RFR: 8348868: AArch64: Add backend support for SelectFromTwoVector [v3]

[Bhavana Kilambi]

On Tue, 17 Jun 2025 08:21:31 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> Hi @XiaohongGong , thanks for your prompt review. I can't use the negate condition here as it will include `T_DOUBLE` and `T_LONG` as well which are not supported. I'll change it to the same basic type check instead.
>
> Yeah, I noticed this as well. Since these types for NEON has been excluded in above function `match_rule_supported_vector()`. Can we just ignore such types? Besides, you have also added the type assertion in the macro assembler implementation.

Ok, I can do that (although I hope it won't be ambiguous/confusing for someone who is just going through the match rules to understand the implementation).

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PR Review Comment: https://git.openjdk.org/jdk/pull/23570#discussion_r2153894406