openmp/runtime/test/parallel/omp_parallel_num_threads.c

// RUN: %libomp-compile-and-run
#include <stdio.h>
#include "omp_testsuite.h"

int test_omp_parallel_num_threads()
{
  int num_failed;
  int threads;
  int nthreads;
  int max_threads = 0;

  num_failed = 0;

  /* first we check how many threads are available */
  #pragma omp parallel
  {
    #pragma omp master
    max_threads = omp_get_num_threads ();
  }

  /* we increase the number of threads from one to maximum:*/
  for(threads = 1; threads <= max_threads; threads++) {
    nthreads = 0;
    #pragma omp parallel reduction(+:num_failed) num_threads(threads)
    {
      num_failed = num_failed + !(threads == omp_get_num_threads());
      #pragma omp atomic
      nthreads += 1;
    }
    num_failed = num_failed + !(nthreads == threads);
  }
  return (!num_failed);
}

int main()
{
  int i;
  int num_failed=0;

  for(i = 0; i < REPETITIONS; i++) {
    if(!test_omp_parallel_num_threads()) {
      num_failed++;
    }
  }
  return num_failed;
}