[interpreter] Ensure optimizations preserve source positions.

test/cctest/interpreter/source-position-matcher.h

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef TEST_CCTEST_INTERPRETER_SOURCE_POSITION_COMPARER_H_
+#define TEST_CCTEST_INTERPRETER_SOURCE_POSITION_COMPARER_H_
+
+#include "src/interpreter/bytecode-array-iterator.h"
+#include "src/interpreter/source-position-table.h"
+#include "src/objects.h"
+#include "src/v8.h"
+
+namespace v8 {
+namespace internal {
+namespace interpreter {
+
+class SourcePositionMatcher final {
+ public:
+  bool Match(Handle<BytecodeArray> original, Handle<BytecodeArray> optimized);
+
+ private:
+  bool HasNewExpressionPositionsInOptimized(
+      const std::vector<PositionTableEntry>* const original_positions,
+      const std::vector<PositionTableEntry>* const optimized_positions);
+
+  bool CompareExpressionPositions(
+      const std::vector<PositionTableEntry>* const original_positions,
+      const std::vector<PositionTableEntry>* const optimized_positions);
+
+  void StripUnneededExpressionPositions(
+      Handle<BytecodeArray> bytecode_array,
+      std::vector<PositionTableEntry>* positions,
+      int next_statement_bytecode_offset);
+
+  bool ExpressionPositionIsNeeded(Handle<BytecodeArray> bytecode_array,
+                                  int start_offset, int end_offset);
+
+  void MoveToNextStatement(
+      SourcePositionTableIterator* iterator,
+      std::vector<PositionTableEntry>* expression_positions);
+
+  void AdvanceBytecodeIterator(BytecodeArrayIterator* iterator,
+                               int bytecode_offset);
+};
+
+}  // namespace interpreter
+}  // namespace internal
+}  // namespace v8
+
+#endif  // TEST_CCTEST_INTERPRETER_SOURCE_POSITION_COMPARER_H_