half4 main() {
    half4 x = half4(1, 1, 1, 1);

    // Verify that break is allowed in a do-while loop.
    do {
        x.r -= 0.25;
        if (x.r <= 0) break;
    } while (x.a == 1);

    // Verify that continue is allowed in a do-while loop.
    do {
        x.b -= 0.25;
        if (x.a == 1) continue; // should always happen
        x.g = 0;
    } while (x.b > 0);

    // x contains green.
    return x;
}