Function decision_ops 

pub fn decision_ops(
    df: &DecisionFabric,
) -> Result<(Vec<FabricOp>, usize), String>

A decision fabric (decision_fabric_from_source: arithmetic cells and compare-selects) as a residual in the pipeline’s op vocabulary, and the index of its result. A compare becomes the mask of its outcome, all ones or zero (compare_mask); a select is e ^ ((t ^ e) & mask). Every op is emitted once, so a predicate many selects test has one mask. A fabric with any other cell (a functional unit, a memory or heap tile) has no combinational form and is refused.