RFR: 8339131: Remove rarely-used accessor methods from Opcode [v2]

[Adam Sotona]

On Tue, 3 Sep 2024 23:22:28 GMT, Chen Liang <liach at openjdk.org> wrote:

>> In offline discussion, we agreed that current fields of `Opcode` violate data oriented design to a large extent. The attributes not generic to all opcode are removed.
>> 
>> Up for preliminary review; needs to be reworked for #20737.
>
> Chen Liang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:
> 
>  - Revert back to enum switch, fix compile error
>  - Merge branch 'master' of https://github.com/openjdk/jdk into fix/opcode-clean
>  - Merge branch 'master' of https://github.com/openjdk/jdk into fix/opcode-clean
>  - Merge branch 'master' of https://github.com/openjdk/jdk into fix/opcode-clean
>  - Fix ofArgument in loadConstant patch instead, improve specs
>  - Merge branch 'master' of https://github.com/openjdk/jdk into fix/opcode-clean
>  - Merge branch 'master' of https://github.com/openjdk/jdk into fix/opcode-clean
>  - Clean up opcode fields

Marked as reviewed by asotona (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/20757#pullrequestreview-2279150127