Reland Implement .eh_frame writer and disassembler.

src/arm64/eh-frame-arm64.cc

+// 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.
+
+#include "src/eh-frame.h"
+
+namespace v8 {
+namespace internal {
+
+static const int kX0DwarfCode = 0;
+static const int kFpDwarfCode = 29;
+static const int kLrDwarfCode = 30;
+static const int kSpDwarfCode = 31;
+
+STATIC_CONST_MEMBER_DEFINITION const int EhFrameWriter::kDataAlignmentFactor =
+    -8;
+
+void EhFrameWriter::WriteReturnAddressRegisterCode() {
+  WriteULEB128(RegisterToDwarfCode(x30));
+}
+
+void EhFrameWriter::WriteInitialState() {
+  SetBaseAddressRegisterAndOffset(x29, 0);
+  RegisterIsValid(x30);
+}
+
+// static
+const char* EhFrameWriter::DwarfRegisterCodeToString(int code) {
+  switch (code) {
+    case kFpDwarfCode:
+      return "fp";
+    case kLrDwarfCode:
+      return "lr";
+    case kSpDwarfCode:
+      return "sp";  // This could be zr as well
+    default:
+      UNIMPLEMENTED();
+      return nullptr;
+  }
+}
+
+// static
+int EhFrameWriter::RegisterToDwarfCode(Register name) {
+  switch (name.code()) {
+    case Register::kCode_x29:
+      return kFpDwarfCode;
+    case Register::kCode_x30:
+      return kLrDwarfCode;
+    case Register::kCode_x31:
+      return kSpDwarfCode;
+    case Register::kCode_x0:
+      return kX0DwarfCode;
+    default:
+      UNIMPLEMENTED();
+      return -1;
+  }
+}
+
+}  // namespace internal
+}  // namespace v8