test/tsan/barrier.cc

   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 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <pthread.h>
   8 #include <unistd.h>
   9
  10 const int kSize = 4;
  11 volatile int kIter = 10;  // prevent unwinding
  12 int data[2][kSize];
  13 pthread_barrier_t barrier;
  14
  15 void *thr(void *p) {
  16   int idx = (int)(long)p;
  17   for (int i = 0; i < kIter; i++) {
  18     int *prev = data[i % 2];
  19     int *curr = data[(i + 1) % 2];
  20     int left = idx - 1 >= 0 ? prev[idx - 1] : 0;
  21     int right = idx + 1 < kSize ? prev[idx + 1] : 0;
  22     curr[idx] = (left + right) / 2;
  23     pthread_barrier_wait(&barrier);
  24   }
  25   return 0;
  26 }
  27
  28 int main() {
  29   pthread_barrier_init(&barrier, 0, kSize);
  30   pthread_t th[kSize];
  31   for (int i = 0; i < kSize; i++)
  32     pthread_create(&th[i], 0, thr, (void*)(long)i);
  33   for (int i = 0; i < kSize; i++)
  34     pthread_join(th[i], 0);
  35   pthread_barrier_destroy(&barrier);
  36   fprintf(stderr, "DONE\n");
  37 }