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diff --git a/clang-r353983/include/llvm/ADT/IndexedMap.h b/clang-r353983/include/llvm/ADT/IndexedMap.h
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+//===- llvm/ADT/IndexedMap.h - An index map implementation ------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements an indexed map. The index map template takes two
+// types. The first is the mapped type and the second is a functor
+// that maps its argument to a size_t. On instantiation a "null" value
+// can be provided to be used as a "does not exist" indicator in the
+// map. A member function grow() is provided that given the value of
+// the maximally indexed key (the argument of the functor) makes sure
+// the map has enough space for it.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_INDEXEDMAP_H
+#define LLVM_ADT_INDEXEDMAP_H
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/STLExtras.h"
+#include <cassert>
+
+namespace llvm {
+
+template <typename T, typename ToIndexT = identity<unsigned>>
+  class IndexedMap {
+    using IndexT = typename ToIndexT::argument_type;
+    // Prefer SmallVector with zero inline storage over std::vector. IndexedMaps
+    // can grow very large and SmallVector grows more efficiently as long as T
+    // is trivially copyable.
+    using StorageT = SmallVector<T, 0>;
+
+    StorageT storage_;
+    T nullVal_;
+    ToIndexT toIndex_;
+
+  public:
+    IndexedMap() : nullVal_(T()) {}
+
+    explicit IndexedMap(const T& val) : nullVal_(val) {}
+
+    typename StorageT::reference operator[](IndexT n) {
+      assert(toIndex_(n) < storage_.size() && "index out of bounds!");
+      return storage_[toIndex_(n)];
+    }
+
+    typename StorageT::const_reference operator[](IndexT n) const {
+      assert(toIndex_(n) < storage_.size() && "index out of bounds!");
+      return storage_[toIndex_(n)];
+    }
+
+    void reserve(typename StorageT::size_type s) {
+      storage_.reserve(s);
+    }
+
+    void resize(typename StorageT::size_type s) {
+      storage_.resize(s, nullVal_);
+    }
+
+    void clear() {
+      storage_.clear();
+    }
+
+    void grow(IndexT n) {
+      unsigned NewSize = toIndex_(n) + 1;
+      if (NewSize > storage_.size())
+        resize(NewSize);
+    }
+
+    bool inBounds(IndexT n) const {
+      return toIndex_(n) < storage_.size();
+    }
+
+    typename StorageT::size_type size() const {
+      return storage_.size();
+    }
+  };
+
+} // end namespace llvm
+
+#endif // LLVM_ADT_INDEXEDMAP_H