Paper assignment. 1. Write the quadruples and compute the dag for the following code fragment: x := a * a + 2 * a * b + b * b; y := a * a - 2 * a * b + b * b; Then generate a better set of quadruples for the block. 2. simple examples of register coloring: Problems 4.26 and 4.27 from text, page 394.