Branching And Multicycle Nops - Texas Instruments TMS320C6000 Series Reference Manual

Figure 6–28. Branching and Multicycle NOPs
Figure 6–28 shows how a multicycle NOP can be affected by a branch. If the
delay slots of a branch finish while a multicycle NOP is still dispatching NOPs
into the pipeline, the branch overrides the multicycle NOP and the branch tar-
get begins execution five delay slots after the branch was issued.
Cycle #
1 EP1
2 EP2
3 EP3
4 EP4
5 EP5
6 EP6
Branch
7
EP7
8
9
10
Normal
11
EP7
† Delay slots of the branch
In one case, execute packet 1 (EP1) does not have a branch. The NOP 5 in
EP6 will force the CPU to wait until cycle 11 to execute EP7.
In the other case, EP1 does have a branch. The delay slots of the branch coin-
cide with cycles 2 through 6. Once the target code reaches E1 in cycle 7, it
executes.
. . .
B
EP without branch
EP without branch
EP without branch
EP without branch
LD MPY ADD NOP5
Branch will execute here
See Figure 6–27(b)
TMS320C67x Pipeline
Performance Considerations
Pipeline Phase
Branch Target
E1 PG
PS
PW
PR
DP
DC
E1
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