Problem 2: Why Not Both? (20 points)

What is the CPI for the following schemes?

a) Detect-and-stall for control and data hazards [5]

b) Speculate-and-squash (always taken) for control hazards and detect-and-forward for data hazards [5]

c) Speculate-and-squash (always taken) for control hazards and detect-and-stall for data hazards [5]

d) Local 2-bit branch predictor for control hazards and detect-and-stall for data hazards [5]

For Problems 1 & 2, reference the following piece of assembly code lW nor loop beq posl negl count 4 done 1 //beqe nor3 nor 4 beq //beq1 even add6 beq e even add 7 else add 3 beq e else //beq2 1 loop //beq3 done halt count .fill 5 pos1 .fill 1 neg1 .fill -1 For Problems 1 & 2, reference the following piece of assembly code lW nor loop beq posl negl count 4 done 1 //beqe nor3 nor 4 beq //beq1 even add6 beq e even add 7 else add 3 beq e else //beq2 1 loop //beq3 done halt count .fill 5 pos1 .fill 1 neg1 .fill -1