1 // RUN: %clangxx_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
2 #include "test.h"
3
4 /*
5 Annotations usage example.
6
7 Tsan does not see synchronization in barrier_wait.
8 ANNOTATE_HAPPENS_BEFORE/AFTER communicate the synchronization to tsan
9 and prevent the race report.
10
11 If the compiler does not support __has_feature macro, then you can build with
12 CFLAGS="-fsanitize=thread -DTHREAD_SANITIZER" and then use
13 #ifdef THREAD_SANITIZER to enabled annotations.
14 */
15
16 #if defined(__has_feature) && __has_feature(thread_sanitizer)
17 # define ANNOTATE_HAPPENS_BEFORE(addr) \
18 AnnotateHappensBefore(__FILE__, __LINE__, (void*)(addr))
19 # define ANNOTATE_HAPPENS_AFTER(addr) \
20 AnnotateHappensAfter(__FILE__, __LINE__, (void*)(addr))
21 extern "C" void AnnotateHappensBefore(const char *f, int l, void *addr);
22 extern "C" void AnnotateHappensAfter(const char *f, int l, void *addr);
23 #else
24 # define ANNOTATE_HAPPENS_BEFORE(addr)
25 # define ANNOTATE_HAPPENS_AFTER(addr)
26 #endif
27
28 int Global;
29
Thread1(void * x)30 void *Thread1(void *x) {
31 barrier_wait(&barrier);
32 ANNOTATE_HAPPENS_AFTER(&barrier);
33 Global++;
34 return NULL;
35 }
36
Thread2(void * x)37 void *Thread2(void *x) {
38 Global--;
39 ANNOTATE_HAPPENS_BEFORE(&barrier);
40 barrier_wait(&barrier);
41 return NULL;
42 }
43
main()44 int main() {
45 barrier_init(&barrier, 2);
46 pthread_t t[2];
47 pthread_create(&t[0], NULL, Thread1, NULL);
48 pthread_create(&t[1], NULL, Thread2, NULL);
49 pthread_join(t[0], NULL);
50 pthread_join(t[1], NULL);
51 fprintf(stderr, "DONE\n");
52 return 0;
53 }
54
55 // CHECK-NOT: WARNING: ThreadSanitizer: data race
56 // CHECK: DONE
57
58