RFR: 8363989: AArch64: Add missing backend support of VectorAPI expand operation [v2]

[erifan]

On Thu, 4 Sep 2025 08:01:40 GMT, erifan <duke at openjdk.org> wrote:

>> src/hotspot/cpu/aarch64/c2_MacroAssembler_aarch64.cpp line 2819:
>> 
>>> 2817:   subv(dst, size, tmp2, tmp1);
>>> 2818:   // dst = 0 0 8 7 0 0 6 5 0 0 4 3 0 0 2 1
>>> 2819:   tbl(dst, size, src, 1, dst);
>> 
>> It would make it a little easier to read the example if the numbers were aligned.
>> Now the minus sign disrupts that a little. Maybe leave 2 spaces if the number is positive?
>
> Make sense, I'll update it in the following commit.

Done, thanks!

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PR Review Comment: https://git.openjdk.org/jdk/pull/26740#discussion_r2324218817