8311691: C2: Remove legacy code related to PostLoopMultiversioning

[pfustc]

As discussed in JDK-8308994, we are working on re-implementation of post loop vectorization and planning to refactor current SuperWord code. As nobody is using or maintaining the old implementation now, to make the refactoring work easier, we propose to remove the legacy code of the old implementation first.

This patch removes all code realted to PostLoopMultiversioning inside and outside SuperWord. After the removal, SLP_extract() in SuperWord should only work on main loops. So we also removed all is_main_loop() checks inside and added assertions instead.

Tested with hotspot::hotspot_all_no_apps, jdk tier1~3, langtools tier1 and 100k fuzzer tests on x86 and AArch64, no issue is found.

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Issue

• JDK-8311691: C2: Remove legacy code related to PostLoopMultiversioning (Enhancement - P4)

Reviewers

• Vladimir Kozlov (@vnkozlov - Reviewer)
• Sandhya Viswanathan (@sviswa7 - Reviewer)

Reviewing

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[openjdk]

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[mlbridge]

Webrevs

• 00: Full (4a46cd08)

[vnkozlov]

Good. Thank you for cleaning this.

[openjdk]

@pfustc 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:

8311691: C2: Remove legacy code related to PostLoopMultiversioning

Reviewed-by: kvn, 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 17 new commits pushed to the master branch:

• f82c818: 8308694: Clarify reversed() default methods' implementation requirements
• 7304316: 8311926: java/lang/ScopedValue/StressStackOverflow.java takes 9mins in tier1
• aa7367f: 8311921: Inform about MaxExpectedDataSegmentSize in case of pthread_create failures on AIX
• 753bd56: 8311870: Split CompressedKlassPointers from compressedOops.hpp
• 0b0e064: 8311656: Shenandoah: Unused ShenandoahSATBAndRemarkThreadsClosure::_claim_token
• fd7fddb: 8295894: Remove SECOM certificate that is expiring in September 2023
• d82ade3: 8310683: Refactor StandardCharset/standard.java to use JUnit
• aac903d: 8311805: Clean up ScrollPane: drop redundant initialiser, mark scroller final
• 15195e6: 8310066: Improve test coverage for JVMTI GetThreadState on carrier and mounted vthread
• 6cb9ec3: 6960866: [Fmt-Ch] ChoiceFormat claims impossible and unimplemented functionality
• ... and 7 more: https://git.openjdk.org/jdk/compare/4b1403d06b99b91ddd89ad6e54669b0595f1f8e5...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.

[pfustc]

Thanks Vladimir for approving this. May I have another review?

[sviswa7]

Looks good to me as well.

[pfustc]

/integrate

[openjdk]

Going to push as commit a38582e.
Since your change was applied there have been 25 commits pushed to the master branch:

• 38f7412: 8311609: [windows] Native stack printing lacks source information for dynamically loaded dlls
• e51472e: 8309566: Migrate away from TagletWriter and TagletWriterImpl
• fb90af8: 8311380: Prepare java.desktop for C++17
• 743e8b8: 8306785: fix deficient spliterators for Sequenced Collections
• 372d0cf: 8311545: Allow test symbol files to be kept in the test image
• 489a32f: 8311813: C1: Uninitialized PhiResolver::_loop field
• 119cc49: 8156889: ListKeychainStore.sh fails in some virtualized environments
• ed9337e: 8155902: DataOuputStream should clarify that it might write primitive types as multiple byte groups
• f82c818: 8308694: Clarify reversed() default methods' implementation requirements
• 7304316: 8311926: java/lang/ScopedValue/StressStackOverflow.java takes 9mins in tier1
• ... and 15 more: https://git.openjdk.org/jdk/compare/4b1403d06b99b91ddd89ad6e54669b0595f1f8e5...master

Your commit was automatically rebased without conflicts.

[openjdk]

@pfustc Pushed as commit a38582e.

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