There's a discussion of "delayed bounds checking", but not "hoisted bounds checking", where bounds checking is done early. Consider

    let mut tab: [usize;100] = [0;100];
    ...
    for i in 0..101 {
        tab[i] = i;
    }

This must panic at i=100. Panic becomes inevitable at entry to the loop. Is the compiler entitled to generate a check that will panic at loop entry? The slides suggest that Rust does not hoist such checks, and, so, with nested loops, it has trouble getting checks out of the loop, which prevents vectorization.