Function midpoint

cranelift/codegen/src/ir/layout.rs:91–96

Compute the midpoint between `a` and `b`. Return `None` if the midpoint would be equal to either.

(a: SequenceNumber, b: SequenceNumber)

/// Compute the midpoint between `a` and `b`.
/// Return `None` if the midpoint would be equal to either.
fn midpoint(a: SequenceNumber, b: SequenceNumber) -> Option<SequenceNumber> {
    debug_assert!(a < b);
    // Avoid integer overflow.
    let m = a + (b - a) / 2;
    if m > a { Some(m) } else { None }
}

impl Layout {
    /// Compare the program points `a` and `b` in the same block relative to this program order.