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diff --git a/llvm/lib/Target/Sparc/RegAlloc/IGNode.h b/llvm/lib/Target/Sparc/RegAlloc/IGNode.h
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+//===-- IGNode.h - Represent a node in an interference graph ----*- C++ -*-===//
+// 
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file represents a node in an interference graph. 
+//
+// For efficiency, the AdjList is updated only once - ie. we can add but not
+// remove nodes from AdjList. 
+//
+// The removal of nodes from IG is simulated by decrementing the CurDegree.
+// If this node is put on stack (that is removed from IG), the CurDegree of all
+// the neighbors are decremented and this node is marked OnStack. Hence
+// the effective neighbors in the AdjList are the ones that do not have the
+// OnStack flag set (therefore, they are in the IG).
+//
+// The methods that modify/use the CurDegree must be called only
+// after all modifications to the IG are over (i.e., all neighbors are fixed).
+//
+// The vector representation is the most efficient one for adj list.
+// Though nodes are removed when coalescing is done, we access it in sequence
+// for far many times when coloring (colorNode()).
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef IGNODE_H
+#define IGNODE_H
+
+#include "LiveRange.h"
+#include <vector>
+
+namespace llvm {
+
+class RegClass;
+
+//----------------------------------------------------------------------------
+// Class IGNode
+//
+// Represents a node in an interference graph.
+//----------------------------------------------------------------------------
+
+class IGNode {
+  const unsigned Index;         // index within IGNodeList 
+  bool OnStack;                 // this has been pushed on to stack for coloring
+  std::vector<IGNode *> AdjList;// adjacency list for this live range
+
+  int CurDegree;     
+  //
+  // set by InterferenceGraph::setCurDegreeOfIGNodes() after calculating
+  // all adjacency lists.
+  // Decremented when a neighbor is pushed on to the stack. 
+  // After that, never incremented/set again nor used.
+
+  LiveRange *const ParentLR;
+public:
+
+  IGNode(LiveRange *LR, unsigned index) : Index(index), ParentLR(LR) {
+    OnStack = false;
+    CurDegree = -1;
+    ParentLR->setUserIGNode(this);
+  }
+
+  inline unsigned int getIndex() const { return Index; }
+
+  // adjLists must be updated only once.  However, the CurDegree can be changed
+  //
+  inline void addAdjIGNode(IGNode *AdjNode) { AdjList.push_back(AdjNode);  } 
+
+  inline IGNode *getAdjIGNode(unsigned ind) const 
+    { assert ( ind < AdjList.size()); return AdjList[ind]; }
+
+  // delete a node in AdjList - node must be in the list
+  // should not be called often
+  //
+  void delAdjIGNode(const IGNode *Node); 
+
+  inline unsigned getNumOfNeighbors() const { return AdjList.size(); }
+
+  // Get the number of unique neighbors if these two nodes are merged
+  unsigned getCombinedDegree(const IGNode* otherNode) const;
+
+  inline bool isOnStack() const { return OnStack; }
+
+  // remove form IG and pushes on to stack (reduce the degree of neighbors)
+  //
+  void pushOnStack(); 
+
+  // CurDegree is the effective number of neighbors when neighbors are
+  // pushed on to the stack during the coloring phase. Must be called
+  // after all modifications to the IG are over (i.e., all neighbors are
+  // fixed).
+  //
+  inline void setCurDegree() {
+    assert(CurDegree == -1);
+    CurDegree = AdjList.size();
+  }
+
+  inline int getCurDegree() const { return CurDegree; }
+
+  // called when a neigh is pushed on to stack
+  //
+  inline void decCurDegree() { assert(CurDegree > 0); --CurDegree; }
+
+  // The following methods call the methods in ParentLR
+  // They are added to this class for convenience
+  // If many of these are called within a single scope,
+  // consider calling the methods directly on LR
+  inline bool hasColor() const { return ParentLR->hasColor();  }
+
+  inline unsigned int getColor() const { return ParentLR->getColor();  }
+
+  inline void setColor(unsigned Col) { ParentLR->setColor(Col);  }
+
+  inline LiveRange *getParentLR() const { return ParentLR; }
+};
+
+} // End llvm namespace
+
+#endif