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

[Tobias Hartmann]

On Tue, 8 Jul 2025 14:21:20 GMT, Marc Chevalier <mchevalier at openjdk.org> wrote:

>> 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.

Yes, that sounds good.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/25760#discussion_r2192809839