RFR: 8339260: Move rarely used constants out of ClassFile [v9]

[Chen Liang]

On Fri, 29 Nov 2024 17:53:43 GMT, Luca Kellermann <duke at openjdk.org> wrote:

>>> Your example is an exact antipattern from our data-oriented model: we would want users to check the object type with `instanceof` (should be `is` in kotlin) instead of checking these constants.
>> 
>> I'm aware, this was just the first example I could come up with.
>> 
>>> Yet I think we can consider promoting Constant Pool tag from byte or char, short, or int to represent a u1 in case it goes over 127.
>> 
>> Maybe just using `int` everywhere for consistency might be a good option too.
>
>> Yet I think we can consider promoting Constant Pool tag from byte or char, short, or int to represent a u1 in case it goes over 127.
> 
> Is there any chance a change like this could make it into JDK 24? I'd imagine it would be too late after that because it's a binary incompatible change.

Don't think so. This imo is fixable  in the future if we do have many new cp/annotation tags (see example of Thread::threadId), though I don't think that is likely

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PR Review Comment: https://git.openjdk.org/jdk/pull/20773#discussion_r1863861563