DRB013-nowait-orig-yes.c

/*
Copyright (c) 2017, Lawrence Livermore National Security, LLC.
Produced at the Lawrence Livermore National Laboratory
Written by Chunhua Liao, Pei-Hung Lin, Joshua Asplund,
Markus Schordan, and Ian Karlin
(email: liao6@llnl.gov, lin32@llnl.gov, asplund1@llnl.gov,
schordan1@llnl.gov, karlin1@llnl.gov)
LLNL-CODE-732144
All rights reserved.

This file is part of DataRaceBench. For details, see
https://github.com/LLNL/dataracebench. Please also see the LICENSE file
for our additional BSD notice.

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or without modification, are permitted provided that the following
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*/

/*
This example is extracted from a paper: 
Ma etc. Symbolic Analysis of Concurrency Errors in OpenMP Programs, ICPP 2013

Some threads may finish the for loop early and execute errors = dt[9]+1
while another thread may still be simultaneously executing
the for worksharing region by writing to d[9], causing data races. 

Data race pair: a[i]@72:7 vs. a[9]@75:13.
*/

#include <stdio.h>
int main()
{
  int i,error;
  int len = 1000;
  int a[len], b=5;

  for (i=0; i<len; i++)
    a[i]= i;
 
#pragma omp parallel shared(b, error) 
  {
#pragma omp for nowait
    for(i = 0; i < len; i++)
      a[i] = b + a[i]*5;

#pragma omp single
    error = a[9] + 1;
  }

  printf ("error = %d\n", error);
  return 0;
}