RFR: 8342095: Add autovectorizer support for subword vector casts [v12]

[Jasmine Karthikeyan]

On Mon, 12 May 2025 06:27:12 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> @eme64 Thanks for the testing results! It looks like byte<->long conversion isn't supported with AVX1, so I've pushed a small to make the test to check for AVX2 in those cases instead.
>
> @jaskarth Excellent! I'll run another round of testing, just to be sure :)
> Please ping me again in 24h!

@eme64 Pinging for test results :)

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PR Comment: https://git.openjdk.org/jdk/pull/23413#issuecomment-2882036030