[crankshaft] Replace stub cache harvesting with a bit of type propagation

[crankshaft] Replace stub cache harvesting with a bit of type propagation

Harvesting maps from the stub cache for megamorphic ICs is both slow
(linear in the size of the stub cache) and imprecise (as it finds all
maps that have a cached handler for the given property name).
In the canonical megamorphic situation, this type feedback is useless
anyway. The interesting case is when we can filter it down to a single
map; however in these cases it is often possible to derive this map
just by looking at the HGraph, which is both faster and more reliable.

Committed: https://crrev.com/5aa2cb3bccbdf339827b3768b1a8f80338b773c7
Cr-Commit-Position: refs/heads/master@{#33998}

[Jakob Kummerow, 2016-02-10 12:46:20]

jkummerow@chromium.org changed reviewers:
+ verwaest@chromium.org

[Jakob Kummerow, 2016-02-10 12:46:21]

PTAL.

[Toon Verwaest, 2016-02-12 14:00:38]

lgtm. Thanks for getting rid of this stub-cache abuse.
The feedback is a bit brittle, but I guess we can wait for TF.

[Jakob Kummerow, 2016-02-12 14:04:00]

The CQ bit was checked by jkummerow@chromium.org

[commit-bot: I haz the power, 2016-02-12 14:04:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1669213003/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1669213003/40001

[commit-bot: I haz the power, 2016-02-12 15:03:52]

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

[commit-bot: I haz the power, 2016-02-12 15:03:52]

Try jobs failed on following builders:
  v8_linux_arm_rel on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_arm_rel/builds/13681)

[Jakob Kummerow, 2016-02-15 14:57:30]

The CQ bit was checked by jkummerow@chromium.org

[Jakob Kummerow, 2016-02-15 14:57:30]

The patchset sent to the CQ was uploaded after l-g-t-m from
verwaest@chromium.org
Link to the patchset: https://codereview.chromium.org/1669213003/#ps60001
(title: "rebased")

[commit-bot: I haz the power, 2016-02-15 14:57:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1669213003/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1669213003/60001

[commit-bot: I haz the power, 2016-02-15 15:21:37]

Committed patchset #4 (id:60001)

[commit-bot: I haz the power, 2016-02-15 15:22:06]

Description was changed from

==========
[crankshaft] Replace stub cache harvesting with a bit of type propagation

Harvesting maps from the stub cache for megamorphic ICs is both slow
(linear in the size of the stub cache) and imprecise (as it finds all
maps that have a cached handler for the given property name).
In the canonical megamorphic situation, this type feedback is useless
anyway. The interesting case is when we can filter it down to a single
map; however in these cases it is often possible to derive this map
just by looking at the HGraph, which is both faster and more reliable.
==========

to

==========
[crankshaft] Replace stub cache harvesting with a bit of type propagation

Harvesting maps from the stub cache for megamorphic ICs is both slow
(linear in the size of the stub cache) and imprecise (as it finds all
maps that have a cached handler for the given property name).
In the canonical megamorphic situation, this type feedback is useless
anyway. The interesting case is when we can filter it down to a single
map; however in these cases it is often possible to derive this map
just by looking at the HGraph, which is both faster and more reliable.

Committed: https://crrev.com/5aa2cb3bccbdf339827b3768b1a8f80338b773c7
Cr-Commit-Position: refs/heads/master@{#33998}
==========

[commit-bot: I haz the power, 2016-02-15 15:22:07]

Patchset 4 (id:??) landed as
https://crrev.com/5aa2cb3bccbdf339827b3768b1a8f80338b773c7
Cr-Commit-Position: refs/heads/master@{#33998}