tso.c

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>

volatile int x, y, tmp1, tmp2;

void *t0(void *arg) {
  x = 1;
  tmp1 = y;
  return 0;
}

void *t1(void *arg) {
  y = 1;
  tmp2 = x;
  return 0;
}

void pthread_create_or_die(pthread_t *thread, void *(*start_routine)(void *)) {
  int res = pthread_create(thread, 0, start_routine, 0);
  if (res != 0) {
    perror("pthread_create");
    exit(-1);
  }
}

void pthread_join_or_die(pthread_t thread) {
  int res = pthread_join(thread, 0);
  if (res != 0) {
    perror("pthread_join");
    exit(-1);
  }
}

int main(void) {
  int a = 0, b = 0, c = 0, d = 0;
  for (long i = 0; i < 10000000; i++) {
    x = y = tmp1 = tmp2 = 0;
    pthread_t thread0, thread1;
    pthread_create_or_die(&thread0, t0);
    pthread_create_or_die(&thread1, t1);
    pthread_join_or_die(thread0);
    pthread_join_or_die(thread1);
    if (tmp1 == 0 && tmp2 == 1)
      a++;
    if (tmp1 == 1 && tmp2 == 0)
      b++;
    if (tmp1 == 0 && tmp2 == 0)
      c++;
    if (tmp1 == 1 && tmp2 == 1)
      d++;
  }
  printf("0,1: %d 1,0: %d 0,0: %d 1,1: %d\n", a, b, c, d);
  return 0;
}