Solution:
Pipelining fiuure:
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
||
ADD |
S3,S4,S6 |
IF |
ID |
EXadd |
MEM |
WB |
|||
SUB |
S5, S5,S2 |
IF |
ID |
EXsub |
MEM |
WB |
|||
lw |
S7,100(s5) |
IF |
ID |
EXlw |
MEM |
WB |
|||
ADD |
S8,S7,S2 |
IF |
ID |
EXlw |
MEM |
WB |
|||
The first forwadin is the value of s5 from EXsub to EXlw.
The second forwadin is the value of S7 from EXlw. To EXadd
Data dependencies:
The third LW instruction is depends on second, since S5 is the result of second.
The last ADD instruction is depends on the load instruction for S7.
Data hazrds :
Data hazrds is the data values which are not available during durin decoding.
Both the above mentioned dependencies will resulr in data hazards if no forwardin is there.
Stall:
Both the above dependies will also result in stall, the ID step will not happen till the previous step execution happens,
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