Function vcombine_u8 

pub fn vcombine_u8(a: uint8x8_t, b: uint8x8_t) -> uint8x16_t

Available on little-endian and target feature neon and (AArch64 or ARM or ARM64EC) and (AArch64 or ARM64EC) and (AArch64 or ARM64EC or target feature v7) only.

Join two smaller vectors into a single larger vector Arm’s documentation