8298225: [AIX] Disable PPC64LE continuations on AIX

[backwaterred]

This small change adds an import to ppc.ad to allow it to find Contiuations::enabled, and sets VMContinuations to false on AIX.

Thanks to @TheRealMDoerr for suggestions to a previous version of this PR.

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Issue

• JDK-8298225: [AIX] Disable PPC64LE continuations on AIX

Reviewers

• Richard Reingruber (@reinrich - Reviewer) ⚠️ Review applies to 74c36006
• Martin Doerr (@TheRealMDoerr - Reviewer)

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[mlbridge]

Webrevs

• 01: Full - Incremental (d3c9a764)
• 00: Full (74c36006)

[reinrich]

Looks reasonable.
Thanks, Richard.

[openjdk]

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

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

8298225: [AIX] Disable PPC64LE continuations on AIX

Reviewed-by: rrich, mdoerr

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 5 new commits pushed to the master branch:

• b7b996c: 8298353: C2 fails with assert(opaq->outcnt() == 1 && opaq->in(1) == limit) failed
• 05d67f6: 8298340: java/net/httpclient/CancelRequestTest.java fails with AssertionError: Found some subscribers for testPostInterrupt
• 5a92bee: 8298455: JFR: Add logging to TestClose.java
• 133ad8e: 8297988: NPE in JavacTypes.getOverriddenMethods from doclint
• 553ba65: 8298402: ProblemList javax/swing/JFileChooser/4847375/bug4847375.java on windows-x64

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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[TheRealMDoerr]

Ok, switching it off for AIX makes sense for JDK 20. Do you know what's wrong on that OS? I believe there's not much missing. I recommend trying test/jdk/java/lang/Thread/virtual/stress tests and debugging it on linux PPC64 Big Endian. Maybe the frame header size is the problem which could cause GC to look at the wrong fields for example.
(But, you can integrate this fix and continue in JDK 21.)

[reinrich]

My recommendation for tracking down issues would be test/jdk/jdk/internal/vm/Continuation/BasicExt.java with -Xlog:continuations=trace switched on.

[backwaterred]

Thanks for the reviews!

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My recommendation for tracking down issues would be test/jdk/jdk/internal/vm/Continuation/BasicExt.java with -Xlog:continuations=trace switched on.

and

Do you know what's wrong on that OS? I believe there's not much missing. I recommend trying test/jdk/java/lang/Thread/virtual/stress tests and debugging it on linux PPC64 Big Endian.

Thanks for the suggestions, I think they will help :-). I have been examining the failures, but not with continuations=trace, and on AIX rather than Linux/PPC64 big-endian. All in all, I am surprised at how well Richard's changes for PPC64-LE are working in a different ABI than they were implemented for. We'll see how much progress I can make before 19 Jan 🤞

[backwaterred]

/integrate

[openjdk]

Going to push as commit a894649.
Since your change was applied there have been 6 commits pushed to the master branch:

• 52fffdd: 8298463: tools/javac/modules/EdgeCases.java fails on Windows after JDK-8297988
• b7b996c: 8298353: C2 fails with assert(opaq->outcnt() == 1 && opaq->in(1) == limit) failed
• 05d67f6: 8298340: java/net/httpclient/CancelRequestTest.java fails with AssertionError: Found some subscribers for testPostInterrupt
• 5a92bee: 8298455: JFR: Add logging to TestClose.java
• 133ad8e: 8297988: NPE in JavacTypes.getOverriddenMethods from doclint
• 553ba65: 8298402: ProblemList javax/swing/JFileChooser/4847375/bug4847375.java on windows-x64

Your commit was automatically rebased without conflicts.

[openjdk]

@backwaterred Pushed as commit a894649.

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