Function decouple_access 

pub fn decouple_access(
    cells: &[LoopCell],
    result: Src,
    n_in: usize,
) -> DaeSchedule

Decouple a straight-line body into an AGU lane + exec lane. The AGU lane is the set of cells that transitively feed a memory tile’s address AND whose dependency cone never crosses a load (untainted) — the address arithmetic that can be precomputed off the compute path. Everything else (compute + the memory tiles + any pointer-chase address whose cone reads memory) stays in the exec lane, in program order. The two are concatenated AGU-first with every Src::Val remapped, so the layout is a valid topological reordering of the SAME cells — semantics-preserving by construction.