text: // RUN: %clangxx_tsan -O1 %s -o %t && not %run %t 2>&1 | FileCheck %s
  #include <pthread.h>
  #include <unistd.h>
  
  int Global;
  
  void *Thread1(void *x) {
    sleep(1);
    __atomic_fetch_add(&Global, 1, __ATOMIC_RELAXED);
    return NULL;
  }
  
  void *Thread2(void *x) {
    Global++;
    return NULL;
  }
  
  int main() {
    pthread_t t[2];
    pthread_create(&t[0], NULL, Thread1, NULL);
    pthread_create(&t[1], NULL, Thread2, NULL);
    pthread_join(t[0], NULL);
    pthread_join(t[1], NULL);
  }
  
  // CHECK: WARNING: ThreadSanitizer: data race
  // CHECK:   Atomic write of size 4
  // CHECK:     #0 __tsan_atomic32_fetch_add
  // CHECK:     #1 Thread1
  