8315934: RISC-V: Disable conservative fences per vendor

[luhenry]

Conservative fences are not a requirement on some RISC-V hardware for correctness, but can bring a performance penalty. Let's make sure we disable them on a per-vendor basis, and keep them enabled for the default case.

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Issue

• JDK-8315934: RISC-V: Disable conservative fences per vendor (Task - P4)

Reviewers

• Robbin Ehn (@robehn - Reviewer)
• Hamlin Li (@Hamlin-Li - Reviewer)
• Fei Yang (@RealFYang - Reviewer)

Reviewing

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[bridgekeeper]

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[mlbridge]

Webrevs

• 00: Full (46feface)

[robehn]

Seems reasonable when looking at other platforms vm versions.

You may consider turn off ztso if someone really wants a lot of extra fencing :)

[openjdk]

@luhenry 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:

8315934: RISC-V: Disable conservative fences per vendor

Reviewed-by: rehn, mli, fyang

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 55 new commits pushed to the master branch:

• f9ab115: 8316050: Use hexadecimal encoding in MemorySegment::toString
• f804f86: 8314612: TestUnorderedReduction.java fails with -XX:MaxVectorSize=32 and -XX:+AlignVector
• f8df754: 8311207: Cleanup for Optimization for UUID.toString
• fecd2fd: 8315898: Open source swing JMenu tests
• bb6b3f2: 8315761: Open source few swing JList and JMenuBar tests
• 2d168c5: 8313202: MutexLocker should disallow null Mutexes
• 36552e7: 8316123: ProblemList serviceability/dcmd/gc/RunFinalizationTest.java on AIX
• fe5ef5f: 8315677: Open source few swing JFileChooser and other tests
• ece9bdf: 8299614: Shenandoah: STW mark should keep nmethod/oops referenced from stack chunk alive
• a36f5a5: 8315663: Open source misc awt tests
• ... and 45 more: https://git.openjdk.org/jdk/compare/b3dfc399dae714958f22624daf76831c6ec2dfe0...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.

[RealFYang]

LGTM. Let's keep the current shape. Please ignore my previous comment.

[luhenry]

/integrate

[openjdk]

Going to push as commit a731a24.
Since your change was applied there have been 56 commits pushed to the master branch:

• b3dad24: 8316021: Serial: Remove unused Generation::post_compact
• f9ab115: 8316050: Use hexadecimal encoding in MemorySegment::toString
• f804f86: 8314612: TestUnorderedReduction.java fails with -XX:MaxVectorSize=32 and -XX:+AlignVector
• f8df754: 8311207: Cleanup for Optimization for UUID.toString
• fecd2fd: 8315898: Open source swing JMenu tests
• bb6b3f2: 8315761: Open source few swing JList and JMenuBar tests
• 2d168c5: 8313202: MutexLocker should disallow null Mutexes
• 36552e7: 8316123: ProblemList serviceability/dcmd/gc/RunFinalizationTest.java on AIX
• fe5ef5f: 8315677: Open source few swing JFileChooser and other tests
• ece9bdf: 8299614: Shenandoah: STW mark should keep nmethod/oops referenced from stack chunk alive
• ... and 46 more: https://git.openjdk.org/jdk/compare/b3dfc399dae714958f22624daf76831c6ec2dfe0...master

Your commit was automatically rebased without conflicts.

[openjdk]

@luhenry Pushed as commit a731a24.

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