RFR: 8375010: C2 VectorAPI: assert(vbox->is_CheckCastPP()) failed: should be expanded [v3]

[Kerem Kat]

On Mon, 19 Jan 2026 17:06:03 GMT, Quan Anh Mai <qamai at openjdk.org> wrote:

>> Kerem Kat 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 four additional commits since the last revision:
>> 
>>  - Merge branch 'master' into fix-c2-checkCastPP
>>  - 8374903: C2 VectorAPI: assert(vbox->as_Phi()->region() == vect->as_Phi()->region()) failed
>>  - Simplify expand_vbox_node_helper by merging VectorBox Phi handling
>>  - 8375010: C2 VectorAPI: assert(vbox->is_CheckCastPP()) failed: should be expanded
>
> src/hotspot/share/opto/vector.cpp line 331:
> 
>> 329:   // Handle the case when the allocation input to VectorBoxNode is a Phi.
>> 330:   // This is generated after the transformation in PhiNode::merge_through_phi:
>> 331:   //   Phi (VectorBox1 VectorBox2) => VectorBox (Phi1 Phi2)
> 
> Should this be something like:
> 
>     Phi(VectorBox(vbox1, vect1), VectorBox(vbox2, vect2)) -> VectorBox(Phi(vbox1, vbox2), Phi(vect1, vect2))
> 
> I think it is a bit clearer, but it is fine either way.

Thanks, leaving as is for now.

> test/hotspot/jtreg/compiler/vectorapi/VectorBoxExpandPhi.java line 1:
> 
>> 1: /*
> 
> Can these 2 tests be merged into 1?

They are isolated tests, I would prefer to keep them separate unless there is a strong reason to merge them.

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PR Review Comment: https://git.openjdk.org/jdk/pull/29200#discussion_r2717070137
PR Review Comment: https://git.openjdk.org/jdk/pull/29200#discussion_r2717072541