8259227: C2 crashes with SIGFPE due to a division that floats above its zero check #89

chhagedorn · 2021-01-06T13:43:17Z

This bug is very similar to JDK-8257822. In this testcase, a Div node has no longer its zero check as direct control input and is later moved before the zero check by IfNode::dominated_by() which updates all data nodes to a dominating If (in JDK-8257822 it was done by PhaseIdealLoop::dominated_by()) .

I suggest to use the same fix for IfNode::dominated_by() as for PhaseIdealLoop::dominated_by() in JDK-8257822 to only move data nodes to the dominating If if it is not a Div or Mod node that could have a zero divisor (i.e. a zero check).

Thanks,
Christian

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Issue

JDK-8259227: C2 crashes with SIGFPE due to a division that floats above its zero check

Reviewers

Vladimir Kozlov (@vnkozlov - Reviewer) ⚠️ Review applies to 4273fcf
Tobias Hartmann (@TobiHartmann - Reviewer)

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$ git fetch https://git.openjdk.java.net/jdk16 pull/89/head:pull/89
$ git checkout pull/89

…ts zero check

bridgekeeper · 2021-01-06T13:44:07Z

👋 Welcome back chagedorn! 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 · 2021-01-06T13:45:38Z

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

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mlbridge · 2021-01-06T14:30:08Z

Webrevs

01: Full - Incremental (461681a)
00: Full (4273fcf)

vnkozlov

Looks good.

openjdk · 2021-01-06T18:12:44Z

@chhagedorn 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:

8259227: C2 crashes with SIGFPE due to a division that floats above its zero check

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 13 new commits pushed to the master branch:

4a478b8: 8250903: jdk/jfr/javaagent/TestLoadedAgent.java fails with Mismatch in TestEvent count
4f914e2: 8249633: doclint reports missing javadoc for JavaFX property methods that have a property description
eef43be: 8251200: False positive messages about missing comments for serialization
f1bc4e0: 8259312: VerifyCACerts.java fails as soneraclass2ca cert will expire in 90 days
4a5786b: 8259075: Update the copyright notice in the files generated by CLDR Converter tool
d25a1be: 8259224: (ann) getAnnotatedReceiverType should not parameterize owner(s) of statically nested classes
ad45678: 8258558: Revert changes for JDK-8252505 and related issues
e66187d: 8259032: MappedMemorySegmentImpl#makeMappedSegment() ignores Unmapper#pagePosition
80110da: 8259007: This test printed a blank page
554e60c: 8258989: JVM is failed to inline in jdk.internal.vm.vector.VectorSupport::convert
... and 3 more: https://git.openjdk.java.net/jdk16/compare/bbc2e9510bb32d69d823bd572b6c0c02bd2335af...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.

chhagedorn · 2021-01-07T10:13:43Z

Thanks for your review Vladimir!

TobiHartmann

Otherwise looks good to me.

TobiHartmann · 2021-01-07T10:57:53Z

test/hotspot/jtreg/compiler/loopopts/TestDivZeroDominatedBy.java

+ * @summary Verify that zero check is executed before division/modulo operation.
+ * @requires vm.compiler2.enabled
+ * @run main/othervm -Xcomp -XX:-TieredCompilation -XX:CompileOnly=compiler/loopopts/TestDivZeroDominatedBy::test
+ *                   -XX:+UnlockDiagnosticVMOptions -XX:+StressGCM -XX:StressSeed=917280111 compiler.loopopts.TestDivZeroDominatedBy


Just wondering if the StressSeed should really be hardcoded? If things change in the VM, this seed might not longer reproduce the issue. Maybe add another @run with no fixed seed?

Good idea. I also updated the test from JDK-8257822 with such an additional run.

Add additional runs without fixed seed

TobiHartmann

Thanks for updating, looks good!

chhagedorn · 2021-01-07T14:57:30Z

Thanks Tobias for your review!

chhagedorn · 2021-01-07T15:02:05Z

/integrate

openjdk · 2021-01-07T15:03:02Z

@chhagedorn Since your change was applied there have been 14 commits pushed to the master branch:

484e23b: 8258657: Doc build is broken by use of new language features
4a478b8: 8250903: jdk/jfr/javaagent/TestLoadedAgent.java fails with Mismatch in TestEvent count
4f914e2: 8249633: doclint reports missing javadoc for JavaFX property methods that have a property description
eef43be: 8251200: False positive messages about missing comments for serialization
f1bc4e0: 8259312: VerifyCACerts.java fails as soneraclass2ca cert will expire in 90 days
4a5786b: 8259075: Update the copyright notice in the files generated by CLDR Converter tool
d25a1be: 8259224: (ann) getAnnotatedReceiverType should not parameterize owner(s) of statically nested classes
ad45678: 8258558: Revert changes for JDK-8252505 and related issues
e66187d: 8259032: MappedMemorySegmentImpl#makeMappedSegment() ignores Unmapper#pagePosition
80110da: 8259007: This test printed a blank page
... and 4 more: https://git.openjdk.java.net/jdk16/compare/bbc2e9510bb32d69d823bd572b6c0c02bd2335af...master

Your commit was automatically rebased without conflicts.

Pushed as commit c1fb521.

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

8259227: C2 crashes with SIGFPE due to a division that floats above i…

4273fcf

…ts zero check

openjdk bot added the rfr Pull request is ready for review label Jan 6, 2021

openjdk bot added the hotspot-compiler hotspot-compiler-dev@openjdk.java.net label Jan 6, 2021

vnkozlov approved these changes Jan 6, 2021

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openjdk bot added the ready Pull request is ready to be integrated label Jan 6, 2021

TobiHartmann approved these changes Jan 7, 2021

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461681a

Add additional runs without fixed seed

TobiHartmann approved these changes Jan 7, 2021

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openjdk bot closed this Jan 7, 2021

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 Jan 7, 2021

8259227: C2 crashes with SIGFPE due to a division that floats above its zero check #89

8259227: C2 crashes with SIGFPE due to a division that floats above its zero check #89

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