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diff --git a/lib/CodeGen/LiveInterval.h b/lib/CodeGen/LiveInterval.h
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+//===-- llvm/CodeGen/LiveInterval.h - Interval representation ---*- 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 implements the LiveRange and LiveInterval classes.  Given some
+// numbering of each the machine instructions an interval [i, j) is said to be a
+// live interval for register v if there is no instruction with number j' > j
+// such that v is live at j' abd there is no instruction with number i' < i such
+// that v is live at i'. In this implementation intervals can have holes,
+// i.e. an interval might look like [1,20), [50,65), [1000,1001).  Each
+// individual range is represented as an instance of LiveRange, and the whole
+// interval is represented as an instance of LiveInterval.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_LIVEINTERVAL_H
+#define LLVM_CODEGEN_LIVEINTERVAL_H
+
+#include <iosfwd>
+#include <vector>
+#include <cassert>
+
+namespace llvm {
+  /// LiveRange structure - This represents a simple register range in the
+  /// program, with an inclusive start point and an exclusive end point.
+  /// These ranges are rendered as [start,end).
+  struct LiveRange {
+    unsigned start;  // Start point of the interval (inclusive)
+    unsigned end;  // End point of the interval (exclusive)
+    LiveRange(unsigned S, unsigned E) : start(S), end(E) {
+      assert(S < E && "Cannot create empty or backwards range");
+    }
+
+    bool operator<(const LiveRange &LR) const {
+      return start < LR.start || (start == LR.start && end < LR.end);
+    }
+    bool operator==(const LiveRange &LR) const {
+      return start == LR.start && end == LR.end;
+    }
+    private:
+    LiveRange(); // DO NOT IMPLEMENT
+  };
+  std::ostream& operator<<(std::ostream& os, const LiveRange &LR);
+
+  /// LiveInterval - This class represents some number of live ranges for a
+  /// register or value.  This class also contains a bit of register allocator
+  /// state.
+  struct LiveInterval {
+    typedef std::vector<LiveRange> Ranges;
+    unsigned reg;        // the register of this interval
+    float weight;        // weight of this interval
+    Ranges ranges;       // the ranges in which this register is live
+    bool isDefinedOnce;  // True if this interval contains one value.
+
+    LiveInterval(unsigned Reg, float Weight)
+      : reg(Reg), weight(Weight), isDefinedOnce(false) {
+    }
+
+    bool containsOneValue() const { return isDefinedOnce; }
+
+    bool empty() const { return ranges.empty(); }
+
+    /// start - Return the lowest numbered slot covered by interval.
+    unsigned start() const {
+      assert(!empty() && "empty interval for register");
+      return ranges.front().start;
+    }
+
+    /// end - return the maximum point of the interval of the whole,
+    /// exclusive.
+    unsigned end() const {
+      assert(!empty() && "empty interval for register");
+      return ranges.back().end;
+    }
+
+    bool expiredAt(unsigned index) const {
+      return end() <= (index + 1);
+    }
+
+    bool liveAt(unsigned index) const;
+
+    bool overlaps(const LiveInterval& other) const;
+
+    void addRange(LiveRange R);
+
+    void join(const LiveInterval& other);
+
+    bool operator<(const LiveInterval& other) const {
+      return start() < other.start();
+    }
+
+    bool operator==(const LiveInterval& other) const {
+      return reg == other.reg;
+    }
+
+  private:
+    Ranges::iterator mergeRangesForward(Ranges::iterator it);
+    Ranges::iterator mergeRangesBackward(Ranges::iterator it);
+  };
+
+  std::ostream& operator<<(std::ostream& os, const LiveInterval& li);
+}
+
+#endif