8317677: Specialize Vtablestubs::entry_for() for VtableBlob

[tschatzl]

Hi all,

please review this change that specializes the call to Vtablestubs::entry_for for vtable blob.

This kind of code blobs must always be in the Vtablestubs table (they are only created by the Vtablestubs class), so trying to find that stub there using it is unnecessary. For verification I added an assert that verifies it's found.

Given that Vtablestubs::entry_point() would take a lock this removal of the lock results in a large speedup (https://bugs.openjdk.org/browse/JDK-8317527) in MT situations and is an even better change than that mentioned CR - and also worth the extra code (I did not retest performance since the Vtablestubs table lookup should be fairly fast).

Fwiw, the first commit contains a different variant of this change, keeping the decision out of Vtablestubs, but I liked the current one better for it encapsulating that decision more. I am fine with reverting the second commit.

Testing: tier1-7, gha, stress testing

Thanks,
Thomas

---

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Issue

• JDK-8317677: Specialize Vtablestubs::entry_for() for VtableBlob (Enhancement - P4)

Reviewers

• Tobias Hartmann (@TobiHartmann - Reviewer)
• Vladimir Kozlov (@vnkozlov - Reviewer)

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[mlbridge]

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• 00: Full (538efab7)

[TobiHartmann]

Nice improvement, looks good to me.

[openjdk]

@tschatzl 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:

8317677: Specialize Vtablestubs::entry_for() for VtableBlob

Reviewed-by: thartmann, kvn

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 69 new commits pushed to the master branch:

• c1f698d: 8317956: Make jdk.internal.util.Architecture current architecture final
• 9355431: 8316426: Optimization for HexFormat.formatHex
• 32ccf01: 8317772: NMT: Make peak values available in release builds
• 4c79e7d: 8170817: G1: Returning MinTLABSize from unsafe_max_tlab_alloc causes TLAB flapping
• 7633a76: 8317998: Temporarily disable malformed control flow assert to reduce noise in testing
• 00ef9f9: 8316947: Write a test to check textArea triggers MouseEntered/MouseExited events properly
• 77dc891: 8317963: Serial: Remove unused GenerationIsInReservedClosure
• d95b548: 8315850: Improve AbstractMap anonymous Iterator classes
• 424de29: 8317866: replace NET_SocketAvailable
• 6d6c900: 8038244: (fs) Check return value of malloc in Java_sun_nio_fs_AixNativeDispatcher_getmntctl()
• ... and 59 more: https://git.openjdk.org/jdk/compare/991ce84e0984414386e2f4dcefecf8da14cc1db3...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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[vnkozlov]

Good.

[tschatzl]

Thanks @TobiHartmann @vnkozlov for your reviews
/integrate

[openjdk]

Going to push as commit 1082c0e.
Since your change was applied there have been 82 commits pushed to the master branch:

• ec310fe: 8317919: pthread_attr_init handle return value and destroy pthread_attr_t object
• ff0b397: 8317959: Check return values of malloc in native java.base coding
• c88b387: 8317987: C2 recompilations cause high memory footprint
• 993951b: 8316464: 3 sun/tools tests ignore VM flags
• 17535c3: 8317818: Combinatorial explosion during 'this' escape analysis
• 61ce739: 8315484: java/awt/dnd/RejectDragDropActionTest.java timed out
• 77fa44f: 8317847: Typo in API documentation of class JPopupMenu
• 0983b54: 8318038: ProblemList runtime/CompressedOops/CompressedClassPointers.java on two platforms
• 64ee3c9: 8317266: Move nmethod::check_all_dependencies to codeCache.cpp and mark it NOT_PRODUCT
• 32ac72c: 8312522: Implementation of Foreign Function & Memory API
• ... and 72 more: https://git.openjdk.org/jdk/compare/991ce84e0984414386e2f4dcefecf8da14cc1db3...master

Your commit was automatically rebased without conflicts.

[openjdk]

@tschatzl Pushed as commit 1082c0e.

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