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diff --git a/js/src/vm/SharedScriptDataTableHolder.h b/js/src/vm/SharedScriptDataTableHolder.h
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+++ b/js/src/vm/SharedScriptDataTableHolder.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef vm_SharedScriptDataTableHolder_h
+#define vm_SharedScriptDataTableHolder_h
+
+#include "mozilla/Assertions.h"  // MOZ_ASSERT
+#include "mozilla/Maybe.h"       // mozilla::Maybe
+
+#include "threading/Mutex.h"   // js::Mutex
+#include "vm/SharedStencil.h"  // js::SharedImmutableScriptDataTable
+
+namespace js {
+
+class AutoLockGlobalScriptData {
+  static js::Mutex mutex_;
+
+ public:
+  AutoLockGlobalScriptData();
+  ~AutoLockGlobalScriptData();
+};
+
+// A class to provide an access to SharedImmutableScriptDataTable,
+// with or without a mutex lock.
+//
+// js::globalSharedScriptDataTableHolder singleton can be used by any thread,
+// and it needs a mutex lock.
+//
+//   AutoLockGlobalScriptData lock;
+//   auto& table = js::globalSharedScriptDataTableHolder::get(lock);
+//
+// Private SharedScriptDataTableHolder instance can be created for thread-local
+// storage, and it can be configured not to require a mutex lock.
+//
+//   SharedScriptDataTableHolder holder(
+//     SharedScriptDataTableHolder::NeedsLock::No);
+//   ...
+//   auto& table = holder.getWithoutLock();
+//
+// getMaybeLocked method can be used for both type of instances.
+//
+//   Maybe<AutoLockGlobalScriptData> lock;
+//   auto& table = holder.getMaybeLocked(lock);
+//
+// Private instance is supposed to be held by the each JSRuntime, including
+// both main thread runtime and worker thread runtime, and used in for
+// non-helper-thread compilation.
+//
+// js::globalSharedScriptDataTableHolder singleton is supposed to be used by
+// all helper-thread compilation.
+class SharedScriptDataTableHolder {
+  bool needsLock_ = true;
+  js::SharedImmutableScriptDataTable scriptDataTable_;
+
+ public:
+  enum class NeedsLock { No, Yes };
+
+  explicit SharedScriptDataTableHolder(NeedsLock needsLock = NeedsLock::Yes)
+      : needsLock_(needsLock == NeedsLock::Yes) {}
+
+  js::SharedImmutableScriptDataTable& get(
+      const js::AutoLockGlobalScriptData& lock) {
+    MOZ_ASSERT(needsLock_);
+    return scriptDataTable_;
+  }
+
+  js::SharedImmutableScriptDataTable& getWithoutLock() {
+    MOZ_ASSERT(!needsLock_);
+    return scriptDataTable_;
+  }
+
+  js::SharedImmutableScriptDataTable& getMaybeLocked(
+      mozilla::Maybe<js::AutoLockGlobalScriptData>& lock) {
+    if (needsLock_) {
+      lock.emplace();
+    }
+    return scriptDataTable_;
+  }
+};
+
+extern SharedScriptDataTableHolder globalSharedScriptDataTableHolder;
+
+} /* namespace js */
+
+#endif /* vm_SharedScriptDataTableHolder_h */