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diff --git a/include/llvm/MC/TargetAsmBackend.h b/include/llvm/MC/TargetAsmBackend.h
new file mode 100644
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+++ b/include/llvm/MC/TargetAsmBackend.h
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+//===-- llvm/MC/TargetAsmBackend.h - Target Asm Backend ---------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TARGET_TARGETASMBACKEND_H
+#define LLVM_TARGET_TARGETASMBACKEND_H
+
+#include "llvm/MC/MCDirectives.h"
+#include "llvm/MC/MCFixup.h"
+#include "llvm/MC/MCFixupKindInfo.h"
+#include "llvm/Support/DataTypes.h"
+
+namespace llvm {
+class MCELFObjectTargetWriter;
+class MCFixup;
+class MCInst;
+class MCObjectWriter;
+class MCSection;
+template<typename T>
+class SmallVectorImpl;
+class raw_ostream;
+
+/// TargetAsmBackend - Generic interface to target specific assembler backends.
+class TargetAsmBackend {
+  TargetAsmBackend(const TargetAsmBackend &);   // DO NOT IMPLEMENT
+  void operator=(const TargetAsmBackend &);  // DO NOT IMPLEMENT
+protected: // Can only create subclasses.
+  TargetAsmBackend();
+
+  unsigned HasReliableSymbolDifference : 1;
+
+public:
+  virtual ~TargetAsmBackend();
+
+  /// createObjectWriter - Create a new MCObjectWriter instance for use by the
+  /// assembler backend to emit the final object file.
+  virtual MCObjectWriter *createObjectWriter(raw_ostream &OS) const = 0;
+
+  /// createELFObjectTargetWriter - Create a new ELFObjectTargetWriter to enable
+  /// non-standard ELFObjectWriters.
+  virtual  MCELFObjectTargetWriter *createELFObjectTargetWriter() const {
+    assert(0 && "createELFObjectTargetWriter is not supported by asm backend");
+    return 0;
+  }
+
+  /// hasReliableSymbolDifference - Check whether this target implements
+  /// accurate relocations for differences between symbols. If not, differences
+  /// between symbols will always be relocatable expressions and any references
+  /// to temporary symbols will be assumed to be in the same atom, unless they
+  /// reside in a different section.
+  ///
+  /// This should always be true (since it results in fewer relocations with no
+  /// loss of functionality), but is currently supported as a way to maintain
+  /// exact object compatibility with Darwin 'as' (on non-x86_64). It should
+  /// eventually should be eliminated.
+  bool hasReliableSymbolDifference() const {
+    return HasReliableSymbolDifference;
+  }
+
+  /// doesSectionRequireSymbols - Check whether the given section requires that
+  /// all symbols (even temporaries) have symbol table entries.
+  virtual bool doesSectionRequireSymbols(const MCSection &Section) const {
+    return false;
+  }
+
+  /// isSectionAtomizable - Check whether the given section can be split into
+  /// atoms.
+  ///
+  /// \see MCAssembler::isSymbolLinkerVisible().
+  virtual bool isSectionAtomizable(const MCSection &Section) const {
+    return true;
+  }
+
+  /// @name Target Fixup Interfaces
+  /// @{
+
+  /// getNumFixupKinds - Get the number of target specific fixup kinds.
+  virtual unsigned getNumFixupKinds() const = 0;
+
+  /// getFixupKindInfo - Get information on a fixup kind.
+  virtual const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const;
+
+  /// @}
+
+  /// ApplyFixup - Apply the \arg Value for given \arg Fixup into the provided
+  /// data fragment, at the offset specified by the fixup and following the
+  /// fixup kind as appropriate.
+  virtual void ApplyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
+                          uint64_t Value) const = 0;
+
+  /// @}
+
+  /// @name Target Relaxation Interfaces
+  /// @{
+
+  /// MayNeedRelaxation - Check whether the given instruction may need
+  /// relaxation.
+  ///
+  /// \param Inst - The instruction to test.
+  virtual bool MayNeedRelaxation(const MCInst &Inst) const = 0;
+
+  /// RelaxInstruction - Relax the instruction in the given fragment to the next
+  /// wider instruction.
+  ///
+  /// \param Inst - The instruction to relax, which may be the same as the
+  /// output.
+  /// \parm Res [output] - On return, the relaxed instruction.
+  virtual void RelaxInstruction(const MCInst &Inst, MCInst &Res) const = 0;
+
+  /// @}
+
+  /// WriteNopData - Write an (optimal) nop sequence of Count bytes to the given
+  /// output. If the target cannot generate such a sequence, it should return an
+  /// error.
+  ///
+  /// \return - True on success.
+  virtual bool WriteNopData(uint64_t Count, MCObjectWriter *OW) const = 0;
+
+  /// HandleAssemblerFlag - Handle any target-specific assembler flags.
+  /// By default, do nothing.
+  virtual void HandleAssemblerFlag(MCAssemblerFlag Flag) {}
+};
+
+} // End llvm namespace
+
+#endif