8284883: JVM crash: guarantee(sect->end() <= sect->limit()) failed: sanity on AVX512

[dean-long]

This fix prevents overflowing the C2 scratch buffer for large ClearArray operations. I also noticed that when IdealizeClearArrayNode is turned off, the "is_large" flag on the ClearArray node was not set correctly, so I fixed that too.

I could use some help testing the x86_32 change.

---

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Issue

• JDK-8284883: JVM crash: guarantee(sect->end() <= sect->limit()) failed: sanity on AVX512

Reviewers

• Vladimir Kozlov (@vnkozlov - Reviewer)
• Jatin Bhateja (@jatin-bhateja - Committer)

Reviewing

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[bridgekeeper]

👋 Welcome back dlong! 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]

@dean-long The following label will be automatically applied to this pull request:

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[mlbridge]

Webrevs

• 01: Full - Incremental (2c6626c5)
• 00: Full (89be65e4)

[vnkozlov]

I think we should fix code in MacroAssembler::clear_mem() to generate loop code (4 in loop and remaining after it) instead of line of instructions if more then 8 64-bytes move instructions are generated.
Even with 256 value, you suggested, there will be 32 instructions. Originally it was assumed that !is_large() will be true for arrays with < InitArrayShortSize (64) so you will have only 8 instructions. But, as you said, InitArrayShortSize could be set to ridiculous value.
Also forcing use Mach instruction with value loaded into register may affect spilling in surrounding code.

[dean-long]

@vnkozlov OK, good suggestion. Let me try that.

[vnkozlov]

Exactly like that. Good!

[openjdk]

@dean-long 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:

8284883: JVM crash: guarantee(sect->end() <= sect->limit()) failed: sanity on AVX512

Reviewed-by: kvn, jbhateja

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 11 new commits pushed to the master branch:

• 0a4a640: 8285301: C2: assert(!requires_atomic_access) failed: can't ensure atomicity
• 40f19c0: 8264666: Change implementation of safeAdd/safeMult in the LCMSImageLayout class
• 1e28fcb: 8155701: The compiler fails with an AssertionError: typeSig ERROR
• 99388ef: 8283624: Create an automated regression test for RFE-4390885
• 94b533a: 8285699: riscv: Provide information when hitting a HaltNode
• e2e943a: 8285688: Add links to JEPs and JSRs to SourceVersion
• 80cf59f: 8285610: TreeInfo.pathFor and its uses appear to be dead code
• 21b62fe: 8195589: T6587786.java failed after JDK-8189997
• 8190217: 8285496: DocLint does not check for missing @param tags for type parameters on classes and interfaces
• 64d98ba: 8285094: Test java/awt/Frame/InvisibleOwner/InvisibleOwner.java failing on Linux
• ... and 1 more: https://git.openjdk.java.net/jdk/compare/bba456a8dbf9027e4b015567c17a79fc7441aa08...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.

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[jatin-bhateja]

Hi @dean-long ,

We already have a loop to perform system initialization if is_large flag is set over ClearArray.
https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/memnode.cpp#L3091
Code bloating will occur if user sets InitArrayShortSize to a very large value, earlier we were emitting 8 bytes store which was later improved to use vector instructions. Your fix to emit a loop for large constant sized initialization will make this flow full proof.

Best Regards,
Jatin
PS: We still may face code bloating with UseAVX=0 which still emit 8 byte stores for initialization.
https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/memnode.cpp#L3111

[dean-long]

Thanks Vladimir and Jatin!

[dean-long]

/integrate

[openjdk]

Going to push as commit cd8709e.
Since your change was applied there have been 25 commits pushed to the master branch:

• 3d07b3c: 8282227: Locale information for nb is not working properly
• cfe67af: 8285938: ProblemList jdk/jshell/HighlightUITest.java on linux-x64
• 67dd8a8: 8285686: Upgrade to FreeType 2.12.0
• 64225e1: 8285919: Remove debug printout from JDK-8285093
• df4d5cf: 8285802: AArch64: Consistently handle offsets in MacroAssembler as 64-bit quantities
• 694556e: 8225433: Clarify behavior of PKIXParameters.setRevocationEnabled when PKIXRevocationChecker is used
• e98ac23: 8285793: C2: optimization of mask checks in counted loops fail in the presence of cast nodes
• 669ac61: 8274597: Some of the dnd tests time out and fail intermittently
• 269eae6: 8285515: (dc) DatagramChannel.disconnect fails with "Invalid argument" on macOS 12.4 beta2
• c4f7a85: 8285828: runtime/execstack/TestCheckJDK.java fails with zipped debug symbols
• ... and 15 more: https://git.openjdk.java.net/jdk/compare/bba456a8dbf9027e4b015567c17a79fc7441aa08...master

Your commit was automatically rebased without conflicts.

[openjdk]

@dean-long Pushed as commit cd8709e.

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