8338538: [JVMCI] Allow HotSpotJVMCIRuntime#getJObjectValue to be called by a HotSpot CompileBroker compiler thread

[tzezula]

The HotSpotJVMCIRuntime#getJObjectValue method is currently invoked in two distinct scenarios:

Truffle Compiler: In this scenario, the method is called by a Truffle compiler thread. This thread is an ordinary Java thread that enters the shared library compiler (libgraal) via a Java native method call. Consequently, it always has a valid JavaFrameAnchor when invoking HotSpotJVMCIRuntime#getJObjectValue within the shared library compiler.

Host Compiler: In the second scenario, the method is called by a HotSpot CompileBroker compiler thread while inlining a Truffle call target into a host method. Here, the compiler thread is a JavaThread in the _thread_in_vm state before entering the shared library compiler (libgraal) and does not have a JavaFrameAnchor.

The HotSpotJVMCIRuntime#getJObjectValue method currently supports only the first scenario by asserting that the caller has a JavaFrameAnchor. However, this method should be adapted to also support the second scenario, where the caller thread lacks a JavaFrameAnchor but has an explicitly pushed JNI handle block. It is crucial that the HotSpotJVMCIRuntime#getJObjectValue method ensures it does not use the top-most JNIHandleBlock, which is never released. Utilizing this block for Java constants could potentially lead to memory leaks in the Java heap. To accommodate both scenarios, the method should be modified to allow execution also by threads without a JavaFrameAnchor provided they have an explicitly pushed JNI handle block.

Implementation Details: The method determines whether the caller thread has pushed a JNI handle block by using THREAD->active_handles()->pop_frame_link(). The pop_frame_link is set when JavaThread::push_jni_handle_block is called and is reset in JavaThread::pop_jni_handle_block. Each active JavaThread has a non-null _active_handles pointer, which is initialized in JavaThread::run.

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Progress

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Issue

• JDK-8338538: [JVMCI] Allow HotSpotJVMCIRuntime#getJObjectValue to be called by a HotSpot CompileBroker compiler thread (Enhancement - P4)

Reviewers

• Doug Simon (@dougxc - Reviewer)

Reviewing

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Update a local copy of the PR:
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$ git pull https://git.openjdk.org/jdk.git pull/20620/head

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$ git pr checkout 20620

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$ git pr show -t 20620

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https://git.openjdk.org/jdk/pull/20620.diff

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[bridgekeeper]

👋 Welcome back tzezula! 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]

@tzezula 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:

8338538: [JVMCI] Allow HotSpotJVMCIRuntime#getJObjectValue to be called by a HotSpot CompileBroker compiler thread

Reviewed-by: dnsimon

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 70 new commits pushed to the master branch:

• 3f00da8: 8338906: Avoid passing EnumDescs and extra classes to type switch methods that don't use them
• e63418e: 8338979: Avoid bootstrapped switches in the classfile API
• 20d8f58: 8331671: Implement JEP 472: Prepare to Restrict the Use of JNI
• ce83f6a: 8338844: C2: remove useless code in PhaseIdealLoop::place_outside_loop() after 8335709
• 0c14579: 8336830: C2: assert(get_loop(lca)->_nest < n_loop->_nest || lca->in(0)->is_NeverBranch()) failed: must not be moved into inner loop
• 5671f83: 8338785: The java.awt.datatransfer.SystemFlavorMap#FLAVOR_MAP_KEY field is not used
• 32b3d70: 8338925: ProblemList runtime/interpreter/LastJsrTest.java on linux-all
• 5d12ac3: 8337715: Update --release 23 symbol information for JDK 23 build 37
• 23dc3b0: 8324048: (fc) Make FileKey fields final
• a461369: 8338700: AttributeMapper type parameter should be bounded by Attribute
• ... and 60 more: https://git.openjdk.org/jdk/compare/8635642dbdfb74d2ae50a51611fd2c5980fe6e74...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 (@dougxc) 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]

@tzezula The following labels will be automatically applied to this pull request:

• graal
• hotspot-compiler

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

• 01: Full - Incremental (aa3838e1)
• 00: Full (03010245)

[openjdk]

⚠️ @tzezula the full name on your profile does not match the author name in this pull requests' HEAD commit. If this pull request gets integrated then the author name from this pull requests' HEAD commit will be used for the resulting commit. If you wish to push a new commit with a different author name, then please run the following commands in a local repository of your personal fork:

$ git checkout JDK-8338538
$ git commit --author='Preferred Full Name <you@example.com>' --allow-empty -m 'Update full name'
$ git push

[tzezula]

/integrate

[openjdk]

@tzezula
Your change (at version aa3838e) is now ready to be sponsored by a Committer.

[dougxc]

/sponsor

[openjdk]

Going to push as commit a15af69.
Since your change was applied there have been 70 commits pushed to the master branch:

• 3f00da8: 8338906: Avoid passing EnumDescs and extra classes to type switch methods that don't use them
• e63418e: 8338979: Avoid bootstrapped switches in the classfile API
• 20d8f58: 8331671: Implement JEP 472: Prepare to Restrict the Use of JNI
• ce83f6a: 8338844: C2: remove useless code in PhaseIdealLoop::place_outside_loop() after 8335709
• 0c14579: 8336830: C2: assert(get_loop(lca)->_nest < n_loop->_nest || lca->in(0)->is_NeverBranch()) failed: must not be moved into inner loop
• 5671f83: 8338785: The java.awt.datatransfer.SystemFlavorMap#FLAVOR_MAP_KEY field is not used
• 32b3d70: 8338925: ProblemList runtime/interpreter/LastJsrTest.java on linux-all
• 5d12ac3: 8337715: Update --release 23 symbol information for JDK 23 build 37
• 23dc3b0: 8324048: (fc) Make FileKey fields final
• a461369: 8338700: AttributeMapper type parameter should be bounded by Attribute
• ... and 60 more: https://git.openjdk.org/jdk/compare/8635642dbdfb74d2ae50a51611fd2c5980fe6e74...master

Your commit was automatically rebased without conflicts.

[openjdk]

@dougxc @tzezula Pushed as commit a15af69.

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