RFR: 8352675: Support Intel AVX10 converged vector ISA feature detection [v3]

[Vladimir Ivanov]

On Thu, 10 Apr 2025 02:27:45 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> src/hotspot/cpu/x86/vm_version_x86.cpp line 895:
>> 
>>> 893:     _features = _cpuid_info.feature_flags(); // These can be changed by VM settings
>>> 894:     _extra_features = _cpuid_info.extra_feature_flags(); // These can be changed by VM settings
>>> 895:     _cpu_features = _features;   // Preserve features
>> 
>> `_cpu_features` now captures only part of CPU features JVM cares about.
>
> It has limited usage and was introduced by JDK-8324734, the comment over it mentions
> +  // Feature identification not affected by VM flags
> https://github.com/openjdk/jdk/pull/17590#issuecomment-1912689152
> 
> Unlike _featues, _cpu_featues is not even captured by JVMCI 
> https://github.com/openjdk/jdk/blob/master/src/hotspot/share/jvmci/vmStructs_jvmci.cpp#L149

I don't see how JVMCI is relevant here. 

JDK-8324734 was related to AVX512. I don't see why a very similar scenario won't be applicable to AVX10.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24329#discussion_r2036411432