Imported Upstream version 6.10.0.49

Former-commit-id: 1d6753294b2993e1fbf92de9366bb9544db4189b

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

@@ -0,0 +1,26 @@
+// RUN: %clangxx_tsan %s -o %t
+// RUN: %run %t 2>&1 | FileCheck %s
+
+// bench.h needs pthread barriers which are not available on OS X
+// UNSUPPORTED: darwin
+
+#include "bench.h"
+
+int x;
+
+void thread(int tid) {
+  if (tid == 0) {
+    for (int i = 0; i < bench_niter; i++)
+      __atomic_store_n(&x, 0, __ATOMIC_RELEASE);
+  } else {
+    for (int i = 0; i < bench_niter; i++)
+      __atomic_load_n(&x, __ATOMIC_ACQUIRE);
+  }
+}
+
+void bench() {
+  start_thread_group(bench_nthread, thread);
+}
+
+// CHECK: DONE
+