Function analog_int_reduction_from_source 

pub fn analog_int_reduction_from_source(
    src: &str,
    fn_name: &str,
    target: &AnalogTarget,
) -> Result<AnalogReduction, AnaLowerError>

Lower a Seq of Int accumulator loop to a GRID-PRESERVING streamed reduction — the integer MAC. The exactness claim is made downstream by super::exactness_gate over the iterated budget.