RFR: 8306075: Micro-optimize Enum.hashCode [v3]

[Chen Liang]

On Tue, 18 Apr 2023 19:32:42 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> `invokespecial` is used to call instance methods in a non‑virtual manner.
>> 
>> --------------------------------------------------------------------------------
>> 
>> Using `super.hashCode()` in `java.lang.Enum` produces the bytecode:
>> 
>> aload_0;
>> invokespecial java/lang/Object.hashCode:()I;
>
> I see. It does not matter here, because for performance, we largely only care about the distinction between virtual/static cases in C2 intrinsic for hashcode.

Also fyi invokespecial now can be virtual calls (mainly calling private methods in the nest) since introduction of nestmates.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13491#discussion_r1170735370