RFR: 8370519: C2: Hit MemLimit when running with +VerifyLoopOptimizations [v3]

[Roland Westrelin]

On Wed, 10 Dec 2025 13:13:48 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Roland Westrelin has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - review
>>  - review
>
> src/hotspot/share/opto/loopnode.hpp line 1217:
> 
>> 1215:     PhaseTransform(Ideal_Loop),
>> 1216:     _arena(mtCompiler, Arena::Tag::tag_idealloop),
>> 1217:     _loop_or_ctrl(&_arena),
> 
> How about some of the other data structures? For example `_idom`?

They are allocated in the thread's resource area. So there's no leak and while for `_loop_or_ctrl` and `_body` there were issues that were solved by moving them to the compile arena, there hasn't been any so far with other data structures such as `_idom`. So, sure, we could pro actively move them to the new arena but do we gain anything from doing that?

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PR Review Comment: https://git.openjdk.org/jdk/pull/28581#discussion_r2610055708