Functional Unit Hazards
6-42
6.3.8
Load Instructions
Data loads require five of the pipeline execute phases to complete their opera-
tions (see Table 6–23). Figure 6–14 shows the pipeline phases the load
instructions use.
Table 6–23. Load Execution
Pipeline
Stage
E1
E2
E3
E4
E5
Read
baseR
offsetR
Written
baseR
dst
Unit in use
.D
Figure 6–14. Load Instruction Phases
PG
PS
PW
PR
DP
DC
E1
E2
E3
E4
E5
4 delay slots
Address
modification
Figure 6–15 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.