8275262: [BACKOUT] AArch64: Implement string_compare intrinsic in SVE

[nick-arm]

This reverts "8269559: AArch64: Implement string_compare intrinsic in SVE" which caused some unknown failures in Oracle's CI.

---

Progress

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Issue

• JDK-8275262: [BACKOUT] AArch64: Implement string_compare intrinsic in SVE

Reviewers

• David Holmes (@dholmes-ora - Reviewer)
• Thomas Schatzl (@tschatzl - Reviewer)

Reviewing

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Update a local copy of the PR:
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[bridgekeeper]

👋 Welcome back ngasson! 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.

[nick-arm]

/label add core-libs

[openjdk]

@nick-arm
The core-libs label was successfully added.

[mlbridge]

Webrevs

• 00: Full (2434d29e)

[dholmes-ora]

Thanks for attending to this so quickly @nick-arm !

The issue is only on (some of) our macOS Aarch64 systems. Let me know if I can provide more info on hardware etc.

David

[dholmes-ora]

/label add hotspot-compiler

[openjdk]

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8275262: [BACKOUT] AArch64: Implement string_compare intrinsic in SVE

Reviewed-by: dholmes, tschatzl

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[openjdk]

@dholmes-ora
The hotspot-compiler label was successfully added.

[nick-arm]

Thanks @dholmes-ora . I'll wait for the GitHub Actions tests to finish. Should I retitle this to "[BACKOUT] AArch64: Implement string_compare intrinsic in SVE" as per the developer's guide?

[mlbridge]

Mailing list message from David Holmes on core-libs-dev:

On 14/10/2021 4:55 pm, Nick Gasson wrote:

On Thu, 14 Oct 2021 06:48:18 GMT, David Holmes <dholmes at openjdk.org> wrote:

This reverts "8269559: AArch64: Implement string_compare intrinsic in SVE" which caused some unknown failures in Oracle's CI.

Thanks for attending to this so quickly @nick-arm !

The issue is only on (some of) our macOS Aarch64 systems. Let me know if I can provide more info on hardware etc.

David

Thanks @dholmes-ora . I'll wait for the GitHub Actions tests to finish. Should I retitle this to "[BACKOUT] AArch64: Implement string_compare intrinsic in SVE" as per the developer's guide?

Yes please follow whatever the dev guide states to do.

Thanks,
David

[tschatzl]

Lgtm.

[theRealAph]

The issue is only on (some of) our macOS Aarch64 systems. Let me know if I can provide more info on hardware etc.

Any info about what failed? A reproducer would be nice.

[nick-arm]

The issue is only on (some of) our macOS Aarch64 systems. Let me know if I can provide more info on hardware etc.

Any info about what failed? A reproducer would be nice.

I just ran tier1 on an M1 Mac with no failures - perhaps it's OS version dependent if it only failed on some systems? I have:

$ uname -a
Darwin [...] 20.2.0 Darwin Kernel Version 20.2.0: Wed Dec  2 20:40:21 PST 2020; root:xnu-7195.60.75~1/RELEASE_ARM64_T8101 arm64

[theRealAph]

It might be a spurious failure, then. I guess we need to see the test logs.

[nick-arm]

It might be a spurious failure, then. I guess we need to see the test logs.

I'll revert it for in now in case we missed something.

[nick-arm]

/integrate

[openjdk]

Going to push as commit 333c469.

[openjdk]

@nick-arm Pushed as commit 333c469.

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

[mlbridge]

Mailing list message from David Holmes on core-libs-dev:

On 14/10/2021 6:27 pm, Andrew Haley wrote:

On Thu, 14 Oct 2021 07:08:20 GMT, David Holmes <david.holmes at oracle.com> wrote:

The issue is only on (some of) our macOS Aarch64 systems. Let me know if I can provide more info on hardware etc.

Any info about what failed? A reproducer would be nice.

See https://bugs.openjdk.java.net/browse/JDK-8275263 for some info on
the failures. It seems really bizarre.

David

[theRealAph]

See https://bugs.openjdk.java.net/browse/JDK-8275263 for some info on the failures. It seems really bizarre.

I would understand this a lot better if the affected machines actually used SVE, but they don't have the hardware.
That does reduce the bug surface: we only need to look at the affected common code, and the only thing I can immediately see is that a couple of unused register arguments have been added.
Unless, of course, the affected Macs think they have SVE... ? I don't think that's possible.
I'd definitely be looking at the host toolchain for differences.