MC: Extract a derived class from ELFObjectWriter. NFCI.

[pcc]

Summary

This class will be used to create regular, non-split ELF files.

Part of PR37466.

Depends on D47048

llvm/trunk/lib/MC/ELFObjectWriter.cpp

public:
 
   uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout);
   void writeSection(const SectionIndexMapTy &SectionIndexMap,
                     uint32_t GroupSymbolIndex, uint64_t Offset, uint64_t Size,
                     const MCSectionELF &Section);
 };
 
 class ELFObjectWriter : public MCObjectWriter {
-  raw_pwrite_stream &OS;
-  bool IsLittleEndian;
-
   /// The target specific ELF writer instance.
   std::unique_ptr<MCELFObjectTargetWriter> TargetObjectWriter;
 
   DenseMap<const MCSectionELF *, std::vector<ELFRelocationEntry>> Relocations;
 
   DenseMap<const MCSymbolELF *, const MCSymbolELF *> Renames;
 
   bool hasRelocationAddend() const;
 
   bool shouldRelocateWithSymbol(const MCAssembler &Asm,
                                 const MCSymbolRefExpr *RefA,
                                 const MCSymbolELF *Sym, uint64_t C,
                                 unsigned Type) const;
 
 public:
-  ELFObjectWriter(std::unique_ptr<MCELFObjectTargetWriter> MOTW,
-                  raw_pwrite_stream &OS, bool IsLittleEndian)
-      : OS(OS), IsLittleEndian(IsLittleEndian),
-        TargetObjectWriter(std::move(MOTW)) {}
+  ELFObjectWriter(std::unique_ptr<MCELFObjectTargetWriter> MOTW)
+      : TargetObjectWriter(std::move(MOTW)) {}
 
   void reset() override {
     Relocations.clear();
     Renames.clear();
     MCObjectWriter::reset();
   }
 
   bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
                                               const MCSymbol &SymA,
                                               const MCFragment &FB, bool InSet,
                                               bool IsPCRel) const override;
 
   void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
                         const MCFragment *Fragment, const MCFixup &Fixup,
                         MCValue Target, uint64_t &FixedValue) override;
 
-  uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override {
-    return ELFWriter(*this, OS, IsLittleEndian).writeObject(Asm, Layout);
-  }
-
   void executePostLayoutBinding(MCAssembler &Asm,
                                 const MCAsmLayout &Layout) override;
 
   friend struct ELFWriter;
 };
 
+class ELFSingleObjectWriter : public ELFObjectWriter {
+  raw_pwrite_stream &OS;
+  bool IsLittleEndian;
+
+public:
+  ELFSingleObjectWriter(std::unique_ptr<MCELFObjectTargetWriter> MOTW,
+                        raw_pwrite_stream &OS, bool IsLittleEndian)
+      : ELFObjectWriter(std::move(MOTW)), OS(OS),
+        IsLittleEndian(IsLittleEndian) {}
+
+  uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override {
+    return ELFWriter(*this, OS, IsLittleEndian).writeObject(Asm, Layout);
+  }
+};
+
 } // end anonymous namespace
 
 void ELFWriter::align(unsigned Alignment) {
   uint64_t Padding = OffsetToAlignment(W.OS.tell(), Alignment);
   W.OS.write_zeros(Padding);
 }
 
 unsigned ELFWriter::addToSectionTable(const MCSectionELF *Sec) {
bool ELFObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(
   }
   return MCObjectWriter::isSymbolRefDifferenceFullyResolvedImpl(Asm, SymA, FB,
                                                                 InSet, IsPCRel);
 }
 
 std::unique_ptr<MCObjectWriter>
 llvm::createELFObjectWriter(std::unique_ptr<MCELFObjectTargetWriter> MOTW,
                             raw_pwrite_stream &OS, bool IsLittleEndian) {
-  return llvm::make_unique<ELFObjectWriter>(std::move(MOTW), OS,
+  return llvm::make_unique<ELFSingleObjectWriter>(std::move(MOTW), OS,
                                                   IsLittleEndian);
 }