8367028: compiler/c2/irTests/TestFloat16ScalarOperations.java failing intermittently because of constant folding

[eme64]

The test uses random constants. But we forgot to exclude special values such as zero, otherwise the operations can be folded (idealized) and the IR tests fail. For example x + 0.42 would not be folded, but x + 0 would be folded to x.

Solution: restrict the range we sample from. Used to be [0, 1), now I just do [0.1, 0.9).

---

Progress

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Issue

• JDK-8367028: compiler/c2/irTests/TestFloat16ScalarOperations.java failing intermittently because of constant folding (Bug - P4)(⚠️ The fixVersion in this issue is [26] but the fixVersion in .jcheck/conf is 27, a new backport will be created when this pr is integrated.)

Reviewers

• Christian Hagedorn (@chhagedorn - Reviewer)
• SendaoYan (@sendaoYan - Committer)
• Roberto Castañeda Lozano (@robcasloz - Reviewer)

Reviewing

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Update a local copy of the PR:
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$ git pull https://git.openjdk.org/jdk.git pull/28678/head

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$ git pr checkout 28678

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[bridgekeeper]

👋 Welcome back epeter! 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]

@eme64 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:

8367028: compiler/c2/irTests/TestFloat16ScalarOperations.java failing intermittently because of constant folding

Reviewed-by: chagedorn, syan, rcastanedalo

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 38 new commits pushed to the master branch:

• 830c4d3: 8366272: The os::xxx APIs do not manage errno correctly
• 0a55789: 8373025: test/hotspot/jtreg/gc/cslocker/TestCSLocker.java may deadlock
• 1f49edd: 4459231: Focus of JTabbedPane(with Scrollable tablayout) changes on change in LookAndFeel
• ... and 35 more: https://git.openjdk.org/jdk/compare/674cc3eeca77f1f2a6d937b1df5c5cd8a13c2d31...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]

@eme64 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 (3a6234ae)

[chhagedorn]

Looks good, thanks!

[eme64]

Thanks @chhagedorn @robcasloz @sendaoYan thanks for the reviews!

/integrate

[openjdk]

Going to push as commit a4eb57c.
Since your change was applied there have been 38 commits pushed to the master branch:

• 830c4d3: 8366272: The os::xxx APIs do not manage errno correctly
• 0a55789: 8373025: test/hotspot/jtreg/gc/cslocker/TestCSLocker.java may deadlock
• 1f49edd: 4459231: Focus of JTabbedPane(with Scrollable tablayout) changes on change in LookAndFeel
• ... and 35 more: https://git.openjdk.org/jdk/compare/674cc3eeca77f1f2a6d937b1df5c5cd8a13c2d31...master

Your commit was automatically rebased without conflicts.

[openjdk]

@eme64 Pushed as commit a4eb57c.

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

[eme64]

/backport jdk26

[openjdk]

@eme64 The target repository jdk26 is not a valid target for backports.
List of valid target repositories: openjdk/jdk, openjdk/jdk11u, openjdk/jdk11u-dev, openjdk/jdk17u, openjdk/jdk17u-dev, openjdk/jdk21u, openjdk/jdk21u-dev, openjdk/jdk25u, openjdk/jdk25u-dev, openjdk/jdk8u, openjdk/jdk8u-dev, openjdk/jfx, openjdk/jfx17u, openjdk/jfx21u, openjdk/jfx25u, openjdk/lilliput-jdk17u, openjdk/lilliput-jdk21u, openjdk/lilliput-jdk25u, openjdk/shenandoah-jdk21u, openjdk/shenandoah-jdk8u.
Supplying the organization/group prefix is optional.

There is a branch jdk26 in the current repository openjdk/jdk.
To target a backport to this branch in the current repository use:
/backport :jdk26

[eme64]

/backport :jdk26

[openjdk]

@eme64 the backport was successfully created on the branch backport-eme64-a4eb57c5-jdk26 in my personal fork of openjdk/jdk. To create a pull request with this backport targeting openjdk/jdk:jdk26, 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 a4eb57c5 from the openjdk/jdk repository.

The commit being backported was authored by Emanuel Peter on 9 Dec 2025 and was reviewed by Christian Hagedorn, SendaoYan and Roberto Castañeda Lozano.

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-eme64-a4eb57c5-jdk26:backport-eme64-a4eb57c5-jdk26
$ git checkout backport-eme64-a4eb57c5-jdk26
# 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-eme64-a4eb57c5-jdk26

⚠️ @eme64 You are not yet a collaborator in my fork openjdk-bots/jdk. An invite will be sent out and you need to accept it before you can proceed.