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8382277: Shenandoah: Improve mutator runtime entry points#30750

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shipilev:JDK-8382277-shenandoah-mutator-entry-points
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8382277: Shenandoah: Improve mutator runtime entry points#30750
shipilev wants to merge 3 commits intoopenjdk:masterfrom
shipilev:JDK-8382277-shenandoah-mutator-entry-points

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@shipilev shipilev commented Apr 15, 2026 •
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This is a separate part of Shenandoah LBE work. On some workloads, the LRB-weak path is very hot, and little optimizations are paying off there.

Currently, we call into load_reference_barrier_mutator for strong loads, and to "normal" load_reference_barrier for weak/phantom loads. This means we are risking two things: a) a performance penalty if compiler does not inline through the Decorator value; b) exposing to interaction with JVMTI/JFR that *forwardee_mutator is protecting us from.

Additional testing:

  • Performance tests (pending)
  • Linux x86_64 server fastdebug, hotspot_gc_shenandoah

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  • Change must not contain extraneous whitespace
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  • Change must be properly reviewed (2 reviews required, with at least 1 Reviewer, 1 Author)

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  • JDK-8382277: Shenandoah: Improve mutator runtime entry points (Enhancement - P4)

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bridgekeeper Bot commented Apr 15, 2026

👋 Welcome back shade! 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.

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openjdk Bot commented Apr 15, 2026 •
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@shipilev 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:

8382277: Shenandoah: Improve mutator runtime entry points

Reviewed-by: kdnilsen, xpeng, rkennke

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 62 new commits pushed to the master branch:

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.

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

@openjdk openjdk Bot added hotspot-gc hotspot-gc-dev@openjdk.org shenandoah shenandoah-dev@openjdk.org labels Apr 15, 2026
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openjdk Bot commented Apr 15, 2026 •
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@shipilev 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.

@openjdk openjdk Bot added the rfr Pull request is ready for review label Apr 15, 2026
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mlbridge Bot commented Apr 15, 2026 •
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rkennke
rkennke approved these changes Apr 16, 2026
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This is a nice improvement! Just one small question. No need for another review, if you choose to change it.

Comment thread src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp Outdated
@openjdk openjdk Bot added the ready Pull request is ready to be integrated label Apr 16, 2026
@openjdk openjdk Bot removed the ready Pull request is ready to be integrated label Apr 16, 2026
kdnilsen
kdnilsen approved these changes Apr 16, 2026
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Thanks for all your work on these barrier improvements.

@openjdk openjdk Bot added the ready Pull request is ready to be integrated label Apr 16, 2026
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openjdk Bot commented Apr 16, 2026

The total number of required reviews for this PR has been set to 2 based on the presence of this label: hotspot-gc. This can be overridden with the /reviewers command.

@openjdk openjdk Bot removed the ready Pull request is ready to be integrated label Apr 16, 2026
pengxiaolong
pengxiaolong approved these changes Apr 20, 2026
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Thanks, looks good.

@openjdk openjdk Bot added the ready Pull request is ready to be integrated label Apr 20, 2026
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shipilev commented Apr 21, 2026

Thanks! Here goes.

/integrate

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openjdk Bot commented Apr 21, 2026

Going to push as commit 7d1ce05.
Since your change was applied there have been 66 commits pushed to the master branch:

Your commit was automatically rebased without conflicts.

@openjdk openjdk Bot added the integrated Pull request has been integrated label Apr 21, 2026
@openjdk openjdk Bot closed this Apr 21, 2026
@openjdk openjdk Bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Apr 21, 2026
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openjdk Bot commented Apr 21, 2026

@shipilev Pushed as commit 7d1ce05.

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

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3 more reviewers

@rkennke rkennke rkennke approved these changes

@pengxiaolong pengxiaolong pengxiaolong approved these changes

@kdnilsen kdnilsen kdnilsen approved these changes

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