Function core::arch::wasm32::u32x4_extend_low_u16x8

pub fn u32x4_extend_low_u16x8(a: v128) -> v128

Available on target_family="wasm" and target feature simd128 and WebAssembly only.

将较小 lane vector 的下半部分转换为较大 lane vector，扩展为零。