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8253756: C2 CompilerThread0 crash in Node::add_req(Node*) #537

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rwestrel
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@rwestrel rwestrel commented Oct 7, 2020

The outer strip mined loop is initially created as a skeleton and then
expanded once loop opts are over. As long as it is a skeleton, the
OuterStripMinedLoopEndNode cannot be constant folded because its input
is a place holder. So OuterStripMinedLoopEndNode::Value() blocks
constant folding. This bug triggers because the
OuterStripMinedLoopEndNode input after expansion is a constant but the
OuterStripMinedLoopEndNode is not constant folded (i.e. it's a dead
loop but it stays in the graph). The fix I propose is to change the
behavior OuterStripMinedLoopEndNode::Value() so it blocks constant
folding only until expansion but not after.


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Testing

Linux x64 Windows x64 macOS x64
Build ✔️ (3/3 passed) ✔️ (2/2 passed) ✔️ (2/2 passed)
Test (tier1) ✔️ (9/9 passed) (1/9 failed) ✔️ (9/9 passed)

Failed test task

Issue

  • JDK-8253756: C2 CompilerThread0 crash in Node::add_req(Node*)

Reviewers

Download

$ git fetch https://git.openjdk.java.net/jdk pull/537/head:pull/537
$ git checkout pull/537

…) once the outer strip mined loop is expanded
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bridgekeeper bot commented Oct 7, 2020

👋 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 label Oct 7, 2020
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openjdk bot commented Oct 7, 2020

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

  • hotspot-compiler

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

@openjdk openjdk bot added the hotspot-compiler label Oct 7, 2020
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mlbridge bot commented Oct 7, 2020

Webrevs

@@ -1726,16 +1726,38 @@ void OuterStripMinedLoopNode::adjust_strip_mined_loop(PhaseIterGVN* igvn) {
igvn->replace_node(outer_le, iff);
inner_cl->clear_strip_mined();
}
igvn->C->print_method(PHASE_DEBUG, 2);
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@iwanowww iwanowww Oct 7, 2020

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Looks like a leftover from debugging. Otherwise, the fix looks good.

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@rwestrel rwestrel Oct 7, 2020

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Good catch. I thought I removed it but obviously didn't. I updated the change. Thanks for the review.

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@iwanowww iwanowww left a comment

Looks good.

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openjdk bot commented Oct 7, 2020

@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:

8253756: C2 CompilerThread0 crash in Node::add_req(Node*)

Reviewed-by: vlivanov, 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 55 new commits pushed to the master branch:

  • 8f9e479: 8254144: Non-x86 Zero builds fail with return-type warning in os_linux_zero.cpp
  • 7952c06: 8254166: Zero: return-type warning in zeroInterpreter_zero.cpp
  • 894ec76: 8254027: gc/g1/TestHumongousConcurrentStartUndo.java failed with "'Concurrent Mark Cycle' missing from stdout/stderr"
  • bc23690: 8254173: Add Zero, Minimal hotspot targets to submit workflow
  • e1187c4: 8248262: Wrong link target in ModuleDescriptor#isAutomatic's API documentation
  • 9cdfd0f: 8254096: remove jdk.test.lib.Utils::getMandatoryProperty(String) method
  • d1e94ee: 8253909: Implement detailed map file for CDS
  • 7733a0e: 8254182: remove Utils.tryFindJvmPid/waitForJvmPid
  • 4e5ef30: 8254104: MethodCounters must exist before nmethod is installed
  • fd0cb98: 8253901: ARM32: SIGSEGV during monitorexit due to incorrect register use (after JDK-8253540)
  • ... and 45 more: https://git.openjdk.java.net/jdk/compare/9604ee82690f89320614b37bfef4178abc869777...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 label Oct 7, 2020
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@TobiHartmann TobiHartmann left a comment

Looks reasonable to me.

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rwestrel commented Oct 8, 2020

/integrate

@openjdk openjdk bot closed this Oct 8, 2020
@openjdk openjdk bot added integrated and removed ready rfr labels Oct 8, 2020
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openjdk bot commented Oct 8, 2020

@rwestrel Since your change was applied there have been 55 commits pushed to the master branch:

  • 8f9e479: 8254144: Non-x86 Zero builds fail with return-type warning in os_linux_zero.cpp
  • 7952c06: 8254166: Zero: return-type warning in zeroInterpreter_zero.cpp
  • 894ec76: 8254027: gc/g1/TestHumongousConcurrentStartUndo.java failed with "'Concurrent Mark Cycle' missing from stdout/stderr"
  • bc23690: 8254173: Add Zero, Minimal hotspot targets to submit workflow
  • e1187c4: 8248262: Wrong link target in ModuleDescriptor#isAutomatic's API documentation
  • 9cdfd0f: 8254096: remove jdk.test.lib.Utils::getMandatoryProperty(String) method
  • d1e94ee: 8253909: Implement detailed map file for CDS
  • 7733a0e: 8254182: remove Utils.tryFindJvmPid/waitForJvmPid
  • 4e5ef30: 8254104: MethodCounters must exist before nmethod is installed
  • fd0cb98: 8253901: ARM32: SIGSEGV during monitorexit due to incorrect register use (after JDK-8253540)
  • ... and 45 more: https://git.openjdk.java.net/jdk/compare/9604ee82690f89320614b37bfef4178abc869777...master

Your commit was automatically rebased without conflicts.

Pushed as commit 76a5852.

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

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