source: CIVL/examples/omp/simplifier/DRB005-indirectaccess1-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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  may be used to endorse or promote products derived from this
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*/
/*
This program is extracted from a real application at LLNL.
Two pointers (xa1 and xa2) have a pair of values with a distance of 12.
They are used as start base addresses for two 1-D arrays.
Their index set has two indices with distance of 12: 999 +12 = 1011.
So there is loop carried dependence.

However, having loop carried dependence does not mean data races will always happen.
The iterations with loop carried dependence must be scheduled to
different threads in order for data races to happen.

In this example, we use schedule(static,1) to increase the chance that
the dependent loop iterations will be scheduled to different threads.
Data race pair: xa1[idx]@128:5 vs. xa2[idx]@129:5
*/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

#define N 180
int indexSet[N] = {
521, 523, 525, 527, 529, 531,
547, 549, 551, 553, 555, 557,
573, 575, 577, 579, 581, 583,
599, 601, 603, 605, 607, 609,
625, 627, 629, 631, 633, 635,

651, 653, 655, 657, 659, 661,
859, 861, 863, 865, 867, 869,
885, 887, 889, 891, 893, 895,
911, 913, 915, 917, 919, 923, // change original 921 to 923 = 911+12
937, 939, 941, 943, 945, 947,

963, 965, 967, 969, 971, 973,
989, 991, 993, 995, 997, 999, 
1197, 1199, 1201, 1203, 1205, 1207,
1223, 1225, 1227, 1229, 1231, 1233,
1249, 1251, 1253, 1255, 1257, 1259,

1275, 1277, 1279, 1281, 1283, 1285,
1301, 1303, 1305, 1307, 1309, 1311,
1327, 1329, 1331, 1333, 1335, 1337,
1535, 1537, 1539, 1541, 1543, 1545,
1561, 1563, 1565, 1567, 1569, 1571,

1587, 1589, 1591, 1593, 1595, 1597,
1613, 1615, 1617, 1619, 1621, 1623,
1639, 1641, 1643, 1645, 1647, 1649,
1665, 1667, 1669, 1671, 1673, 1675,
1873, 1875, 1877, 1879, 1881, 1883,

1899, 1901, 1903, 1905, 1907, 1909,
1925, 1927, 1929, 1931, 1933, 1935,
1951, 1953, 1955, 1957, 1959, 1961,
1977, 1979, 1981, 1983, 1985, 1987,
2003, 2005, 2007, 2009, 2011, 2013};

int main (int argc, char* argv[])
{
  // max index value is 2013. +12 to obtain a valid xa2[idx] after xa1+12.
  // +1 to ensure a reference like base[2015] is within the bound.
  double * base = (double*) malloc(sizeof(double)* (2013+12+1));
  if (base == 0)
  {
    printf ("Error in malloc(). Aborting ...\n");
    return 1;  
  }

  double * xa1 = base;
  double * xa2 = xa1 + 12;
  int i;

  // initialize segments touched by indexSet
  for (i =521; i<= 2025; ++i)
  {
    base[i]=0.5*i;
  }
// default static even scheduling may not trigger data race, using static,1 instead.
#pragma omp parallel for schedule(static,1)
  for (i =0; i< N; ++i) 
  {
    int idx = indexSet[i];
    xa1[idx]+= 1.0 + i;
    xa2[idx]+= 3.0 + i;
  }

  printf("x1[999]=%f xa2[1285]=%f\n", xa1[999], xa2[1285]);
  free (base);
  return  0;
}