[lworld] RFR: 8376221: [lworld] Do not store array of InlineLayoutInfo for all InstanceKlasses [v4]

[Joel Sikström]

On Mon, 26 Jan 2026 12:01:03 GMT, Joel Sikström <jsikstro at openjdk.org> wrote:

>> 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.

After looking at this for a bit longer I argue that we should never get a resolved klass (non-nullptr) with a pending exception, so the code can be simplified a bit further.

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PR Review Comment: https://git.openjdk.org/valhalla/pull/1966#discussion_r2731177921