RFR: Fix, improve and refactor matrix barrier on AAarch64

[Aleksey Shipilev]

On 09/14/2017 05:19 PM, Roman Kennke wrote:
> Am 14.09.2017 um 16:42 schrieb Aleksey Shipilev:
>> On 09/14/2017 04:39 PM, Roman Kennke wrote:
>>> Am 14.09.2017 um 15:52 schrieb Aleksey Shipilev:
>>>> *) Passing third parameter makes the method consistent with what? shenandoah_write_barrier_post in
>>>> x86 uses rscratch1 without having it passed via register. g1_write_barrier_post also does not pass
>>>> rscratch1, but uses it.
>>> Most with itself. It seemed wrong to me to declare two temp regs as args, then use 3, and use 1
>>> implicitely. Also, it made experimenting/changing temp reg while debugging easier. Do you want me to
>>> change it back?
>> Yeah, change it back: I'd like to be consistent across arches and collectors.
>>
>>> http://cr.openjdk.java.net/~rkennke/fix-matrix-barrier-aarch64/webrev.01/
>> Good, except for rscratch1 change.
> 
> Ok, I made it a compromise: kept the method signature the same (i.e. 2 tmp args), and declare tmp3
> at the beginning of the code block to be rscratch1.
> 
> http://cr.openjdk.java.net/~rkennke/fix-matrix-barrier-aarch64/webrev.02/

Fine then.

-Aleksey