RFR: 8363989: AArch64: Add missing backend support of VectorAPI expand operation

[erifan]

On Tue, 16 Sep 2025 07:30:20 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> @theRealAph @e1iu could you help take another look of this PR, thanks !
>
> @erifan I'm seeing `gtest/GTestWrapper.java` fail on `aarch64` machines.
> 
> Looks like this:
> 
> [ RUN      ] AssemblerAArch64.validate_vm
> [12.324s][warning][os] Loading hsdis library failed
> .../test/hotspot/gtest/aarch64/test_assembler_aarch64.cpp:49: Failure
> Expected equality of these values:
>   insns[i]
>     Which is: 335545527
>   insns1[i]
>     Which is: 335545526
> Ours:
> 
> Loading hsdis library failed, undisassembled code is shown in MachCode section
> [MachCode]
>   0x0000ffff97c20548: b604 0014 
> [/MachCode]
> Theirs:
> 
> Loading hsdis library failed, undisassembled code is shown in MachCode section
> [MachCode]
>   0x0000ffff853eb0a8: b704 0014 
> [/MachCode]
> 
> Could this be related?

Hi @eme64 I can't reproduce the test failure on my local and Jenkins test environments. I see this from the above error log:

Loading hsdis library failed, undisassembled code is shown in MachCode section

Not sure if this is related.

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PR Comment: https://git.openjdk.org/jdk/pull/26740#issuecomment-3297410878