Function save_as_intervals 

fn save_as_intervals<'tcx>(
    elements: &DenseLocationMap,
    body: &Body<'tcx>,
    relevant: &RelevantLocals,
    results: Results<DenseBitSet<Local>>,
) -> SparseIntervalMatrix<RelevantLocal, TwoStepIndex>

Add points depending on the result of the given dataflow analysis.