8354890: AOT-initialize j.l.i.MethodHandleImpl and inner classes #24956

iklam · 2025-04-29T22:59:29Z

This is a general fix for all the "points to a static field that may hold a different value" failures related to java/lang/invoke/MethodHandleImpl. E.g., JDK-8354840, JDK-8353330.

AOT-cached method handles quite often refer to the static fields in MethodHandleImpl or its inner classes. In the production run, if the value of these static field changes, we may have unexpected behavior related to identity of objects in these static fields. CDSHeapVerifier makes a very conservative check for such static fields, but sometimes gives false positives (as in the above two JBS issues)

In this PR, we AOT-initialize MethodHandleImpl and its inner classes. This is a more authentic snapshot of the state of java.lang.invoke during the assembly phase. We also avoid the need to add and maintain entries in the cdsHeapVerifier.cpp table.

I also added more code in MethodHandleTest.java to simulate potential usage patterns of MethodHandle by the Java core libraries. Hopefully this will reduce the likelihood for innocent core lib changes breaking the AOT assembly phase.

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Change must not contain extraneous whitespace
Commit message must refer to an issue
Change must be properly reviewed (2 reviews required, with at least 2 Reviewers)

Issue

JDK-8354890: AOT-initialize j.l.i.MethodHandleImpl and inner classes (Enhancement - P3)

Reviewers

Chen Liang (@liach - Reviewer)
Vladimir Ivanov (@iwanowww - Reviewer)

Reviewing

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Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/24956/head:pull/24956
$ git checkout pull/24956

Update a local copy of the PR:
$ git checkout pull/24956
$ git pull https://git.openjdk.org/jdk.git pull/24956/head

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Checkout this PR locally:
$ git pr checkout 24956

View PR using the GUI difftool:
$ git pr show -t 24956

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https://git.openjdk.org/jdk/pull/24956.diff

Using Webrev

Link to Webrev Comment

…en repo)

@fisk

…ptions on GC behavior. Suggested by @fisk

…/hotspot/jtreg/runtime/invokedynamic"

…DanHeidinga

…DanHeidinga comment -- renamed to MethodType::assemblySetup()

…r AOTReferenceObjSupport::is_enabled()

bridgekeeper · 2025-04-29T23:00:18Z

👋 Welcome back iklam! A progress list of the required criteria for merging this PR into pr/24757 will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2025-04-29T23:01:17Z

@iklam 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:

8354890: AOT-initialize j.l.i.MethodHandleImpl and inner classes

Reviewed-by: liach, vlivanov

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 master 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 master branch, type /integrate in a new comment.

openjdk · 2025-04-29T23:01:49Z

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

core-libs
hotspot

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-notifier · 2025-04-30T18:10:21Z

The parent pull request that this pull request depends on has now been integrated and the target branch of this pull request has been updated. This means that changes from the dependent pull request can start to show up as belonging to this pull request, which may be confusing for reviewers. To remedy this situation, simply merge the latest changes from the new target branch into this pull request by running commands similar to these in the local repository for your personal fork:

git checkout 8354890-aot-init-methodhandleimpl-and-inner-classes
git fetch https://git.openjdk.org/jdk.git master
git merge FETCH_HEAD
# if there are conflicts, follow the instructions given by git merge
git commit -m "Merge master"
git push

openjdk · 2025-04-30T18:11:09Z

@iklam this pull request can not be integrated into master due to one or more merge conflicts. To resolve these merge conflicts and update this pull request you can run the following commands in the local repository for your personal fork:

git checkout 8354890-aot-init-methodhandleimpl-and-inner-classes
git fetch https://git.openjdk.org/jdk.git master
git merge FETCH_HEAD
# resolve conflicts and follow the instructions given by git merge
git commit -m "Merge master"
git push

…r-classes

…patterns for MethodHandles

iklam · 2025-04-30T21:44:11Z

src/hotspot/share/oops/instanceKlass.cpp

+    // of <clinit>
+    initialize(CHECK);
+    return;
+  }


This change is to avoid deadlock in the previous implementation.

mlbridge · 2025-04-30T21:48:56Z

Webrevs

liach

The tests look good to me.

liach · 2025-04-30T21:49:04Z

src/java.base/share/classes/java/lang/invoke/MethodHandleImpl.java

@@ -1525,7 +1525,12 @@ private static NamedFunction createFunction(byte func) {
        }
    }

+    // Called from JVM when loading an AOT cache


Suggested change

// Called from JVM when loading an AOT cache

liach · 2025-04-30T21:49:12Z

src/java.base/share/classes/java/lang/invoke/MethodHandleImpl.java

+
+    private static void runtimeSetup() {


Suggested change

private static void runtimeSetup() {

// Called from JVM when loading an AOT cache

private static void runtimeSetup() {

Same problem in Reference, credit to @ExE-Boss

liach · 2025-04-30T21:52:52Z

test/hotspot/jtreg/runtime/cds/appcds/aotClassLinking/MethodHandleTest.java

+            throw new RuntimeException("o has wrong interfaces");
+        }
+
+        statementEnum(MyEnum.A);


String s = statementEnum(MyEnum.A); if (!s.equals("A")) { throw new RuntimeException("enum switch incorrect"); }

adinn · 2025-05-01T18:52:22Z

@iklam We have seen this problem with Red Hat deployments in jdk24 as well as jdk25-ea.

I'm saying that mostly for information. However, I do have to ask: If this is fixed for jdk25 is there any question of also fixing it in jdk24? I would be content to receive a no answer -- a similar issue with patch that could be backported from jdk26 -> jdk25 might be something to think about a bit more?

iklam · 2025-05-05T23:41:40Z

@iklam We have seen this problem with Red Hat deployments in jdk24 as well as jdk25-ea.

I'm saying that mostly for information. However, I do have to ask: If this is fixed for jdk25 is there any question of also fixing it in jdk24? I would be content to receive a no answer -- a similar issue with patch that could be backported from jdk26 -> jdk25 might be something to think about a bit more?

Backporting this to jdk 24 would require a lot of effort. I think it might be easier to update CDSHeapVerifier to add more rules to filter out the false positives. CDSHeapVerifier is too conservative and reports error for things that are actually OK.

liach

The Java code change and the BSM coverage looks good to me. Requiring another reviewer for hotspot changes.

/reviewers 2 reviewer

openjdk · 2025-05-05T23:51:44Z

@liach
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 2 Reviewers).

iwanowww

Looks good.

…r-classes

iklam · 2025-05-09T05:59:22Z

Thanks @liach @iwanowww for the review
/integrate

openjdk · 2025-05-09T06:00:27Z

Going to push as commit 591e71e.
Since your change was applied there has been 1 commit pushed to the master branch:

53ad4b2: 8355364: [REDO] Missing REX2 prefix accounting in ZGC barriers leads to incorrect encoding

Your commit was automatically rebased without conflicts.

openjdk · 2025-05-09T06:00:35Z

@iklam Pushed as commit 591e71e.

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

Mat Carter and others added 16 commits April 17, 2025 20:13

8354897: Support Soft/Weak Reference in AOT cache (imported from Leyd…

a23331a

…en repo)

Added code to process Universe::reference_pending_list()

c6beb85

Avoid the need to Universe::reference_pending_list() and remove assum…

2d82e36

…ptions on GC behavior. Suggested by @fisk

Added missing files

dc5ad26

cleaned up test cases

2544cc7

Merge branch 'master' into 8354897-soft-weak-references-in-aot-cache

6678482

Work around hotspot/jtreg/sources/TestNoNULL.java

1898399

Fixed error when running "make test JTREG=AOT_JDK=true TEST=open/test…

73786f2

…/hotspot/jtreg/runtime/invokedynamic"

Refactored code

2c31ca7

Fixed windows path issues

643eec2

@fisk comment

bba16ee

@DanHeidinga comments

a25aab0

@fisk offline comments -- tighten up and simplify eligibility check; @…

331acfa

…DanHeidinga comment -- renamed to MethodType::assemblySetup()

Merge branch 'master' into 8354897-soft-weak-references-in-aot-cache

7021656

@fisk comment -- use proper HeapAccess to load referent; Also refacto…

01f0ea0

…r AOTReferenceObjSupport::is_enabled()

8354890: AOT-initialize j.l.i.MethodHandleImpl and inner classes

d0929ac

openjdk bot added hotspot [email protected] core-libs [email protected] labels Apr 29, 2025

openjdk-notifier bot changed the base branch from pr/24757 to master April 30, 2025 18:10

openjdk bot added the merge-conflict Pull request has merge conflict with target branch label Apr 30, 2025

Merge branch 'master' into 8354890-aot-init-methodhandleimpl-and-inne…

31bbf4c

…r-classes

openjdk bot removed the merge-conflict Pull request has merge conflict with target branch label Apr 30, 2025

Added more test case to increase coverage on possible core-lib usage …

0f6a2e0

…patterns for MethodHandles

iklam commented Apr 30, 2025

View reviewed changes

iklam marked this pull request as ready for review April 30, 2025 21:44

openjdk bot added the rfr Pull request is ready for review label Apr 30, 2025

liach reviewed Apr 30, 2025

View reviewed changes

Comments from @liach and @ExE-Boss

a1e3743

liach approved these changes May 5, 2025

View reviewed changes

openjdk bot added the ready Pull request is ready to be integrated label May 5, 2025

openjdk bot removed the ready Pull request is ready to be integrated label May 5, 2025

iwanowww approved these changes May 8, 2025

View reviewed changes

openjdk bot added the ready Pull request is ready to be integrated label May 8, 2025

Merge branch 'master' into 8354890-aot-init-methodhandleimpl-and-inne…

0571ddc

…r-classes

openjdk bot added the integrated Pull request has been integrated label May 9, 2025

openjdk bot closed this May 9, 2025

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels May 9, 2025

8354890: AOT-initialize j.l.i.MethodHandleImpl and inner classes #24956

8354890: AOT-initialize j.l.i.MethodHandleImpl and inner classes #24956

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