Initial support for emitting unwinding information in perf jitdump.

src/eh-frame.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_EH_FRAME_H_
+#define V8_EH_FRAME_H_
+
+#include <cstdint>
+
+namespace v8 {
+namespace internal {
+
+class Code;
+
+class EhFrameHdr final {
+ public:
+  static const int kRecordSize = 20;
+  static const int kCIESize;
+
+  explicit EhFrameHdr(Code* code);
+
+  int32_t offset_to_eh_frame() const { return offset_to_eh_frame_; }
+  uint32_t lut_entries_number() const { return lut_entries_number_; }
+  int32_t offset_to_procedure() const { return offset_to_procedure_; }
+  int32_t offset_to_fde() const { return offset_to_fde_; }
+
+ private:
+  uint8_t version_;
+  uint8_t eh_frame_ptr_encoding_;
+  uint8_t lut_size_encoding_;
+  uint8_t lut_entries_encoding_;
+  int32_t offset_to_eh_frame_;
+  uint32_t lut_entries_number_;
+  int32_t offset_to_procedure_;
+  int32_t offset_to_fde_;
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif