JDK-8319784: VM crash during heap dump after JDK-8287061

[JohnTortugo]

This fixes an incorrect assert in debugInfo.hpp. The assert is incorrect because this method may be called before rematerialization of the ObjectValue takes place, and therefore, _selected will be nullptr. This pull request patches the method to just return Handle() => nullptr if the rematerialization of the object hasn't taken place yet. This is the same behavior used by scalar-replaced objects not participating in merges.

I added a test to reproduce a scenario where the assert was causing a problem.

Tested on Ubuntu/MacOS/Windows x86_64 tier1-4.

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8319784: VM crash during heap dump after JDK-8287061 (Bug - P2)

Reviewers

• Vladimir Kozlov (@vnkozlov - Reviewer) ⚠️ Review applies to aa723f50
• Tobias Hartmann (@TobiHartmann - Reviewer) ⚠️ Review applies to 26f7c936
• Aleksey Shipilev (@shipilev - Reviewer) ⚠️ Review applies to 26f7c936

Reviewing

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Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/16622/head:pull/16622
$ git checkout pull/16622

Update a local copy of the PR:
$ git checkout pull/16622
$ git pull https://git.openjdk.org/jdk.git pull/16622/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 16622

View PR using the GUI difftool:
$ git pr show -t 16622

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/16622.diff

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[bridgekeeper]

👋 Welcome back cslucas! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

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

• hotspot-compiler

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[mlbridge]

Webrevs

• 03: Full - Incremental (80b7e0a3)
• 02: Full - Incremental (43856812)
• 01: Full - Incremental (26f7c936)
• 00: Full (aa723f50)

[vnkozlov]

Looks good. You need second review.

[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:

8319784: VM crash during heap dump after JDK-8287061

Reviewed-by: kvn, thartmann, 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 100 new commits pushed to the master branch:

• 6e86904: 8319973: AArch64: Save and restore FPCR in the call stub
• 04fd17e: 8320410: Reflow markdown in building.md
• 7f23110: 8319928: Exceptions thrown by cleanup actions should be handled correctly
• a6098e4: 8320280: RISC-V: Avoid passing t0 as temp register to MacroAssembler::lightweight_lock/unlock
• 60c8d9c: 8320300: Adjust hs_err output in malloc/mmap error cases
• 9f6a4a3: 8320386: Remove java/nio/channels/vthread/BlockingChannelOps.java#direct-register from ProblemList
• db1d823: 8320168: handle setsocktopt return values
• 6c5e15c: 8316557: Make fields final in 'sun.util' package
• de51aa1: 8283214: [macos] Screen magnifier does not show the magnified text for JcomboBox
• 179f505: 8320361: Doc error in RemoteRecordingStream.java
• ... and 90 more: https://git.openjdk.org/jdk/compare/ea1ffa34192448317ce9a61a3588b0dee3a2ef44...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 (@vnkozlov, @TobiHartmann, @shipilev) 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).

[TobiHartmann]

Looks good to me. I've re-submitted testing and will report back once it passed.

[TobiHartmann]

All tests passed.

[shipilev]

Good. I have just a few cosmetic suggestions.

[JohnTortugo]

/integrate

[openjdk]

@JohnTortugo
Your change (at version 80b7e0a) is now ready to be sponsored by a Committer.

[TobiHartmann]

/sponsor

[openjdk]

Going to push as commit 3544d2d.
Since your change was applied there have been 113 commits pushed to the master branch:

• 303757b: 8319879: Stress mode to randomize incremental inlining decision
• 099a8f5: 8308144: Uncontrolled memory consumption in SSLFlowDelegate.Reader
• fcb4df2: 8320192: SHAKE256 does not work correctly if n >= 137
• 2b4e991: 8320208: Update Public Suffix List to b5bf572
• 6b96bb6: 8319777: Zero: Support 8-byte cmpxchg
• 020c900: 8320052: Zero: Use __atomic built-ins for atomic RMW operations
• 30d8953: 8275889: Search dialog has redundant scrollbars
• cee54de: 8319988: Wrong heading for inherited nested classes
• 32098ce: 8320348: test/jdk/java/io/File/GetAbsolutePath.windowsDriveRelative fails if working directory is not on drive C
• a2c0fa6: 8320372: test/jdk/sun/security/x509/DNSName/LeadingPeriod.java validity check failed
• ... and 103 more: https://git.openjdk.org/jdk/compare/ea1ffa34192448317ce9a61a3588b0dee3a2ef44...master

Your commit was automatically rebased without conflicts.

[openjdk]

@TobiHartmann @JohnTortugo Pushed as commit 3544d2d.

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