8352914: Shenandoah: Change definition of ShenandoahSharedValue to int32_t to leverage platform atomics

[benty-amzn]

The STATIC_ASSERT below this typedef appears to be out of date.

The barriers check thread local copy of gc state, which is stored in ShenandoahThreadLocalData::_gc_state and is type char, so the size requirement described by the assert is maintained even after this change.

Change passes all tier1 tests locally when run with Shenandoah GC.

---

Progress

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Issue

• JDK-8352914: Shenandoah: Change definition of ShenandoahSharedValue to int32_t to leverage platform atomics (Enhancement - P4)

Reviewers

• William Kemper (@earthling-amzn - Reviewer)
• Y. Srinivas Ramakrishna (@ysramakrishna - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/28681/head:pull/28681
$ git checkout pull/28681

Update a local copy of the PR:
$ git checkout pull/28681
$ git pull https://git.openjdk.org/jdk.git pull/28681/head

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Checkout this PR locally:
$ git pr checkout 28681

View PR using the GUI difftool:
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https://git.openjdk.org/jdk/pull/28681.diff

Using Webrev

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[bridgekeeper]

👋 Welcome back btaylor! 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]

@benty-amzn 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:

8352914: Shenandoah: Change definition of ShenandoahSharedValue to int32_t to leverage platform atomics

Reviewed-by: wkemper, ysr

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 29 new commits pushed to the master branch:

• 8df3f3d: 8373117: Update build doc link in README.md
• b118caf: 8373285: Update JCov for class file version 71
• d34ef19: 8370198: Test gc/arguments/TestShrinkHeapInSteps.java crashed: assert(left >= right) failed: avoid underflow
• ... and 26 more: https://git.openjdk.org/jdk/compare/5ec5a6ea6c8e887b4e21f81e382f57129bffbab8...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@earthling-amzn, @ysramakrishna) but any other Committer may sponsor as well.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

[openjdk]

@benty-amzn The following labels will be automatically applied to this pull request:

• hotspot-gc
• shenandoah

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing lists. If you would like to change these labels, use the /label pull request command.

[mlbridge]

Webrevs

• 00: Full (90923ab3)

[earthling-amzn]

/reviewers 2

This looks good to me, but would appreciate another reviewer.

[openjdk]

@earthling-amzn
The total number of required reviews for this PR (including the jcheck configuration and the last /reviewers command) is now set to 2 (with at least 1 Reviewer, 1 Author).

[ysramakrishna]

Any comparative performance numbers?

🚢

[benty-amzn]

I will check some performance numbers before and after this patch.

/integrate

[openjdk]

@benty-amzn
Your change (at version 90923ab) is now ready to be sponsored by a Committer.

[ysramakrishna]

/sponsor

[openjdk]

Going to push as commit b86b2cb.
Since your change was applied there have been 29 commits pushed to the master branch:

• 8df3f3d: 8373117: Update build doc link in README.md
• b118caf: 8373285: Update JCov for class file version 71
• d34ef19: 8370198: Test gc/arguments/TestShrinkHeapInSteps.java crashed: assert(left >= right) failed: avoid underflow
• ... and 26 more: https://git.openjdk.org/jdk/compare/5ec5a6ea6c8e887b4e21f81e382f57129bffbab8...master

Your commit was automatically rebased without conflicts.

[openjdk]

@ysramakrishna @benty-amzn Pushed as commit b86b2cb.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.