RFR: 8352675: Support Intel AVX10 converged vector ISA feature detection [v15]

[Vladimir Ivanov]

On Wed, 7 May 2025 11:40:05 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> - Intel AVX10[1] extends and enhances the capabilities of Intel AVX-512 to benefit all Intel® products and will be the vector ISA of choice moving into the future. 
>> - It supports a new ISA versioning scheme which simplifies the existing AVX512 feature enumeration scheme. Feature set supported by an AVX10 ISA version will be supported by all the versions above it.
>> - The initial, fully-featured version of Intel® AVX10 will be enumerated as Version 2 (denoted as Intel® AVX10.2). This will include the new ISA extension over the existing AVX512 instructions. 
>> - An early version of Intel® AVX10 (Version 1, or Intel® AVX10.1) that only enumerates the Intel® AVX-512 instruction set at 128, 256, and 512 bits will be enabled on the Granite Rapids Server for software pre-enabling.
>> 
>> This patch adds the necessary CPUID feature detection for AVX10 ISA version 1 and 2.  In terms of architectural state save restoration, AVX10 is isomorphic to AVX512 support up till Granite Rapids. State components affected by AVX10 extension include SSE, AVX, Opmask, ZMM_Hi256, and Hi16_ZMM registers. 
>> 
>> The patch has been regressed through tier1 and jvmci tests 
>> 
>> Please review and share your feedback.
>> 
>> Best Regards,
>> Jatin
>> 
>> [1] https://www.intel.com/content/www/us/en/content-details/844829/intel-advanced-vector-extensions-10-2-intel-avx10-2-architecture-specification.html
>
> Jatin Bhateja has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Making _features_bitmap size configurable
>  - cleanups & refactorings

There are some SA-related failures. Fixed by [1]. Otherwise, testing results are good.

[1] https://github.com/iwanowww/jdk/commit/9100ef190befbb1967f477532a0776c135a9b728

src/hotspot/cpu/x86/vm_version_x86.hpp line 458:

> 456: 
> 457:    private:
> 458:     uint64_t _features_bitmap[(MAX_CPU_FEATURES >> 6) + 1];

Suggestion:

    uint64_t _features_bitmap[(MAX_CPU_FEATURES / BitsPerLong) + 1];

src/hotspot/cpu/x86/vm_version_x86.hpp line 460:

> 458:     uint64_t _features_bitmap[(MAX_CPU_FEATURES >> 6) + 1];
> 459: 
> 460:     STATIC_ASSERT(sizeof(_features_bitmap) * BitsPerByte > MAX_CPU_FEATURES);

Suggestion:

    STATIC_ASSERT(sizeof(_features_bitmap) * BitsPerByte >= MAX_CPU_FEATURES);

-------------

PR Review: https://git.openjdk.org/jdk/pull/24329#pullrequestreview-2822970103
PR Review Comment: https://git.openjdk.org/jdk/pull/24329#discussion_r2078346536
PR Review Comment: https://git.openjdk.org/jdk/pull/24329#discussion_r2078354983