RFR: 8284563: AArch64: bitperm feature detection for SVE2 on Linux

[Ningsheng Jian]

On Mon, 18 Apr 2022 03:27:18 GMT, Eric Liu <eliu at openjdk.org> wrote:

>> src/hotspot/cpu/aarch64/vm_version_aarch64.hpp line 132:
>> 
>>> 130:   // Feature identification
>>> 131: #define CPU_FEATURE_DETECTION(id, name, bit) \
>>> 132:   static bool supports_##name() { return (_features & CPU_##id) != 0; };
>> 
>> Having supports_a53mac() looks a bit weird to me.
>
> Yeah, I was thinking this before. Indeed, A53MAC and  STXR_PREFETCH are not CPU feature. Considering that some codes depend on that, it's acceptable to me leaving them here at this moment.

OK. Then could you also update the usages of these two `features` with your new functions?

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PR: https://git.openjdk.java.net/jdk/pull/8258