RFR: 8347901: C2 should remove unused leaf / pure runtime calls [v4]

[Marc Chevalier]

On Mon, 7 Jul 2025 08:30:00 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

>> Marc Chevalier has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   typo
>
> src/hotspot/share/opto/divnode.cpp line 1528:
> 
>> 1526:   bool not_dead = proj_out_or_null(TypeFunc::Control) != nullptr;
>> 1527:   if (result_is_unused && not_dead) {
>> 1528:     return replace_with_con(igvn, TypeF::make(0.));
> 
> Can we replace all the other usages of `ModFloatingNode::replace_with_con` by `TupleNode` and get rid of that method?

Yes, that sounds like a good idea. One still need to build the right `TupleNode`, which takes a bit of code. So in detail, I'd rather replace `replace_with_con` with a function returning the right `TupleNode` to be as concise on the call-site.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25760#discussion_r2192669986