8373724: Assertion failure in TestSignumVector.java with UseAPX #28999

jatin-bhateja · 2025-12-26T12:31:39Z

Existing demotable instruction patterns for negI/L_rReg_ndd have 'src' as their second operand, this leads to an failure during register biasing. Changing the NDD demotion flags names to encode explicit operand position i.e. Flag_ndd_demotable_opr1 and Flag_ndd_demotable_opr2 , splitting commutative flag into seperate new flags and fine tuning assertion checks based on new naming convention fixes the issue.

Failing test test/hotspot/jtreg/compiler/vectorization/TestSignumVector.java passes with the patch.

Kindly review and share your feedback.

Best Regards,
Jatin
PS: Validation performed using Intel SDE 9.58.

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Issue

JDK-8373724: Assertion failure in TestSignumVector.java with UseAPX (Bug - P3)(⚠️ 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.)

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Sandhya Viswanathan (@sviswa7 - Reviewer)

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bridgekeeper · 2025-12-26T12:33:45Z

👋 Welcome back jbhateja! 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 · 2025-12-26T12:35:15Z

@jatin-bhateja 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:

8373724: Assertion failure in TestSignumVector.java with UseAPX

Reviewed-by: sviswanathan

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 34 new commits pushed to the master branch:

3541bc8: 8373538: Migrate all tests to null-safe "SimpleSSLContext" methods
da14813: 8373453: C2 SuperWord: must handle load slices that have loads with different memory inputs
929864b: 8362087: Test containers/docker/ShareTmpDir.java intermittent fails
... and 31 more: https://git.openjdk.org/jdk/compare/27dbdec297fc8030812f7290a7601b6a99defb46...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 · 2025-12-26T12:36:17Z

@jatin-bhateja 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 · 2025-12-26T12:40:37Z

Webrevs

openjdk · 2025-12-26T12:52:26Z

@jatin-bhateja Please do not rebase or force-push to an active PR as it invalidates existing review comments. Note for future reference, the bots always squash all changes into a single commit automatically as part of the integration. See OpenJDK Developers’ Guide for more information.

sviswa7 · 2026-01-05T17:02:25Z

@jatin-bhateja Thanks for looking into this. There is a build failure in GHA with the following message:
"src/hotspot/cpu/x86/x86.ad:2645:13: error: ‘bool is_ndd_demotable(const MachNode*)’ defined but not used [-Werror=unused-function]"

…ild failure

src/hotspot/cpu/x86/x86.ad

sviswa7 · 2026-01-05T18:02:50Z

src/hotspot/cpu/x86/x86.ad

  match(Set dst (OrL src1 (LoadL src2)));
  effect(KILL cr);
-  flag(PD::Flag_sets_sign_flag, PD::Flag_sets_zero_flag, PD::Flag_sets_parity_flag, PD::Flag_clears_overflow_flag, PD::Flag_clears_carry_flag, PD::Flag_ndd_demotable_commutative);
+  flag(PD::Flag_sets_sign_flag, PD::Flag_sets_zero_flag, PD::Flag_sets_parity_flag, PD::Flag_clears_overflow_flag, PD::Flag_clears_carry_flag, PD::Flag_ndd_demotable_opr1, PD::Flag_ndd_demotable_opr2);


Remove PD::Flag_ndd_demotable_opr2 as the second operand is a memory operand.

We already have a check for memory operands (mapping to multiple input edges) in place, ADLC generates DFA for both direct and flipped versions of the memory patterns. So Flag_ndd_demotable_opr2 will cover the flipped operand case.

Thanks for the clarification. May be we should then add PD::Flag_ndd_demotable_opr2 to the following as well to be consistent:
xorI_rReg_rReg_mem_ndd
orI_rReg_rReg_mem_ndd
mulI_rReg_rReg_mem_ndd

Thanks @sviswa7 , comment addressed

src/hotspot/cpu/x86/x86.ad

sviswa7

Looks good to me.

jatin-bhateja · 2026-01-07T16:59:27Z

/integrate

jatin-bhateja · 2026-01-07T17:00:30Z

Looks good to me.

Thanks @sviswa7 for your reviews.

openjdk · 2026-01-07T17:00:58Z

Going to push as commit 640343f.
Since your change was applied there have been 34 commits pushed to the master branch:

3541bc8: 8373538: Migrate all tests to null-safe "SimpleSSLContext" methods
da14813: 8373453: C2 SuperWord: must handle load slices that have loads with different memory inputs
929864b: 8362087: Test containers/docker/ShareTmpDir.java intermittent fails
... and 31 more: https://git.openjdk.org/jdk/compare/27dbdec297fc8030812f7290a7601b6a99defb46...master

Your commit was automatically rebased without conflicts.

openjdk · 2026-01-07T17:01:04Z

@jatin-bhateja Pushed as commit 640343f.

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

dlunde · 2026-01-07T17:27:01Z

I will review this changeset now after integration, but, for future reference, please note that HotSpot changes require at least two reviews before integration (see https://openjdk.org/guide/#life-of-a-pr).

missa-prime · 2026-01-08T18:05:04Z

I will review this changeset now after integration, but, for future reference, please note that HotSpot changes require at least two reviews before integration (see https://openjdk.org/guide/#life-of-a-pr).

@dlunde I'm planning to backport this to JDK-26. Please let me know when you're finished reviewing as soon as possible, so I can do so. Thanks!

dlunde · 2026-01-09T12:31:15Z

@dlunde I'm planning to backport this to JDK-26. Please let me know when you're finished reviewing as soon as possible, so I can do so. Thanks!

@missa-prime Will do!

dlunde · 2026-01-09T20:16:02Z

I agree with these changes. Nice that the assert caught this case!

I'm running some tests for the changeset over the weekend, for both JDK 26 and JDK 27. I'll report back on Monday, and then you can go ahead with the backport @missa-prime (if no issues show up in testing).

openjdk bot added the hotspot-compiler [email protected] label Dec 26, 2025

openjdk bot added the rfr Pull request is ready for review label Dec 26, 2025

8373724: Assertion failure in TestSignumVector.java with UseAPX

bc86d54

jatin-bhateja force-pushed the JDK-8373724 branch from b75d280 to bc86d54 Compare December 26, 2025 12:50

Merge branch 'master' of http://github.com/openjdk/jdk into JDK-8373724

2a63c92

jbhateja added 3 commits January 5, 2026 17:37

Merge branch 'master' of http://github.com/openjdk/jdk into JDK-8373724

3addcda

Use ASSERT pre-processor macro instead of PRODUCT to fix optimized bu…

05db565

…ild failure

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sviswa7 approved these changes Jan 7, 2026

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missa-prime mentioned this pull request Jan 7, 2026

8373724: [BACKOUT] RA support for EVEX to REX/REX2 demotion to optimize NDD instructions #28972

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8373724: Assertion failure in TestSignumVector.java with UseAPX #28999

8373724: Assertion failure in TestSignumVector.java with UseAPX #28999

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