8353182: [lworld] C2: Multiple IR test failures in compiler/gcbarriers/TestZGCBarrierElision.java after JDK-8351569

[dafedafe]

This is a very similar issue to JDK-8343420.

A few TestZGCBarrierElision tests fail after JDK-8351569. These tests check that ZGC barrier elision optimization does not elide necessary barriers and partially do so using VarHandle::getAndSet and checking that GetAndSetP nodes with barriers are created.
As found out in JDK-8343420, JDK-8351569 refactored Unsafe::getAndSet (which is used by VarHandle::getAndSet) to take value-classes into account, which implies that checks must be introduced to see if the target and argument objects are value-classes. This is done with a new overloaded getAndSet method that is now called instead of the old one. This method is not intrinsified (only inlined) and doesn't result in a GetAndSet node. It instead relies on the compareAndSet method (which gets intrinsified) and results in a CompareAndSwap node.

Here as well, as the goal of the test is mainly to check for ZGC barrier presence, the sensible fix for now seems to be to modify the TestZGCBarrierElision tests to make them check for CompareAndSwap instead of GetAndSet nodes.

Tests: Tier 1-3+

---

Progress

• Change must not contain extraneous whitespace

Issue

• JDK-8353182: [lworld] C2: Multiple IR test failures in compiler/gcbarriers/TestZGCBarrierElision.java after JDK-8351569 (Bug - P4)

Reviewers

• Tobias Hartmann (@TobiHartmann - Committer)

Reviewing

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[bridgekeeper]

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

[openjdk]

@dafedafe This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8353182: [lworld] C2: Multiple IR test failures in compiler/gcbarriers/TestZGCBarrierElision.java after JDK-8351569

Reviewed-by: thartmann

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[openjdk]

@dafedafe this pull request can not be integrated into lworld 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 JDK-8353182
git fetch https://git.openjdk.org/valhalla.git lworld
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[mlbridge]

Webrevs

• 01: Full (b3ab62f9)
• 00: Full (6fdc6fbe)

[TobiHartmann]

Thanks again Damon. Looks good to me!

[dafedafe]

Thanks for your review @TobiHartmann.

[dafedafe]

/integrate

[openjdk]

@dafedafe
Your change (at version b3ab62f) is now ready to be sponsored by a Committer.

[TobiHartmann]

/sponsor

[openjdk]

Going to push as commit ed2a03e.
Since your change was applied there have been 2 commits pushed to the lworld branch:

• bdfe15a: 8361302:
• 6541b8b: 8346307: [lworld] Clarify identity vs value in Class, Objects, and document limitations of value objects

Your commit was automatically rebased without conflicts.

[openjdk]

@TobiHartmann @dafedafe Pushed as commit ed2a03e.

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