[aarch64-port-dev ] RFR 8233401: Shenandoah: Refactor/cleanup Shenandoah load barrier code

[Zhengyu Gu]

>> On AArch64, you usually get noreg for tmp1 and tmp_thread. I can not
>> tell if you can safely use tmp1 if it is valid.
>>
>> I don't use tmp1 here, since I don't think it is worth the trouble, as
>> we have spare scratch registers. I do use tmp1 in x86 through.
> 
> OK, so please just do this for now:

Thanks!

-Zhengyu

> 
>>> void ShenandoahBarrierSetAssembler::load_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,
>>>                                               Register dst, Address src, Register, Register) {
> 
> I'm working on a redesign of the way that scratch registers are used in
> AArch64, and this code is likely to have to be changed. Accurate information
> about register usage is likely to be crucial for that.
>