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diff --git a/include/llvm/CodeGen/TailDuplicator.h b/include/llvm/CodeGen/TailDuplicator.h
new file mode 100644
index 0000000000000..8e65199418a6b
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+++ b/include/llvm/CodeGen/TailDuplicator.h
@@ -0,0 +1,92 @@
+//===-- llvm/CodeGen/TailDuplicator.h ---------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the TailDuplicator class. Used by the
+// TailDuplication pass, and MachineBlockPlacement.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_TAILDUPLICATOR_H
+#define LLVM_CODEGEN_TAILDUPLICATOR_H
+
+#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/MachineSSAUpdater.h"
+#include "llvm/CodeGen/RegisterScavenging.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
+
+namespace llvm {
+
+/// Utility class to perform tail duplication.
+class TailDuplicator {
+  const TargetInstrInfo *TII;
+  const TargetRegisterInfo *TRI;
+  const MachineBranchProbabilityInfo *MBPI;
+  const MachineModuleInfo *MMI;
+  MachineRegisterInfo *MRI;
+  bool PreRegAlloc;
+
+  // A list of virtual registers for which to update SSA form.
+  SmallVector<unsigned, 16> SSAUpdateVRs;
+
+  // For each virtual register in SSAUpdateVals keep a list of source virtual
+  // registers.
+  typedef std::vector<std::pair<MachineBasicBlock *, unsigned>> AvailableValsTy;
+
+  DenseMap<unsigned, AvailableValsTy> SSAUpdateVals;
+
+public:
+  void initMF(MachineFunction &MF, const MachineModuleInfo *MMI,
+              const MachineBranchProbabilityInfo *MBPI);
+  bool tailDuplicateBlocks(MachineFunction &MF);
+  static bool isSimpleBB(MachineBasicBlock *TailBB);
+  bool shouldTailDuplicate(const MachineFunction &MF, bool IsSimple,
+                           MachineBasicBlock &TailBB);
+  bool tailDuplicateAndUpdate(MachineFunction &MF, bool IsSimple,
+                              MachineBasicBlock *MBB);
+
+private:
+  typedef TargetInstrInfo::RegSubRegPair RegSubRegPair;
+
+  void addSSAUpdateEntry(unsigned OrigReg, unsigned NewReg,
+                         MachineBasicBlock *BB);
+  void processPHI(MachineInstr *MI, MachineBasicBlock *TailBB,
+                  MachineBasicBlock *PredBB,
+                  DenseMap<unsigned, RegSubRegPair> &LocalVRMap,
+                  SmallVectorImpl<std::pair<unsigned, RegSubRegPair>> &Copies,
+                  const DenseSet<unsigned> &UsedByPhi, bool Remove);
+  void duplicateInstruction(MachineInstr *MI, MachineBasicBlock *TailBB,
+                            MachineBasicBlock *PredBB, MachineFunction &MF,
+                            DenseMap<unsigned, RegSubRegPair> &LocalVRMap,
+                            const DenseSet<unsigned> &UsedByPhi);
+  void updateSuccessorsPHIs(MachineBasicBlock *FromBB, bool isDead,
+                            SmallVectorImpl<MachineBasicBlock *> &TDBBs,
+                            SmallSetVector<MachineBasicBlock *, 8> &Succs);
+  bool canCompletelyDuplicateBB(MachineBasicBlock &BB);
+  bool duplicateSimpleBB(MachineBasicBlock *TailBB,
+                         SmallVectorImpl<MachineBasicBlock *> &TDBBs,
+                         const DenseSet<unsigned> &RegsUsedByPhi,
+                         SmallVectorImpl<MachineInstr *> &Copies);
+  bool tailDuplicate(MachineFunction &MF, bool IsSimple,
+                     MachineBasicBlock *TailBB,
+                     SmallVectorImpl<MachineBasicBlock *> &TDBBs,
+                     SmallVectorImpl<MachineInstr *> &Copies);
+  void appendCopies(MachineBasicBlock *MBB,
+                 SmallVectorImpl<std::pair<unsigned,RegSubRegPair>> &CopyInfos,
+                 SmallVectorImpl<MachineInstr *> &Copies);
+
+  void removeDeadBlock(MachineBasicBlock *MBB);
+};
+
+} // End llvm namespace
+
+#endif