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 30 void *Thread1(void *x) { 31 barrier_wait(&barrier); 32 ANNOTATE_HAPPENS_AFTER(&barrier); 33 Global++; 34 return NULL; 35 } 36 37 void *Thread2(void *x) { 38 Global--; 39 ANNOTATE_HAPPENS_BEFORE(&barrier); 40 barrier_wait(&barrier); 41 return NULL; 42 } 43 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
