Freescale Semiconductor PowerPC e500 Core, Reference Manual

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Execution Timing
PowerPC e500 Core Family Reference Manual, Rev. 1
Freescale Semiconductor 4-31
4.6 Instruction Latency Summary
Instruction timing is shown in Table 4-3 through Table 4-7 . The latency tables use the following
conventions:
• Pipelined load/store and floating-point instructions are shown with cycles of total latency
and throughput cycles separated by a colon.
• Floating-point instructions with a single entry in the cycles column are not pipelined.
Integer divide instructions are also not pipelined with other divides.
Table 4-3 through Table 4-7 list latencies associated with instructions executed by each execution
unit. Figure 4-3 describes branch instruction latencies.
Table 4-4 lists system operation instruction latencies. The instructions in Table 4-4 are grouped by
the serialization they require. Except where otherwise noted, throughput is the same for the
instructions within each serialization grouping.
Table 4-3. Branch Operation Execution Latencies
Mnemonic Cycles Serialization
bbelr 1 Pre- and postsync
bblels 1 Pre- and postsync
bcctr [ l ] 1 —
bclr [ l ] 1 —
bc [ l ][ a ] 1 —
b [ l ][ a ] 1 —
Table 4-4. System Operation Instruction Execution Latencies
Mnemonic Serialization
1
Unit Cycles
isync Refetch —
2
0
mbar Store LSU 3:1
msync Store and postsync. LSU Latency depends on bus response time.
mfcr Move-from SU1 only 4
mfspr [XER]
mfmsr None SU1 4
mfpmr None SU1 only 4
7
mfspr [CTR]
3, 4
None SU1 or SU2 1
mfspr [LR]
3,5
mfspr [DBSR] Presync, postsync SU1 only 4
mfspr [SSCR] Presync SU1 only 4