8271202 C1: assert(false) failed: live_in set of first block must be empty

[veresov]

The root cause seems to be because of the irreducible loops (and therefore an unusual block traversal order when inserting phis) the phi invalidation logic in try_merge() doesn't invalidate phis that have invalid locals as inputs. I've attached a drawing: 8271202.pdf. Notice that i54 = phi (i43, 96) is not invalidated even though 96 is illegal. Transitively, i43, it should be illegal too. I would propose that we add a check for that and bailout in move_phi().

This has also been discussed here: openjdk/jdk#6683

Testing is clean.

---

Progress

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Issue

• JDK-8271202: C1: assert(false) failed: live_in set of first block must be empty

Reviewers

• Vladimir Ivanov (@iwanowww - Reviewer)
• Vladimir Kozlov (@vnkozlov - Reviewer)

Contributors

• Martin Doerr <mdoerr@openjdk.org>

Reviewing

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[bridgekeeper]

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[openjdk]

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[veresov]

/contributor add @TheRealMDoerr

[openjdk]

@veresov
Contributor Martin Doerr <mdoerr@openjdk.org> successfully added.

[mlbridge]

Webrevs

• 00: Full (ed8740e7)

[iwanowww]

Looks good.

[openjdk]

@veresov 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:

8271202: C1: assert(false) failed: live_in set of first block must be empty

Co-authored-by: Martin Doerr <mdoerr@openjdk.org>
Reviewed-by: vlivanov, kvn

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At the time when this comment was updated there had been 25 new commits pushed to the master branch:

• 2945b78: 8279195: Document the -XX:+NeverActAsServerClassMachine flag
• 6588bed: 8278889: AArch64: [vectorapi] VectorMaskLoadStoreTest.testMaskCast() test fail
• 04ad668: 8279204: [BACKOUT] JDK-8278413: C2 crash when allocating array of size too large
• 730f670: 8268297: jdk/jfr/api/consumer/streaming/TestLatestEvent.java times out
• 9d5ae2e: 8279076: C2: Bad AD file when matching SqrtF with UseSSE=0
• 04ee921: 8278967: rmiregistry fails to start because SecurityManager is disabled
• 2be3e7e: 8278239: vmTestbase/nsk/jvmti/RedefineClasses/StressRedefine failed with EXCEPTION_ACCESS_VIOLATION at 0x000000000000000d
• dfb15c3: 8274315: JFR: One closed state per file or stream
• e49d4a9: 8271447: java.nio.file.InvalidPathException: Malformed input or input contains unmappable characters
• 713fbeb: 8278987: RunThese24H.java failed with EXCEPTION_ACCESS_VIOLATION in write_sample_info
• ... and 15 more: https://git.openjdk.java.net/jdk18/compare/b46f0b0b1f2ada705f8b5aac9b7d8423699437a1...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.

[vnkozlov]

Agree.

[veresov]

Thanks, guys!
/integrate

[openjdk]

Going to push as commit 54b800d.
Since your change was applied there have been 25 commits pushed to the master branch:

• 2945b78: 8279195: Document the -XX:+NeverActAsServerClassMachine flag
• 6588bed: 8278889: AArch64: [vectorapi] VectorMaskLoadStoreTest.testMaskCast() test fail
• 04ad668: 8279204: [BACKOUT] JDK-8278413: C2 crash when allocating array of size too large
• 730f670: 8268297: jdk/jfr/api/consumer/streaming/TestLatestEvent.java times out
• 9d5ae2e: 8279076: C2: Bad AD file when matching SqrtF with UseSSE=0
• 04ee921: 8278967: rmiregistry fails to start because SecurityManager is disabled
• 2be3e7e: 8278239: vmTestbase/nsk/jvmti/RedefineClasses/StressRedefine failed with EXCEPTION_ACCESS_VIOLATION at 0x000000000000000d
• dfb15c3: 8274315: JFR: One closed state per file or stream
• e49d4a9: 8271447: java.nio.file.InvalidPathException: Malformed input or input contains unmappable characters
• 713fbeb: 8278987: RunThese24H.java failed with EXCEPTION_ACCESS_VIOLATION in write_sample_info
• ... and 15 more: https://git.openjdk.java.net/jdk18/compare/b46f0b0b1f2ada705f8b5aac9b7d8423699437a1...master

Your commit was automatically rebased without conflicts.

[openjdk]

@veresov Pushed as commit 54b800d.

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

[TheRealMDoerr]

Thanks for digging through the graph and for providing this fix. Looks good. I didn't have enough time before my vacation.