macro_rules! impl_vec_cmp {
    ([$Trait:ident $m:ident] ($b:ident, $h:ident, $w:ident)) => { ... };
    ([$Trait:ident $m:ident] ($ub:ident, $sb:ident, $uh:ident, $sh:ident, $uw:ident, $sw:ident)) => { ... };
}
🔬This is a nightly-only experimental API. (stdsimd #48556)
Available on PowerPC or PowerPC-64 only.