Function vrhaddq_s8 

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

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

Rounding halving add Arm’s documentation