8347718: Unexpected NullPointerException in C2 compiled code due to ReduceAllocationMerges

[JohnTortugo]

Please, review this patch to fix an issue in reducing allocation merges used by Cmp nodes. The attached test case, adapted from the one attached to the JBS issue, can be used to reproduce the issue. The root of the problem was not properly checking the return value of optimize_ptr_compare against different Cmp mask predicates.

I tested this on OSX(ARM64) & Linux(Intel) tier1-4.

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Progress

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Issue

• JDK-8347718: Unexpected NullPointerException in C2 compiled code due to ReduceAllocationMerges (Bug - P3)

Reviewers

• Vladimir Kozlov (@vnkozlov - Reviewer)
• Tobias Hartmann (@TobiHartmann - Reviewer)

Reviewing

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Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/23312/head:pull/23312
$ git checkout pull/23312

Update a local copy of the PR:
$ git checkout pull/23312
$ git pull https://git.openjdk.org/jdk.git pull/23312/head

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$ git pr checkout 23312

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https://git.openjdk.org/jdk/pull/23312.diff

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[bridgekeeper]

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[openjdk]

@JohnTortugo 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:

8347718: Unexpected NullPointerException in C2 compiled code due to ReduceAllocationMerges

Reviewed-by: kvn, thartmann

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 57 new commits pushed to the master branch:

• a224f12: 8348205: Improve cutover time selection when building available currencies set
• 8103256: 8348348: Remove unnecessary #ifdef STATIC_BUILD around DEF_STATIC_JNI_OnLoad from zip_util.c
• fb066ca: 8347272: [ubsan] JvmLauncher.cpp:262:52: runtime error: applying non-zero offset 40 to null pointer
• 5fec999: 8339668: Parallel: Adopt PartialArrayState to consolidate marking stack in Full GC
• 2bef5b4: 8348323: Corrupted timezone string in JVM crash log
• 3a8680e: 8347058: When automatically translating the page to pt-br, all CSS styling disappears
• a4942a2: 8348286: [AIX] clang 17 introduces new warning Wtentative-Definitions which produces Build errors
• 558255a: 8328919: Add BodyHandlers / BodySubscribers methods to handle excessive server input
• 1f74caa: 8348401: [IR Framework] PrintTimes should not require verbose
• f71541c: 8344976: Remove the jmx.invoke.getters compatibility property
• ... and 47 more: https://git.openjdk.org/jdk/compare/356e2a8f48679ea31f1483cf60803818934fc53f...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.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@dafedafe, @vnkozlov, @TobiHartmann) but any other Committer may sponsor as well.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

[openjdk]

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

• hotspot-compiler

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[mlbridge]

Webrevs

• 01: Full - Incremental (42052475)
• 00: Full (9b0bd41f)

[dafedafe]

Thanks for the fix @JohnTortugo.

[vnkozlov]

Tentatively approved. Need run our testing before final approval.

[vnkozlov]

I submitted new testing.

[TobiHartmann]

Looks good to me.

[vnkozlov]

My testing passed.

[JohnTortugo]

/integrate

[openjdk]

@JohnTortugo
Your change (at version 4205247) is now ready to be sponsored by a Committer.

[vnkozlov]

/sponsor

[openjdk]

Going to push as commit 9f4d3de.
Since your change was applied there have been 57 commits pushed to the master branch:

• a224f12: 8348205: Improve cutover time selection when building available currencies set
• 8103256: 8348348: Remove unnecessary #ifdef STATIC_BUILD around DEF_STATIC_JNI_OnLoad from zip_util.c
• fb066ca: 8347272: [ubsan] JvmLauncher.cpp:262:52: runtime error: applying non-zero offset 40 to null pointer
• 5fec999: 8339668: Parallel: Adopt PartialArrayState to consolidate marking stack in Full GC
• 2bef5b4: 8348323: Corrupted timezone string in JVM crash log
• 3a8680e: 8347058: When automatically translating the page to pt-br, all CSS styling disappears
• a4942a2: 8348286: [AIX] clang 17 introduces new warning Wtentative-Definitions which produces Build errors
• 558255a: 8328919: Add BodyHandlers / BodySubscribers methods to handle excessive server input
• 1f74caa: 8348401: [IR Framework] PrintTimes should not require verbose
• f71541c: 8344976: Remove the jmx.invoke.getters compatibility property
• ... and 47 more: https://git.openjdk.org/jdk/compare/356e2a8f48679ea31f1483cf60803818934fc53f...master

Your commit was automatically rebased without conflicts.

[openjdk]

@vnkozlov @JohnTortugo Pushed as commit 9f4d3de.

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