[Bug tree-optimization/84235] New: [8 Regression] Miscompilation of floating point code by dom2

["jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84235

            Bug ID: 84235
           Summary: [8 Regression] Miscompilation of floating point code
                    by dom2
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

int
main ()
{
  double d = 1.0 / 0.0;
  _Bool b = d == d && (d - d) != (d - d);
  if (!b)
    __builtin_abort ();
  return 0;
}

is miscompiled at -O2 starting with r251279.  I have a fix.