RFR: 8352675: Support Intel AVX10 converged vector ISA feature detection [v4]

[Jatin Bhateja]

On Thu, 24 Apr 2025 01:32:19 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

> It looks much better! Thanks, Jatin.
> 
> I'm curious why don't you represent feature bitmap as a POD (with all the accessors on it) and pass it around by value when needed? (It's size will vary across platforms, but will be fixed at runtime.) It should significantly simplify the implementation.
> 
> As an example, take a look at `RegMask` in C2. It accommodates significantly more bits than needed for `VM_Version`.

Hi @iwanowww,
RegMask is part of opto code, and it may not be accessible to the JVMCI interface, Currently, JVMCI captures the native address of various fields of VM_Struct, which are of interest to Graal. In the proposed solution, we are adding a new dynamically sized feature vector whose each element is 64 bits wide. JVMCI book-keeps the dynamic feature vector and its size, then uses the UNSAFE access API to compute the enabled feature set on the Java side.

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PR Comment: https://git.openjdk.org/jdk/pull/24329#issuecomment-2828550031