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Adjust the sequence of the following instructions to avoid data hazards by utili...
May 21, 2024
Adjust the sequence of the following instructions to avoid data hazards by utilizing the dynamic pipeline scheduling. Note that: the NOP and forwarding are available.
lw t0,0(s0)
add t1,t0, s1
addi s0, s0,4subs1, s0,t1
sw t1,0(s0)
Solution by Steps
step 1
Identify the data hazards in the given instructions. The data hazards occur when an instruction depends on the result of a previous instruction that has not yet completed
step 2
The given instructions are:
1. lwt0,0(s0)
2. addt1,t0,s1
3. addis0,s0,4
4. subs1,s0,t1
5. swt1,0(s0)
The add instruction depends on the lw instruction, and the sub instruction depends on the addi instruction
step 3
To avoid data hazards, we can insert NOPs (No Operation) or use forwarding. Here, we will use forwarding and NOPs where necessary
step 4
Adjust the sequence with NOPs and forwarding:
1. lwt0,0(s0)
2. NOP
3. addt1,t0,s1
4. addis0,s0,4
5. NOP
6. subs1,s0,t1
7. swt1,0(s0)
This sequence ensures that each instruction has the necessary data available when it executes, avoiding data hazards
Answer
The adjusted sequence is:
1. lwt0,0(s0)
2. NOP
3. addt1,t0,s1
4. addis0,s0,4
5. NOP
6. subs1,s0,t1
7. swt1,0(s0)
Key Concept
Dynamic Pipeline Scheduling
Explanation
Dynamic pipeline scheduling involves reordering instructions and inserting NOPs to avoid data hazards, ensuring that each instruction has the necessary data available when it executes.
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