RFR: 8337791: VectorAPI jtreg ABSMaskedByteMaxVectorTests crashes with UseAVX=0 -XX:MaxVectorSize=8 [v9]

[Emanuel Peter]

On Wed, 3 Dec 2025 18:30:50 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> This bug patch fixes a crash seen while querying the bottom type of MachTempNode corresponding to [rxmm0 operand](https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/x86/x86.ad#L22509) of blend pattern during late scheduling. Here, MaxVectorSize is contrainted to 8 bytes thus during C2 type system initialization, [TypeVect::VECTX ](https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/type.cpp#L719) guarded by target supprted vector size remains uninitialized.
>> 
>> Its better to reject matching of VectorBlend in such a scenario.
>> 
>> All exisitng VectorAPI jtreg tests are passing with -XX:UseAVX=0 and -XX:MaxVectorSize=8
>> 
>> Kindly review and share your feedback.
>> 
>> Best Regards,
>> Jatin
>
> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update test/hotspot/jtreg/compiler/vectorapi/TestABSMaskedMaxByteVector.java
>   
>   Co-authored-by: Daniel Lundén <daniel.lunden at oracle.com>

Marked as reviewed by epeter (Reviewer).

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

PR Review: https://git.openjdk.org/jdk/pull/28533#pullrequestreview-3538701546