RFR: 8337791: VectorAPI jtreg ABSMaskedByteMaxVectorTests crashes with UseAVX=0 -XX:MaxVectorSize=8 [v4]

[Emanuel Peter]

On Mon, 1 Dec 2025 07:15:41 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:
> 
>   Adding a testpoint

test/hotspot/jtreg/compiler/vectorapi/TestABSMaskedMaxByteVector.java line 48:

> 46:     @Test
> 47:     @IR(failOn = {IRNode.ABS_VB}, applyIfAnd={"MaxVectorSize", " <= 8 ", "UseAVX", "0"})
> 48:     @IR(counts = {IRNode.ABS_VB, "1"}, applyIf={"MaxVectorSize", " > 8 "})

Are you sure this is going to pass on all platforms? Does this test run ok on `aarch64` where there is no `UseAVX` flag?

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PR Review Comment: https://git.openjdk.org/jdk/pull/28533#discussion_r2576273485