kernel void image_filter(a, b, c, d)
{
    func1(a, b, c, d);
    if(<condition>)
        func2(a, b, c, d);
}

kernel void image_filter(a, b, c, d)
{
    // Vertical pass
    func1(a, b, c, d);
    if(<condition>)
        func2(a, b, c, d);

    // When execution of the above functions is complete
    // Horizontal pass
    // Some computation
    func1(a, b, c, d);
    if(<condition>)
        func2(a, b, c, d);
}