8259020: null-check of g1 write_ref_field_pre_entry is not necessary

[navyxliu]

orig is not null because G1BarrierSetC2 won't invoke write_ref_field_pre_entry
if pre_val is NULL.
/cc hotspot-gc

---

Progress

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Issue

• JDK-8259020: null-check of g1 write_ref_field_pre_entry is not necessary

Reviewers

• Kim Barrett (@kimbarrett - Reviewer)
• Albert Mingkun Yang (@albertnetymk - Author)
• @javawithjiva (no known github.com user name / role)
• Paul Hohensee (@phohensee - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jdk pull/1913/head:pull/1913
$ git checkout pull/1913

[bridgekeeper]

👋 Welcome back xliu! 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]

@navyxliu
The hotspot-gc label was successfully added.

[mlbridge]

Webrevs

• 00: Full (99cbe6e)

[kimbarrett]

Looks good.

[openjdk]

@navyxliu 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:

8259020: null-check of g1 write_ref_field_pre_entry is not necessary

Reviewed-by: kbarrett, ayang, phh

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 10 new commits pushed to the master branch:

• e6f9926: 8257809: JNI warnings from Toolkit JPEG image decoding
• 9d160aa: 8257815: Replace global log2 functions with efficient implementations
• f80c63b: 8258490: Shenandoah: Full GC does not need to remark threads and drain SATB buffers
• 7f04d23: 8258800: Deprecate -XX:+AlwaysLockClassLoader
• d679caa: 8196466: javax/swing/JFileChooser/8062561/bug8062561.java fails
• a2a3f4a: 8258924: javax/swing/JSplitPane/4201995/bug4201995.java fails in GTk L&F
• f351e15: 8258382: Fix optimization-unstable code involving pointer overflow
• 526c000: 8255729: com.sun.tools.javac.processing.JavacFiler.FilerOutputStream is inefficient
• 497efef: 8225116: Test OwnedWindowsLeak.java intermittently fails
• f5ee356: 8179503: Java should support GET OCSP calls

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

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[navyxliu]

Regression tests is clear.
https://github.com/navyxliu/jdk/actions/runs/454177250

I can confirm it's safe for hotspot/c2 and I haven't found evidence that c1 generates call of write_ref_field_pre_entry.
on the other side, it is exported to external via JVMCIRuntime::write_barrier_pre. I am not familiar with jvmci. I guess it's used by graal compiler, but I don't understand it much. Can a graal expert tell me if it's safe on your site?

[navyxliu]

/integrate

[openjdk]

@navyxliu
Your change (at version 99cbe6e) is now ready to be sponsored by a Committer.

[phohensee]

/sponsor

[openjdk]

@phohensee @navyxliu Since your change was applied there have been 10 commits pushed to the master branch:

• e6f9926: 8257809: JNI warnings from Toolkit JPEG image decoding
• 9d160aa: 8257815: Replace global log2 functions with efficient implementations
• f80c63b: 8258490: Shenandoah: Full GC does not need to remark threads and drain SATB buffers
• 7f04d23: 8258800: Deprecate -XX:+AlwaysLockClassLoader
• d679caa: 8196466: javax/swing/JFileChooser/8062561/bug8062561.java fails
• a2a3f4a: 8258924: javax/swing/JSplitPane/4201995/bug4201995.java fails in GTk L&F
• f351e15: 8258382: Fix optimization-unstable code involving pointer overflow
• 526c000: 8255729: com.sun.tools.javac.processing.JavacFiler.FilerOutputStream is inefficient
• 497efef: 8225116: Test OwnedWindowsLeak.java intermittently fails
• f5ee356: 8179503: Java should support GET OCSP calls

Your commit was automatically rebased without conflicts.

Pushed as commit f0aae81.

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

[navyxliu]

Thank you all reviewers and @phohensee for sponsoring it.