MOTOROLA
Chapter 10. Instruction Execution Timing
10-5
Part II. PowerPC Microprocessor Module
Figure 10-7. Branch Folding Timing
10.1.7 Branch Prediction
In this example, the blt instruction is dependent on the cmpi instruction. Nevertheless, the
BPU predicts the correct path and allows an overlap of its bubbles with those of lwz. When
cmpi writes back, the BPU reevaluates the decision. If the prediction is correct, no more
action is taken and execution continues. Instructions on the predicted path cannot be
dispatched before the condition is resolved.
while:
mulli
r3,r12,r4
addi
r4,3(r0)
...
lwz r12,64
(r2)
cmpi
0,r12,3
addic
r6,r5,1
blt
cr0,while
...
Figure 10-8. Branch Prediction Timing
addic
lwz
lwz
sub
bl
Bubble
addic
mulli
sub
sub
Bubble
mulli
lwz
Bubble
lwz
lwz
bl
lwz
bl
sub
addic
addic
mulli
Fetch
Decode
Read + Execute
Writeback
L Address Drive
L Data
Load Writeback
Branch Decode
Branch Execute
addi
GCLK1
addic
lwz
lwz
cmpi
blt
Bubble
addic
mulli
cmpi
cmpi
Bubble
mulli
lwz
Bubble
lwz
lwz
blt
lwz
blt
cmp
addic
addic
mulli
Fetch
Decode
Read + Execute
Writeback
L Address Drive
L Data
Load Writeback
Branch Decode
Branch Execute
addi
Branch Final
Decision
blt
GCLK1
Summary of Contents for MPC860 PowerQUICC
Page 3: ...MPC860UM AD 07 98 REV 1 MPC860 PowerQUICC ª UserÕs Manual ...
Page 36: ...xxxvi MPC860 PowerQUICC UserÕs Manual MOTOROLA CONTENTS Paragraph Number Title Page Number ...
Page 78: ...I iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 88: ...1 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 114: ...3 16 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part I Overview ...
Page 226: ...8 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
Page 262: ...9 36 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part II PowerPC Microprocessor Module ...
Page 274: ...III iv MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Page 320: ...12 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part III Configuration ...
Page 325: ...MOTOROLA Part IV Hardware Interface IV v Part IV Hardware Interface ...
Page 326: ...IV vi MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 352: ...13 26 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 394: ...14 42 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 426: ...15 32 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 530: ...17 26 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part IV Hardware Interface ...
Page 632: ...21 44 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 660: ...22 28 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 708: ...24 24 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 748: ...27 20 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 846: ...31 20 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 914: ...35 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 948: ...36 34 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part V The Communications Processor Module ...
Page 998: ...37 48 MPC860 PowerQUICC UserÕs Manual MOTOROLA Part VI Debug and Test ...
Page 1016: ...A 10 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1024: ...B 8 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1030: ...C 6 MPC860 PowerQUICC UserÕs Manual MOTOROLA Appendixes ...
Page 1086: ...Glossary 12 MPC860 PowerQUICC UserÕs Manual MOTOROLA ...
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