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diff --git a/include/llvm/CodeGen/MachineRegisterInfo.h b/include/llvm/CodeGen/MachineRegisterInfo.h
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+++ b/include/llvm/CodeGen/MachineRegisterInfo.h
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+//===-- llvm/CodeGen/MachineRegisterInfo.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 MachineRegisterInfo class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_MACHINEREGISTERINFO_H
+#define LLVM_CODEGEN_MACHINEREGISTERINFO_H
+
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/iterator.h"
+#include <vector>
+
+namespace llvm {
+  
+/// MachineRegisterInfo - Keep track of information for virtual and physical
+/// registers, including vreg register classes, use/def chains for registers,
+/// etc.
+class MachineRegisterInfo {
+  /// VRegInfo - Information we keep for each virtual register.  The entries in
+  /// this vector are actually converted to vreg numbers by adding the 
+  /// TargetRegisterInfo::FirstVirtualRegister delta to their index.
+  ///
+  /// Each element in this list contains the register class of the vreg and the
+  /// start of the use/def list for the register.
+  std::vector<std::pair<const TargetRegisterClass*, MachineOperand*> > VRegInfo;
+
+  /// RegClassVRegMap - This vector acts as a map from TargetRegisterClass to
+  /// virtual registers. For each target register class, it keeps a list of
+  /// virtual registers belonging to the class.
+  std::vector<std::vector<unsigned> > RegClass2VRegMap;
+  
+  /// PhysRegUseDefLists - This is an array of the head of the use/def list for
+  /// physical registers.
+  MachineOperand **PhysRegUseDefLists; 
+  
+  /// UsedPhysRegs - This is a bit vector that is computed and set by the
+  /// register allocator, and must be kept up to date by passes that run after
+  /// register allocation (though most don't modify this).  This is used
+  /// so that the code generator knows which callee save registers to save and
+  /// for other target specific uses.
+  BitVector UsedPhysRegs;
+  
+  /// LiveIns/LiveOuts - Keep track of the physical registers that are
+  /// livein/liveout of the function.  Live in values are typically arguments in
+  /// registers, live out values are typically return values in registers.
+  /// LiveIn values are allowed to have virtual registers associated with them,
+  /// stored in the second element.
+  std::vector<std::pair<unsigned, unsigned> > LiveIns;
+  std::vector<unsigned> LiveOuts;
+  
+  MachineRegisterInfo(const MachineRegisterInfo&); // DO NOT IMPLEMENT
+  void operator=(const MachineRegisterInfo&);      // DO NOT IMPLEMENT
+public:
+  explicit MachineRegisterInfo(const TargetRegisterInfo &TRI);
+  ~MachineRegisterInfo();
+  
+  //===--------------------------------------------------------------------===//
+  // Register Info
+  //===--------------------------------------------------------------------===//
+
+  /// reg_begin/reg_end - Provide iteration support to walk over all definitions
+  /// and uses of a register within the MachineFunction that corresponds to this
+  /// MachineRegisterInfo object.
+  template<bool Uses, bool Defs>
+  class defusechain_iterator;
+
+  /// reg_iterator/reg_begin/reg_end - Walk all defs and uses of the specified
+  /// register.
+  typedef defusechain_iterator<true,true> reg_iterator;
+  reg_iterator reg_begin(unsigned RegNo) const {
+    return reg_iterator(getRegUseDefListHead(RegNo));
+  }
+  static reg_iterator reg_end() { return reg_iterator(0); }
+
+  /// reg_empty - Return true if there are no instructions using or defining the
+  /// specified register (it may be live-in).
+  bool reg_empty(unsigned RegNo) const { return reg_begin(RegNo) == reg_end(); }
+
+  /// def_iterator/def_begin/def_end - Walk all defs of the specified register.
+  typedef defusechain_iterator<false,true> def_iterator;
+  def_iterator def_begin(unsigned RegNo) const {
+    return def_iterator(getRegUseDefListHead(RegNo));
+  }
+  static def_iterator def_end() { return def_iterator(0); }
+
+  /// def_empty - Return true if there are no instructions defining the
+  /// specified register (it may be live-in).
+  bool def_empty(unsigned RegNo) const { return def_begin(RegNo) == def_end(); }
+
+  /// use_iterator/use_begin/use_end - Walk all uses of the specified register.
+  typedef defusechain_iterator<true,false> use_iterator;
+  use_iterator use_begin(unsigned RegNo) const {
+    return use_iterator(getRegUseDefListHead(RegNo));
+  }
+  static use_iterator use_end() { return use_iterator(0); }
+  
+  /// use_empty - Return true if there are no instructions using the specified
+  /// register.
+  bool use_empty(unsigned RegNo) const { return use_begin(RegNo) == use_end(); }
+
+  
+  /// replaceRegWith - Replace all instances of FromReg with ToReg in the
+  /// machine function.  This is like llvm-level X->replaceAllUsesWith(Y),
+  /// except that it also changes any definitions of the register as well.
+  void replaceRegWith(unsigned FromReg, unsigned ToReg);
+  
+  /// getRegUseDefListHead - Return the head pointer for the register use/def
+  /// list for the specified virtual or physical register.
+  MachineOperand *&getRegUseDefListHead(unsigned RegNo) {
+    if (RegNo < TargetRegisterInfo::FirstVirtualRegister)
+      return PhysRegUseDefLists[RegNo];
+    RegNo -= TargetRegisterInfo::FirstVirtualRegister;
+    return VRegInfo[RegNo].second;
+  }
+  
+  MachineOperand *getRegUseDefListHead(unsigned RegNo) const {
+    if (RegNo < TargetRegisterInfo::FirstVirtualRegister)
+      return PhysRegUseDefLists[RegNo];
+    RegNo -= TargetRegisterInfo::FirstVirtualRegister;
+    return VRegInfo[RegNo].second;
+  }
+
+  /// getVRegDef - Return the machine instr that defines the specified virtual
+  /// register or null if none is found.  This assumes that the code is in SSA
+  /// form, so there should only be one definition.
+  MachineInstr *getVRegDef(unsigned Reg) const;
+  
+#ifndef NDEBUG
+  void dumpUses(unsigned RegNo) const;
+#endif
+  
+  //===--------------------------------------------------------------------===//
+  // Virtual Register Info
+  //===--------------------------------------------------------------------===//
+  
+  /// getRegClass - Return the register class of the specified virtual register.
+  ///
+  const TargetRegisterClass *getRegClass(unsigned Reg) const {
+    Reg -= TargetRegisterInfo::FirstVirtualRegister;
+    assert(Reg < VRegInfo.size() && "Invalid vreg!");
+    return VRegInfo[Reg].first;
+  }
+
+  /// setRegClass - Set the register class of the specified virtual register.
+  ///
+  void setRegClass(unsigned Reg, const TargetRegisterClass *RC);
+
+  /// createVirtualRegister - Create and return a new virtual register in the
+  /// function with the specified register class.
+  ///
+  unsigned createVirtualRegister(const TargetRegisterClass *RegClass);
+
+  /// getLastVirtReg - Return the highest currently assigned virtual register.
+  ///
+  unsigned getLastVirtReg() const {
+    return (unsigned)VRegInfo.size()+TargetRegisterInfo::FirstVirtualRegister-1;
+  }
+
+  /// getRegClassVirtRegs - Return the list of virtual registers of the given
+  /// target register class.
+  std::vector<unsigned> &getRegClassVirtRegs(const TargetRegisterClass *RC) {
+    return RegClass2VRegMap[RC->getID()];
+  }
+  
+  //===--------------------------------------------------------------------===//
+  // Physical Register Use Info
+  //===--------------------------------------------------------------------===//
+  
+  /// isPhysRegUsed - Return true if the specified register is used in this
+  /// function.  This only works after register allocation.
+  bool isPhysRegUsed(unsigned Reg) const { return UsedPhysRegs[Reg]; }
+  
+  /// setPhysRegUsed - Mark the specified register used in this function.
+  /// This should only be called during and after register allocation.
+  void setPhysRegUsed(unsigned Reg) { UsedPhysRegs[Reg] = true; }
+  
+  /// setPhysRegUnused - Mark the specified register unused in this function.
+  /// This should only be called during and after register allocation.
+  void setPhysRegUnused(unsigned Reg) { UsedPhysRegs[Reg] = false; }
+  
+
+  //===--------------------------------------------------------------------===//
+  // LiveIn/LiveOut Management
+  //===--------------------------------------------------------------------===//
+  
+  /// addLiveIn/Out - Add the specified register as a live in/out.  Note that it
+  /// is an error to add the same register to the same set more than once.
+  void addLiveIn(unsigned Reg, unsigned vreg = 0) {
+    LiveIns.push_back(std::make_pair(Reg, vreg));
+  }
+  void addLiveOut(unsigned Reg) { LiveOuts.push_back(Reg); }
+  
+  // Iteration support for live in/out sets.  These sets are kept in sorted
+  // order by their register number.
+  typedef std::vector<std::pair<unsigned,unsigned> >::const_iterator
+  livein_iterator;
+  typedef std::vector<unsigned>::const_iterator liveout_iterator;
+  livein_iterator livein_begin() const { return LiveIns.begin(); }
+  livein_iterator livein_end()   const { return LiveIns.end(); }
+  bool            livein_empty() const { return LiveIns.empty(); }
+  liveout_iterator liveout_begin() const { return LiveOuts.begin(); }
+  liveout_iterator liveout_end()   const { return LiveOuts.end(); }
+  bool             liveout_empty() const { return LiveOuts.empty(); }
+
+  bool isLiveIn(unsigned Reg) const {
+    for (livein_iterator I = livein_begin(), E = livein_end(); I != E; ++I)
+      if (I->first == Reg || I->second == Reg)
+        return true;
+    return false;
+  }
+
+private:
+  void HandleVRegListReallocation();
+  
+public:
+  /// defusechain_iterator - This class provides iterator support for machine
+  /// operands in the function that use or define a specific register.  If
+  /// ReturnUses is true it returns uses of registers, if ReturnDefs is true it
+  /// returns defs.  If neither are true then you are silly and it always
+  /// returns end().
+  template<bool ReturnUses, bool ReturnDefs>
+  class defusechain_iterator
+    : public forward_iterator<MachineInstr, ptrdiff_t> {
+    MachineOperand *Op;
+    explicit defusechain_iterator(MachineOperand *op) : Op(op) {
+      // If the first node isn't one we're interested in, advance to one that
+      // we are interested in.
+      if (op) {
+        if ((!ReturnUses && op->isUse()) ||
+            (!ReturnDefs && op->isDef()))
+          ++*this;
+      }
+    }
+    friend class MachineRegisterInfo;
+  public:
+    typedef forward_iterator<MachineInstr, ptrdiff_t>::reference reference;
+    typedef forward_iterator<MachineInstr, ptrdiff_t>::pointer pointer;
+    
+    defusechain_iterator(const defusechain_iterator &I) : Op(I.Op) {}
+    defusechain_iterator() : Op(0) {}
+    
+    bool operator==(const defusechain_iterator &x) const {
+      return Op == x.Op;
+    }
+    bool operator!=(const defusechain_iterator &x) const {
+      return !operator==(x);
+    }
+    
+    /// atEnd - return true if this iterator is equal to reg_end() on the value.
+    bool atEnd() const { return Op == 0; }
+    
+    // Iterator traversal: forward iteration only
+    defusechain_iterator &operator++() {          // Preincrement
+      assert(Op && "Cannot increment end iterator!");
+      Op = Op->getNextOperandForReg();
+      
+      // If this is an operand we don't care about, skip it.
+      while (Op && ((!ReturnUses && Op->isUse()) || 
+                    (!ReturnDefs && Op->isDef())))
+        Op = Op->getNextOperandForReg();
+      
+      return *this;
+    }
+    defusechain_iterator operator++(int) {        // Postincrement
+      defusechain_iterator tmp = *this; ++*this; return tmp;
+    }
+    
+    MachineOperand &getOperand() const {
+      assert(Op && "Cannot dereference end iterator!");
+      return *Op;
+    }
+    
+    /// getOperandNo - Return the operand # of this MachineOperand in its
+    /// MachineInstr.
+    unsigned getOperandNo() const {
+      assert(Op && "Cannot dereference end iterator!");
+      return Op - &Op->getParent()->getOperand(0);
+    }
+    
+    // Retrieve a reference to the current operand.
+    MachineInstr &operator*() const {
+      assert(Op && "Cannot dereference end iterator!");
+      return *Op->getParent();
+    }
+    
+    MachineInstr *operator->() const {
+      assert(Op && "Cannot dereference end iterator!");
+      return Op->getParent();
+    }
+  };
+  
+};
+
+} // End llvm namespace
+
+#endif