RFR: 8253795: Implementation of JEP 391: macOS/AArch64 Port [v10]

[Anton Kozlov]

On Thu, 4 Feb 2021 22:58:39 GMT, Gerard Ziemski <gziemski at openjdk.org> wrote:

>> Anton Kozlov has updated the pull request incrementally with six additional commits since the last revision:
>> 
>>  - Merge remote-tracking branch 'origin/jdk/jdk-macos' into jdk-macos
>>  - Add comments to WX transitions
>>    
>>    + minor change of placements
>>  - Use macro conditionals instead of empty functions
>>  - Add W^X to tests
>>  - Do not require known W^X state
>>  - Revert w^x in gtests
>
> src/hotspot/os_cpu/bsd_aarch64/os_bsd_aarch64.cpp line 420:
> 
>> 418: size_t os::Posix::_compiler_thread_min_stack_allowed = 72 * K;
>> 419: size_t os::Posix::_java_thread_min_stack_allowed = 72 * K;
>> 420: size_t os::Posix::_vm_internal_thread_min_stack_allowed = 72 * K;
> 
> Those are slightly larger than their x86_64 counter parts. Are they conservative/aggressive values? How did we arrive at those?

These values were copied from linux_aarch64. The motivation is that clang on macos/aarch64 will likely to produce stack frames for C++ functions similar to frames generates by gcc on linux/aarch64. And sizes of java stack frames should not change.

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PR: https://git.openjdk.java.net/jdk/pull/2200