RFR: 8189871: Refactor GC barriers to use declarative semantics

[Kim Barrett]

> On Nov 21, 2017, at 11:33 AM, Erik Österlund <erik.osterlund at oracle.com> wrote:
> 
> Hi Kim,
> 
> On 2017-11-21 08:16, Kim Barrett wrote:
>>> On Nov 21, 2017, at 2:07 AM, Kim Barrett <kim.barrett at oracle.com> wrote:
>>> 
>>> Noticed another issue while looking for something else.
>> And another one.
>> 
>> The modified unsafe.cpp doesn't use field_offset_(to|from)_byte_offset
>> in places where Access is being used. Those functions and their use
>> is intentional documentation and abstraction, despite their
>> implementations presently being nops. Where Access is being used, the
>> offset is now just quietly assumed to be in bytes, ignoring that
>> abstraction. I think the use of those functions ought to be retained.
> 
> I will file an RFE to re-introduce this no-op abstraction.

Thanks.