[Support] Join threads when stopping ThreadPoolExecutor

Author: momo5502

llvm/lib/Support/Parallel.cpp

@@ -82,26 +82,26 @@ class ThreadPoolExecutor : public Executor {
   ThreadPoolExecutor() = delete;
 
   void stop() {
+    Stop = true;
+    Cond.notify_all();
+    ThreadsCreated.get_future().wait();
+
+    std::vector<std::thread> ThreadsToJoin;
     {
       std::lock_guard<std::mutex> Lock(Mutex);
-      if (Stop)
-        return;
-      Stop = true;
+      ThreadsToJoin.swap(Threads);
     }
-    Cond.notify_all();
-    ThreadsCreated.get_future().wait();
-  }
 
-  ~ThreadPoolExecutor() override {
-    stop();
     std::thread::id CurrentThreadId = std::this_thread::get_id();
-    for (std::thread &T : Threads)
+    for (std::thread &T : ThreadsToJoin)
       if (T.get_id() == CurrentThreadId)
         T.detach();
       else
         T.join();
   }
 
+  ~ThreadPoolExecutor() override { stop(); }
+
   struct Creator {
     static void *call() { return new ThreadPoolExecutor(strategy); }
   };