Function check_postfix_segment 

fn check_postfix_segment(
    path: &[usize],
    enter: usize,
    segment_counts: &mut FxHashMap<Vec<usize>, usize>,
    max_repeats: usize,
) -> bool

Check whether the current entry→entry sub-path introduces a new block sequence (not just new blocks). Different branch choices inside the SCC produce different sequences even when all block IDs have already been seen, e.g. if i % 2 == 0 { A } else { B } alternates between two paths through the same set of blocks on successive loop iterations.