ELFObjectWriter::computeSymbolTable(
 
   for (ELFSymbolData &MSD : ExternalSymbolData) {
     unsigned StringIndex = StrTabBuilder.getOffset(MSD.Name);
     MSD.Symbol->setIndex(Index++);
     writeSymbol(Writer, StringIndex, MSD, Layout);
     assert(MSD.Symbol->getBinding() != ELF::STB_LOCAL);
   }
 
-  uint64_t SecEnd = OS.tell();
+  uint64_t SecEnd = getStream().tell();
   SectionOffsets[SymtabSection] = std::make_pair(SecStart, SecEnd);
 
   ArrayRef<uint32_t> ShndxIndexes = Writer.getShndxIndexes();
   if (ShndxIndexes.empty()) {
     assert(SymtabShndxSectionIndex == 0);
     return;
   }
   assert(SymtabShndxSectionIndex != 0);
 
-  SecStart = OS.tell();
+  SecStart = getStream().tell();
   const MCSectionELF *SymtabShndxSection =
       SectionTable[SymtabShndxSectionIndex - 1];
   for (uint32_t Index : ShndxIndexes)
     write(Index);
-  SecEnd = OS.tell();
+  SecEnd = getStream().tell();
   SectionOffsets[SymtabShndxSection] = std::make_pair(SecStart, SecEnd);
 }
 
 MCSectionELF *
 ELFObjectWriter::createRelocationSection(MCContext &Ctx,
                                          const MCSectionELF &Sec) {
   if (Relocations[&Sec].empty())
     return nullptr;
ELFObjectWriter::createRelocationSection(MCContext &Ctx,
 
   MCSectionELF *RelaSection = Ctx.createELFRelSection(
       RelaSectionName, hasRelocationAddend() ? ELF::SHT_RELA : ELF::SHT_REL,
       Flags, EntrySize, Sec.getGroup(), &Sec);
   RelaSection->setAlignment(is64Bit() ? 8 : 4);
   return RelaSection;
 }
 
-static SmallVector<char, 128>
-getUncompressedData(const MCAsmLayout &Layout,
-                    const MCSection::FragmentListType &Fragments) {
-  SmallVector<char, 128> UncompressedData;
-  for (const MCFragment &F : Fragments) {
-    const SmallVectorImpl<char> *Contents;
-    switch (F.getKind()) {
-    case MCFragment::FT_Data:
-      Contents = &cast<MCDataFragment>(F).getContents();
-      break;
-    case MCFragment::FT_Dwarf:
-      Contents = &cast<MCDwarfLineAddrFragment>(F).getContents();
-      break;
-    case MCFragment::FT_DwarfFrame:
-      Contents = &cast<MCDwarfCallFrameFragment>(F).getContents();
-      break;
-    default:
-      llvm_unreachable(
-          "Not expecting any other fragment types in a debug_* section");
-    }
-    UncompressedData.append(Contents->begin(), Contents->end());
-  }
-  return UncompressedData;
-}
-
 // Include the debug info compression header:
 // "ZLIB" followed by 8 bytes representing the uncompressed size of the section,
 // useful for consumers to preallocate a buffer to decompress into.
 static bool
 prependCompressionHeader(uint64_t Size,
                          SmallVectorImpl<char> &CompressedContents) {
   const StringRef Magic = "ZLIB";
   if (Size <= Magic.size() + sizeof(Size) + CompressedContents.size())
void ELFObjectWriter::writeSectionData(const MCAssembler &Asm, MCSection &Sec,
   // more work (possibly generalizing MCAssembler.cpp:writeFragment to allow
   // for writing to arbitrary buffers) for little benefit.
   if (!Asm.getContext().getAsmInfo()->compressDebugSections() ||
       !SectionName.startswith(".debug_") || SectionName == ".debug_frame") {
     Asm.writeSectionData(&Section, Layout);
     return;
   }
 
-  // Gather the uncompressed data from all the fragments.
-  const MCSection::FragmentListType &Fragments = Section.getFragmentList();
-  SmallVector<char, 128> UncompressedData =
-      getUncompressedData(Layout, Fragments);
+  SmallVector<char, 128> UncompressedData;
+  raw_svector_ostream VecOS(UncompressedData);
+  raw_pwrite_stream &OldStream = getStream();
+  setStream(VecOS);
+  Asm.writeSectionData(&Section, Layout);
+  setStream(OldStream);
 
   SmallVector<char, 128> CompressedContents;
   zlib::Status Success = zlib::compress(
       StringRef(UncompressedData.data(), UncompressedData.size()),
       CompressedContents);
   if (Success != zlib::StatusOK) {
-    Asm.writeSectionData(&Section, Layout);
+    getStream() << UncompressedData;
     return;
   }
 
   if (!prependCompressionHeader(UncompressedData.size(), CompressedContents)) {
-    Asm.writeSectionData(&Section, Layout);
+    getStream() << UncompressedData;
     return;
   }
   Asm.getContext().renameELFSection(&Section,
                                     (".z" + SectionName.drop_front(1)).str());
-  OS << CompressedContents;
+  getStream() << CompressedContents;
 }
 
 void ELFObjectWriter::WriteSecHdrEntry(uint32_t Name, uint32_t Type,
                                        uint64_t Flags, uint64_t Address,
                                        uint64_t Offset, uint64_t Size,
                                        uint32_t Link, uint32_t Info,
                                        uint64_t Alignment,
                                        uint64_t EntrySize) {
if (is64Bit()) {
       if (hasRelocationAddend())
         write(uint32_t(Entry.Addend));
     }
   }
 }
 
 const MCSectionELF *ELFObjectWriter::createStringTable(MCContext &Ctx) {
   const MCSectionELF *StrtabSection = SectionTable[StringTableIndex - 1];
-  OS << StrTabBuilder.data();
+  getStream() << StrTabBuilder.data();
   return StrtabSection;
 }
 
 void ELFObjectWriter::writeSection(const SectionIndexMapTy &SectionIndexMap,
                                    uint32_t GroupSymbolIndex, uint64_t Offset,
                                    uint64_t Size, const MCSectionELF &Section) {
   uint64_t sh_link = 0;
   uint64_t sh_info = 0;
void ELFObjectWriter::writeObject(MCAssembler &Asm,
   std::vector<MCSectionELF *> Groups;
   std::vector<MCSectionELF *> Relocations;
   for (MCSection &Sec : Asm) {
     MCSectionELF &Section = static_cast<MCSectionELF &>(Sec);
 
     align(Section.getAlignment());
 
     // Remember the offset into the file for this section.
-    uint64_t SecStart = OS.tell();
+    uint64_t SecStart = getStream().tell();
 
     const MCSymbolELF *SignatureSymbol = Section.getGroup();
     writeSectionData(Asm, Section, Layout);
 
-    uint64_t SecEnd = OS.tell();
+    uint64_t SecEnd = getStream().tell();
     SectionOffsets[&Section] = std::make_pair(SecStart, SecEnd);
 
     MCSectionELF *RelSection = createRelocationSection(Ctx, Section);
 
     if (SignatureSymbol) {
       Asm.registerSymbol(*SignatureSymbol);
       unsigned &GroupIdx = RevGroupMap[SignatureSymbol];
       if (!GroupIdx) {
if (RelSection) {
       Relocations.push_back(RelSection);
     }
   }
 
   for (MCSectionELF *Group : Groups) {
     align(Group->getAlignment());
 
     // Remember the offset into the file for this section.
-    uint64_t SecStart = OS.tell();
+    uint64_t SecStart = getStream().tell();
 
     const MCSymbol *SignatureSymbol = Group->getGroup();
     assert(SignatureSymbol);
     write(uint32_t(ELF::GRP_COMDAT));
     for (const MCSectionELF *Member : GroupMembers[SignatureSymbol]) {
       uint32_t SecIndex = SectionIndexMap.lookup(Member);
       write(SecIndex);
     }
 
-    uint64_t SecEnd = OS.tell();
+    uint64_t SecEnd = getStream().tell();
     SectionOffsets[Group] = std::make_pair(SecStart, SecEnd);
   }
 
   // Compute symbol table information.
   computeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap, SectionOffsets);
 
   for (MCSectionELF *RelSection : Relocations) {
     align(RelSection->getAlignment());
 
     // Remember the offset into the file for this section.
-    uint64_t SecStart = OS.tell();
+    uint64_t SecStart = getStream().tell();
 
     writeRelocations(Asm, *RelSection->getAssociatedSection());
 
-    uint64_t SecEnd = OS.tell();
+    uint64_t SecEnd = getStream().tell();
     SectionOffsets[RelSection] = std::make_pair(SecStart, SecEnd);
   }
 
   {
-    uint64_t SecStart = OS.tell();
+    uint64_t SecStart = getStream().tell();
     const MCSectionELF *Sec = createStringTable(Ctx);
-    uint64_t SecEnd = OS.tell();
+    uint64_t SecEnd = getStream().tell();
     SectionOffsets[Sec] = std::make_pair(SecStart, SecEnd);
   }
 
   uint64_t NaturalAlignment = is64Bit() ? 8 : 4;
   align(NaturalAlignment);
 
-  const unsigned SectionHeaderOffset = OS.tell();
+  const unsigned SectionHeaderOffset = getStream().tell();
 
   // ... then the section header table ...
   writeSectionHeader(Layout, SectionIndexMap, SectionOffsets);
 
   uint16_t NumSections = (SectionTable.size() + 1 >= ELF::SHN_LORESERVE)
                              ? (uint16_t)ELF::SHN_UNDEF
                              : SectionTable.size() + 1;
   if (sys::IsLittleEndianHost != IsLittleEndian)
     sys::swapByteOrder(NumSections);
   unsigned NumSectionsOffset;
 
   if (is64Bit()) {
     uint64_t Val = SectionHeaderOffset;
     if (sys::IsLittleEndianHost != IsLittleEndian)
       sys::swapByteOrder(Val);
-    OS.pwrite(reinterpret_cast<char *>(&Val), sizeof(Val),
+    getStream().pwrite(reinterpret_cast<char *>(&Val), sizeof(Val),
                        offsetof(ELF::Elf64_Ehdr, e_shoff));
     NumSectionsOffset = offsetof(ELF::Elf64_Ehdr, e_shnum);
   } else {
     uint32_t Val = SectionHeaderOffset;
     if (sys::IsLittleEndianHost != IsLittleEndian)
       sys::swapByteOrder(Val);
-    OS.pwrite(reinterpret_cast<char *>(&Val), sizeof(Val),
+    getStream().pwrite(reinterpret_cast<char *>(&Val), sizeof(Val),
                        offsetof(ELF::Elf32_Ehdr, e_shoff));
     NumSectionsOffset = offsetof(ELF::Elf32_Ehdr, e_shnum);
   }
-  OS.pwrite(reinterpret_cast<char *>(&NumSections), sizeof(NumSections),
-            NumSectionsOffset);
+  getStream().pwrite(reinterpret_cast<char *>(&NumSections),
+                     sizeof(NumSections), NumSectionsOffset);
 }
 
 bool ELFObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(
     const MCAssembler &Asm, const MCSymbol &SA, const MCFragment &FB,
     bool InSet, bool IsPCRel) const {
   const auto &SymA = cast<MCSymbolELF>(SA);
   if (IsPCRel) {
     assert(!InSet);

llvm/trunk/lib/MC/MachObjectWriter.cpp

void MachObjectWriter::writeHeader(MachO::HeaderFileType Type,
   uint32_t Flags = 0;
 
   if (SubsectionsViaSymbols)
     Flags |= MachO::MH_SUBSECTIONS_VIA_SYMBOLS;
 
   // struct mach_header (28 bytes) or
   // struct mach_header_64 (32 bytes)
 
-  uint64_t Start = OS.tell();
+  uint64_t Start = getStream().tell();
   (void) Start;
 
   write32(is64Bit() ? MachO::MH_MAGIC_64 : MachO::MH_MAGIC);
 
   write32(TargetObjectWriter->getCPUType());
   write32(TargetObjectWriter->getCPUSubtype());
 
   write32(Type);
   write32(NumLoadCommands);
   write32(LoadCommandsSize);
   write32(Flags);
   if (is64Bit())
     write32(0); // reserved
 
-  assert(OS.tell() - Start ==
-         (is64Bit()?sizeof(MachO::mach_header_64): sizeof(MachO::mach_header)));
+  assert(
+      getStream().tell() - Start ==
+      (is64Bit() ? sizeof(MachO::mach_header_64) : sizeof(MachO::mach_header)));
 }
 
 /// writeSegmentLoadCommand - Write a segment load command.
 ///
 /// \param NumSections The number of sections in this segment.
 /// \param SectionDataSize The total size of the sections.
 void MachObjectWriter::writeSegmentLoadCommand(
     StringRef Name, unsigned NumSections, uint64_t VMAddr, uint64_t VMSize,
     uint64_t SectionDataStartOffset, uint64_t SectionDataSize, uint32_t MaxProt,
     uint32_t InitProt) {
   // struct segment_command (56 bytes) or
   // struct segment_command_64 (72 bytes)
 
-  uint64_t Start = OS.tell();
+  uint64_t Start = getStream().tell();
   (void) Start;
 
   unsigned SegmentLoadCommandSize =
     is64Bit() ? sizeof(MachO::segment_command_64):
     sizeof(MachO::segment_command);
   write32(is64Bit() ? MachO::LC_SEGMENT_64 : MachO::LC_SEGMENT);
   write32(SegmentLoadCommandSize +
           NumSections * (is64Bit() ? sizeof(MachO::section_64) :
void MachObjectWriter::writeSegmentLoadCommand(
   }
   // maxprot
   write32(MaxProt);
   // initprot
   write32(InitProt);
   write32(NumSections);
   write32(0); // flags
 
-  assert(OS.tell() - Start == SegmentLoadCommandSize);
+  assert(getStream().tell() - Start == SegmentLoadCommandSize);
 }
 
 void MachObjectWriter::writeSection(const MCAsmLayout &Layout,
                                     const MCSection &Sec, uint64_t VMAddr,
                                     uint64_t FileOffset, unsigned Flags,
                                     uint64_t RelocationsStart,
                                     unsigned NumRelocations) {
   uint64_t SectionSize = Layout.getSectionAddressSize(&Sec);
   const MCSectionMachO &Section = cast<MCSectionMachO>(Sec);
 
   // The offset is unused for virtual sections.
   if (Section.isVirtualSection()) {
     assert(Layout.getSectionFileSize(&Sec) == 0 && "Invalid file size!");
     FileOffset = 0;
   }
 
   // struct section (68 bytes) or
   // struct section_64 (80 bytes)
 
-  uint64_t Start = OS.tell();
+  uint64_t Start = getStream().tell();
   (void) Start;
 
   writeBytes(Section.getSectionName(), 16);
   writeBytes(Section.getSegmentName(), 16);
   if (is64Bit()) {
     write64(VMAddr);      // address
     write64(SectionSize); // size
   } else {
     write32(VMAddr);      // address
     write32(SectionSize); // size
   }
   write32(FileOffset);
 
   assert(isPowerOf2_32(Section.getAlignment()) && "Invalid alignment!");
   write32(Log2_32(Section.getAlignment()));
   write32(NumRelocations ? RelocationsStart : 0);
   write32(NumRelocations);
   write32(Flags);
   write32(IndirectSymBase.lookup(&Sec)); // reserved1
   write32(Section.getStubSize()); // reserved2
   if (is64Bit())
     write32(0); // reserved3
 
-  assert(OS.tell() - Start == (is64Bit() ? sizeof(MachO::section_64) :
-                               sizeof(MachO::section)));
+  assert(getStream().tell() - Start ==
+         (is64Bit() ? sizeof(MachO::section_64) : sizeof(MachO::section)));
 }
 
 void MachObjectWriter::writeSymtabLoadCommand(uint32_t SymbolOffset,
                                               uint32_t NumSymbols,
                                               uint32_t StringTableOffset,
                                               uint32_t StringTableSize) {
   // struct symtab_command (24 bytes)
 
-  uint64_t Start = OS.tell();
+  uint64_t Start = getStream().tell();
   (void) Start;
 
   write32(MachO::LC_SYMTAB);
   write32(sizeof(MachO::symtab_command));
   write32(SymbolOffset);
   write32(NumSymbols);
   write32(StringTableOffset);
   write32(StringTableSize);
 
-  assert(OS.tell() - Start == sizeof(MachO::symtab_command));
+  assert(getStream().tell() - Start == sizeof(MachO::symtab_command));
 }
 
 void MachObjectWriter::writeDysymtabLoadCommand(uint32_t FirstLocalSymbol,
                                                 uint32_t NumLocalSymbols,
                                                 uint32_t FirstExternalSymbol,
                                                 uint32_t NumExternalSymbols,
                                                 uint32_t FirstUndefinedSymbol,
                                                 uint32_t NumUndefinedSymbols,
                                                 uint32_t IndirectSymbolOffset,
                                                 uint32_t NumIndirectSymbols) {
   // struct dysymtab_command (80 bytes)
 
-  uint64_t Start = OS.tell();
+  uint64_t Start = getStream().tell();
   (void) Start;
 
   write32(MachO::LC_DYSYMTAB);
   write32(sizeof(MachO::dysymtab_command));
   write32(FirstLocalSymbol);
   write32(NumLocalSymbols);
   write32(FirstExternalSymbol);
   write32(NumExternalSymbols);
   write32(FirstUndefinedSymbol);
   write32(NumUndefinedSymbols);
   write32(0); // tocoff
   write32(0); // ntoc
   write32(0); // modtaboff
   write32(0); // nmodtab
   write32(0); // extrefsymoff
   write32(0); // nextrefsyms
   write32(IndirectSymbolOffset);
   write32(NumIndirectSymbols);
   write32(0); // extreloff
   write32(0); // nextrel
   write32(0); // locreloff
   write32(0); // nlocrel
 
-  assert(OS.tell() - Start == sizeof(MachO::dysymtab_command));
+  assert(getStream().tell() - Start == sizeof(MachO::dysymtab_command));
 }
 
 MachObjectWriter::MachSymbolData *
 MachObjectWriter::findSymbolData(const MCSymbol &Sym) {
   for (auto *SymbolData :
        {&LocalSymbolData, &ExternalSymbolData, &UndefinedSymbolData})
     for (MachSymbolData &Entry : *SymbolData)
       if (Entry.Symbol == &Sym)
if (is64Bit())
     write64(Address);
   else
     write32(Address);
 }
 
 void MachObjectWriter::writeLinkeditLoadCommand(uint32_t Type,
                                                 uint32_t DataOffset,
                                                 uint32_t DataSize) {
-  uint64_t Start = OS.tell();
+  uint64_t Start = getStream().tell();
   (void) Start;
 
   write32(Type);
   write32(sizeof(MachO::linkedit_data_command));
   write32(DataOffset);
   write32(DataSize);
 
-  assert(OS.tell() - Start == sizeof(MachO::linkedit_data_command));
+  assert(getStream().tell() - Start == sizeof(MachO::linkedit_data_command));
 }
 
 static unsigned ComputeLinkerOptionsLoadCommandSize(
   const std::vector<std::string> &Options, bool is64Bit)
 {
   unsigned Size = sizeof(MachO::linker_option_command);
   for (const std::string &Option : Options)
     Size += Option.size() + 1;
   return RoundUpToAlignment(Size, is64Bit ? 8 : 4);
 }
 
 void MachObjectWriter::writeLinkerOptionsLoadCommand(
   const std::vector<std::string> &Options)
 {
   unsigned Size = ComputeLinkerOptionsLoadCommandSize(Options, is64Bit());
-  uint64_t Start = OS.tell();
+  uint64_t Start = getStream().tell();
   (void) Start;
 
   write32(MachO::LC_LINKER_OPTION);
   write32(Size);
   write32(Options.size());
   uint64_t BytesWritten = sizeof(MachO::linker_option_command);
   for (const std::string &Option : Options) {
     // Write each string, including the null byte.
     writeBytes(Option.c_str(), Option.size() + 1);
     BytesWritten += Option.size() + 1;
   }
 
   // Pad to a multiple of the pointer size.
   writeBytes("", OffsetToAlignment(BytesWritten, is64Bit() ? 8 : 4));
 
-  assert(OS.tell() - Start == Size);
+  assert(getStream().tell() - Start == Size);
 }
 
 void MachObjectWriter::recordRelocation(MCAssembler &Asm,
                                         const MCAsmLayout &Layout,
                                         const MCFragment *Fragment,
                                         const MCFixup &Fixup, MCValue Target,
                                         bool &IsPCRel, uint64_t &FixedValue) {
   TargetObjectWriter->recordRelocation(this, Asm, Layout, Fragment, Fixup,
for (MCAssembler::const_data_region_iterator
     write32(Start);
     write16(End - Start);
     write16(Data->Kind);
   }
 
   // Write out the loh commands, if there is one.
   if (LOHSize) {
 #ifndef NDEBUG
-    unsigned Start = OS.tell();
+    unsigned Start = getStream().tell();
 #endif
     Asm.getLOHContainer().emit(*this, Layout);
     // Pad to a multiple of the pointer size.
     writeBytes("", OffsetToAlignment(LOHRawSize, is64Bit() ? 8 : 4));
-    assert(OS.tell() - Start == LOHSize);
+    assert(getStream().tell() - Start == LOHSize);
   }
 
   // Write the symbol table data, if used.
   if (NumSymbols) {
     // Write the indirect symbol entries.
     for (MCAssembler::const_indirect_symbol_iterator
            it = Asm.indirect_symbol_begin(),
            ie = Asm.indirect_symbol_end(); it != ie; ++it) {
if (NumSymbols) {
 
     // Write the symbol table entries.
     for (auto *SymbolData :
          {&LocalSymbolData, &ExternalSymbolData, &UndefinedSymbolData})
       for (MachSymbolData &Entry : *SymbolData)
         writeNlist(Entry, Layout);
 
     // Write the string table.
-    OS << StringTable.data();
+    getStream() << StringTable.data();
   }
 }
 
 MCObjectWriter *llvm::createMachObjectWriter(MCMachObjectTargetWriter *MOTW,
                                              raw_pwrite_stream &OS,
                                              bool IsLittleEndian) {
   return new MachObjectWriter(MOTW, OS, IsLittleEndian);
 }

llvm/trunk/lib/MC/WinCOFFObjectWriter.cpp

WriteFileHeader(Header);
     for (i = Sections.begin(), ie = Sections.end(), j = Asm.begin(),
         je = Asm.end();
          (i != ie) && (j != je); ++i, ++j) {
 
       if ((*i)->Number == -1)
         continue;
 
       if ((*i)->Header.PointerToRawData != 0) {
-        assert(OS.tell() <= (*i)->Header.PointerToRawData &&
+        assert(getStream().tell() <= (*i)->Header.PointerToRawData &&
                "Section::PointerToRawData is insane!");
 
-        unsigned SectionDataPadding = (*i)->Header.PointerToRawData - OS.tell();
+        unsigned SectionDataPadding =
+            (*i)->Header.PointerToRawData - getStream().tell();
         assert(SectionDataPadding < 4 &&
                "Should only need at most three bytes of padding!");
 
         WriteZeros(SectionDataPadding);
 
         Asm.writeSectionData(&*j, Layout);
       }
 
       if ((*i)->Relocations.size() > 0) {
-        assert(OS.tell() == (*i)->Header.PointerToRelocations &&
+        assert(getStream().tell() == (*i)->Header.PointerToRelocations &&
                "Section::PointerToRelocations is insane!");
 
         if ((*i)->Relocations.size() >= 0xffff) {
           // In case of overflow, write actual relocation count as first
           // relocation. Including the synthetic reloc itself (+ 1).
           COFF::relocation r;
           r.VirtualAddress = (*i)->Relocations.size() + 1;
           r.SymbolTableIndex = 0;
           r.Type = 0;
           WriteRelocation(r);
         }
 
         for (const auto &Relocation : (*i)->Relocations)
           WriteRelocation(Relocation.Data);
       } else
         assert((*i)->Header.PointerToRelocations == 0 &&
                "Section::PointerToRelocations is insane!");
     }
   }
 
-  assert(OS.tell() == Header.PointerToSymbolTable &&
+  assert(getStream().tell() == Header.PointerToSymbolTable &&
          "Header::PointerToSymbolTable is insane!");
 
   for (auto &Symbol : Symbols)
     if (Symbol->getIndex() != -1)
       WriteSymbol(*Symbol);
 
-  OS.write(Strings.data().data(), Strings.data().size());
+  getStream().write(Strings.data().data(), Strings.data().size());
 }
 
 MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_)
     : Machine(Machine_) {}
 
 // Pin the vtable to this file.
 void MCWinCOFFObjectTargetWriter::anchor() {}
 
 //------------------------------------------------------------------------------
 // WinCOFFObjectWriter factory function
 
 MCObjectWriter *
 llvm::createWinCOFFObjectWriter(MCWinCOFFObjectTargetWriter *MOTW,
                                 raw_pwrite_stream &OS) {
   return new WinCOFFObjectWriter(MOTW, OS);
 }