[FeedbackVector] Clarify the way the feedback vector is installed.

[FeedbackVector] Clarify the way the feedback vector is installed.

Installing a feedback vector in a closure is a multi-step process.
The closure actually points to a Cell that points to a feedback
vector or undefined if we haven't created one yet.
This happens because we often create closures before we've compiled
the code.

JSFunction::EnsureLiterals is the bottleneck in our system that
creates a feedback vector if necessary. The predicates it used to
determine what to do were arcane. This CL allows it to think it
terms of state, and clarifies the reading of that useful
bottleneck.

I also did a few renamings in parts of the code that referred
to a "literals array," which we don't have any more.

BUG=

Review-Url: https://codereview.chromium.org/2681773004
Cr-Commit-Position: refs/heads/master@{#43035}
Committed: https://chromium.googlesource.com/v8/v8/+/a1bba7fe3b9e52a5c5f556060b563427404231be

[mvstanton, 2017-02-08 10:03:54]

mvstanton@chromium.org changed reviewers:
+ ishell@chromium.org

[mvstanton, 2017-02-08 10:03:54]

Hi Igor,
Here is some cleanup that accumulated in the last weeks. PTAL, thanks!

[mvstanton, 2017-02-08 10:08:02]

Description was changed from

==========
[TypeFeedbackVector] Clarify the way the feedback vector is installed.

Installing a feedback vector in a closure is a multi-step process.
The closure actually points to a Cell that points to a feedback
vector or undefined if we haven't created one yet.
This happens because we often create closures before we've compiled
the code.

JSFunction::EnsureLiterals is the bottleneck in our system that
creates a feedback vector if necessary. The predicates it used to
determine what to do were arcane. This CL allows it to think it
terms of state, and clarifies the reading of that useful
bottleneck.

I also did a few renamings in parts of the code that referred
to a "literals array," which we don't have any more.

BUG=
==========

to

==========
[FeedbackVector] Clarify the way the feedback vector is installed.

Installing a feedback vector in a closure is a multi-step process.
The closure actually points to a Cell that points to a feedback
vector or undefined if we haven't created one yet.
This happens because we often create closures before we've compiled
the code.

JSFunction::EnsureLiterals is the bottleneck in our system that
creates a feedback vector if necessary. The predicates it used to
determine what to do were arcane. This CL allows it to think it
terms of state, and clarifies the reading of that useful
bottleneck.

I also did a few renamings in parts of the code that referred
to a "literals array," which we don't have any more.

BUG=
==========

[Igor Sheludko, 2017-02-08 10:24:11]

lgtm with nits:

https://codereview.chromium.org/2681773004/diff/1/src/objects.cc
File src/objects.cc (right):

https://codereview.chromium.org/2681773004/diff/1/src/objects.cc#newcode12113
src/objects.cc:12113: FeedbackVectorState state =
function->GetFeedbackVectorState();
Maybe it makes sense to pass an isolate that we already have here.

https://codereview.chromium.org/2681773004/diff/1/src/objects.cc#newcode12126
src/objects.cc:12126: // Re-get the feedback_vector() value as GC may have
occurred.
I think this comment does not make sense anymore.

[mvstanton, 2017-02-08 10:36:36]

The CQ bit was checked by mvstanton@chromium.org

[mvstanton, 2017-02-08 10:36:36]

The patchset sent to the CQ was uploaded after l-g-t-m from ishell@chromium.org
Link to the patchset: https://codereview.chromium.org/2681773004/#ps20001
(title: "Code comments+REBASE.")

[commit-bot: I haz the power, 2017-02-08 10:36:39]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-02-08 11:51:08]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1486550196132850,
"parent_rev": "0c137304e6e9ff6d6e627260f2877ba1944738c4", "commit_rev":
"a1bba7fe3b9e52a5c5f556060b563427404231be"}

[commit-bot: I haz the power, 2017-02-08 11:51:11]

Description was changed from

==========
[FeedbackVector] Clarify the way the feedback vector is installed.

Installing a feedback vector in a closure is a multi-step process.
The closure actually points to a Cell that points to a feedback
vector or undefined if we haven't created one yet.
This happens because we often create closures before we've compiled
the code.

JSFunction::EnsureLiterals is the bottleneck in our system that
creates a feedback vector if necessary. The predicates it used to
determine what to do were arcane. This CL allows it to think it
terms of state, and clarifies the reading of that useful
bottleneck.

I also did a few renamings in parts of the code that referred
to a "literals array," which we don't have any more.

BUG=
==========

to

==========
[FeedbackVector] Clarify the way the feedback vector is installed.

Installing a feedback vector in a closure is a multi-step process.
The closure actually points to a Cell that points to a feedback
vector or undefined if we haven't created one yet.
This happens because we often create closures before we've compiled
the code.

JSFunction::EnsureLiterals is the bottleneck in our system that
creates a feedback vector if necessary. The predicates it used to
determine what to do were arcane. This CL allows it to think it
terms of state, and clarifies the reading of that useful
bottleneck.

I also did a few renamings in parts of the code that referred
to a "literals array," which we don't have any more.

BUG=

Review-Url: https://codereview.chromium.org/2681773004
Cr-Commit-Position: refs/heads/master@{#43035}
Committed:
https://chromium.googlesource.com/v8/v8/+/a1bba7fe3b9e52a5c5f556060b563427404...
==========

[commit-bot: I haz the power, 2017-02-08 11:51:13]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/v8/v8/+/a1bba7fe3b9e52a5c5f556060b563427404...