RFR: 8253795: Implementation of JEP 391: macOS/AArch64 Port [v2]

[Vladimir Kempik]

On Sat, 23 Jan 2021 11:43:31 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> Anton Kozlov has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Address feedback for signature generators
>>  - Enable -Wformat-nonliteral back
>
> src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp line 5272:
> 
>> 5270: void MacroAssembler::get_thread(Register dst) {
>> 5271:   RegSet saved_regs = RegSet::range(r0, r1) + BSD_ONLY(RegSet::range(r2, r17)) + lr - dst;
>> 5272:   push(saved_regs, sp);
> 
> This isn't very nice.

Hello
Why is it not nice ?
linux_aarch64 uses some linux specific tls function _ZN10JavaThread25aarch64_get_thread_helperEv from hotspot/os_cpu/linux_aarch64/threadLS_linux_aarch64.s
which clobbers only r0 and r1
macos_aarch64 has no such tls code and uses generic C-call to Thread::current();
Hence we  are saving possibly clobbered regs here.

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