[lworld] RFR: 8376221: [lworld] Do not store array of InlineLayoutInfo for all InstanceKlasses [v2]

[Joel Sikström]

On Mon, 26 Jan 2026 10:10:07 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

>> Joel Sikström has updated the pull request incrementally with four additional commits since the last revision:
>> 
>>  - Clear exception before setting inline klass
>>  - Split assert in field sorting methods
>>  - IOOB assert message
>>  - InstanceKlass instead of Klass for set_inline_layout_info_klass
>
> src/hotspot/share/classfile/classFileParser.cpp line 6298:
> 
>> 6296:           if (klass != nullptr) {
>> 6297:             if (klass->is_inline_klass()) {
>> 6298:               set_inline_layout_info_klass(fieldinfo.index(), klass, CHECK);
> 
> I see that this can throw a Metaspace OOME (hence the CHECK) and that we later have this comment:
> 
> 
>           // Loads triggered by the LoadableDescriptors attribute are speculative, failures must not impact loading of current class
>           if (HAS_PENDING_EXCEPTION) {
>             CLEAR_PENDING_EXCEPTION;
>           }
> 
> Can you verify that using CHECK here is really appropriate? The `resolve_super_or_fail` uses THREAD, and I think that's what the comment refer to. But with the current patch there's a "returning" call in-between those two parts of the function.

No, I didn't consider any pending exceptions when I added the CHECK. I see that we have an `assert(false, ...)` down in the Metaspace allocation if there's a pending exception, so we really shouldn't try to allocate the array of InlineLayoutInfo if there's a pending exception, which makes sense.

Looking at the code, I think we should re-arrange it so that we clear any pending exception before calling `set_inline_layout_info_klass`, while keeping the `CHECK` so that we exit from `ClassFileParser::post_process_parsed_stream` if we fail to allocate in Metaspace. This seems to me to be consistent with the old behavior, but it would be nice for someone to fill in here.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1966#discussion_r2727341149