Review Board 2.0.15


cpu: Resolve targets of predicted 'taken' conditional direct branches at decode (o3)

Review Request #3710 - Created Nov. 17, 2016 and submitted - Latest diff uploaded

Information
Arthur Perais
gem5
Reviewers
Default

Changeset 11707:1d085f66c4ca

cpu: Resolve targets of predicted 'taken' conditional direct branches at decode (o3)

The target of taken conditional direct branches does not
need to be resolved in IEW: the target can be computed at
decode, usually using the decoded instruction word and the PC.

The higher-than-necessary penalty is taken only on conditional
branches that are predicted taken but miss in the BTB. Thus,
this is mostly inconsequential on IPC if the BTB is big/associative
enough (fewer capacity/conflict misses). Nonetheless, what gem5
simulates is not representative of how conditional branch targets
can be handled.

util/regress --modes=se

build/NULL/tests/opt/quick/se/51.memcheck/null/none/memcheck: FAILED! (Python says "NameError: name 'TrafficGen' is not defined"). I'm guessing this is OK as I get the same error without my patch.