1 files changed, 65 insertions, 0 deletions
diff --git a/test/tsan/stack_sync_reuse.cc b/test/tsan/stack_sync_reuse.cc
new file mode 100644
index 000000000000..5ea9e84b085a
--- /dev/null
+++ b/test/tsan/stack_sync_reuse.cc
@@ -0,0 +1,65 @@
+// RUN: %clang_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
+#include "test.h"
+
+// Test case https://code.google.com/p/thread-sanitizer/issues/detail?id=87
+// Tsan sees false HB edge on address pointed to by syncp variable.
+// It is false because when acquire is done syncp points to a var in one frame,
+// and during release it points to a var in a different frame.
+// The code is somewhat tricky because it prevents compiler from optimizing
+// our accesses away, structured to not introduce other data races and
+// not introduce other synchronization, and to arrange the vars in different
+// frames to occupy the same address.
+
+// The data race CHECK-NOT below actually must be CHECK, because the program
+// does contain the data race on global.
+
+// CHECK-NOT: WARNING: ThreadSanitizer: data race
+// CHECK: DONE
+
+long global;
+long *syncp;
+long *addr;
+long sink;
+
+void *Thread(void *x) {
+  while (__atomic_load_n(&syncp, __ATOMIC_ACQUIRE) == 0)
+    usleep(1000);  // spin wait
+  global = 42;
+  __atomic_store_n(syncp, 1, __ATOMIC_RELEASE);
+  __atomic_store_n(&syncp, 0, __ATOMIC_RELAXED);
+  return NULL;
+}
+
+void __attribute__((noinline)) foobar() {
+  long s;
+  addr = &s;
+  __atomic_store_n(&s, 0, __ATOMIC_RELAXED);
+  __atomic_store_n(&syncp, &s, __ATOMIC_RELEASE);
+  while (__atomic_load_n(&syncp, __ATOMIC_RELAXED) != 0)
+    usleep(1000);  // spin wait
+}
+
+void __attribute__((noinline)) barfoo() {
+  long s;
+  if (addr != &s) {
+    printf("address mismatch addr=%p &s=%p\n", addr, &s);
+    exit(1);
+  }
+  __atomic_store_n(&addr, &s, __ATOMIC_RELAXED);
+  __atomic_store_n(&s, 0, __ATOMIC_RELAXED);
+  sink = __atomic_load_n(&s, __ATOMIC_ACQUIRE);
+  global = 43;
+}
+
+int main() {
+  pthread_t t;
+  pthread_create(&t, 0, Thread, 0);
+  foobar();
+  barfoo();
+  pthread_join(t, 0);
+  if (sink != 0)
+    exit(1);
+  fprintf(stderr, "DONE\n");
+  return 0;
+}
+