8371164: ArrayList.addAll() optimizations

[olivergillespie]

Hi all,

This pull request contains a backport of commit aeea8497 from the openjdk/jdk repository.

The commit being backported was authored by John Engebretson on 18 Nov 2025 and was reviewed by Stuart Marks and Oli Gillespie.

Almost clean, just a trivial conflict in the MOAT buglist (upstream has one extra bug mentioned). Plus copyright years.

Thanks!

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8371164 needs maintainer approval

Issue

• JDK-8371164: ArrayList.addAll() optimizations (Enhancement - P4 - Requested)

Reviewers

• Paul Hohensee (@phohensee - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk25u-dev.git pull/542/head:pull/542
$ git checkout pull/542

Update a local copy of the PR:
$ git checkout pull/542
$ git pull https://git.openjdk.org/jdk25u-dev.git pull/542/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 542

View PR using the GUI difftool:
$ git pr show -t 542

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk25u-dev/pull/542.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back ogillespie! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[mlbridge]

Webrevs

• 01: Full - Incremental (86dfa05e)
• 00: Full (e99df203)

[phohensee]

Copyright date in ArrayList.java should be 2025, not 2026. There should be no copyright date update in Collections.java and MOAT.java.

[olivergillespie]

Copyright date in ArrayList.java should be 2025, not 2026. There should be no copyright date update in Collections.java and MOAT.java.

Thanks. Why is that? Because the copyright is connected to the original contribution, not the backport?

[phohensee]

The rule is that copyright update happens only if the update is in the original commit. Reason as I understand it is that makes later updates more likely to be clean.

[openjdk]

⚠️ @olivergillespie This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[olivergillespie]

/approval request Performance improvement in core class. Some risk due to high exposure, but has been in tip for 6 months, and in 26 since release with no reported issues, and it's quite a simple isolated change. Backport is effectively clean.

[openjdk]

@olivergillespie
8371164: The approval request has been created successfully.