Function moe_w4a16_grouped_gemm_ptrtable_m256 

pub fn moe_w4a16_grouped_gemm_ptrtable_m256(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    a: DevicePtr,
    b_packed_ptrs: DevicePtr,
    b_scale_ptrs: DevicePtr,
    scale2_vals: DevicePtr,
    c: DevicePtr,
    expert_offsets: DevicePtr,
    sorted_token_ids: DevicePtr,
    num_experts: u32,
    n_out: u32,
    k: u32,
    max_m_tiles: u32,
    stream: u64,
) -> Result<()>

2026-09-25: moe_w4a16_grouped_gemm_ptrtable with a 256-row M tile and a 512-thread block. max_m_tiles counts 256-row tiles: MoeLayer::launch_grouped_gemm divides the 64-row count by 4. Loaded only under METRALE_MOE_GROUPED_M256=1 (moe/init.rs); the measurement behind that is on launch_grouped_gemm.