8290964: C2 compilation fails with assert "non-reduction loop contains reduction nodes"

[robcasloz]

This changeset removes the reduction information consistency assertion in SuperWord::output(), which has proven to report too many false positives (inconsistencies that do not lead to miscompilation) since its introduction by JDK-8279622, despite the efforts to reduce the false positive rate in JDK-8286177. During the time the assertion has been enabled in our internal CI system, no true positive case (reported inconsistencies actually leading to a miscompilation or a crash) has been observed.

An alternative solution would be to wait for JDK-8287087 (work in progress), which proposes a refactoring of the reduction analysis logic that eliminates by construction the need for this assertion. This changeset proposes removing the assertion earlier, to reduce noise in test environments.

Testing

• hs-tier1 (windows-x64, linux-x64, linux-aarch64, and macosx-x64).

---

Progress

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Issue

• JDK-8290964: C2 compilation fails with assert "non-reduction loop contains reduction nodes"

Reviewers

• Tobias Hartmann (@TobiHartmann - Reviewer)
• Christian Hagedorn (@chhagedorn - Reviewer)

Reviewing

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[mlbridge]

Webrevs

• 00: Full (429f5a87)

[TobiHartmann]

That looks reasonable to me.

[openjdk]

@robcasloz 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:

8290964: C2 compilation fails with assert "non-reduction loop contains reduction nodes"

Reviewed-by: thartmann, chagedorn

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 14 new commits pushed to the master branch:

• 16047e8: 8292780: misc tests failed "assert(false) failed: graph should be schedulable"
• bf39b18: 8288302: Shenandoah: SIGSEGV in vm maybe related to jit compiling xerces
• f957ce9: 8294564: IGV: IllegalArgumentException for "Difference to current graph"
• ae79af2: 8294740: Add cgroups keyword to TestDockerBasic.java
• 07ed68e: 8288907: serviceability/jvmti/vthread/SuspendResume1/SuspendResume1.java fails with -XX:TieredStopAtLevel=2,3
• 090cdfc: 8294726: Update URLs in minefield tests
• ed40d88: 8276849: Refresh the window icon on graphics configuration changes
• 081691a: 8294593: Check the size of the target on invocations of BigInteger::isProbablePrime
• a4f2078: 8294437: java/nio/channels/FileChannel tests slow on Windows
• c6e3daa: 8242115: C2 SATB barriers are not safepoint-safe
• ... and 4 more: https://git.openjdk.org/jdk/compare/f2a32d996ae09620474771c46a649f6c4e1148ad...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.

[robcasloz]

That looks reasonable to me.

Thanks, Tobias.

[chhagedorn]

That makes sense, looks good!

[robcasloz]

That makes sense, looks good!

Thanks for reviewing, Christian.

[robcasloz]

/integrate

[openjdk]

Going to push as commit 4bdd1c9.
Since your change was applied there have been 32 commits pushed to the master branch:

• b4e74ae: 8294514: Wrong initialization of nmethod::_consts_offset for native nmethods
• 953ce8d: 8293701: jdeps InverseDepsAnalyzer runs into NoSuchElementException: No value present
• be82cff: 8294748: Cleanup unneeded references to hg
• 43dbf58: 8186765: Speed up test sun/net/www/protocol/https/HttpsClient/ProxyAuthTest.java
• 755958e: 8294376: Minimize disabled warnings in java.base
• 1dafbe3: 8294539: Augment discussion of equivalence relations on floating-point values
• b2e86a6: 8294255: Add link to DEFAULT_WAIT_TIME in javadoc for SunToolKit.realsSync
• b22a38d: 8292309: Fix java/awt/PrintJob/ConstrainedPrintingTest/ConstrainedPrintingTest.java test
• 121d4a5: 8293579: tools/jpackage/share/jdk/jpackage/tests/UnicodeArgsTest.java fails on Japanese Windows platform
• 1166a8a: 8292214: Memory leak in getAllConfigs of awt_GraphicsEnv.c:386
• ... and 22 more: https://git.openjdk.org/jdk/compare/f2a32d996ae09620474771c46a649f6c4e1148ad...master

Your commit was automatically rebased without conflicts.

[openjdk]

@robcasloz Pushed as commit 4bdd1c9.

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