[Bug c/29947] New: OpenMP parallel for fails for reversed loop range

["spaine at cfa dot harvard dot edu" <gcc-bugzilla at gcc dot gnu dot org>]

The following test program works as expected when compiled without -fopenmp. 
In some cases, such as shown below, it fails when the loop termination
condition is already satisfied on entry:

[spaine@carmenere tmp]$ uname -a
Linux carmenere.cfa.harvard.edu 2.6.18-1.2200.fc5 #1 SMP Sat Oct 14 16:59:56
EDT 2006 x86_64 x86_64 x86_64 GNU/Linux
[spaine@carmenere tmp]$ gcc --version
gcc (GCC) 4.1.1 20060525 (Red Hat 4.1.1-1)
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[spaine@carmenere tmp]$ cat example.c
#include <stdio.h>

int main(int argc, char *argv[])
{
        int i, j, k;
        j = atoi(argv[1]);
        k = atoi(argv[2]);
        #pragma omp parallel for
        for (i = j; i <= k; ++i)
                printf("%d ", i);
        printf("done\n");
        return 0;
}
[spaine@carmenere tmp]$ gcc -o example example.c
[spaine@carmenere tmp]$ ./example 1 5
1 2 3 4 5 done
[spaine@carmenere tmp]$ ./example 5 1
done
[spaine@carmenere tmp]$ gcc -o example -fopenmp -lgomp example.c
[spaine@carmenere tmp]$ ./example 1 5
4 5 1 2 3 done
[spaine@carmenere tmp]$ ./example 5 1
-2147483644 -2147483643 -2147483642 -2147483641 -2147483640 -2147483639
-2147483638 -2147483637 -2147483636 -2147483635 -2147483634 -2147483633
-2147483632 -2147483631 -2147483630 -2147483629 -2147483628 -2147483627
-2147483626 -2147483625 -2147483624 -2147483623 -2147483622 -2147483621
-2147483620 -2147483619 -2147483618 -2147483617 -2147483616 -2147483615
-2147483614 -2147483613 -2147483612 -2147483611 -2147483610 -2147483609
-2147483608 -2147483607 -2147483606 -2147483605 -2147483604 -2147483603 .....
etc.


-- 
           Summary: OpenMP parallel for fails for reversed loop range
           Product: gcc
           Version: 4.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: spaine at cfa dot harvard dot edu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29947