S390: [simulator] Initial 2-level jump table implementation

S390: [simulator] Initial 2-level jump table implementation

The old switch-case instruction decode implementation results in a
sparse table, which is not resolved by a fast jump table routing.
Therefore, it is really slow in instruction decoding phase.

R=joransiu@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com
BUG=

Committed: https://crrev.com/4b2b34f1186f575e2ba21aa8a87762cc00d4863b
Cr-Commit-Position: refs/heads/master@{#35589}

[john.yan, 2016-04-08 20:50:40]

PTAL

[JoranSiu, 2016-04-12 21:28:24]

Spoke with @john.yan.  We'd like to implement the EVALUATE_XX functions for the
top ~10 opcodes (accounts for ~2/3 of all simulated instructions) to validate
that this approach will speed up simulation execution before landing this CL.

[john.yan, 2016-04-18 14:37:53]

The CQ bit was checked by jyan@ca.ibm.com to run a CQ dry run

[commit-bot: I haz the power, 2016-04-18 14:38:00]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1873963002/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1873963002/60001

[JoranSiu, 2016-04-18 14:42:36]

lgtm

[commit-bot: I haz the power, 2016-04-18 14:58:09]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-04-18 14:58:10]

Dry run: This issue passed the CQ dry run.

[john.yan, 2016-04-18 16:11:58]

The CQ bit was checked by jyan@ca.ibm.com

[commit-bot: I haz the power, 2016-04-18 16:12:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1873963002/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1873963002/60001

[commit-bot: I haz the power, 2016-04-18 16:14:18]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2016-04-18 16:15:12]

Description was changed from

==========
S390: [simulator] Initial 2-level jump table implementation

The old switch-case instruction decode implementation results in a
sparse table, which is not resolved by a fast jump table routing.
Therefore, it is really slow in instruction decoding phase.

R=joransiu@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com
BUG=
==========

to

==========
S390: [simulator] Initial 2-level jump table implementation

The old switch-case instruction decode implementation results in a
sparse table, which is not resolved by a fast jump table routing.
Therefore, it is really slow in instruction decoding phase.

R=joransiu@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com
BUG=

Committed: https://crrev.com/4b2b34f1186f575e2ba21aa8a87762cc00d4863b
Cr-Commit-Position: refs/heads/master@{#35589}
==========

[commit-bot: I haz the power, 2016-04-18 16:15:13]

Patchset 4 (id:??) landed as
https://crrev.com/4b2b34f1186f575e2ba21aa8a87762cc00d4863b
Cr-Commit-Position: refs/heads/master@{#35589}