RFR: 8198949: Modularize arraycopy stub routine GC barriers

[Erik Österlund]

Hi Roman,

Thank you for the review.

/Erik

On 2018-03-19 14:42, Roman Kennke wrote:
> I liked BSCodeGen better, but BarrierSetAssembler is ok too. Go for it!
>
> Roman
>
>
>> After some internal discussions, it turns out that the name "*BSCodeGen"
>> was not so popular, and has been changed to *BarrierSetAssembler instead.
>> I have rebased this on top of 8199604: Rename CardTableModRefBS to
>> CardTableBarrierSet and went ahead with the performing the required
>> renaming.
>>
>> New full webrev:
>> http://cr.openjdk.java.net/~eosterlund/8198949/webrev.03/
>>
>> New incremental webrev (from the rebased version):
>> http://cr.openjdk.java.net/~eosterlund/8198949/webrev.02_03/
>>
>> Thanks,
>> /Erik
>>
>> On 2018-03-13 10:47, Erik Österlund wrote:
>>> Hi Roman,
>>>
>>> Thanks for the review.
>>>
>>> /Erik
>>>
>>> On 2018-03-13 10:26, Roman Kennke wrote:
>>>> Am 09.03.2018 um 17:58 schrieb Erik Österlund:
>>>>> Hi,
>>>>>
>>>>> The GC barriers for arraycopy stub routines are not as modular as they
>>>>> could be. They currently use switch statements to check which GC
>>>>> barrier
>>>>> set is being used, and call one or another barrier based on that, with
>>>>> registers already allocated in such a way that it can only be used for
>>>>> write barriers.
>>>>>
>>>>> My solution to the problem is to introduce a platform-specific GC
>>>>> barrier set code generator. The abstract super class is
>>>>> BarrierSetCodeGen, and you can get it from the active BarrierSet. A
>>>>> virtual call to the BarrierSetCodeGen generates the relevant GC
>>>>> barriers
>>>>> for the arraycopy stub routines.
>>>>>
>>>>> The BarrierSetCodeGen inheritance hierarchy exactly matches the
>>>>> corresponding BarrierSet inheritance hierarchy. In other words, every
>>>>> BarrierSet class has a corresponding BarrierSetCodeGen class.
>>>>>
>>>>> The various switch statements that generate different GC barriers
>>>>> depending on the enum type of the barrier set have been changed to call
>>>>> a corresponding virtual member function in the BarrierSetCodeGen class
>>>>> instead.
>>>>>
>>>>> Thanks to Martin Doerr and Roman Kennke for providing platform specific
>>>>> code for PPC, S390 and AArch64.
>>>>>
>>>>> Webrev:
>>>>> http://cr.openjdk.java.net/~eosterlund/8198949/webrev.00/
>>>>>
>>>>> CR:
>>>>> https://bugs.openjdk.java.net/browse/JDK-8198949
>>>>>
>>>>> Thanks,
>>>>> /Erik
>>>> I looked over x86, aarch64 and shared code (in webrev.01), and it looks
>>>> good to me!
>>>>
>>>> As I commented earlier in private, I would find it useful if the
>>>> barriers could 'take over' the whole arraycopy, for example to do the
>>>> pre- and post-barrier and arraycopy in one pass, instead of 3. However,
>>>> let's keep that for later.
>>>>
>>>> Awesome work, thank you!
>>>>
>>>> Cheers,
>>>> Roman
>>>>
>>>>
>