8357396: Refactor nmethod::make_not_entrant to use Enum instead of "const char*"

[JohnTortugo]

Please review this refactor to transform the reasons for making an nmethod not entrant from const char* into enum values.

Tested on Linux x64 with JTREG tier1-3 in fastdebug and release mode.

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Issue

• JDK-8357396: Refactor nmethod::make_not_entrant to use Enum instead of "const char*" (Enhancement - P4)

Reviewers

• Manuel Hässig (@mhaessig - Author)
• Aleksey Shipilev (@shipilev - Reviewer)

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[openjdk]

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8357396: Refactor nmethod::make_not_entrant to use Enum instead of "const char*"

Reviewed-by: mhaessig, shade

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At the time when this comment was updated there had been 914 new commits pushed to the master branch:

• af87035: 8355746: Start of release updates for JDK 26
• c59e44a: 8357914: TestEmptyBootstrapMethodsAttr.java fails when run with TEST_THREAD_FACTORY=Virtual
• 23f1d4f: 8337666: AArch64: SHA3 GPR intrinsic
• ... and 911 more: https://git.openjdk.org/jdk/compare/a2d7f441b8616e0cd8c231f3358b1b508e76686d...master

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[mhaessig]

Thank you for working on this. I agree that an enum is the better option here.
However, a scoped enum might be more appropriate here. For one, because that is the guidance in the style guide. Secondly, I would argue that this enum should have some as_string-like function so the reason is still printed in plain text insteatd of an int. That spares me going into the source and counting down the enum, when I'm debugging a deopt 😅 . Once the codes does no rely on implicint conversion to print an int, we do not care about the underlying type.

[shipilev]

I added this argument to make_not_entrant recently in JDK-8351640 -- mostly to print it in PrintCompilation logs. Putting enum might be fine, but it has to maintain the same level of human readability. Do not just print made not entrant: 42.

[JohnTortugo]

Thank you for the comments. I'll make the refactoring.

[shipilev]

Looks conceptually fine. Cosmetics:

[shipilev]

Almost there, more cosmetics.

[shipilev]

Looks good to me. Compiler folks might want to ack as well.

/reviewers 2

[openjdk]

@shipilev
The total number of required reviews for this PR (including the jcheck configuration and the last /reviewers command) is now set to 2 (with at least 1 Reviewer, 1 Author).

[mhaessig]

Thank you for addressing the comments. It looks good now.

I ran some additional testing that passed.

[JohnTortugo]

Thank you @shipilev , @mhaessig for reviewing/testing.

[JohnTortugo]

/integrate

[openjdk]

Going to push as commit 62fde68.
Since your change was applied there have been 914 commits pushed to the master branch:

• af87035: 8355746: Start of release updates for JDK 26
• c59e44a: 8357914: TestEmptyBootstrapMethodsAttr.java fails when run with TEST_THREAD_FACTORY=Virtual
• 23f1d4f: 8337666: AArch64: SHA3 GPR intrinsic
• ... and 911 more: https://git.openjdk.org/jdk/compare/a2d7f441b8616e0cd8c231f3358b1b508e76686d...master

Your commit was automatically rebased without conflicts.

[openjdk]

@JohnTortugo Pushed as commit 62fde68.

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