Function vraddhn_s64 

pub fn vraddhn_s64(a: int64x2_t, b: int64x2_t) -> int32x2_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 Add returning High Narrow. Arm’s documentation