Function ba_gates_warp 

pub fn ba_gates_warp(local_out: u32, lane: u32) -> u32

2026-09-25: The block-wide warp that holds lane lane of output local_out. The parent writes its warp partial to smem[local_out * 2 + lane / 32] and the twin to red[g * BA_GATES_WARPS + threadIdx.x / 32]; they match because threadIdx.x / 32 == local_out * 2 + lane / 32.