RFR: 8370220: C2: rename methods and improve documentation around get_ctrl and idom lazy updating/forwarding of ctrl and idom via dead ctrl nodes [v5]

[Emanuel Peter]

On Mon, 20 Oct 2025 13:50:08 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> Emanuel Peter has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Apply suggestions from code review
>>   
>>   Co-authored-by: Christian Hagedorn <christian.hagedorn at oracle.com>
>
> src/hotspot/share/opto/loopnode.hpp line 1262:
> 
>> 1260:       // forwarding installed, using "install_lazy_ctrl_and_idom_forwarding".
>> 1261:       // We now have to jump from the old (dead) ctrl node to the new (live)
>> 1262:       // ctrl/idom node, in possibly multiple ctrl/idom forwarding steps.
> 
> Maybe for clarification since it's somehow surprising at first that we reuse `_loop_or_ctrl`:
> Suggestion:
> 
>       // idom node, in possibly multiple idom forwarding steps.
>       // Note that we piggy back on `_loop_or_ctrl` do the the forwarding.

Applied with even more information.

> src/hotspot/share/opto/loopnode.hpp line 1274:
> 
>> 1272:   }
>> 1273: 
>> 1274:   Node* idom(uint didx) const {
> 
> While at it: Maybe also name this `node_index`?

I chose to replace it with `node_idx`, since it comes from `n->_idx`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27892#discussion_r2447068474
PR Review Comment: https://git.openjdk.org/jdk/pull/27892#discussion_r2447075460