 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| • |
Speculation
implies prediction
|
|
|
| • |
many
conditional branches are bimodal but not static
|
|
|
| • |
a
significant minority are dynamic - not bimodal
|
|
|
| • |
many
of those are correlated with other branches
|
|
|
| • |
analysis
of payoff matrix can tell you when it’s better to
|
|
execute
both branches - predication
|
|
|
| • |
many
branch predictor variants, including ‘selective’
|
|
|
predictor,
attempts to use best of several other
|
|
|
predictors
|
|
|
| • |
multi-issue
processors need to predict a trace of
|
|
|
branches
|
|
|
| • |
similar
ideas can be applied to other forms of
|
|
|
speculation,
including prefetching, load-no-allocate,
|
|
|
adaptive
load-exclusive, value prediction etc
|
|
