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diff --git a/build/clang-plugin/StmtToBlockMap.h b/build/clang-plugin/StmtToBlockMap.h
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+++ b/build/clang-plugin/StmtToBlockMap.h
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef StmtToBlockMap_h__
+#define StmtToBlockMap_h__
+
+#include "Utils.h"
+
+// This method is copied from clang-tidy's ExprSequence.cpp.
+//
+// Returns the Stmt nodes that are parents of 'S', skipping any potential
+// intermediate non-Stmt nodes.
+//
+// In almost all cases, this function returns a single parent or no parents at
+// all.
+inline SmallVector<const Stmt *, 1> getParentStmts(const Stmt *S,
+                                                   ASTContext *Context) {
+  SmallVector<const Stmt *, 1> Result;
+
+  auto Parents = Context->getParents(*S);
+
+  SmallVector<clang::DynTypedNode, 1> NodesToProcess(Parents.begin(),
+                                                     Parents.end());
+
+  while (!NodesToProcess.empty()) {
+    clang::DynTypedNode Node = NodesToProcess.back();
+    NodesToProcess.pop_back();
+
+    if (const auto *S = Node.get<Stmt>()) {
+      Result.push_back(S);
+    } else {
+      Parents = Context->getParents(Node);
+      NodesToProcess.append(Parents.begin(), Parents.end());
+    }
+  }
+
+  return Result;
+}
+
+// This class is a modified version of the class from clang-tidy's
+// ExprSequence.cpp
+//
+// Maps `Stmt`s to the `CFGBlock` that contains them. Some `Stmt`s may be
+// contained in more than one `CFGBlock`; in this case, they are mapped to the
+// innermost block (i.e. the one that is furthest from the root of the tree).
+// An optional outparameter provides the index into the block where the `Stmt`
+// was found.
+class StmtToBlockMap {
+public:
+  // Initializes the map for the given `CFG`.
+  StmtToBlockMap(const CFG *TheCFG, ASTContext *TheContext)
+      : Context(TheContext) {
+    for (const auto *B : *TheCFG) {
+      for (size_t I = 0; I < B->size(); ++I) {
+        if (Optional<CFGStmt> S = (*B)[I].getAs<CFGStmt>()) {
+          Map[S->getStmt()] = std::make_pair(B, I);
+        }
+      }
+    }
+  }
+
+  // Returns the block that S is contained in. Some `Stmt`s may be contained
+  // in more than one `CFGBlock`; in this case, this function returns the
+  // innermost block (i.e. the one that is furthest from the root of the tree).
+  //
+  // The optional outparameter `Index` is set to the index into the block where
+  // the `Stmt` was found.
+  const CFGBlock *blockContainingStmt(const Stmt *S,
+                                      size_t *Index = nullptr) const {
+    while (!Map.count(S)) {
+      SmallVector<const Stmt *, 1> Parents = getParentStmts(S, Context);
+      if (Parents.empty())
+        return nullptr;
+      S = Parents[0];
+    }
+
+    const auto &E = Map.lookup(S);
+    if (Index)
+      *Index = E.second;
+    return E.first;
+  }
+
+private:
+  ASTContext *Context;
+
+  llvm::DenseMap<const Stmt *, std::pair<const CFGBlock *, size_t>> Map;
+};
+
+#endif // StmtToBlockMap_h__