RFR: 8370220: C2: rename methods and improve documentation around get_ctrl and idom lazy updating/forwarding of ctrl and idom via dead ctrl nodes [v10]

[Tobias Hartmann]

On Mon, 27 Oct 2025 10:22:53 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> When working on https://github.com/openjdk/jdk/pull/27889, I was irritated by the lack of documentation and suboptimal naming.
>> 
>> Here, I'm doing the following:
>> - Add more documentation, and improve it in other cases.
>> - Rename "lazy" methods: "lazy" could indicate that we delay it somehow until later, but it is unclear what is delayed.
>>   - `lazy_replace` -> `replace_ctrl_node_and_forward_ctrl_and_idom`
>>   - `lazy_update` -> `install_lazy_ctrl_and_idom_forwarding`
>> - Made some methods private, and added some additional asserts.
>> 
>> I'd be more than happy for even better names, and suggestions how to improve the documentation further :)
>> 
>> Related issues:
>> https://github.com/openjdk/jdk/pull/27889
>> https://github.com/openjdk/jdk/pull/15720
>
> Emanuel Peter has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 19 additional commits since the last revision:
> 
>  - Merge branch 'master' into JDK-8370220-get-ctrl-documentation
>  - Merge branch 'JDK-8370220-get-ctrl-documentation' of https://github.com/eme64/jdk into JDK-8370220-get-ctrl-documentation
>  - Apply suggestions from code review
>    
>    Co-authored-by: Christian Hagedorn <christian.hagedorn at oracle.com>
>  - fix shenandoah replace for phis
>  - renaming for Tobias
>  - Apply suggestions from code review
>    
>    Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>
>  - more for Christian part 3
>  - more for Christian part 2
>  - Apply suggestions from code review
>    
>    Co-authored-by: Christian Hagedorn <christian.hagedorn at oracle.com>
>  - for Christian part 1
>  - ... and 9 more: https://git.openjdk.org/jdk/compare/ca257175...e4bcb769

Marked as reviewed by thartmann (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/27892#pullrequestreview-3383556091