8362171: C2 fails with unexpected node in SuperWord truncation: ModI

[jaskarth]

Hi all,
This is a small fix for an assert failure in SuperWord truncation with ModI nodes. The failure itself is harmless and shouldn't lead to any miscompilations in product mode. I've added ModI to the assert switch and adapted the test in the bug report. Let me know what you think!

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8362171: C2 fails with unexpected node in SuperWord truncation: ModI (Bug - P2)(⚠️ The fixVersion in this issue is [25] but the fixVersion in .jcheck/conf is 26, a new backport will be created when this pr is integrated.)

Reviewers

• Tobias Hartmann (@TobiHartmann - Reviewer)
• Christian Hagedorn (@chhagedorn - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/26334/head:pull/26334
$ git checkout pull/26334

Update a local copy of the PR:
$ git checkout pull/26334
$ git pull https://git.openjdk.org/jdk.git pull/26334/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 26334

View PR using the GUI difftool:
$ git pr show -t 26334

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/26334.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back jkarthikeyan! 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]

@jaskarth 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:

8362171: C2 fails with unexpected node in SuperWord truncation: ModI

Reviewed-by: thartmann, chagedorn

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 33 new commits pushed to the master branch:

• bdd37b0: 8361836: RISC-V: Relax min vector length to 32-bit for short vectors
• 5ddeb56: Merge
• 413c6bd: 8360147: Better Glyph drawing redux
• ... and 30 more: https://git.openjdk.org/jdk/compare/a10ee46e6dd94a279e0821d431944bb096493664...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]

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

• hotspot-compiler

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

• 00: Full (741cf3df)

[TobiHartmann]

Thanks for quickly jumping on this! Looks good to me. I submitted testing and will report back once it passed.

[chhagedorn]

Looks good to me, too. Thanks for prioritizing this to get it in quickly.

[TobiHartmann]

Testing is all clean. Ship it! 🙂

[jaskarth]

Thanks for the reviews @TobiHartmann @chhagedorn! :)
/integrate

[openjdk]

Going to push as commit 70c1ff7.
Since your change was applied there have been 45 commits pushed to the master branch:

• 6ed8164: 8362250: ARM32: forward_exception_entry missing return address
• 5e4a2ea: 8357653: Inner classes of type parameters emitted as raw types in signatures
• b787ad6: 8361401: Warnings for use of Sun APIs should not be mandatory
• ... and 42 more: https://git.openjdk.org/jdk/compare/a10ee46e6dd94a279e0821d431944bb096493664...master

Your commit was automatically rebased without conflicts.

[openjdk]

@jaskarth Pushed as commit 70c1ff7.

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

[TobiHartmann]

/backport :jdk25

[openjdk]

@TobiHartmann the backport was successfully created on the branch backport-TobiHartmann-70c1ff7e-jdk25 in my personal fork of openjdk/jdk. To create a pull request with this backport targeting openjdk/jdk:jdk25, just click the following link:

➡️ Create pull request

The title of the pull request is automatically filled in correctly and below you find a suggestion for the pull request body:

Hi all,

This pull request contains a backport of commit 70c1ff7e from the openjdk/jdk repository.

The commit being backported was authored by Jasmine Karthikeyan on 16 Jul 2025 and was reviewed by Tobias Hartmann and Christian Hagedorn.

Thanks!

If you need to update the source branch of the pull then run the following commands in a local clone of your personal fork of openjdk/jdk:

$ git fetch https://github.com/openjdk-bots/jdk.git backport-TobiHartmann-70c1ff7e-jdk25:backport-TobiHartmann-70c1ff7e-jdk25
$ git checkout backport-TobiHartmann-70c1ff7e-jdk25
# make changes
$ git add paths/to/changed/files
$ git commit --message 'Describe additional changes made'
$ git push https://github.com/openjdk-bots/jdk.git backport-TobiHartmann-70c1ff7e-jdk25