[Bug libgomp/58756] FAIL: libgomp.c/pr58392.c execution test

ubizjak at gmail dot com gcc-bugzilla@gcc.gnu.org
Thu Dec 12 20:21:00 GMT 2013


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58756

--- Comment #2 from Uroš Bizjak <ubizjak at gmail dot com> ---
Some unscientific printf debugging yields following runtime difference:

foo (int a, int b)
{
  int j, c = 0;
  #pragma omp parallel for reduction(+: c)
    for (j = 0; j < a; j += b)
      {
    int l;
    #pragma omp simd reduction(+: c)
      for (l = 0; l < b; ++l)
        c += d[j + l];
    printf ("%i\n", c);
      }
  printf ("tot %i\n", c);
  return c;
}

alpha:

$ ./a.out
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
496
tot 1984
Aborted

Alpha spawned 3 new threads (as reported by gdb), so 4 * 496 = 1984.

x86_64:

$ ./pr58392.exe 
496
992
1488
496
992
1488
496
992
496
992
1488
496
992
1488
496
992
1488
496
992
496
992
1488
496
992
496
992
1488
496
992
496
992
1488
tot 15872


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