Function rustc_mir_transform::separate_const_switch::is_likely_const

fn is_likely_const<'tcx>(
    tracked_place: Place<'tcx>,
    block: &BasicBlockData<'tcx>
) -> bool

This function describes a rough heuristic guessing whether a place is last set with a const within the block. Notably, it will be overly pessimistic in cases that are already not handled by separate_const_switch.