8338727: RISC-V: Avoid synthetic data dependency in nmethod barrier on Ztso

[robehn]

Hi please consider,

On TSO we don't need the synthetic data dependency in between the loads.
Also added some comment about this.

Sanity tested

---

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Issue

• JDK-8338727: RISC-V: Avoid synthetic data dependency in nmethod barrier on Ztso (Enhancement - P4)

Reviewers

• Hamlin Li (@Hamlin-Li - Reviewer)
• Fei Yang (@RealFYang - Reviewer)

Reviewing

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$ git pull https://git.openjdk.org/jdk.git pull/20661/head

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[bridgekeeper]

👋 Welcome back rehn! 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]

@robehn 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:

8338727: RISC-V: Avoid synthetic data dependency in nmethod barrier on Ztso

Reviewed-by: 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 45 new commits pushed to the master branch:

• b704bfa: 8298920: Improve microbenchmark build times
• b8e8e96: 8338668: Test javax/swing/JFileChooser/8080628/bug8080628.java doesn't test for GTK L&F
• cd9e241: 8336289: Obliterate most references to _snprintf in the Windows JDK
• 78f53ef: 8338938: The result of the combine method of SettingsControl is not used
• 16df090: 8338947: Deprecate the UseLinuxPosixThreadCPUClocks flag and remove it in a future release
• a827ff0: 8335577: runtime/cds/appcds/TestParallelGCWithCDS.java still fails with JNI error
• 5ecbecf: 8338936: StringConcatFactory optimize the construction of MethodType and MethodTypeDesc
• 0c744ea: 8338928: Update SwingSet2 "About" image to reference openjdk.org
• a15af69: 8338538: [JVMCI] Allow HotSpotJVMCIRuntime#getJObjectValue to be called by a HotSpot CompileBroker compiler thread
• 3f00da8: 8338906: Avoid passing EnumDescs and extra classes to type switch methods that don't use them
• ... and 35 more: https://git.openjdk.org/jdk/compare/c4cf1e93bb22bf7c65ce1943fff91f74839434df...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.

[openjdk]

@robehn The following label will be automatically applied to this pull request:

• hotspot

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

[mlbridge]

Webrevs

• 01: Full - Incremental (0a7727a2)
• 00: Full (925b527f)

[Hamlin-Li]

Make sense to me. Thanks!

[RealFYang]

This change looks fine. But I have a question about the code comment.

[RealFYang]

Looks good. Thanks for the update.

[robehn]

I'm still confused by the re-review thingy.
If I integrate now will @Hamlin-Li still get credit or do he need to re-review?

[Hamlin-Li]

Yeah, the new process is bit tedious, espcially for additional minor change after one approval.
Maybe we can improve it a bit ourself in riscv area? For minor changes after approval, we can skip re-review/approve?

[robehn]

/integrate

[openjdk]

Going to push as commit aefdbdc.
Since your change was applied there have been 45 commits pushed to the master branch:

• b704bfa: 8298920: Improve microbenchmark build times
• b8e8e96: 8338668: Test javax/swing/JFileChooser/8080628/bug8080628.java doesn't test for GTK L&F
• cd9e241: 8336289: Obliterate most references to _snprintf in the Windows JDK
• 78f53ef: 8338938: The result of the combine method of SettingsControl is not used
• 16df090: 8338947: Deprecate the UseLinuxPosixThreadCPUClocks flag and remove it in a future release
• a827ff0: 8335577: runtime/cds/appcds/TestParallelGCWithCDS.java still fails with JNI error
• 5ecbecf: 8338936: StringConcatFactory optimize the construction of MethodType and MethodTypeDesc
• 0c744ea: 8338928: Update SwingSet2 "About" image to reference openjdk.org
• a15af69: 8338538: [JVMCI] Allow HotSpotJVMCIRuntime#getJObjectValue to be called by a HotSpot CompileBroker compiler thread
• 3f00da8: 8338906: Avoid passing EnumDescs and extra classes to type switch methods that don't use them
• ... and 35 more: https://git.openjdk.org/jdk/compare/c4cf1e93bb22bf7c65ce1943fff91f74839434df...master

Your commit was automatically rebased without conflicts.

[openjdk]

@robehn Pushed as commit aefdbdc.

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

[dcubed-ojdk]

I'm still confused by the re-review thingy.
If I integrate now will @Hamlin-Li still get credit or do he need to re-review?

Folks who have officially reviewed (and approved) do not get removed.
The re-review "thingy" is just to make sure that all changes are reviewed
before integration. Make a change after folks have reviewed, you just need
someone to re-review to verify that the latest change was looked at.

[Hamlin-Li]

Folks who have officially reviewed (and approved) do not get removed. The re-review "thingy" is just to make sure that all changes are reviewed before integration. Make a change after folks have reviewed, you just need someone to re-review to verify that the latest change was looked at.

Thanks for confirmation, I also verified this via this pr

[robehn]

I'm still confused by the re-review thingy.
If I integrate now will @Hamlin-Li still get credit or do he need to re-review?

Folks who have officially reviewed (and approved) do not get removed. The re-review "thingy" is just to make sure that all changes are reviewed before integration. Make a change after folks have reviewed, you just need someone to re-review to verify that the latest change was looked at.

Thanks, Dan!