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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors—Intel XScale
®
Processor
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
Developer’s Manual
August 2006
184
Order Number: 306262-004US
the code fragment, there is a result dependency between the UMLAL instruction and
the SUB instruction. In
, UMLAL starts to issue at cycle 0 and the SUB issues
at cycle 5. thus the Result Latency is five.
3.9.4.2
Branch Instruction Timings
(
3.9.4.3
Data Processing Instruction Timings
Table 80.
Latency Example
Cycle
Issue
Executing
0
umlal (1st cycle)
--
1
umlal (2nd cycle)
umlal
2
add
umlal
3
sub (stalled)
umlal & add
4
sub (stalled)
umlal
5
sub
umlal
6
mov
sub
7
--
mov
Table 81.
Branch Instruction Timings (Those Predicted by the BTB)
Mnemonic
Minimum Issue Latency When
Correctly Predicted by the BTB
Minimum Issue Latency with Branch
Misprediction
B
1
5
BL
1
5
Table 82.
Branch Instruction Timings (Those not Predicted by the BTB)
Mnemonic
Minimum Issue Latency
When the Branch is not Taken
Minimum Issue Latency
When the Branch is Taken
BLX(1)
N/A
5
BLX(2)
1
5
BX
1
5
Data Processing Instruction with
PC as the destination
4 + numbers in
LDR PC,<>
2
8
LDM with PC in register list
3 + numreg
10 + max (0, numreg-3)
†
numreg is the number of registers in the register list including the PC.
Table 83.
Data Processing Instruction Timings (Sheet 1 of 2)
Mnemonic
<shifter operand> is NOT a Shift/
Rotate by Register
<shifter operand> is a Shift/Rotate
by Register OR
<shifter operand> is RRX
Minimum Issue
Latency
Minimum Result
Latency
Minimum Issue
Latency
Minimum Result
Latency
ADC
1
1
2
2
ADD
1
1
2
2
AND
1
1
2
2
BIC
1
1
2
2
†
If the next instruction needs to use the result of the data processing for a shift by immediate or as Rn
in a QDADD or QDSUB, one extra cycle of result latency is added to the number listed.