8374525: RISC-V: Several masked float16 vector operations are not supported

[DingliZhang]

Hi all,

This pull request contains a backport of commit df5b49e6 from the openjdk/jdk repository.

The commit being backported was authored by Dingli Zhang on 6 Jan 2026 and was reviewed by Feilong Jiang and Fei Yang.

Thanks!

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8374525 needs maintainer approval

Issue

• JDK-8374525: RISC-V: Several masked float16 vector operations are not supported (Bug - P4 - Approved)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk25u-dev.git pull/133/head:pull/133
$ git checkout pull/133

Update a local copy of the PR:
$ git checkout pull/133
$ git pull https://git.openjdk.org/jdk25u-dev.git pull/133/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 133

View PR using the GUI difftool:
$ git pr show -t 133

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk25u-dev/pull/133.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back dzhang! 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]

@DingliZhang 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:

8374525: RISC-V: Several masked float16 vector operations are not supported

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 7 new commits pushed to the master branch:

• 33e74e0: 8358735: GenShen: block_start() may be incorrect after class unloading
• a5bb313: 8358735: GenShen: block_start() may be incorrect after class unloading
• 0f49389: 8372589: VM crashes on init when NonNMethodCodeHeapSize is set too small and UseTransparentHugePages is enabled
• ... and 4 more: https://git.openjdk.org/jdk25u-dev/compare/c288508b4d25a17f775fe8fb6be1a633d6ce57fd...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.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[openjdk]

⚠️ @DingliZhang This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[mlbridge]

Webrevs

• 00: Full (bac60bcf)

[DingliZhang]

/approval request Same issue exists in jdk25u-dev repo as well.
Backport to fix incorrect enabling of masked Float16 vector operations on RISC-V platforms with Zvfh.
This is a RISC-V specific change, should be low risk.

[openjdk]

@DingliZhang
8374525: The approval request has been created successfully.

[DingliZhang]

/integrate

[openjdk]

@DingliZhang
Your change (at version bac60bc) is now ready to be sponsored by a Committer.

[RealFYang]

/sponsor

[openjdk]

Going to push as commit fd0436b.
Since your change was applied there have been 7 commits pushed to the master branch:

• 33e74e0: 8358735: GenShen: block_start() may be incorrect after class unloading
• a5bb313: 8358735: GenShen: block_start() may be incorrect after class unloading
• 0f49389: 8372589: VM crashes on init when NonNMethodCodeHeapSize is set too small and UseTransparentHugePages is enabled
• ... and 4 more: https://git.openjdk.org/jdk25u-dev/compare/c288508b4d25a17f775fe8fb6be1a633d6ce57fd...master

Your commit was automatically rebased without conflicts.

[openjdk]

@RealFYang @DingliZhang Pushed as commit fd0436b.

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