Every cycle that does not initiate a new operation in a pipe is a lost opportunity, in the sense that your hardware is not “living up to its potential.”

a. [10] In your reordered code from Exercise 2.5, what fraction of all cycles, counting both pipes, were wasted (did not initiate a new op)?

b. [10] Loop unrolling is one standard compiler technique for finding more parallelism in code, in order to minimize the lost opportunities for per- formance.

c. Hand-unroll two iterations of the loop in your reordered code from Exercise

2.5. What speedup did you obtain? (For this exercise, just color the N + 1 iteration’s instructions green to distinguish them from the N th iteration’s; if you were actually unrolling the loop you would have to reassign registers to pre- vent collisions between the iterations.)