rust/tests/run-make/intrinsic-unreachable/rmake.rs

// intrinsics::unreachable tells the compiler that a certain point in the code
// is not reachable by any means, which enables some useful optimizations.
// In this test, exit-unreachable contains this instruction and exit-ret does not,
// which means the emitted artifacts should be shorter in length.
// See https://github.com/rust-lang/rust/pull/16970

//@ needs-asm-support
//@ ignore-windows
// Reason: Because of Windows exception handling, the code is not necessarily any shorter.

use run_make_support::{rfs, rustc};

fn main() {
    rustc().opt().emit("asm").input("exit-ret.rs").run();
    rustc().opt().emit("asm").input("exit-unreachable.rs").run();
    assert!(
        rfs::read_to_string("exit-unreachable.s").lines().count()
            < rfs::read_to_string("exit-ret.s").lines().count()
    );
}