8328107: Shenandoah/C2: TestVerifyLoopOptimizations test failure

[rwestrel]

The failure occurs because a load barrier is expanded on the backedge
of the counted loop. That breaks the expected counted loop shape. The
fix I propose is to replace the CountedLoop with a Loop node when
that happens. We're basically done with optimizations related to
counted loop at this point so this shouldn't make a difference.

/cc hotspot-compiler

---

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Issue

• JDK-8328107: Shenandoah/C2: TestVerifyLoopOptimizations test failure (Bug - P3)

Reviewers

• Aleksey Shipilev (@shipilev - Reviewer)

Reviewing

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[bridgekeeper]

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[openjdk]

@rwestrel 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:

8328107: Shenandoah/C2: TestVerifyLoopOptimizations test failure

Reviewed-by: shade

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At the time when this comment was updated there had been 346 new commits pushed to the master branch:

• 2a37764: 8333743: Change .jcheck/conf branches property to match valid branches
• 75dc2f8: 8330182: Start of release updates for JDK 24
• 054362a: 8332550: [macos] Voice Over: java.awt.IllegalComponentStateException: component must be showing on the screen to determine its location
• 9b436d0: 8333674: Disable CollectorPolicy.young_min_ergo_vm for PPC64
• 487c477: 8333647: C2 SuperWord: some additional PopulateIndex tests
• d02cb74: 8333270: HandlersOnComplexResetUpdate and HandlersOnComplexUpdate tests fail with "Unexpected reference" if timeoutFactor is less than 1/3
• 02f2404: 8333560: -Xlint:restricted does not work with --release
• 606df44: 8332670: C1 clone intrinsic needs memory barriers
• 33fd6ae: 8333622: ubsan: relocInfo_x86.cpp:101:56: runtime error: pointer index expression with base (-1) overflowed
• 8de5d20: 8332865: ubsan: os::attempt_reserve_memory_between reports overflow
• ... and 336 more: https://git.openjdk.org/jdk/compare/7ce4a13c0a891e606480e138f4025ffa328a18b3...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.

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[openjdk]

@rwestrel
The hotspot-compiler label was successfully added.

[mlbridge]

Webrevs

• 00: Full (9d2d06d0)

[shipilev]

This looks reasonable, thanks. Passes all the tests I throw at it.

[rwestrel]

@shipilev thanks for the review.

[rwestrel]

/integrate

[openjdk]

Going to push as commit b5212d7.
Since your change was applied there have been 442 commits pushed to the master branch:

• efab48c: 8333714: Cleanup the usages of CHECK_EXCEPTION_NULL_FAIL macro in java launcher
• cc64aea: 8332400: isspace argument should be a valid unsigned char
• 9b0a5c5: 8333248: VectorGatherMaskFoldingTest.java failed when maximum vector bits is 64
• 6861766: 8332818: ubsan: archiveHeapLoader.cpp:70:27: runtime error: applying non-zero offset 18446744073707454464 to null pointer
• b818679: 8293980: Resolve CONSTANT_FieldRef at CDS dump time
• eb2488f: 8330198: Add some class loading related perf counters to measure VM startup
• c4702ca: 8333827: JDK 23 RDP1 L10n resource files update
• bb7ef03: 8333599: Improve description of \b matcher in j.u.r.Pattern
• 0721dbe: 8334032: javax.print: Missing @SInCE tag in new class OutputBin
• 6462b87: 8333685: Make update-copyright-year script more useful
• ... and 432 more: https://git.openjdk.org/jdk/compare/7ce4a13c0a891e606480e138f4025ffa328a18b3...master

Your commit was automatically rebased without conflicts.

[openjdk]

@rwestrel Pushed as commit b5212d7.

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