8298470: Short cut java.lang.Object super class loading

[coleenp]

While investigating another bug, I found doing this simple optimization saves taking out a SystemDictionary_lock, adding and removing a placeholder and some Symbol refcounting.
Tested with tier1-4.

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Progress

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Issue

• JDK-8298470: Short cut java.lang.Object super class loading

Reviewers

• David Holmes (@dholmes-ora - Reviewer)
• Ioi Lam (@iklam - Reviewer)

Reviewing

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Update a local copy of the PR:
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$ git pr checkout 11711

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[bridgekeeper]

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[openjdk]

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[mlbridge]

Webrevs

• 00: Full (bceb1916)

[dholmes-ora]

Looks simple and clean. Have to wonder why this shortcut hasn't always been there?

Thanks.

[openjdk]

@coleenp 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:

8298470: Short cut java.lang.Object super class loading

Reviewed-by: dholmes, iklam

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 34 new commits pushed to the master branch:

• 756a06d: 8299022: Linux ppc64le and s390x build issues after JDK-8160404
• de0ce79: 8297801: printnm crashes with invalid address due to null pointer dereference
• da38d43: 8296412: Special case infinite loops with unmerged backedges in IdealLoopTree::check_safepts
• 8e49fcd: 8295661: CompileTask::compile_id() should be passed as int
• 86d588b: 8283740: C1: Convert flag TwoOperandLIRForm to a constant on all platforms
• ec95991: 8298736: Revisit usages of log10 in compiler code
• 1622563: 8265688: Unused ciMethodType::ptype_at should be removed
• 3637660: 8298813: [C2] Converting double to float cause a loss of precision and resulting crypto.aes scores fluctuate
• 5e678f7: 8298824: C2 crash: assert(is_Bool()) failed: invalid node class: ConI
• ba942c2: 8298244: AArch64: Optimize vector implementation of AddReduction for floating point
• ... and 24 more: https://git.openjdk.org/jdk/compare/5412439445fadcf66101018a9bd051f8e5d751e8...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.

[iklam]

LGTM!

[coleenp]

Thanks for the reviews David and Ioi! I think I tried this optimization once and did it wrong, or decided that calling into resolve_super_or_fail was necessary, or didn't want to skip the CDS code in the beginning of resolve_super_or_fail. Just checked with Ioi and it has no side effects so the optimization is good. I don't think it saves a lot of time but it does help with debugging. Thanks!
/integrate

[openjdk]

Going to push as commit 4c927df.
Since your change was applied there have been 34 commits pushed to the master branch:

• 756a06d: 8299022: Linux ppc64le and s390x build issues after JDK-8160404
• de0ce79: 8297801: printnm crashes with invalid address due to null pointer dereference
• da38d43: 8296412: Special case infinite loops with unmerged backedges in IdealLoopTree::check_safepts
• 8e49fcd: 8295661: CompileTask::compile_id() should be passed as int
• 86d588b: 8283740: C1: Convert flag TwoOperandLIRForm to a constant on all platforms
• ec95991: 8298736: Revisit usages of log10 in compiler code
• 1622563: 8265688: Unused ciMethodType::ptype_at should be removed
• 3637660: 8298813: [C2] Converting double to float cause a loss of precision and resulting crypto.aes scores fluctuate
• 5e678f7: 8298824: C2 crash: assert(is_Bool()) failed: invalid node class: ConI
• ba942c2: 8298244: AArch64: Optimize vector implementation of AddReduction for floating point
• ... and 24 more: https://git.openjdk.org/jdk/compare/5412439445fadcf66101018a9bd051f8e5d751e8...master

Your commit was automatically rebased without conflicts.

[openjdk]

@coleenp Pushed as commit 4c927df.

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