spRegNum

pub fn spRegNum(arch: std.Target.Cpu.Arch) u16 {
    return switch (arch) {
        .aarch64, .aarch64_be => 31,
        .alpha => 30,
        .arc, .arceb => 28,
        .arm, .armeb, .thumb, .thumbeb => 13,
        .csky => 14,
        .hexagon => 29,
        .kvx => 12,
        .lanai => 4,
        .loongarch32, .loongarch64 => 3,
        .m68k => 15,
        .m88k => 31,
        .mips, .mipsel, .mips64, .mips64el => 29,
        .or1k => 1,
        .powerpc, .powerpcle, .powerpc64, .powerpc64le => 1,
        .riscv32, .riscv32be, .riscv64, .riscv64be => 2,
        .s390x => 15,
        .sparc, .sparc64 => 14,
        .ve => 11,
        .x86 => 4,
        .x86_64 => 7,
        else => unreachable,
    };
}