8367694: Fix jtreg test failure when Intel APX is enabled for KNL platforms #27299

vamsi-parasa · 2025-09-15T16:19:29Z

This goal of this PR is fix the jtreg test failure observed in compiler test: test/hotspot/jtreg/compiler/loopopts/superword/TestDependencyOffsets.java

The test failure is occurring specifically for the tests with ids = {avx512-v064-A, avx512-v064-U, avx512-v032-A, avx512-v032-U}. These tests are run with KNL hardware features enabled (-XX:+UseKNLSetting).

The two main causes of test failure are:

KNL does not support Intel APX. Currently, APX is not turned off when using KNL. This PR fixes this issue.
BMI2 instructions like sarxl are encoded incorrectly with uses_vl=true (use vector length). This PR fixes the encoding to use the correct one:uses_vl=false.

After fixing these two bugs, TestDependencyOffsets.java is passing using the SDE emulator when APX is enabled.

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Issue

JDK-8367694: Fix jtreg test failure when Intel APX is enabled for KNL platforms (Bug - P4)

Reviewers

Sandhya Viswanathan (@sviswa7 - Reviewer)
Emanuel Peter (@eme64 - Reviewer)

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bridgekeeper · 2025-09-15T16:20:36Z

👋 Welcome back sparasa! 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 · 2025-09-15T16:22:08Z

@vamsi-parasa 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:

8367694: Fix jtreg test failure when Intel APX is enabled for KNL platforms

Reviewed-by: sviswanathan, epeter

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 16 new commits pushed to the master branch:

c7f014e: 8356813: Improve Mod(I|L)Node::Value
ca89cd0: 8367410: ZGC: Remove unused ZNmethodTable::wait_until_iteration_done()
eb26865: 8367552: JCmdTestFileSafety.java fails when run by root user
... and 13 more: https://git.openjdk.org/jdk/compare/e8dda2b67524b6575124581464921d46335dcad7...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 · 2025-09-15T16:23:39Z

@vamsi-parasa The following label will be automatically applied to this pull request:

hotspot

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 · 2025-09-15T16:28:26Z

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01: Full - Incremental (a1ef0159)
00: Full (c795d9b0)

sviswa7 · 2025-09-15T18:26:37Z

src/hotspot/cpu/x86/vm_version_x86.cpp


  // Currently APX support is only enabled for targets supporting AVX512VL feature.
-  bool apx_supported = os_supports_apx_egprs() && supports_apx_f() && supports_avx512vl();
+  bool apx_supported = !is_knights_family() && os_supports_apx_egprs() && supports_apx_f() && supports_avx512vl();


Instead of adding is_knights_family check here, it is better to move the lines 1020-1028 after 1070.

Moved the APX feature check from 1020-1028 to 1070. Please see the updated code.

sviswa7

Looks good to me.

eme64

Looks reasonable. Let me do some testing, takes about 24h.

eme64

Tests passed, looks reasonable. Thanks for the work!

vamsi-parasa · 2025-09-16T18:11:07Z

Tests passed, looks reasonable. Thanks for the work!

Thanks Emanuel!

vamsi-parasa · 2025-09-16T18:11:13Z

/integrate

openjdk · 2025-09-16T18:14:19Z

Going to push as commit e883dec.
Since your change was applied there have been 22 commits pushed to the master branch:

c41add8: 8354348: Enable Extended EVEX to REX2/REX demotion for commutative operations with same dst and src2
075ebb4: 8366229: runtime/Thread/TooSmallStackSize.java runs with all collectors
15d42c6: 8366978: dead code in SunCertPathBuilder
... and 19 more: https://git.openjdk.org/jdk/compare/e8dda2b67524b6575124581464921d46335dcad7...master

Your commit was automatically rebased without conflicts.

openjdk · 2025-09-16T18:14:42Z

@vamsi-parasa Pushed as commit e883dec.

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

vamsi-parasa · 2025-09-29T21:01:00Z

/backport e883dec

openjdk · 2025-09-29T21:01:37Z

@vamsi-parasa The target repository e883dec 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/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.

vamsi-parasa · 2025-09-29T21:03:52Z

/backport openjdk/jdk25u

openjdk · 2025-09-29T21:05:27Z

@vamsi-parasa the backport was successfully created on the branch backport-vamsi-parasa-e883dec6-master in my personal fork of openjdk/jdk25u. To create a pull request with this backport targeting openjdk/jdk25u:master, 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 e883dec6 from the openjdk/jdk repository.

The commit being backported was authored by Srinivas Vamsi Parasa on 16 Sep 2025 and was reviewed by Sandhya Viswanathan and Emanuel Peter.

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/jdk25u:

$ git fetch https://github.com/openjdk-bots/jdk25u.git backport-vamsi-parasa-e883dec6-master:backport-vamsi-parasa-e883dec6-master
$ git checkout backport-vamsi-parasa-e883dec6-master
# make changes
$ git add paths/to/changed/files
$ git commit --message 'Describe additional changes made'
$ git push https://github.com/openjdk-bots/jdk25u.git backport-vamsi-parasa-e883dec6-master

vamsi-parasa added 2 commits September 15, 2025 09:08

8367694: Fix jtreg test failure when Intel APX is enabled for KNL pla…

832fed4

…tforms

Update assembler_x86.cpp

c795d9b

openjdk bot added hotspot hotspot-dev@openjdk.org rfr Pull request is ready for review labels Sep 15, 2025

sviswa7 reviewed Sep 15, 2025

View reviewed changes

change the location of APX feature check

a1ef015

sviswa7 approved these changes Sep 15, 2025

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openjdk bot added the ready Pull request is ready to be integrated label Sep 15, 2025

eme64 reviewed Sep 16, 2025

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eme64 approved these changes Sep 16, 2025

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openjdk bot added the integrated Pull request has been integrated label Sep 16, 2025

openjdk bot closed this Sep 16, 2025

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Sep 16, 2025

8367694: Fix jtreg test failure when Intel APX is enabled for KNL platforms #27299

8367694: Fix jtreg test failure when Intel APX is enabled for KNL platforms #27299

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