[lworld] RFR: 8374729: [lworld] Enabling CDS crash with UseAltSubstitutabilityMethod

[Frederic Parain]

On Fri, 16 Jan 2026 19:44:03 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> The alternate substitutability method relies on an injected Java object "acmp_maps" which is currently not being archived and thus leads to crashes attempting to run with a CDS archive. The issue stems from inline klasses being archived and thus loaded at dumptime while the acmp_maps oops is generated in the class file parser, leading this oop to be absent at runtime. 
>> 
>> Additionally, the other injected static field "null_reset" was not being archived either, so both of these fields are properly stored in the archived heap. In the case of CDS/AOT configurations where the heap is not dumped, acmp_maps is regenerated at class loading using a copy of the array stored in metadata.
>> 
>> Tests and APIs are updated to conform to the new output generated by the use of acmp_maps and remove some test cases which target the old substitutability method.
>
> src/hotspot/share/classfile/classFileParser.cpp line 5571:
> 
>> 5569: 
>> 5570:     // Clear out this field so it doesn't get deallocated by the destructor
>> 5571:     _acmp_maps_array = nullptr;
> 
> This is right.  It didn't look necessary but it is if oopFactory::new_intArray() throws an OOM.
> 
> You could remove this field from ClassFileParser and this handling, and make it a local variable if you reverse lines 5549 and 5550.

+1 to use a local variable.
It looks weird to have this _acmp_maps_array field in ClassFilerParser whose content's ownership is not transferred to the InstanceKlass using the apply_parsed_class_metadata() method.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1903#discussion_r2699890402