8370481: C2 SuperWord: Long/Integer.compareUnsigned return wrong value in SLP

[Hamlin-Li]

Hi,
Can you help to review the patch? @eme64

Issue

Currently, in SLP when transform from (Bool + CmpU + CMove) to (VectorMaskCmp + VectorBlend), the unsigned-ness in CmpU is lost, then end up doing a signed instead of unsigned comparison in VectorMaskCmp.
For details please check code at SuperWordVTransformBuilder::make_vector_vtnode_for_pack and PackSet::get_bool_test.

 Fix

Currently, BoolTest does not support an unsigned construction (BoolTest( mask btm ) : _test(btm) { assert((btm & unsigned_compare) == 0, "unsupported");}), seems to me a feasible solution would be get the unsigned information from CmpU (which could be an input of Bool) and pass it to VectorMaskCmp.

Thanks

This pr could also lead to more optimizations, like: #25336 and #25341.

---

Progress

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Issue

• JDK-8370481: C2 SuperWord: Long/Integer.compareUnsigned return wrong value in SLP (Bug - P3)

Reviewers

• Emanuel Peter (@eme64 - Reviewer)
• Antonios Printezis (@gctony - Reviewer)

Reviewing

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[openjdk]

@Hamlin-Li 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:

8370481: C2 SuperWord: Long/Integer.compareUnsigned return wrong value in SLP

Reviewed-by: epeter, tonyp

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 148 new commits pushed to the master branch:

• 2c07214: 8368249: HttpClient: Translate exceptions thrown by sendAsync
• 0f34b02: 8365896: Remove unnecessary explicit buffer nul-termination after using os::snprintf
• 6964ced: 8369346: Remove default value of and deprecate the MaxRAM flag
• ... and 145 more: https://git.openjdk.org/jdk/compare/f158451c259a7f86af0851131af374d68d011003...master

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[mlbridge]

Webrevs

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[eme64]

@Hamlin-Li That looks like a great improvement :)

All I am missing are some test cases. And if possible: IR rules 😉

[Hamlin-Li]

@Hamlin-Li That looks like a great improvement :)

Thank you for having a look! :)

All I am missing are some test cases. And if possible: IR rules 😉

Yes, I also added some tests and IR rules of course. :)

[Hamlin-Li]

/solves JDK-8370481

[openjdk]

@Hamlin-Li
Adding additional issue to solves list: 8370481: C2 SuperWord: Long/Integer.compareUnsigned return wrong value in SLP.

[eme64]

@Hamlin-Li
I just looked at your Bug report JDK-8370481.
Can you add a reproducer, and on what platforms you have experienced the failure?

If you are fixing a bug here, we should focus on the bug only. After all, we may want to backport the bugfix.

[Hamlin-Li]

@eme64 I just keep Op_CmpI/L.
Test running, will update the result or code accordingly later.

[Hamlin-Li]

@eme64 I just keep Op_CmpI/L. Test running, will update the result or code accordingly later.

I ran all the tests under test/hotspot/jtreg/compiler on x86, the default case (i.e. ShouldNotReachHere) is not triggerred. Plus github CI, I think we are good at these switch cases.

[eme64]

The code looks really good now (modulo one tiny suggestion).

I'll run some internal testing now...

[Hamlin-Li]

The code looks really good now (modulo one tiny suggestion).

Fixed with github help, thanks for the suggestion! :)

I'll run some internal testing now...

Thank you!

[Hamlin-Li]

Hi, while @eme64 running some tests, can someone else have another look at this pr? Thanks!

[eme64]

Testing passed - Approved. Thanks for all the work, and looking forward to what you have still planned :)

[Hamlin-Li]

Testing passed - Approved. Thanks for all the work, and looking forward to what you have still planned :)

@eme64 Thank you for reviewing and testing!
I'll tag you when I send out other prs. :)

[gctony]

LGTM

[Hamlin-Li]

LGTM

@gctony Thank you for reviewing! :)

[Hamlin-Li]

/integrate

[openjdk]

Going to push as commit eab5644.
Since your change was applied there have been 148 commits pushed to the master branch:

• 2c07214: 8368249: HttpClient: Translate exceptions thrown by sendAsync
• 0f34b02: 8365896: Remove unnecessary explicit buffer nul-termination after using os::snprintf
• 6964ced: 8369346: Remove default value of and deprecate the MaxRAM flag
• ... and 145 more: https://git.openjdk.org/jdk/compare/f158451c259a7f86af0851131af374d68d011003...master

Your commit was automatically rebased without conflicts.

[openjdk]

@Hamlin-Li Pushed as commit eab5644.

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