Function w4a16_gemm_n128_m128_bf16 

pub fn w4a16_gemm_n128_m128_bf16(
    gpu: &dyn GpuBackend,
    kernel: KernelHandle,
    input: DevicePtr,
    weight: &QuantizedWeight,
    output: DevicePtr,
    m: u32,
    n: u32,
    k: u32,
    stream: u64,
) -> Result<()>

8-arg launcher for w4a16_gemm_t_m128_bf16 (v1) ONLY. The _v2 sibling’s compiled signature has a 9th ldb param — launching it through this helper makes cuLaunchKernel read one-past-the-end of the param array (observed as CUDA_ERROR_INVALID_VALUE or a host SIGSEGV depending on the neighboring heap word). Launch v2 via w4a16_gemm_n128_m128_bf16_ldb (ldb = N when the transposed twin is unpadded).