[Bug tree-optimization/56321] [4.8 Regression] ICE:segfault in midend for -funsafe-math-optimizations -O3

[wschmidt at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56321

--- Comment #6 from William J. Schmidt <wschmidt at gcc dot gnu.org> 2013-02-14 20:11:32 UTC ---
Odd.  Reassociation makes a correct and profitable transformation into

foo (int n)
{
  double _2;
  double _5;
  double _6;
  double _7;
  double _8;
  float _9;

  <bb 2>:
  _2 = (double) n_1(D);
  _6 = _2 * 6.6666666666666662965923251249478198587894439697265625e-1;
  _7 = _6 + 2.0e+0;
  _5 = _7 * _2;
  _8 = _5;
  _9 = (float) _8;
  return _9;

}

but somehow verify_ssa() thinks the last statement (return _9;) contains a use
of the undefined SSA name _4.

Will continue to investigate later.