// There is a loop in this interval iff one of the predecessors of the header
// node lives in the interval.
for (::pred_iterator I = ::pred_begin(HeaderNode), E = ::pred_end(HeaderNode);
// There is a loop in this interval iff one of the predecessors of the header
// node lives in the interval.
for (::pred_iterator I = ::pred_begin(HeaderNode), E = ::pred_end(HeaderNode);