RFR: 8349582: APX NDD code generation for OpenJDK [v14]

[Emanuel Peter]

On Thu, 13 Mar 2025 17:50:20 GMT, Srinivas Vamsi Parasa <sparasa at openjdk.org> wrote:

>> The goal of this PR is to generate x86 code using Intel Advanced Performance Extensions (APX) instructions which doubles the number of general-purpose registers, from 16 to 32. Intel APX adds nondestructive destination (NDD) and no flags (NF) flavor for the scalar instructions through EVEX encoding.
>> 
>> For more information about APX, see https://www.intel.com/content/www/us/en/developer/articles/technical/advanced-performance-extensions-apx.html.
>
> Srinivas Vamsi Parasa has updated the pull request incrementally with one additional commit since the last revision:
> 
>   add comments for encoding and UCF

test/hotspot/gtest/x86/x86-asmtest.py line 60:

> 58: registers_mapping = {
> 59:     # skip rax, rsi, rdi, rsp, rbp as they have special encodings
> 60:     'rax': {64: 'rax', 32: 'eax', 16: 'ax', 8: 'al'},

You should probably update the copyright year, right?

Also: is this script ever run in testing? I didn't know we had python files in the repository 😅

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PR Review Comment: https://git.openjdk.org/jdk/pull/23501#discussion_r2007174854