8368732: RISC-V: Detect support for misaligned vector access via hwprobe

[DingliZhang]

Hi,
Please help review this backport to jdk25u, thanks!

Backport of JDK-8368732.

The original patch cannot be directly applied because of jdk25u do not have JDK-8367253 or JDK-8367103.

Manually checked the result on platforms w/wo fast misaligned vector accesses by running:

$ java -XX:+PrintFlagsFinal -version | grep AlignVector

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• JDK-8368732 needs maintainer approval
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8368732: RISC-V: Detect support for misaligned vector access via hwprobe (Enhancement - P4 - Approved)

Reviewers

• Fei Yang (@RealFYang - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk25u.git pull/252/head:pull/252
$ git checkout pull/252

Update a local copy of the PR:
$ git checkout pull/252
$ git pull https://git.openjdk.org/jdk25u.git pull/252/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 252

View PR using the GUI difftool:
$ git pr show -t 252

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk25u/pull/252.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:

8368732: RISC-V: Detect support for misaligned vector access via hwprobe

Reviewed-by: fyang

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 14 new commits pushed to the master branch:

• a3854cf: 8368698: runtime/cds/appcds/aotCache/OldClassSupport.java assert(can_add()) failed: Cannot add TrainingData objects
• f5c2756: 8362204: test/jdk/sun/awt/font/TestDevTransform.java fails on Ubuntu 24.04
• ee6a040: 8365265: x86 short forward jump exceeds 8-bit offset in methodHandles_x86.cpp when using Intel APX
• ... and 11 more: https://git.openjdk.org/jdk25u/compare/3747153d91e8f412fec9b3db4e42691eafc4f290...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. Possible candidates are the reviewers of this PR (@RealFYang) but any other Committer may sponsor as well.

➡️ 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.

[mlbridge]

Webrevs

• 00: Full (9b949a17)

[RealFYang]

Looks good.

[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.

[DingliZhang]

/approval Backport to jdk25u for performance reasons.
That is if the misaligned vector access is fast, we set AlignVector to false in the hope that it will save instructions handling address alignment thus improves performance.

[openjdk]

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

[DingliZhang]

/approval request Backport to jdk25u for performance reasons.
That is if the misaligned vector access is fast, we set AlignVector to false in the hope that it will save instructions handling address alignment thus improves performance.

[openjdk]

@DingliZhang
8368732: The approval request has been created successfully.

[DingliZhang]

/integrate

[openjdk]

@DingliZhang
Your change (at version 9b949a1) is now ready to be sponsored by a Committer.

[RealFYang]

/sponsor

[openjdk]

Going to push as commit 66de4b4.
Since your change was applied there have been 14 commits pushed to the master branch:

• a3854cf: 8368698: runtime/cds/appcds/aotCache/OldClassSupport.java assert(can_add()) failed: Cannot add TrainingData objects
• f5c2756: 8362204: test/jdk/sun/awt/font/TestDevTransform.java fails on Ubuntu 24.04
• ee6a040: 8365265: x86 short forward jump exceeds 8-bit offset in methodHandles_x86.cpp when using Intel APX
• ... and 11 more: https://git.openjdk.org/jdk25u/compare/3747153d91e8f412fec9b3db4e42691eafc4f290...master

Your commit was automatically rebased without conflicts.

[openjdk]

@RealFYang @DingliZhang Pushed as commit 66de4b4.

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