test.rs

#![feature(asm)]

fn condition(f: i32) -> bool {
    match f {
        1 | 2 => opaque(true),
        _ => opaque(false)
    }
}

#[inline(never)]
fn opaque<T>(thing: T) -> T {
    unsafe {
        asm!("" : : "r"(&thing))
    }
    thing
}

fn main() {
    let integer = opaque(42);
    if condition(integer) {
        println!("true")
    } else {
        println!("false");
    }
}