8389840: Verifier is not setting flagThisUninit when uninitializedThis is on the stack

[matias9927]

JDK-8376522 indicates that the thisUninit should be applied even when uninitializedThis is on the stack. Previous implementations failed to do this, so this patch properly enforces this spec change.

Now that both the stack and locals must be considered when applying flagThisUninit, the origin of the flag needs to be preserved, so the StackMapReader now tracks if the flag originated from locals or the stack. Since the stack is cleared between frames, only an uninitializedThis from locals is preserved.

In addition to VM changes, the ClassFile API had to be updated as it only considered stack frame locals. The test case offered by @liach in the JBS issue has been adapted to a JASM test to verify the change. Verified with tier 1-5 tests.

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Issue

• JDK-8389840: Verifier is not setting flagThisUninit when uninitializedThis is on the stack (Bug - P3)

Reviewers

• Chen Liang (@liach - Reviewer)
• Frederic Parain (@fparain - Reviewer)

Reviewing

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[bridgekeeper]

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[openjdk]

@matias9927 This change now passes all automated pre-integration checks.

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8389840: Verifier is not setting flagThisUninit when uninitializedThis is on the stack

Reviewed-by: liach, fparain

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At the time when this comment was updated there had been 21 new commits pushed to the master branch:

• c9dccc0: 8337680: failure_handler does not handle repeated commands well
• 91394cb: 8389846: GenShen: ShenandoahScanRemembered::process_clusters may miss dirty cards when use write table
• 221f42c: 8382272: Update nsk/jdb tests to use ThreadWrapper
• ... and 18 more: https://git.openjdk.org/jdk/compare/c61f5b7ad8f6f9a00bf0161e4c2c6e6e5c6b3463...master

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[liach]

I recommend the implementation to add a separate tracking flag for uninitializedThis on stack, because each stack map frame clears the previous stack.

[liach]

You can rollback the jdk/internal/classfile changes: They are fixed in #32224

[mlbridge]

Webrevs

• 01: Full - Incremental (03aaae56)
• 00: Full (8934c446)

[liach]

Looks perfect, thank you so much!

[fparain]

LGTM