source: CIVL/examples/omp/dotProduct_critical.cvl

/* CIVL model of dotProduct_critical.c.  To verify:
 *   civl verify dotProduct_critical.cvl
 */
#include <civlc.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

#define N 10
#define THREAD_MAX 4
/* Does thread t own iteration i in loop with n iterations? */
#define CIVL_owns(t, n, i) ((i)%(n)==(t))

_Bool critical_lock = $false;

int main (int argc, char *argv[]) {
  double a[N], b[N];
  double sum = 0.0;
  int nthreads;

  // translation of parallel construct
  // #pragma omp parallel shared(a,b,sum) private(i, localsum)
  // note: tid should be private. corrected here.
  {
    int _nthreads = 1+$choose_int(THREAD_MAX);
    $proc threads[_nthreads];
    $gbarrier gbarrier = $gbarrier_create($here, _nthreads);
    void thread(int _tid) {
      int i, tid;
      double localsum;
      $barrier barrier = $barrier_create($here, gbarrier, _tid);
      
      tid = _tid;
      if (_tid == 0) {
        nthreads =_nthreads;
        printf("Number of threads = %d\n", nthreads);
      }
      for (i=0; i < N; i++) {
        if (CIVL_owns(_tid, _nthreads, i)) {
          a[i] = b[i] = (double)i;
        }
      }
      $barrier_call(barrier);
      localsum = 0;
      for (i=0; i < N; i++) {
        if (CIVL_owns(_tid, _nthreads, i)) {
          localsum = localsum + (a[i] * b[i]);
        }
      }
      $when (!critical_lock) critical_lock = $true;
      sum = sum + localsum;
      critical_lock = $false;
      $barrier_destroy(barrier);
    }

    for (int i=0; i<_nthreads; i++)
      threads[i] = $spawn thread(i);
    for (int i=0; i<_nthreads; i++)
      $wait(threads[i]);
    $gbarrier_destroy(gbarrier);
  }
  printf("   Sum = %2.1f\n",sum);
  assert(sum==285.0);
}