8315046: [Lilliput/JDK21] Cherry-pick: 8305896: Alternative full GC forwarding

[rkennke]

Let's cherry-pick the alternative full GC forwarding PR in its current state into Lilliput-21.
I needed to make some adjustments because PreservedMarks stuff has been refactored between 21 and 22.

Testing:

• hotspot_gc +UseAltGCForwarding
• hotspot_gc -UseAltGCForwarding

---

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

Issue

• JDK-8315046: [Lilliput/JDK21] Cherry-pick: 8305896: Alternative full GC forwarding (Enhancement - P4)

Reviewers

• Aleksey Shipilev (@shipilev - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/lilliput-jdk21u.git pull/3/head:pull/3
$ git checkout pull/3

Update a local copy of the PR:
$ git checkout pull/3
$ git pull https://git.openjdk.org/lilliput-jdk21u.git pull/3/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 3

View PR using the GUI difftool:
$ git pr show -t 3

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/lilliput-jdk21u/pull/3.diff

Webrev

Link to Webrev Comment

[bridgekeeper]

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

[mlbridge]

Webrevs

• 01: Full - Incremental (7e4e993f)
• 00: Full (fd29cbb7)

[openjdk]

@rkennke This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8315046: [Lilliput/JDK21] Cherry-pick: 8305896: Alternative full GC forwarding

Reviewed-by: shade

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been no new commits pushed to the lilliput branch. If another commit should be pushed before you perform the /integrate command, your PR will be automatically rebased. If you prefer to avoid any potential automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the lilliput branch, type /integrate in a new comment.

[rkennke]

/integrate

[openjdk]

Going to push as commit 882ff14.

[openjdk]

@rkennke Pushed as commit 882ff14.

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