[tsan] add a run-time-side regression test for https://code.google.com/p/thread-sanitizer/issues/detail?id=40 (tsan-hostile load speculation)

llvm-svn: 195325

compiler-rt/lib/tsan/lit_tests/race_on_speculative_load.cc

@@ -0,0 +1,24 @@
+// RUN: %clangxx_tsan -O1 %s -o %t && %t
+// Regtest for https://code.google.com/p/thread-sanitizer/issues/detail?id=40
+// This is a correct program and tsan should not report a race.
+#include <pthread.h>
+#include <unistd.h>
+int g;
+__attribute__((noinline))
+int foo(int cond) {
+  if (cond)
+    return g;
+  return 0;
+}
+void *Thread1(void *p) {
+  long res = foo((long)p);
+  sleep(1);
+  return (void*) res;
+}
+
+int main() {
+  pthread_t t;
+  pthread_create(&t, 0, Thread1, 0);
+  g = 1;
+  pthread_join(t, 0);
+}