source: CIVL/examples/omp/dataracebench-1.3.2/micro-benchmarks/DRB015-outofbounds-var-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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*/

/* NOTE by WenhaoWu (wuwenhao@udel.edu)
 * This example is modified so that the bound can be adjusted 
 * by defining 'N' and if it isn't defined then the bound value 
 * in the original example is used as the default value of 'N' 
 * And both 'argc' and 'argv' are assumed by using '$assume', 
 * which is included in <civlc.cvh>.
 */
#ifndef N
#define N 100
#endif
#ifdef _CIVL
#include <civlc.cvh>
#endif

/* 
The outmost loop is be parallelized.
But the inner level loop has out of bound access for b[i][j] when j equals to 0.
This will case memory access of a previous row's last element.

For example, an array of 4x4: 
    j=0 1 2 3
 i=0  x x x x
   1  x x x x
   2  x x x x
   3  x x x x
   
  outer loop: i=2, 
  inner loop: j=0
  array element accessed b[i][j-1] becomes b[2][-1], which in turn is b[1][3]
  due to linearized row-major storage of the 2-D array.

This causes loop-carried data dependence between i=2 and i=1.
Data race pair: b[i][j]@100:7 vs. b[i][j-1]@100:15
*/
#include <stdlib.h>
int main(int argc, char* argv[]) 
{

#ifdef _CIVL
    $assume(argc == 2);
    $assume(atoi(argv[1]) == N);
#endif

  int i,j;
  int len=100;
  if (argc>1)
    len = atoi(argv[1]);

  int n=len, m=len;
  double b[n][m];
#pragma omp parallel for private(j)
  for (i=1;i<n;i++)
    for (j=0;j<m;j++) // Note there will be out of bound access
      b[i][j]=b[i][j-1];

 return 0;     
}