RFR: 8337958: Out-of-bounds array access in secondary_super_cache

[Vladimir Ivanov]

On Tue, 6 Aug 2024 23:35:55 GMT, Andrew Haley <aph at openjdk.org> wrote:

> The fix for [JDK-8180450](https://bugs.openjdk.org/browse/JDK-8180450), secondary_super_cache does not scale well, has a rare (and benign) out-of-bounds array access. While this bug is very unlikely ever to cause a failure, it should be fixed.

The fix looks good. I submitted it for testing.

src/hotspot/share/oops/klass.cpp line 347:

> 345:   }
> 346: 
> 347:   // Invariant: _secondary_supers.length >= population_count(_secondary_supers_bitmap)

It makes sense to assert the invariant in `Klass::set_secondary_supers()` (and, probably, `Klass::restore_unshareable_info()` for a shared klass loaded from CDS archive).

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Marked as reviewed by vlivanov (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/20483#pullrequestreview-2222493458
PR Review Comment: https://git.openjdk.org/jdk/pull/20483#discussion_r1706284693