RFR: 8334717: Add JVMCI support for APX EGPRs

[Yudi Zheng]

On Tue, 8 Apr 2025 13:15:29 GMT, Doug Simon <dnsimon at openjdk.org> wrote:

>> This PR marks extra general purpose registers introduced by Intel APX as Graal allocatables. It also drops AMD64/AArch64/RISCV64.flags and RegisterArray
>
> src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/code/RegisterAttributes.java line 58:
> 
>> 56:      *         element at index i holds the attributes of the register whose number is i.
>> 57:      */
>> 58:     public static RegisterAttributes[] createMap(RegisterConfig registerConfig, List<Register> registers) {
> 
> We should remove raw arrays as much as possible in JVMCI and replace them with immutable Lists:
> 
>      * @return an immutable list whose length is the max register number in {@code registers} plus 1. An
>      *         element at index i holds the attributes of the register whose number is i.
>      */
>     public static List<RegisterAttributes[] createMap(RegisterConfig registerConfig, List<Register> registers) {

I have audited all the .clone() on array objects and changed as much as possible. Let me know if there is still some opportunity

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PR Review Comment: https://git.openjdk.org/jdk/pull/23159#discussion_r2095952012