8293998: [PPC64] JfrGetCallTrace: assert(_pc != nullptr) failed: must have PC

[TheRealMDoerr]

JfrGetCallTrace can still observe last_Java_pc == 0 (see JBS for more details). We can just skip the sample in this very rare case.

---

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Issue

• JDK-8293998: [PPC64] JfrGetCallTrace: assert(_pc != nullptr) failed: must have PC

Reviewers

• Aleksey Shipilev (@shipilev - Reviewer)
• Lutz Schmidt (@RealLucy - Reviewer)

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[bridgekeeper]

👋 Welcome back mdoerr! 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]

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[mlbridge]

Webrevs

• 00: Full (f3a977b3)

[shipilev]

I understand this is due to data race against unsynchronized writers? So only the partial fix from JDK-8293998 works, but not completely? If so, is there any way to strengthen the writers, so that we do not have to do this?

[TheRealMDoerr]

Adding release barriers at all places where we save the last Java sp and pc should also help. But that is mainly in assembly code which is spread over several files, not so nice to maintain and may have performance impact. I don' think it's worth the effort just to avoid extremely rare occurrences of last Java pc = 0. Dropping the sample makes more sense to me.

[shipilev]

All right then. Yeah, the last time I looked at the anchor code that does this racily, it was not very nice to fix...

[TheRealMDoerr]

Thanks for the review!

[openjdk]

@TheRealMDoerr 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:

8293998: [PPC64] JfrGetCallTrace: assert(_pc != nullptr) failed: must have PC

Reviewed-by: shade, lucy

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 94 new commits pushed to the master branch:

• 02ea338: 8293887: AArch64 build failure with GCC 12 due to maybe-uninitialized warning in libfdlibm k_rem_pio2.c
• 49a7347: 8294408: Problemlist runtime/handshake/HandshakeSuspendExitTest.java
• aa48705: 8289422: Fix and re-enable vector conditional move
• 1ddc92f: 8294404: [BACKOUT] JDK-8294142: make test should report only executed tests
• 1e222bc: 8293462: [macos] app image signature invalid when creating DMG or PKG from post processed signed image
• 43eff2b: 8272687: Replace StringBuffer with StringBuilder in RuleBasedCollator
• b88ee1e: 6251738: Want a top-level summary page that itemizes all spec documents referenced from javadocs (OEM spec)
• aca4276: 8294379: Missing comma after copyright year
• 1f521a1: 8225012: sanity/client/SwingSet/src/ToolTipDemoTest.java fails on Windows
• 5ae6bc2: 8234262: Unmask SIGQUIT in a child process
• ... and 84 more: https://git.openjdk.org/jdk/compare/8082c24a0df3f4861ea391266bdfe6cdd1a77bab...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.

[RealLucy]

Changes look good.

[TheRealMDoerr]

Thanks for the review!
/integrate

[openjdk]

Going to push as commit 14c6ac4.
Since your change was applied there have been 94 commits pushed to the master branch:

• 02ea338: 8293887: AArch64 build failure with GCC 12 due to maybe-uninitialized warning in libfdlibm k_rem_pio2.c
• 49a7347: 8294408: Problemlist runtime/handshake/HandshakeSuspendExitTest.java
• aa48705: 8289422: Fix and re-enable vector conditional move
• 1ddc92f: 8294404: [BACKOUT] JDK-8294142: make test should report only executed tests
• 1e222bc: 8293462: [macos] app image signature invalid when creating DMG or PKG from post processed signed image
• 43eff2b: 8272687: Replace StringBuffer with StringBuilder in RuleBasedCollator
• b88ee1e: 6251738: Want a top-level summary page that itemizes all spec documents referenced from javadocs (OEM spec)
• aca4276: 8294379: Missing comma after copyright year
• 1f521a1: 8225012: sanity/client/SwingSet/src/ToolTipDemoTest.java fails on Windows
• 5ae6bc2: 8234262: Unmask SIGQUIT in a child process
• ... and 84 more: https://git.openjdk.org/jdk/compare/8082c24a0df3f4861ea391266bdfe6cdd1a77bab...master

Your commit was automatically rebased without conflicts.

[openjdk]

@TheRealMDoerr Pushed as commit 14c6ac4.

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