1// RUN: %clang_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
2// CHECK-NOT: ThreadSanitizer: data race
3// CHECK: DONE
4
5// pthread barriers are not available on OS X
6// UNSUPPORTED: darwin
7
8#include <stdio.h>
9#include <stdlib.h>
10#include <pthread.h>
11#include <unistd.h>
12
13const int kSize = 4;
14volatile int kIter = 10; // prevent unwinding
15int data[2][kSize];
16pthread_barrier_t barrier;
17
18void *thr(void *p) {
19 int idx = (int)(long)p;
20 for (int i = 0; i < kIter; i++) {
21 int *prev = data[i % 2];
22 int *curr = data[(i + 1) % 2];
23 int left = idx - 1 >= 0 ? prev[idx - 1] : 0;
24 int right = idx + 1 < kSize ? prev[idx + 1] : 0;
25 curr[idx] = (left + right) / 2;
26 pthread_barrier_wait(&barrier);
27 }
28 return 0;
29}
30
31int main() {
32 pthread_barrier_init(&barrier, 0, kSize);
33 pthread_t th[kSize];
34 for (int i = 0; i < kSize; i++)
35 pthread_create(&th[i], 0, thr, (void*)(long)i);
36 for (int i = 0; i < kSize; i++)
37 pthread_join(th[i], 0);
38 pthread_barrier_destroy(&barrier);
39 fprintf(stderr, "DONE\n");
40}
41