8371187: [BigEndian Platforms] Vector lane reversal error

[offamitkumar]

Hi all,

This pull request contains a backport of commit ee2deade from the openjdk/jdk repository.

The commit being backported was authored by Varada M on 27 Jan 2026 and was reviewed by Martin Doerr and Amit Kumar.

Thanks!

---

Progress

• Change must not contain extraneous whitespace
• JDK-8371187 needs maintainer approval
• Commit message must refer to an issue

Issue

• JDK-8371187: [BigEndian Platforms] Vector lane reversal error (Bug - P3)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk25u-dev.git pull/361/head:pull/361
$ git checkout pull/361

Update a local copy of the PR:
$ git checkout pull/361
$ git pull https://git.openjdk.org/jdk25u-dev.git pull/361/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 361

View PR using the GUI difftool:
$ git pr show -t 361

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk25u-dev/pull/361.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back amitkumar! 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]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

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

[openjdk]

⚠️ @offamitkumar 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 (59408e78)

[offamitkumar]

/approval The issue persists in JDK 25 LTS as well, so we have been requested to backport the changes.

[openjdk]

@offamitkumar usage: /approval [<id>] (request|cancel) [<text>]

[offamitkumar]

/approval request The issue persists in JDK 25 LTS as well, so we have been requested to backport the changes.

[openjdk]

@offamitkumar
8371187: The approval request has been created successfully.

[GoeLin]

HI @offamitkumar
can you please give a proper approval request comment?
List Reason/Risk/testing
"we have been requested" is not a proper reason.
Reason : Explain what is outstanding here that it should be backported while we omit lots of other bug fixes because we want to reduce the risk to break 25?
See also https://wiki.openjdk.org/spaces/JDKUpdates/pages/42598906/How+to+contribute+or+backport+a+fix
Especially part 6.

[GoeLin]

Hi @offamitkumar
Also, please backport to 26 first.
Removing the label in the meantime. Feel free to request approval again.
Thanks!

[offamitkumar]

Hi @GoeLin,

will this reason be well enough:

This backport fixes the vector lane reversal error on big endian platform, where if vector operations are used then it will produce reversed vector lane output. More about this here: https://github.com/andreaTP/s390x-vector-bug-reproducer, Patch is clean and tier1 test are clean.