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diff --git a/third_party/llvm-project/include/llvm/ADT/edit_distance.h b/third_party/llvm-project/include/llvm/ADT/edit_distance.h
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+//===-- llvm/ADT/edit_distance.h - Array edit distance function --- 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 defines a Levenshtein distance function that works for any two
+// sequences, with each element of each sequence being analogous to a character
+// in a string.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_EDIT_DISTANCE_H
+#define LLVM_ADT_EDIT_DISTANCE_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include <algorithm>
+#include <memory>
+
+namespace llvm {
+
+/// Determine the edit distance between two sequences.
+///
+/// \param FromArray the first sequence to compare.
+///
+/// \param ToArray the second sequence to compare.
+///
+/// \param AllowReplacements whether to allow element replacements (change one
+/// element into another) as a single operation, rather than as two operations
+/// (an insertion and a removal).
+///
+/// \param MaxEditDistance If non-zero, the maximum edit distance that this
+/// routine is allowed to compute. If the edit distance will exceed that
+/// maximum, returns \c MaxEditDistance+1.
+///
+/// \returns the minimum number of element insertions, removals, or (if
+/// \p AllowReplacements is \c true) replacements needed to transform one of
+/// the given sequences into the other. If zero, the sequences are identical.
+template<typename T>
+unsigned ComputeEditDistance(ArrayRef<T> FromArray, ArrayRef<T> ToArray,
+                             bool AllowReplacements = true,
+                             unsigned MaxEditDistance = 0) {
+  // The algorithm implemented below is the "classic"
+  // dynamic-programming algorithm for computing the Levenshtein
+  // distance, which is described here:
+  //
+  //   http://en.wikipedia.org/wiki/Levenshtein_distance
+  //
+  // Although the algorithm is typically described using an m x n
+  // array, only one row plus one element are used at a time, so this
+  // implementation just keeps one vector for the row.  To update one entry,
+  // only the entries to the left, top, and top-left are needed.  The left
+  // entry is in Row[x-1], the top entry is what's in Row[x] from the last
+  // iteration, and the top-left entry is stored in Previous.
+  typename ArrayRef<T>::size_type m = FromArray.size();
+  typename ArrayRef<T>::size_type n = ToArray.size();
+
+  const unsigned SmallBufferSize = 64;
+  unsigned SmallBuffer[SmallBufferSize];
+  std::unique_ptr<unsigned[]> Allocated;
+  unsigned *Row = SmallBuffer;
+  if (n + 1 > SmallBufferSize) {
+    Row = new unsigned[n + 1];
+    Allocated.reset(Row);
+  }
+
+  for (unsigned i = 1; i <= n; ++i)
+    Row[i] = i;
+
+  for (typename ArrayRef<T>::size_type y = 1; y <= m; ++y) {
+    Row[0] = y;
+    unsigned BestThisRow = Row[0];
+
+    unsigned Previous = y - 1;
+    for (typename ArrayRef<T>::size_type x = 1; x <= n; ++x) {
+      int OldRow = Row[x];
+      if (AllowReplacements) {
+        Row[x] = std::min(
+            Previous + (FromArray[y-1] == ToArray[x-1] ? 0u : 1u),
+            std::min(Row[x-1], Row[x])+1);
+      }
+      else {
+        if (FromArray[y-1] == ToArray[x-1]) Row[x] = Previous;
+        else Row[x] = std::min(Row[x-1], Row[x]) + 1;
+      }
+      Previous = OldRow;
+      BestThisRow = std::min(BestThisRow, Row[x]);
+    }
+
+    if (MaxEditDistance && BestThisRow > MaxEditDistance)
+      return MaxEditDistance + 1;
+  }
+
+  unsigned Result = Row[n];
+  return Result;
+}
+
+} // End llvm namespace
+
+#endif