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diff --git a/include/llvm/ADT/UniqueVector.h b/include/llvm/ADT/UniqueVector.h
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+//===-- llvm/ADT/UniqueVector.h ---------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_UNIQUEVECTOR_H
+#define LLVM_ADT_UNIQUEVECTOR_H
+
+#include <cassert>
+#include <map>
+#include <vector>
+
+namespace llvm {
+
+//===----------------------------------------------------------------------===//
+/// UniqueVector - This class produces a sequential ID number (base 1) for each
+/// unique entry that is added.  T is the type of entries in the vector. This
+/// class should have an implementation of operator== and of operator<.
+/// Entries can be fetched using operator[] with the entry ID.
+template<class T> class UniqueVector {
+private:
+  // Map - Used to handle the correspondence of entry to ID.
+  std::map<T, unsigned> Map;
+
+  // Vector - ID ordered vector of entries. Entries can be indexed by ID - 1.
+  //
+  std::vector<T> Vector;
+
+public:
+  /// insert - Append entry to the vector if it doesn't already exist.  Returns
+  /// the entry's index + 1 to be used as a unique ID.
+  unsigned insert(const T &Entry) {
+    // Check if the entry is already in the map.
+    unsigned &Val = Map[Entry];
+
+    // See if entry exists, if so return prior ID.
+    if (Val) return Val;
+
+    // Compute ID for entry.
+    Val = static_cast<unsigned>(Vector.size()) + 1;
+
+    // Insert in vector.
+    Vector.push_back(Entry);
+    return Val;
+  }
+
+  /// idFor - return the ID for an existing entry.  Returns 0 if the entry is
+  /// not found.
+  unsigned idFor(const T &Entry) const {
+    // Search for entry in the map.
+    typename std::map<T, unsigned>::const_iterator MI = Map.find(Entry);
+
+    // See if entry exists, if so return ID.
+    if (MI != Map.end()) return MI->second;
+
+    // No luck.
+    return 0;
+  }
+
+  /// operator[] - Returns a reference to the entry with the specified ID.
+  ///
+  const T &operator[](unsigned ID) const {
+    assert(ID-1 < size() && "ID is 0 or out of range!");
+    return Vector[ID - 1];
+  }
+
+  /// size - Returns the number of entries in the vector.
+  ///
+  size_t size() const { return Vector.size(); }
+
+  /// empty - Returns true if the vector is empty.
+  ///
+  bool empty() const { return Vector.empty(); }
+
+  /// reset - Clears all the entries.
+  ///
+  void reset() {
+    Map.clear();
+    Vector.resize(0, 0);
+  }
+};
+
+} // End of namespace llvm
+
+#endif // LLVM_ADT_UNIQUEVECTOR_H