8285558: IGV: scheduling crashes on control-unreachable CFG nodes

[robcasloz]

This changeset relaxes IGV's schedule approximation algorithm to handle CFG nodes that are not reachable from the root node via a control path. This is done by 1) removing the assumption that, after ServerCompilerScheduler::buildBlocks(), Node::block is non-null for CFG nodes; and 2) leaving the assignment of blockless nodes to an artificial "no block" to InputGraph::ensureNodesInBlocks(), which is always called after running the schedule approximation algorithm.

Additionally, the changeset marks unreachable CFG nodes with a warning, making it easier to identify ill-formed graphs:

Testing

• Tested manually on the two graphs reported in the JBS issue.

• Tested automatically that scheduling tens of thousands of graphs (by instrumenting IGV to schedule parsed graphs eagerly and running java -Xcomp -XX:-TieredCompilation -XX:PrintIdealGraphLevel=4) does not introduce any exception or assertion failure.

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
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• Commit message must refer to an issue

Issue

• JDK-8285558: IGV: scheduling crashes on control-unreachable CFG nodes

Reviewers

• Vladimir Kozlov (@vnkozlov - Reviewer)
• Christian Hagedorn (@chhagedorn - Reviewer)

Reviewing

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[bridgekeeper]

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[openjdk]

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[mlbridge]

Webrevs

• 00: Full (c247e1fb)

[vnkozlov]

Good.

[openjdk]

@robcasloz 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:

8285558: IGV: scheduling crashes on control-unreachable CFG nodes

Reviewed-by: kvn, chagedorn

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 19 new commits pushed to the master branch:

• a27ba1a: 8287363: null pointer should use NULL instead of 0
• 744b822: 8287073: NPE from CgroupV2Subsystem.getInstance()
• 5848a60: 8286093: java/awt/geom/Path2D/UnitTest.java failed with "RuntimeException: 2D bounds too small"
• 3d2d039: 8287440: Typo in package-info.java of java.util.random
• 36350bf: 8287484: JFR: Seal RecordedObject
• a6e2e22: 8285008: JFR: jdk/jfr/jmx/streaming/TestClose.java failed with "Exception: Expected repository to be empty"
• 2c461ac: 8287492: ProblemList compiler/jvmci/errors/TestInvalidDebugInfo.java
• 6634037: 8287362: FieldAccessWatch testcase failed on AIX platform
• 410a25d: 8286562: GCC 12 reports some compiler warnings
• ed8e8ac: 8284400: Improve XPath exception handling
• ... and 9 more: https://git.openjdk.java.net/jdk/compare/176bb23de18d9ab448e77e85a9c965a7c02f2c50...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.

[robcasloz]

Good.

Thanks for reviewing, Vladimir!

[chhagedorn]

Looks good! That's useful to mark them with a warning when analyzing dead loop problems.

[robcasloz]

Looks good! That's useful to mark them with a warning when analyzing dead loop problems.

Thanks for reviewing, Christian!

[robcasloz]

/integrate

[openjdk]

Going to push as commit 8f59422.
Since your change was applied there have been 31 commits pushed to the master branch:

• 8a9aeff: 8287497: Use String.contains() instead of String.indexOf() in java.naming
• b2ba9fc: 8286180: Enable construction of LogStreamImpl from LogMessageImpl
• 0c420e0: 8287430: MemorySessionImpl::addOrCleanupIfFail does not rethrow exceptions
• 1606d55: 8286855: javac error on invalid jar should only print filename
• f086d94: 8287378: GHA: Update cygwin to fix issues in langtools tests on Windows
• 73ba7fd: 8287157: Clean up G1Policy::next_gc_should_be_mixed()
• b1b9674: 8287437: Temporarily disable Continuations::enabled() for platforms which don't have an implementation, yet
• eb8d067: 8287433: [PPC64] g1_write_barrier_pre needs extension for Loom
• d833173: 8286711: AArch64: serviceability agent tests fail with PAC enabled
• 19fb8ab: 8287195: AArch64: Client VM build failure after JDK-8283689
• ... and 21 more: https://git.openjdk.java.net/jdk/compare/176bb23de18d9ab448e77e85a9c965a7c02f2c50...master

Your commit was automatically rebased without conflicts.

[openjdk]

@robcasloz Pushed as commit 8f59422.

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