RFR: 8352675: Support Intel AVX10 converged vector ISA feature detection [v10]

[Jatin Bhateja]

On Sat, 3 May 2025 08:13:11 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>>> Ok, thanks! I wasn't sure you finished the pass.
>>> 
>>> I'm still seeing dynamic memory allocation which IMO unnecessarily complicates the implementation. Bitmap size is fixed and well-known at compile time. It enables `VM_Feature` class to embed the array of proper size inline. And it eliminates all the problems related to undesired sharing of backed array. (Also, `pre_initialize()` is not needed as well.)
>> 
>> Bitmap size depends on the maximum feature enum value, I made it dynamic to keep it flexible. Do you want the feature vector size to be made constant and manually bump it when we exhaust the limit?
>
>> Bitmap size depends on the maximum feature enum value, I made it dynamic to keep it flexible. Do you want the feature vector size to be made constant and manually bump it when we exhaust the limit?
> 
> Yes, please. (The limit may be precise - number of  elements in Feature_Flag enum - but the logic which computes the size of backing array can automatically round it and bump the size once the actual limit is reached.) 
> 
>> pre_initialize was put in place because codeCache_init() proceeds VM_Version_init() 
> 
> I wanted to say that the sole purpose of `pre_initialize` is to allocate memory. Once it goes away, there's no reason to keep it.

Thanks @iwanowww , @sviswa7 , @mur47x111 , @merykitty  for your reviews.

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PR Comment: https://git.openjdk.org/jdk/pull/24329#issuecomment-2868092244