Function vqaddq_s64 

pub fn vqaddq_s64(a: int64x2_t, b: int64x2_t) -> int64x2_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.

Saturating add Arm’s documentation