[Bug tree-optimization/61279] [4.10 Regression] ICE in loop_preheader_edge, at cfgloop.c:1668 w/ -O1 -ftree-loop-vectorize

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61279

--- Comment #4 from Arseny Solokha <asolokha at gmx dot com> ---
I even have another reproducer which is basically identical to the original one
but not completely.

int t;
int n[1] = { 0 };

void
x(void)
{
  int v;
  int r;
  int i[4] = { 0 };
  for (v = 0; v < 1; ++v) {
    ++i[3];
    for (r = 0; r < 1; ++r) {
      for (t = 0; t < 1; ++t)
        return;
      for (t = 0; t < 1; ++t)
        /* Irregardless of i's declared size, the ICE only occurs
           when the array subscript on lines 18 and 11 is exactly 3
           (I've checked only the nearest values, however). */
        i[3] = n[t];
      for (t = 0; t < 1; ++t)
        return;
    }
  }
}