compiler-rt/test/tsan/barrier.cpp

   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
  13 const int kSize = 4;
  14 volatile int kIter = 10;  // prevent unwinding
  15 int data[2][kSize];
  16 pthread_barrier_t barrier;
  17
  18 void *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
  31 int 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 }