Imported Upstream version 6.10.0.49

Former-commit-id: 1d6753294b2993e1fbf92de9366bb9544db4189b

external/llvm-project/compiler-rt/test/tsan/custom_mutex2.cc

@@ -0,0 +1,34 @@
+// RUN: %clangxx_tsan -O1 --std=c++11 %s -o %t && %deflake %run %t 2>&1 | FileCheck %s
+#include "custom_mutex.h"
+
+// Test that Broadcast does not induce parasitic synchronization.
+
+Mutex mu(true, 0);
+long data;
+
+void *thr(void *arg) {
+  barrier_wait(&barrier);
+  mu.Lock();
+  data++;
+  mu.Unlock();
+  data++;
+  mu.Broadcast();
+  return 0;
+}
+
+int main() {
+  barrier_init(&barrier, 2);
+  pthread_t th;
+  pthread_create(&th, 0, thr, 0);
+  mu.Lock();
+  barrier_wait(&barrier);
+  while (data == 0)
+    mu.Wait();
+  mu.Unlock();
+  pthread_join(th, 0);
+  fprintf(stderr, "DONE\n");
+  return 0;
+}
+
+// CHECK: ThreadSanitizer: data race
+// CHECK: DONE