[tsan] added tsan-vs-gvn test

llvm-svn: 174875

compiler-rt/lib/tsan/lit_tests/tsan-vs-gvn.cc

@@ -0,0 +1,40 @@
+// RUN: %clangxx_tsan -O1 %s -o %t && %t 2>&1 | FileCheck %s --check-prefix=CHECK_O1
+// ---RUN: %clangxx_tsan -O2 %s -o %t && %t 2>&1 | FileCheck %s --check-prefix=CHECK_O2
+//
+// Check that load widening is not tsan-hostile.
+#include <pthread.h>
+#include <stdio.h>
+#include <string.h>
+
+struct {
+  int i;
+  char c1, c2, c3, c4;
+} S;
+
+int G;
+
+void *Thread1(void *x) {
+  G = S.c1 + S.c3;
+  return NULL;
+}
+
+void *Thread2(void *x) {
+  S.c2 = 1;
+  return NULL;
+}
+
+int main() {
+  pthread_t t[2];
+  memset(&S, 123, sizeof(S));
+  pthread_create(&t[0], NULL, Thread1, NULL);
+  pthread_create(&t[1], NULL, Thread2, NULL);
+  pthread_join(t[0], NULL);
+  pthread_join(t[1], NULL);
+  printf("PASS\n");
+}
+
+// FIXME: currently, this test fails at -O2 (reports false positive).
+// CHECK_O2: WARNING: ThreadSanitizer: data race
+
+// CHECK_O1: PASS
+// CHECK_O1-NOT: WARNING: ThreadSanitizer: data race