IBM PowerPC 750GX

User’s Manual
IBM PowerPC 750GX and 750GL RISC Microprocessor
gx_06.fm.(1.2)
March 27, 2006
Instruction Timing
Page 231 of 377
1. During clock cycle 0, instructions 0 and 1 are dispatched to their respective execution units. Instruction 2
is a branch instruction that updates the CTR. It is predicted as not taken in clock cycle 0. Instruction 3 is a
Multiply High Word (mulhw) instruction on which instruction 4 depends.
Figure 6-10. Branch Instruction Timing
5 fadd
T3 add
4 bc
123456780 910
•••
•••
Fetch
In dispatch entry (IQ0/IQ1)
Predict
Execute
Complete (In CQ)
In retirement entry (CQ0/CQ1)
1 add
T2 add
3
2 (bc)
1
0
T1
T0
T5
T4
T3
T2
T5
T4
T3
T2
(8)
(7)
6
5
5
4
3
2
3
2
1
0
T1
T0
3
2
T1
T0
3
6
5
(8)
(7)
6
5
(8)
(7)
6
5
(8)
(7)
6
5
1
0
Instruction
Queue
Completion
Queue
0 add
T1 add
T0 add
2 bc
3 mulhw
T5 or
T4 and
5 fadd *
6 and*
* Instructions 5 and 6 are not in the IQ in clock cycle 5. Here, the fetch stage shows cache latency.