RFR: 8372845: Fold identity hash code if object is constant

[Vladimir Ivanov]

On Tue, 2 Dec 2025 20:58:23 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>>> I'm not sure it makes sense to support Object::hashCode unless C2 can eliminate generate_virtual_guard for a constant receiver. I'd just limit constant folding to !is_virtual case for now.
>> 
>> Or, alternatively, inspect constant object's v-table during compilation and ensure that corresponding slot points at `Object::hashCode`.
>
> @iwanowww please fix title to match JBS.

@vnkozlov I can't since I'm not the author of the PR :-)

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PR Comment: https://git.openjdk.org/jdk/pull/28589#issuecomment-3604211003