[ignition] Add a reverse bytecode iterator

src/interpreter/bytecode-array-reverse-iterator.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 V8_INTERPRETER_BYTECODE_ARRAY_REVERSE_ITERATOR_H_
+#define V8_INTERPRETER_BYTECODE_ARRAY_REVERSE_ITERATOR_H_
+
+#include "src/interpreter/bytecode-array-accessor.h"
+#include "src/zone/zone-containers.h"
+#include "src/zone/zone.h"
+
+namespace v8 {
+namespace internal {
+namespace interpreter {
+
+class V8_EXPORT_PRIVATE BytecodeArrayReverseIterator final
+    : public BytecodeArrayAccessor {
+ public:
+  explicit BytecodeArrayReverseIterator(Handle<BytecodeArray> bytecode_array,
+                                        Zone* zone);
+
+  void Advance();
+  void Reset();
+  bool done() const;
+
+ private:
+  ZoneVector<int> offsets_;
+  ZoneVector<int>::const_reverse_iterator it_offsets_;
+
+  void UpdateOffsetFromIterator();
+
+  DISALLOW_COPY_AND_ASSIGN(BytecodeArrayReverseIterator);
+};
+
+}  // namespace interpreter
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_INTERPRETER_BYTECODE_ARRAY_REVERSE_ITERATOR_H_