source: CIVL/examples/omp/DataRaceBench/micro-benchmarks/outofbounds-orig-yes.c@ e5cec5ae

1.23 2.0 acw/focus-triggers main test-branch
Last change on this file since e5cec5ae was 36a61f3, checked in by Ziqing Luo <ziqing@…>, 9 years ago

Commit DataRaceBench into CIVL examples

git-svn-id: svn://vsl.cis.udel.edu/civl/trunk@4225 fb995dde-84ed-4084-dfe6-e5aef3e2452c

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File size: 864 bytes
Line 
1/* The outmost loop is parallelized.
2 But the inner level loop has out of bound access for b[i][j]
3 when j==0.
4 This will case memory access of a previous row's last element.
5
6 For example, an array of 4x4:
7 j=0 1 2 3
8 i=0 x x x x
9 1 x x x x
10 2 x x x x
11 3 x x x x
12
13 outer loop: i=2,
14 inner loop: j=0
15 array element accessed b[i][j-1] becomes b[2][-1], which in turn is b[1][3]
16 due to linearized row-major storage of the 2-D array.
17
18 This causes loop-carried data dependence between i=2 and i=1.
19*/
20#include <stdio.h>
21int main(int argc, char* argv[])
22{
23 int i,j;
24 int n=100, m=100;
25 double b[n][m];
26#pragma omp parallel for private(j)
27 for (i=0;i<n;i++)
28 for (j=0;j<m;j++) // Note there will be out of bound access
29 b[i][j]=b[i][j-1];
30
31 printf ("b[50][50]=%f\n",b[50][50]);
32
33 return 0;
34}
35
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