Function vrhaddq_s8 

pub fn vrhaddq_s8(a: int8x16_t, b: int8x16_t) -> int8x16_t

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

Rounding halving add Arm’s documentation