Reland Implement .eh_frame writer and disassembler.

src/x64/eh-frame-x64.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 kRaxDwarfCode = 0;
+static const int kRbpDwarfCode = 6;
+static const int kRspDwarfCode = 7;
+static const int kRipDwarfCode = 16;
+
+STATIC_CONST_MEMBER_DEFINITION const int EhFrameWriter::kDataAlignmentFactor =
+    -8;
+
+void EhFrameWriter::WriteReturnAddressRegisterCode() {
+  WriteULEB128(16);  // x64 rip (r16) has no Register instance associated.
+}
+
+void EhFrameWriter::WriteInitialState() {
+  SetBaseAddressRegisterAndOffset(rsp, 8);
+  RegisterSavedToStack(16, kInt64Size);  // r16 is rip
+}
+
+// static
+const char* EhFrameWriter::DwarfRegisterCodeToString(int code) {
+  switch (code) {
+    case kRbpDwarfCode:
+      return "rbp";
+    case kRspDwarfCode:
+      return "rsp";
+    case kRipDwarfCode:
+      return "rip";
+    default:
+      UNIMPLEMENTED();
+      return nullptr;
+  }
+}
+
+// static
+int EhFrameWriter::RegisterToDwarfCode(Register name) {
+  switch (name.code()) {
+    case Register::kCode_rbp:
+      return kRbpDwarfCode;
+    case Register::kCode_rsp:
+      return kRspDwarfCode;
+    case Register::kCode_rax:
+      return kRaxDwarfCode;
+    default:
+      UNIMPLEMENTED();
+      return -1;
+  }
+}
+
+}  // namespace internal
+}  // namespace v8