RFR: 8353290: C2: Refactor PhaseIdealLoop::is_counted_loop() [v23]

[Christian Hagedorn]

On Tue, 25 Nov 2025 15:00:11 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> Kangcheng Xu has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   fix trip counter loop-variant detection
>
> src/hotspot/share/opto/loopnode.cpp line 2572:
> 
>> 2570:     nphi = igvn->register_new_node_with_optimizer(nphi);
>> 2571:     _phase->set_ctrl(nphi, _phase->get_ctrl(phi));
>> 2572:     igvn->replace_node(_structure.phi(), nphi);
> 
> You can use `phi` instead of fetching it again with `_structure.phi()`:
> Suggestion:
> 
>   Node* phi = _structure.phi();
>   if (!TypeInteger::bottom(_iv_bt)->higher_equal(phi->bottom_type())) {
>     Node* nphi =
>         PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInteger::bottom(_iv_bt));
>     nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl));
>     nphi = igvn->register_new_node_with_optimizer(nphi);
>     _phase->set_ctrl(nphi, _phase->get_ctrl(phi));
>     igvn->replace_node(phi, nphi);
>     phi = nphi->as_Phi();
>   }

Maybe also rename `nphi` to `new_phi` to better distinguish `phi` from `nphi`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24458#discussion_r2560327529