1 files changed, 57 insertions, 0 deletions
diff --git a/test/tsan/annotate_happens_before.cc b/test/tsan/annotate_happens_before.cc
new file mode 100644
index 0000000000000..011661699a7a0
--- /dev/null
+++ b/test/tsan/annotate_happens_before.cc
@@ -0,0 +1,57 @@
+// RUN: %clangxx_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
+#include "test.h"
+
+/*
+Annotations usage example.
+
+Tsan does not see synchronization in barrier_wait.
+ANNOTATE_HAPPENS_BEFORE/AFTER communicate the synchronization to tsan
+and prevent the race report.
+
+If the compiler does not support __has_feature macro, then you can build with
+CFLAGS="-fsanitize=thread -DTHREAD_SANITIZER" and then use
+#ifdef THREAD_SANITIZER to enabled annotations.
+*/
+
+#if defined(__has_feature) && __has_feature(thread_sanitizer)
+# define ANNOTATE_HAPPENS_BEFORE(addr) \
+    AnnotateHappensBefore(__FILE__, __LINE__, (void*)(addr))
+# define ANNOTATE_HAPPENS_AFTER(addr) \
+    AnnotateHappensAfter(__FILE__, __LINE__, (void*)(addr))
+extern "C" void AnnotateHappensBefore(const char *f, int l, void *addr);
+extern "C" void AnnotateHappensAfter(const char *f, int l, void *addr);
+#else
+# define ANNOTATE_HAPPENS_BEFORE(addr)
+# define ANNOTATE_HAPPENS_AFTER(addr)
+#endif
+
+int Global;
+
+void *Thread1(void *x) {
+  barrier_wait(&barrier);
+  ANNOTATE_HAPPENS_AFTER(&barrier);
+  Global++;
+  return NULL;
+}
+
+void *Thread2(void *x) {
+  Global--;
+  ANNOTATE_HAPPENS_BEFORE(&barrier);
+  barrier_wait(&barrier);
+  return NULL;
+}
+
+int main() {
+  barrier_init(&barrier, 2);
+  pthread_t t[2];
+  pthread_create(&t[0], NULL, Thread1, NULL);
+  pthread_create(&t[1], NULL, Thread2, NULL);
+  pthread_join(t[0], NULL);
+  pthread_join(t[1], NULL);
+  fprintf(stderr, "DONE\n");
+  return 0;
+}
+
+// CHECK-NOT: WARNING: ThreadSanitizer: data race
+// CHECK: DONE
+