8370039: GenShen: array copy SATB barrier improvements

[earthling-amzn]

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• JDK-8373116 needs maintainer approval
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8370039 needs maintainer approval

Issues

• JDK-8370039: GenShen: array copy SATB barrier improvements (Enhancement - P4 - Requested)
• JDK-8373116: Genshen: arraycopy_work should be always done for arrays in old gen during young concurrent marking (Bug - P3 - Requested)

Reviewers

• Kelvin Nilsen (@kdnilsen - no project role)
• Xiaolong Peng (@pengxiaolong - Author)
• Paul Hohensee (@phohensee - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk25u-dev.git pull/503/head:pull/503
$ git checkout pull/503

Update a local copy of the PR:
$ git checkout pull/503
$ git pull https://git.openjdk.org/jdk25u-dev.git pull/503/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 503

View PR using the GUI difftool:
$ git pr show -t 503

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk25u-dev/pull/503.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back wkemper! 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.

[openjdk]

⚠️ @earthling-amzn 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.

[mlbridge]

Webrevs

• 01: Full - Incremental (3382f005)
• 00: Full (2586fbfb)

[earthling-amzn]

/issue add JDK-8373116

[openjdk]

@earthling-amzn
Adding additional issue to issue list: 8373116: Genshen: arraycopy_work should be always done for arrays in old gen during young concurrent marking.

[kdnilsen]

Thanks.

[pengxiaolong]

Thanks for the effort on backport.

[earthling-amzn]

/approval request This changes fixes an issue that would cause the generational mode for Shenandoah to exercise the array copy barrier twice in some situations. It is a performance improvement and it also simplifies the code somewhat. This PR also contains a follow up fix.

[openjdk]

@earthling-amzn
8370039: The approval request has been created successfully.
8373116: The approval request has been created successfully.