[Exercise 4.27] Problems in this exercise refer to the following sequence of instructions, and assume that it is executed on a five-stage pipelined datapath: add x15, x12, x11 ld x13, 4(x15) ld x12, 0(x2) or x13, x15, x13 sd x13, 0(x15) a) If there is no forwarding or hazard detection for this sequence of instructions, insert NOPs (stalls) in the correct locations between instructions to ensure correct execution. b)Are there hazards present in this sequence of instructions? If so, for each hazard do the following: Indicate which instructions are involved in the hazard. Indicate which registers are in contention for the hazard. Provide a brief explanation for why this hazard exists. c) If the processor has forwarding and hazard detection, indicate how forwarding can be used to resolve or at least lessen the impact of the hazards discussed in Part A. (For each hazard, indicate which stages of which instruction the forward must originate from, and which stage of which instruction the forward must be sent to, and reasoning for your answer). d) How many cycles will be needed to complete this set of instructions without forwarding? With forwarding? Show the process you used to find both answers.
- [Exercise 4.27] Problems in this exercise refer to the following sequence of instructions, and assume that it is executed on a five-stage pipelined datapath:
add x15, x12, x11
ld x13, 4(x15)
ld x12, 0(x2)
or x13, x15, x13
sd x13, 0(x15)
a) If there is no forwarding or hazard detection for this sequence of instructions, insert NOPs (stalls) in the correct locations between instructions to ensure correct execution.
b)Are there hazards present in this sequence of instructions? If so, for each hazard do the following:
Indicate which instructions are involved in the hazard.
Indicate which registers are in contention for the hazard. Provide a brief explanation for why this hazard exists.
c) If the processor has forwarding and hazard detection, indicate how forwarding can be used to resolve or at least lessen the impact of the hazards discussed in Part A. (For each hazard, indicate which stages of which instruction the forward must originate from, and which stage of which instruction the forward must be sent to, and reasoning for your answer).
d) How many cycles will be needed to complete this set of instructions without forwarding? With forwarding? Show the process you used to find both answers.
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