Function svqsubr_n_s64_z 

pub fn svqsubr_n_s64_z(pg: svbool_t, op1: svint64_t, op2: i64) -> svint64_t

🔬This is a nightly-only experimental API. (stdarch_aarch64_sve #145052)

Available on (AArch64 or ARM64EC) and target feature sve and target feature sve2 only.

Saturating subtract reversed Arm’s documentation