RFR: 8367611: Enable vblendvp[sd] on Future ECore [v2]

[Manuel Hässig]

On Fri, 19 Sep 2025 06:51:50 GMT, Manuel Hässig <mhaessig at openjdk.org> wrote:

>> Mohamed Issa has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Use function to identify Darkmont cores instead of global flag
>
> Thank you for this improvement, @missa-prime! The change looks good to me, but I have a question.
> 
>> 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.
>> -  jtreg:test/hotspot/jtreg/compiler/intrinsics/math/TestSignumIntrinsic.java
> 
> Can you elaborate, what this verification entails? Why this test?

> @mhaessig I used this test because it frequently calls vblendvps() and vblendvpd() in the macro assembler. On Darkmont and non-Darkmont cores, I checked the right code paths were followed with asserts. Also, I wrote some sample code and checked the instructions generated at runtime.

Did you also run a some tests generating vblendvps with sde to verify the correct result with the new code paths?

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PR Comment: https://git.openjdk.org/jdk/pull/27354#issuecomment-3317327037