Function dense4l

cranelift/bforest/src/set.rs:550–560

Generate a densely populated 4-level tree. Level 1: 1 root Level 2: 8 inner Level 3: 64 inner Level 4: 512 leaves, up to 7680 elements A 3-level tree can hold at most 960 elements.

(f: &mut SetForest<i32>)

    //
    // A 3-level tree can hold at most 960 elements.
    fn dense4l(f: &mut SetForest<i32>) -> Set<i32> {
        f.clear();
        let mut s = Set::new();

        // Insert 400 elements in 7 passes over the range to avoid the half-full leaf node pattern
        // that comes from sequential insertion. This will generate a normal leaf layer.
        for n in 0..4000 {
            assert!(s.insert((n * 7) % 4000, f, &()));
        }
        s
    }

    #[test]
    fn four_level() {