RFR: 8248238: Implementation of JEP: Windows AArch64 Support [v7]

[Andrew Haley]

On Thu, 24 Sep 2020 15:15:45 GMT, Monica Beckwith <mbeckwit at openjdk.org> wrote:

>> This is a continuation of https://mail.openjdk.java.net/pipermail/aarch64-port-dev/2020-August/009566.html
>>  
>> Changes since then:
>> * We've improved the write barrier as suggested by Andrew [1]
>> * The define-guards around R18 have been changed to `R18_RESERVED`. This will be enabled for Windows only for now but
>>   will be required for the upcoming macOS+Aarch64 [2] port as well.
>> * We've incorporated https://github.com/openjdk/jdk/pull/154 by @AntonKozlov in our PR for now and built the
>>   Windows-specific CPU feature detection on top of it.
>> 
>> [1] https://mail.openjdk.java.net/pipermail/aarch64-port-dev/2020-August/009597.html
>> [2] https://openjdk.java.net/jeps/8251280
>
> Monica Beckwith has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - os_windows: remove duplicated UMA handling
>  - test_safefetch{32,N} works fine on win+aarch64

Marked as reviewed by aph (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/212