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diff --git a/lib/CodeGen/AsmPrinter/DwarfExpression.h b/lib/CodeGen/AsmPrinter/DwarfExpression.h
new file mode 100644
index 0000000..b90b7b6
--- /dev/null
+++ b/lib/CodeGen/AsmPrinter/DwarfExpression.h
@@ -0,0 +1,133 @@
+//===-- llvm/CodeGen/DwarfExpression.h - Dwarf Compile Unit ---*- C++ -*--===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for writing dwarf compile unit.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFEXPRESSION_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFEXPRESSION_H
+
+#include "llvm/IR/DebugInfo.h"
+#include "llvm/Support/DataTypes.h"
+
+namespace llvm {
+
+class AsmPrinter;
+class ByteStreamer;
+class TargetRegisterInfo;
+class DwarfUnit;
+class DIELoc;
+
+/// Base class containing the logic for constructing DWARF expressions
+/// independently of whether they are emitted into a DIE or into a .debug_loc
+/// entry.
+class DwarfExpression {
+protected:
+  const AsmPrinter &AP;
+  // Various convenience accessors that extract things out of AsmPrinter.
+  const TargetRegisterInfo *getTRI() const;
+  unsigned getDwarfVersion() const;
+
+public:
+  DwarfExpression(const AsmPrinter &AP) : AP(AP) {}
+  virtual ~DwarfExpression() {}
+
+  /// Output a dwarf operand and an optional assembler comment.
+  virtual void EmitOp(uint8_t Op, const char *Comment = nullptr) = 0;
+  /// Emit a raw signed value.
+  virtual void EmitSigned(int Value) = 0;
+  /// Emit a raw unsigned value.
+  virtual void EmitUnsigned(unsigned Value) = 0;
+  /// Return whether the given machine register is the frame register in the
+  /// current function.
+  virtual bool isFrameRegister(unsigned MachineReg) = 0;
+
+  /// Emit a dwarf register operation.
+  void AddReg(int DwarfReg, const char *Comment = nullptr);
+  /// Emit an (double-)indirect dwarf register operation.
+  void AddRegIndirect(int DwarfReg, int Offset, bool Deref = false);
+
+  /// Emit a dwarf register operation for describing
+  /// - a small value occupying only part of a register or
+  /// - a register representing only part of a value.
+  void AddOpPiece(unsigned SizeInBits, unsigned OffsetInBits = 0);
+  /// Emit a shift-right dwarf expression.
+  void AddShr(unsigned ShiftBy);
+
+  /// Emit an indirect dwarf register operation for the given machine register.
+  /// \return false if no DWARF register exists for MachineReg.
+  bool AddMachineRegIndirect(unsigned MachineReg, int Offset = 0);
+
+  /// \brief Emit a partial DWARF register operation.
+  /// \param MachineReg        the register
+  /// \param PieceSizeInBits   size and
+  /// \param PieceOffsetInBits offset of the piece in bits, if this is one
+  ///                          piece of an aggregate value.
+  ///
+  /// If size and offset is zero an operation for the entire
+  /// register is emitted: Some targets do not provide a DWARF
+  /// register number for every register.  If this is the case, this
+  /// function will attempt to emit a DWARF register by emitting a
+  /// piece of a super-register or by piecing together multiple
+  /// subregisters that alias the register.
+  ///
+  /// \return false if no DWARF register exists for MachineReg.
+  bool AddMachineRegPiece(unsigned MachineReg, unsigned PieceSizeInBits = 0,
+                          unsigned PieceOffsetInBits = 0);
+
+  /// Emit a signed constant.
+  void AddSignedConstant(int Value);
+  /// Emit an unsigned constant.
+  void AddUnsignedConstant(unsigned Value);
+
+  /// Emit an entire DIExpression on top of a machine register location.
+  /// \param PieceOffsetInBits If this is one piece out of a fragmented
+  /// location, this is the offset of the piece inside the entire variable.
+  /// \return false if no DWARF register exists for MachineReg.
+  bool AddMachineRegExpression(DIExpression Expr, unsigned MachineReg,
+                               unsigned PieceOffsetInBits = 0);
+  /// Emit a the operations remaining the DIExpressionIterator I.
+  /// \param PieceOffsetInBits If this is one piece out of a fragmented
+  /// location, this is the offset of the piece inside the entire variable.
+  void AddExpression(DIExpression::iterator I, DIExpression::iterator E,
+                     unsigned PieceOffsetInBits = 0);
+};
+
+/// DwarfExpression implementation for .debug_loc entries.
+class DebugLocDwarfExpression : public DwarfExpression {
+  ByteStreamer &BS;
+
+public:
+  DebugLocDwarfExpression(const AsmPrinter &AP, ByteStreamer &BS)
+      : DwarfExpression(AP), BS(BS) {}
+
+  void EmitOp(uint8_t Op, const char *Comment = nullptr) override;
+  void EmitSigned(int Value) override;
+  void EmitUnsigned(unsigned Value) override;
+  bool isFrameRegister(unsigned MachineReg) override;
+};
+
+/// DwarfExpression implementation for singular DW_AT_location.
+class DIEDwarfExpression : public DwarfExpression {
+  DwarfUnit &DU;
+  DIELoc &DIE;
+
+public:
+  DIEDwarfExpression(const AsmPrinter &AP, DwarfUnit &DU, DIELoc &DIE)
+      : DwarfExpression(AP), DU(DU), DIE(DIE) {}
+
+  void EmitOp(uint8_t Op, const char *Comment = nullptr) override;
+  void EmitSigned(int Value) override;
+  void EmitUnsigned(unsigned Value) override;
+  bool isFrameRegister(unsigned MachineReg) override;
+};
+}
+
+#endif