RFR: 8367611: Enable vblendvp[sd] on Future ECore [v3]

[Sandhya Viswanathan]

On Fri, 19 Sep 2025 21:57:30 GMT, Mohamed Issa <missa at openjdk.org> wrote:

>> The upcoming ECore platforms will benefit from using `vblendvps` and `vblendvpd` instructions when the destination register is the same as the source register. This change takes that situation into account.
>> 
>> The JTREG test shown below was used to verify correctness against the [OpenJDK v26-b15](https://github.com/openjdk/jdk/releases/tag/jdk-26%2B15) baseline build. This test frequently calls vblendvps() and vblendvpd() in the macro assembler. On Darkmont and non-Darkmont cores, the right code paths are followed when checking with asserts.
>> 
>> 1. `jtreg:test/hotspot/jtreg/compiler/intrinsics/math/TestSignumIntrinsic.java`
>
> Mohamed Issa has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Combine boolean flags to avoid ambiguity

Looks good to me.

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Marked as reviewed by sviswanathan (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/27354#pullrequestreview-3254504880