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+//===-- llvm/Support/ThreadPool.h - A ThreadPool implementation -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines a crude C++11 based thread pool.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_THREAD_POOL_H
+#define LLVM_SUPPORT_THREAD_POOL_H
+
+#include "llvm/Config/llvm-config.h"
+#include "llvm/Support/thread.h"
+
+#include <future>
+
+#include <atomic>
+#include <condition_variable>
+#include <functional>
+#include <memory>
+#include <mutex>
+#include <queue>
+#include <utility>
+
+namespace llvm {
+
+/// A ThreadPool for asynchronous parallel execution on a defined number of
+/// threads.
+///
+/// The pool keeps a vector of threads alive, waiting on a condition variable
+/// for some work to become available.
+class ThreadPool {
+public:
+  using TaskTy = std::function<void()>;
+  using PackagedTaskTy = std::packaged_task<void()>;
+
+  /// Construct a pool with the number of threads found by
+  /// hardware_concurrency().
+  ThreadPool();
+
+  /// Construct a pool of \p ThreadCount threads
+  ThreadPool(unsigned ThreadCount);
+
+  /// Blocking destructor: the pool will wait for all the threads to complete.
+  ~ThreadPool();
+
+  /// Asynchronous submission of a task to the pool. The returned future can be
+  /// used to wait for the task to finish and is *non-blocking* on destruction.
+  template <typename Function, typename... Args>
+  inline std::shared_future<void> async(Function &&F, Args &&... ArgList) {
+    auto Task =
+        std::bind(std::forward<Function>(F), std::forward<Args>(ArgList)...);
+    return asyncImpl(std::move(Task));
+  }
+
+  /// Asynchronous submission of a task to the pool. The returned future can be
+  /// used to wait for the task to finish and is *non-blocking* on destruction.
+  template <typename Function>
+  inline std::shared_future<void> async(Function &&F) {
+    return asyncImpl(std::forward<Function>(F));
+  }
+
+  /// Blocking wait for all the threads to complete and the queue to be empty.
+  /// It is an error to try to add new tasks while blocking on this call.
+  void wait();
+
+private:
+  /// Asynchronous submission of a task to the pool. The returned future can be
+  /// used to wait for the task to finish and is *non-blocking* on destruction.
+  std::shared_future<void> asyncImpl(TaskTy F);
+
+  /// Threads in flight
+  std::vector<llvm::thread> Threads;
+
+  /// Tasks waiting for execution in the pool.
+  std::queue<PackagedTaskTy> Tasks;
+
+  /// Locking and signaling for accessing the Tasks queue.
+  std::mutex QueueLock;
+  std::condition_variable QueueCondition;
+
+  /// Locking and signaling for job completion
+  std::mutex CompletionLock;
+  std::condition_variable CompletionCondition;
+
+  /// Keep track of the number of thread actually busy
+  std::atomic<unsigned> ActiveThreads;
+
+#if LLVM_ENABLE_THREADS // avoids warning for unused variable
+  /// Signal for the destruction of the pool, asking thread to exit.
+  bool EnableFlag;
+#endif
+};
+}
+
+#endif // LLVM_SUPPORT_THREAD_POOL_H