Is there a stable way to use likely/unlikely on branch prediction?

[psionic12]

In my case I want to use 'unlikely' to check some error which has a low chance to happen. I found that std::intrinsics::unlikely is unstable since it's an intrinsic, but I only found one crate called likely stable (and all others are RFCs), and it implement likely as below:

pub const fn likely(b: bool) -> bool {
    #[allow(clippy::needless_bool)]
    if (1i32).checked_div(if b { 1 } else { 0 }).is_some() {
        true
    } else {
        false
    }
}

I don't understand how it works. Will it has performance issue? Any other way to use likely in Rust?

[anon80458984]

Compiler hint for unlikely/likely for if branches

Here is how hashbrown does to implement likely and unlikely on stable: #[inline] #[cold] fn cold() {} #[inline] fn likely(b: bool) -> bool { if !b { cold() } b } #[inline] fn unlikely(b: bool) -> bool { if b { cold() } b }