8288360: CI: ciInstanceKlass::implementor() is not consistent for well-known classes

[iwanowww]

ciInstanceKlass::implementor() doesn't cache the result for well-known interfaces (is_shared() == true). Due to concurrent class loading, compilers can observe a change in reported unique implementor (in the worst case: from having no implementors to having one, then to having many) thus introducing paradoxical situations during a compilation.

What makes it very hard/impossible to trigger the bug is there's only a single well-known interface (java.util.Iterable) present as of now, which gets multiple implementors loaded early during startup.

Testing: hs-tier1 - hs-tier2

---

Progress

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Issue

• JDK-8288360: CI: ciInstanceKlass::implementor() is not consistent for well-known classes

Reviewers

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

Reviewing

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[openjdk]

@iwanowww The following label will be automatically applied to this pull request:

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[mlbridge]

Webrevs

• 00: Full (47547cd4)

[TobiHartmann]

Looks good.

[openjdk]

@iwanowww 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:

8288360: CI: ciInstanceKlass::implementor() is not consistent for well-known classes

Reviewed-by: thartmann, kvn

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At the time when this comment was updated there had been 1 new commit pushed to the master branch:

• 5a8e1e4: 8287889: (fs) Files.copy description of REPLACE_EXISTING is hard to read

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[vnkozlov]

Good.

[iwanowww]

Thanks for the reviews, Tobias and Vladimir.

/integrate

[openjdk]

Going to push as commit 50f99c3.
Since your change was applied there has been 1 commit pushed to the master branch:

• 5a8e1e4: 8287889: (fs) Files.copy description of REPLACE_EXISTING is hard to read

Your commit was automatically rebased without conflicts.

[openjdk]

@iwanowww Pushed as commit 50f99c3.

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