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8269746: C2: assert(!in->is_CFG()) failed: CFG Node with no controlling input? #222

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@rwestrel rwestrel commented Jul 7, 2021

The backedge and the exit test of an inner strip mined loop are
removed. A safepoint is right above the inner loop exit test when that
happens. The outer strip mined loop safepoint is then processed by
igvn which finds the other safepoint. This causes the outer loop
safepoint to be replaced by the safepoint that was in the inner
loop. Then the outer loop back edge is removed by igvn. This is done
by replacing the loop exit by the control of the outer loop
safepoint. Given the outer loop safepoint was replaced by a dominating
safepoint, that logic replaces the oiter loop exit with the dominating
safepoint control input. That must be harmless most of the time, but
in this particular case a Store was between the 2 safepoints. That
Store is still reachable in the graph but its control is not.

Note: test case not included because the crash no longer reproduces (supposedly because order of node processing by igvn matters)


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  • JDK-8269746: C2: assert(!in->is_CFG()) failed: CFG Node with no controlling input?

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👋 Welcome back roland! 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 openjdk bot added the rfr Pull request is ready for review label Jul 7, 2021
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@rwestrel The following label will be automatically applied to this pull request:

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@openjdk openjdk bot added the hotspot-compiler hotspot-compiler-dev@openjdk.java.net label Jul 7, 2021
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Webrevs

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Looks good!

Have you tried playing around with -XX:+StressIGVN to trigger it again?

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openjdk bot commented Jul 7, 2021

@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:

8269746: C2: assert(!in->is_CFG()) failed: CFG Node with no controlling input?

Reviewed-by: chagedorn, 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 17 new commits pushed to the master branch:

  • 1f2bf1d: 8269879: [PPC64] C2: Math.rint intrinsic uses wrong rounding mode
  • 7fcd5ca: 8266036: class file for sun.misc.Contended not found
  • a49b1dc: 8269772: [macos-aarch64] test compilation failed with "SocketException: No buffer space available"
  • 820f290: 8268859: jshell throws exception while parsing illegal "case true"
  • 815e4af: 8269802: javac fails to compile nested pattern matching switches
  • 2daf39a: 8269830: SA's vm object vtable matching code sometimes matches on incorrect type
  • 0ebf8aa: 8268778: CDS check_excluded_classes needs DumpTimeTable_lock
  • 0d1cd3a: 8269825: [TESTBUG] Missing testing for x86 KNL platforms
  • e0c130f: 8269955: ProblemList compiler/vectorapi/VectorCastShape[64|128]Test.java tests on x86
  • 1166ef2: 8268966: AArch64: 'bad AD file' in some vector conversion tests
  • ... and 7 more: https://git.openjdk.java.net/jdk17/compare/e14801cdd9b108aa4ca47d0bc1dc67fca575764c...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.

@openjdk openjdk bot added the ready Pull request is ready to be integrated label Jul 7, 2021
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rwestrel commented Jul 7, 2021

Have you tried playing around with -XX:+StressIGVN to trigger it again?

Thanks for the suggestion. I tried running the test case 1000 times in a loop with -XX:+StressIGVN but the crash doesn't reproduce.

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Looks reasonable to me.

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Have you tried playing around with -XX:+StressIGVN to trigger it again?

Thanks for the suggestion. I tried running the test case 1000 times in a loop with -XX:+StressIGVN but the crash doesn't reproduce.

Okay, thanks for trying it!

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rwestrel commented Jul 8, 2021

@TobiHartmann @chhagedorn thanks for the reviews

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rwestrel commented Jul 8, 2021

/integrate

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openjdk bot commented Jul 8, 2021

Going to push as commit 8f798b8.
Since your change was applied there have been 19 commits pushed to the master branch:

  • c812bbb: 8269929: (test) Add diagnostic info to ProceessBuilder/Basic.java for unexpected output
  • 6000950: 8269185: Directories in /opt/runtimepackagetest and /path/to/jdk-17 are different
  • 1f2bf1d: 8269879: [PPC64] C2: Math.rint intrinsic uses wrong rounding mode
  • 7fcd5ca: 8266036: class file for sun.misc.Contended not found
  • a49b1dc: 8269772: [macos-aarch64] test compilation failed with "SocketException: No buffer space available"
  • 820f290: 8268859: jshell throws exception while parsing illegal "case true"
  • 815e4af: 8269802: javac fails to compile nested pattern matching switches
  • 2daf39a: 8269830: SA's vm object vtable matching code sometimes matches on incorrect type
  • 0ebf8aa: 8268778: CDS check_excluded_classes needs DumpTimeTable_lock
  • 0d1cd3a: 8269825: [TESTBUG] Missing testing for x86 KNL platforms
  • ... and 9 more: https://git.openjdk.java.net/jdk17/compare/e14801cdd9b108aa4ca47d0bc1dc67fca575764c...master

Your commit was automatically rebased without conflicts.

@openjdk openjdk bot closed this Jul 8, 2021
@openjdk openjdk bot added integrated Pull request has been integrated and removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Jul 8, 2021
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openjdk bot commented Jul 8, 2021

@rwestrel Pushed as commit 8f798b8.

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

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