[Bug tree-optimization/126464] New: [16/17 Regression] wrong code with FP ranges

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126464

            Bug ID: 126464
           Summary: [16/17 Regression] wrong code with FP ranges
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ktkachov at gcc dot gnu.org
  Target Milestone: ---

__attribute__((noipa)) double
scale (double x)
{
  float y = (float) x;

  if (y == -__builtin_inf ())
    return x * 0.5;           /* retry at half scale */
  return y;
}

/* Same shape, widening the other way, to show it is not _Float16 or float
   specific.  */
__attribute__((noipa)) long double
scale2 (long double x)
{
  double y = (double) x;

  if (y == __builtin_inf ())
    return x * 0.5L;
  return y;
}

int
main (void)
{
  if (scale (-1e300) != -5e299)
    __builtin_abort ();

  if (sizeof (long double) > sizeof (double)
      && scale2 (1e4000L) != 5e3999L)
    __builtin_abort ();

  return 0;
}

runs fine at -O0 and aborts at -O1 and above. Also with GCC 15 it works fine.
I think something to do with fp ranges