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diff --git a/include/clang/Serialization/ContinuousRangeMap.h b/include/clang/Serialization/ContinuousRangeMap.h
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+++ b/include/clang/Serialization/ContinuousRangeMap.h
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+//===--- ContinuousRangeMap.h - Map with int range as key -------*- 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 ContinuousRangeMap class, which is a highly
+//  specialized container used by serialization.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_SERIALIZATION_CONTINUOUS_RANGE_MAP_H
+#define LLVM_CLANG_SERIALIZATION_CONTINUOUS_RANGE_MAP_H
+
+#include "llvm/ADT/SmallVector.h"
+#include <algorithm>
+#include <utility>
+
+namespace clang {
+
+/// \brief A map from continuous integer ranges to some value, with a very
+/// specialized interface.
+///
+/// CRM maps from integer ranges to values. The ranges are continuous, i.e.
+/// where one ends, the next one begins. So if the map contains the stops I0-3,
+/// the first range is from I0 to I1, the second from I1 to I2, the third from
+/// I2 to I3 and the last from I3 to infinity.
+///
+/// Ranges must be inserted in order. Inserting a new stop I4 into the map will
+/// shrink the fourth range to I3 to I4 and add the new range I4 to inf.
+template <typename Int, typename V, unsigned InitialCapacity>
+class ContinuousRangeMap {
+public:
+  typedef std::pair<Int, V> value_type;
+  typedef value_type &reference;
+  typedef const value_type &const_reference;
+  typedef value_type *pointer;
+  typedef const value_type *const_pointer;
+
+private:
+  typedef SmallVector<value_type, InitialCapacity> Representation;
+  Representation Rep;
+
+  struct Compare {
+    bool operator ()(const_reference L, Int R) const {
+      return L.first < R;
+    }
+    bool operator ()(Int L, const_reference R) const {
+      return L < R.first;
+    }
+    bool operator ()(Int L, Int R) const { 
+      return L < R;
+    }
+    bool operator ()(const_reference L, const_reference R) const {
+      return L.first < R.first;
+    }
+  };
+
+public:
+  void insert(const value_type &Val) {
+    if (!Rep.empty() && Rep.back() == Val)
+      return;
+
+    assert((Rep.empty() || Rep.back().first < Val.first) &&
+           "Must insert keys in order.");
+    Rep.push_back(Val);
+  }
+
+  typedef typename Representation::iterator iterator;
+  typedef typename Representation::const_iterator const_iterator;
+
+  iterator begin() { return Rep.begin(); }
+  iterator end() { return Rep.end(); }
+  const_iterator begin() const { return Rep.begin(); }
+  const_iterator end() const { return Rep.end(); }
+
+  iterator find(Int K) {
+    iterator I = std::upper_bound(Rep.begin(), Rep.end(), K, Compare());
+    // I points to the first entry with a key > K, which is the range that
+    // follows the one containing K.
+    if (I == Rep.begin())
+      return Rep.end();
+    --I;
+    return I;
+  }
+  const_iterator find(Int K) const {
+    return const_cast<ContinuousRangeMap*>(this)->find(K);
+  }
+
+  reference back() { return Rep.back(); }
+  const_reference back() const { return Rep.back(); }
+  
+  /// \brief An object that helps properly build a continuous range map
+  /// from a set of values.
+  class Builder {
+    ContinuousRangeMap &Self;
+    
+    Builder(const Builder&); // DO NOT IMPLEMENT
+    Builder &operator=(const Builder&); // DO NOT IMPLEMENT
+    
+  public:
+    explicit Builder(ContinuousRangeMap &Self) : Self(Self) { }
+    
+    ~Builder() {
+      std::sort(Self.Rep.begin(), Self.Rep.end(), Compare());
+    }
+    
+    void insert(const value_type &Val) {
+      Self.Rep.push_back(Val);
+    }
+  };
+  friend class Builder;
+};
+
+}
+
+#endif