Functional Unit Constraints
Pipeline4-38 SPRU733

Table 422 shows the instruction constraints for ADDDP/SUBDP instructions

executing on the .S unit.
Table 422. ADDDP/SUBDP .S-Unit Instruction Constraints
Instruction Execution
Cycle 1 2 3 4 5 6 7
ADDDP/SUBDP R R W W
Instruction Type Subsequent Same-Unit Instruction Executable
Single-cycle Xr   Xw Xw
2-cycle DP Xr Xw Xw Xw
DP compare Xr Xw Xw
ADDDP/SUBDP Xr 
ADDSP/SUBSP Xr Xw Xw 
Branch Xr 
Instruction Type Same Side, Different Unit, Both Using Cross Path Executable
Single-cycle Xr 
DP compare Xr 
2-cycle DP Xr 
4-cycle Xr 
Load 
Store 
Branch Xr 
16 ×16 multiply Xr 
MPYI Xr 
MPYID Xr 
MPYDP Xr 
Legend: = E1 phase of the single-cycle instruction; R = Sources read for the instruction; W = Destinations written for the
instruction; = Next instruction can enter E1 during cycle; Xr = Next instruction cannot enter E1 during cycle-read/
decode constraint; Xw = Next instruction cannot enter E1 during cyclewrite constraint