RFR: 8248238: Implementation of JEP: Windows AArch64 Support [v10]

[Vladimir Kempik]

On Mon, 28 Sep 2020 14:07:16 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 with a new target base due to a merge or a rebase. The pull request now
> contains 24 commits:
>  - Merge remote-tracking branch 'upstream/master' into jdk-windows
>  - SA: update copyright
>  - Fix graal codestyle
>  - Reduce includes
>  - Merge remote-tracking branch 'upstream/master' into jdk-windows
>  - os_windows: remove duplicated UMA handling
>  - test_safefetch{32,N} works fine on win+aarch64
>  - cleanup for 8253539: Remove unused JavaThread functions for set_last_Java_fp/pc
>  - cleanup for 8253457: Remove unimplemented register stack functions
>  - Merge remote-tracking branch 'upstream/master' into jdk-windows
>  - ... and 14 more: https://git.openjdk.java.net/jdk/compare/ec9bee68...a7cdaad6

src/hotspot/cpu/aarch64/register_aarch64.cpp line 44:

> 42:     "rscratch1", "rscratch2",
> 43:     "r10", "r11", "r12", "r13", "r14", "r15", "r16",
> 44:     "r17", NOT_R18_RESERVED("r18") WIN64_ONLY("rtls"), "r19",

For me this line doesn't look good in case of expanding this functionality to macos-aarch64
as it's just the name of register and it's r18 on every platform except WIN64 and has nothing to do with reserving r18.

-------------

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