RFR: 8355915: [leyden] Crash in MDO clearing the unloaded array type [v3]

[Igor Veresov]

On Wed, 30 Apr 2025 10:01:58 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Caught this when doing benchmarks with Spring Boot. See the bug for reproducer.
>> 
>> The lifecycle of array types of `T` is bound to the lifecycle of `T` themselves. So the fix does similar thing to `is_excluded` and other code: when we encounter the `T[]`, we ask if its bottom component classes is not yet initialized. This fits nicely with our current uses, which skip such classes, and ever touch their (potentially nullptr) CLDs.
>> 
>> Additional testing:
>>  - [x] Ad-hoc testing with most recent spring-boot-petclinic
>>  - [x] Linux x86_64 server fastdebug, `runtime/cds`
>
> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:
> 
>  - Co-opt Igor's fix
>  - Merge branch 'premain' into JDK-8355915-mdo-array-crash
>  - More robust fix
>  - Fix
>  - Fix

src/hotspot/share/ci/ciMethodData.cpp line 317:

> 315:   for (uint row = 0; row < row_limit(); row++) {
> 316:     Klass* k = data->as_ReceiverTypeData()->receiver(row);
> 317:     if (k != nullptr && k->is_loader_present_and_alive() && is_klass_loaded(k)) {

This little part is actually incorrect. It should be just `k->class_loader_data() != nullptr` because there are different branch before for handling if `is_loader_alive()` and if not. I'll push the fix.

-------------

PR Review Comment: https://git.openjdk.org/leyden/pull/64#discussion_r2070695947