Functional Unit Hazards
6-24
Table 6–6 shows the instruction hazards for branch instructions executing on
the .S unit.
Table 6–6. Branch .S-Unit Instruction Hazards
Instruction Execution
Cycle
1
2
3
4
5
6
7
8
Branch
†
R
Instruction Type
Subsequent Same-Unit Instruction Executable
Single-cycle
n
n
n
n
n
n
n
DP compare
n
n
n
n
n
n
n
2-cycle DP
n
n
n
n
n
n
n
Branch
n
n
n
n
n
n
n
Instruction Type
Same Side, Different Unit, Both Using Cross Path Executable
Single-cycle
n
n
n
n
n
n
n
Load
n
n
n
n
n
n
n
Store
n
n
n
n
n
n
n
INTDP
n
n
n
n
n
n
n
ADDDP/SUBDP
n
n
n
n
n
n
n
16
16 multiply
n
n
n
n
n
n
n
4-cycle
n
n
n
n
n
n
n
MPYI
n
n
n
n
n
n
n
MPYID
n
n
n
n
n
n
n
MPYDP
n
n
n
n
n
n
n
Legend:
E1 phase of the single-cyle instruction
R
Sources read for the instruction
n
Next instruction can enter E1 during cycle
†
The branch on register instruction is the only branch instruction that reads a
general-purpose register