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diff --git a/include/llvm/ADT/MapVector.h b/include/llvm/ADT/MapVector.h
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+++ b/include/llvm/ADT/MapVector.h
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+//===- llvm/ADT/MapVector.h - Map with deterministic value order *- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements a map that provides insertion order iteration. The
+// interface is purposefully minimal. The key is assumed to be cheap to copy
+// and 2 copies are kept, one for indexing in a DenseMap, one for iteration in
+// a std::vector.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_MAPVECTOR_H
+#define LLVM_ADT_MAPVECTOR_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMap.h"
+#include <vector>
+
+namespace llvm {
+
+/// This class implements a map that also provides access to all stored values
+/// in a deterministic order. The values are kept in a std::vector and the
+/// mapping is done with DenseMap from Keys to indexes in that vector.
+template<typename KeyT, typename ValueT,
+         typename MapType = llvm::DenseMap<KeyT, unsigned>,
+         typename VectorType = std::vector<std::pair<KeyT, ValueT> > >
+class MapVector {
+  typedef typename VectorType::size_type SizeType;
+
+  MapType Map;
+  VectorType Vector;
+
+public:
+  typedef typename VectorType::iterator iterator;
+  typedef typename VectorType::const_iterator const_iterator;
+
+  SizeType size() const {
+    return Vector.size();
+  }
+
+  iterator begin() {
+    return Vector.begin();
+  }
+
+  const_iterator begin() const {
+    return Vector.begin();
+  }
+
+  iterator end() {
+    return Vector.end();
+  }
+
+  const_iterator end() const {
+    return Vector.end();
+  }
+
+  bool empty() const {
+    return Vector.empty();
+  }
+
+  void clear() {
+    Map.clear();
+    Vector.clear();
+  }
+
+  ValueT &operator[](const KeyT &Key) {
+    std::pair<KeyT, unsigned> Pair = std::make_pair(Key, 0);
+    std::pair<typename MapType::iterator, bool> Result = Map.insert(Pair);
+    unsigned &I = Result.first->second;
+    if (Result.second) {
+      Vector.push_back(std::make_pair(Key, ValueT()));
+      I = Vector.size() - 1;
+    }
+    return Vector[I].second;
+  }
+
+  unsigned count(const KeyT &Key) const {
+    typename MapType::const_iterator Pos = Map.find(Key);
+    return Pos == Map.end()? 0 : 1;
+  }
+};
+
+}
+
+#endif