[Bug tree-optimization/69213] [6 Regression] g++ ICE (segfault) at -O1 and above on x86_64-linux-gnu in "add_dependency"

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69213

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
The SSA _1 doesn't have a def stmt ...

int main() ()
{
  bool a_lsm.9;
  int a_lsm.8;
  bool b_lsm.7;
  int b_lsm.6;
  unsigned int _1;
  unsigned int _3;
  int _7;
  int a.0_9;

  <bb 2>:
  a.0_9 = a;
  if (a.0_9 >= 0)
    goto <bb 7>;
  else
    goto <bb 3>;

  <bb 3>:
  b_lsm.6_12 = b;

  <bb 4>:
  # b_lsm.6_6 = PHI <b_lsm.6_12(3), _7(5)>
  _7 = b_lsm.6_6 + 1;
  b_lsm.6_14 = (int) _1;
  if (b_lsm.6_14 >= 0)
    goto <bb 6>;
  else
    goto <bb 5>;

  <bb 5>:
  goto <bb 4>;

  <bb 6>:
  # a_lsm.8_22 = PHI <b_lsm.6_6(4)>
  # b_lsm.6_24 = PHI <_7(4)>
  b = b_lsm.6_24;
  a = a_lsm.8_22;

  <bb 7>:
  return 0;

already broken in IVOPTs.