8321225: [JVMCI] HotSpotResolvedObjectTypeImpl.isLeafClass shouldn't create strong references

[tkrodriguez]

Checking for leaf Klasses requires seeing if the subklass field is null. As part of the fix for JVMCI support for ZGC, JDK-8299229, it was changed to call into the runtime which had the side effect of creating a strong reference to an the class. Since it's only checking for non-null it's ok to just perform thread directly as was done prior to JDK-8299229. This avoids causing class unloading problems.

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Issue

• JDK-8321225: [JVMCI] HotSpotResolvedObjectTypeImpl.isLeafClass shouldn't create strong references (Bug - P3)

Reviewers

• Tobias Hartmann (@TobiHartmann - Reviewer)
• Erik Österlund (@fisk - Reviewer)
• Vladimir Kozlov (@vnkozlov - Reviewer)

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[openjdk]

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[mlbridge]

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• 00: Full (2467c5a5)

[TobiHartmann]

Looks reasonable to me.

[openjdk]

@tkrodriguez 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:

8321225: [JVMCI] HotSpotResolvedObjectTypeImpl.isLeafClass shouldn't create strong references

Reviewed-by: thartmann, eosterlund, kvn

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 35 new commits pushed to the master branch:

• 027b5db: 8321215: Incorrect x86 instruction encoding for VSIB addressing mode
• 61d0db3: 8318468: compiler/tiered/LevelTransitionTest.java fails with -XX:CompileThreshold=100 -XX:TieredStopAtLevel=1
• 87516e2: 8320943: Files/probeContentType/Basic.java fails on latest Windows 11 - content type mismatch
• 800f347: 8321216: SerialGC attempts to access the card table beyond the end of the heap during card table scan
• a1fe16b: 8321300: Cleanup TestHFA
• 5b02188: 8321105: Enable UseCryptoPmullForCRC32 for Neoverse V2
• 4fbf22b: 8320652: ThreadInfo.isInNative needs to be updated to say what executing native code means
• 672f373: 8321163: [test] OutputAnalyzer.getExitValue() unnecessarily logs even when process has already completed
• 30817b7: 8317809: Insertion of free code blobs into code cache can be very slow during class unloading
• a56286f: 8321269: Require platforms to define DEFAULT_CACHE_LINE_SIZE
• ... and 25 more: https://git.openjdk.org/jdk/compare/949846986f572dfb82912e7d71e7bfd37a90871e...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.

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

[fisk]

Looks good. I suppose this can yield some false negatives when the link isn't null but the subclass is concurrently unloading. But that probably doesn't matter, and you would have received the same negative answer had it been asked a bit earlier.

[vnkozlov]

Looks good to me.

[vnkozlov]

java/util/stream/GathererTest.java failure in GHA is known issue.

[tkrodriguez]

Yes the possible negative answer just seems like a race that could end up happening either way depending when you compile.

Thanks for the reviews. Testing was clean.

/integrate

[openjdk]

Going to push as commit fddc02e.
Since your change was applied there have been 41 commits pushed to the master branch:

• 640d7f3: 8314327: Issues with JShell when using "local" execution engine
• db5613a: 8317288: [macos] java/awt/Window/Grab/GrabTest.java: Press on the outside area didn't cause ungrab
• b1cb374: 8320349: Simplify FileChooserSymLinkTest.java by using single-window testUI
• 18c7922: 8321224: ct.sym for JDK 22 contains references to internal modules
• 83ffc1a: 8320303: Allow PassFailJFrame to accept single window creator
• fd31f6a: 8321183: Incorrect warning from cds about the modules file
• 027b5db: 8321215: Incorrect x86 instruction encoding for VSIB addressing mode
• 61d0db3: 8318468: compiler/tiered/LevelTransitionTest.java fails with -XX:CompileThreshold=100 -XX:TieredStopAtLevel=1
• 87516e2: 8320943: Files/probeContentType/Basic.java fails on latest Windows 11 - content type mismatch
• 800f347: 8321216: SerialGC attempts to access the card table beyond the end of the heap during card table scan
• ... and 31 more: https://git.openjdk.org/jdk/compare/949846986f572dfb82912e7d71e7bfd37a90871e...master

Your commit was automatically rebased without conflicts.

[openjdk]

@tkrodriguez Pushed as commit fddc02e.

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