RFR: 8371667: Shenandoah: Re-design alloc request type enum for better efficiency and cleaner code [v13]

[Kelvin Nilsen]

On Mon, 17 Nov 2025 09:52:13 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> src/hotspot/share/gc/shenandoah/shenandoahFreeSet.cpp line 3272:
>> 
>>> 3270:     switch (req.type()) {
>>> 3271:       case ShenandoahAllocRequest::_alloc_shared:
>>> 3272:       case ShenandoahAllocRequest::_alloc_shared_gc:
>> 
>> humongous objects never move, not possible to be _alloc_shared_gc here?
>
> Yes, I am not sure why we have the case for `_alloc_shared_gc` here. But I would leave it for extra safety in this "optimization/cleanup" change. We can yank this case later.

Humongous objects do move under full gc, and may eventually move under concurrent GC with some refactoring.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28247#discussion_r2534995388