Pipeline Execution of Instruction Types
Pipeline
4-20
SPRU733
4.2.4 Load Instructions
Data loads require five, E1
−
E5, of the pipeline execute phases to complete
their operations (see Table 4
−
6). Figure 4
−
14 shows the fetch, decode, and
execute phases of the pipeline that the load instructions use.
Figure 4
−
15 shows the operations occurring in the pipeline phases for a load.
In the E1 phase, the data address pointer is modified in its register. In the E2
phase, the data address is sent to data memory. In the E3 phase, a memory
read at that address is performed.
Table 4
−
6. Load Instruction Execution
Pipeline Stage
E1
E2
E3
E4
E5
Read
baseR
offsetR
Written
baseR
dst
Unit in use
.D
Figure 4
−
14. Load Instruction Phases
PG
PS
PW
PR
DP
DC
E1
E2
E3
E4
E5
4 delay slots
Address
modification