8255894: Remove unused StubRoutines::_zero_aligned_words

[cl4es]

_zero_aligned_words was a SPARC-only optimization added by JDK-7059037

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Progress

• Change must not contain extraneous whitespace
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Testing

	Linux x64	Linux x86	Windows x64	macOS x64
Build	✔️ (5/5 passed)	✔️ (2/2 passed)	✔️ (2/2 passed)	✔️ (2/2 passed)
Test (tier1)	✔️ (9/9 passed)	✔️ (9/9 passed)	❌ (2/9 failed)	❌ (1/9 failed)

Failed test tasks

• Windows x64 (hs/tier1 gc)
• Windows x64 (hs/tier1 serviceability)
• macOS x64 (hs/tier1 gc)

Issue

• JDK-8255894: Remove unused StubRoutines::_zero_aligned_words

Reviewers

• Aleksey Shipilev (@shipilev - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jdk pull/1053/head:pull/1053
$ git checkout pull/1053

[bridgekeeper]

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[openjdk]

@cl4es The following label will be automatically applied to this pull request:

• hotspot

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[mlbridge]

Webrevs

• 00: Full (03167b7)

[glaubitz]

FWIW, we are still building Zero on SPARC in Debian. So, if there is an extra alignment that's needed on SPARC, I'd appreciate if it could stay in in case it's required for SPARC.

[shipilev]

FWIW, we are still building Zero on SPARC in Debian. So, if there is an extra alignment that's needed on SPARC, I'd appreciate if it could stay in in case it's required for SPARC.

This is not about Zero VM. This stub is supposed to be zeroing the memory, and it is not used at all, AFAICS. So there is no breakage for Zero VM on SPARC.

[glaubitz]

This is not about Zero VM. This stub is supposed to be zeroing the memory, and it is not used at all, AFAICS. So there is no breakage for Zero VM on SPARC.

OK, thanks. I just wanted to be sure since I remember there were parts in Hotspot that were used both for Zero and the native versions of Hotspot.

[cl4es]

FWIW, we are still building Zero on SPARC in Debian. So, if there is an extra alignment that's needed on SPARC, I'd appreciate if it could stay in in case it's required for SPARC.

This routine was used as part of an optimization of pd_fill_to_aligned_words on SPARC. I'm not sure how this method looks in your source tree now since all the flags that control this has been dropped from the mainline.

[shipilev]

After looking at copy_zero.hpp, I believe Zero uses its own pd_fill_to_aligned_words and pd_fill_to_words. AFAIU, Zero tries to avoid the arch-specific code as much as possible, and that also extends to not using the "usual" stubs that require arch-specific generators.

[openjdk]

@cl4es 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:

8255894: Remove unused StubRoutines::_zero_aligned_words

Reviewed-by: shade

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 3 new commits pushed to the master branch:

• 61c9247: 8255895: Submit workflow artifacts miss hs_errs/replays due to ZIP include mismatch
• 7f4d873: 8255215: Unsupported 'valign' attribute for 'tr' tag used in j.s.t.h.HTMLDocument
• 724217c: 8255893: Problemlist runtime/cds/appcds/jigsaw/NewModuleFinderTest.java

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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.

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[cl4es]

@shipilev thanks for verifying that (and for reviewing)!

[cl4es]

/integrate

[openjdk]

@cl4es Since your change was applied there have been 34 commits pushed to the master branch:

• fc894ab: 8255955: Shenandoah: Only STW GC should process concurrent roots at pauses
• d6f0940: 8255913: Decrease number of iterations in TestMaxCachedBufferSize
• 1b59595: 8255914: [AOT] Using AOT flag should give warning when AOT is not included in build
• a50fdd5: 8219014: (bf) Add absolute bulk put methods which accept a source Buffer
• 3a02578: 8255452: Doing GC during JVMTI MethodExit event posting breaks return oop
• ba2ff3a: 8250637: UseOSErrorReporting times out (on Mac and Linux)
• 31918c5: 8255847: Shenandoah: Shenandoah should not mark through weak roots
• 867a484: 8255214: Unsupported 'valign' attribute for 'th' tag used in j.u.l.LogManager
• d3c43c2: 8255937: Better cleanup for test/jdk/javax/imageio/stream/StreamFlush.java
• b65ff60: 8255226: (tz) Upgrade time-zone data to tzdata2020d
• ... and 24 more: https://git.openjdk.java.net/jdk/compare/6023f6b1bf99de413e78c6373674649cbd68fae8...master

Your commit was automatically rebased without conflicts.

Pushed as commit 140c162.

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