ccl_device float compatible_powf(float x, float y)
{
#ifdef __KERNEL_GPU__
  if (y == 0.0f) /* x^0 -> 1, including 0^0 */
    return 1.0f;

  /* GPU pow doesn't accept negative x, do manual checks here */
  if (x < 0.0f) {
    if (fmodf(-y, 2.0f) == 0.0f)
      return powf(-x, y);
    else
      return -powf(-x, y);
  }
  else if (x == 0.0f)
    return 0.0f;
#endif
  return powf(x, y);
}

ccl_device float safe_powf(float a, float b)
{
  if (UNLIKELY(a < 0.0f && b != float_to_int(b)))
    return 0.0f;

  return compatible_powf(a, b);
}