RFR: 8254315: Shenandoah: Concurrent weak reference processing [v12]

[Roman Kennke]

On Tue, 27 Oct 2020 10:49:58 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Roman Kennke has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Rename native argument to maybe_narrow_oop for more clarity
>
> src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp line 1062:
> 
>> 1060:     Node* in2 = n->in(2);
>> 1061:     if (in1->bottom_type() == TypePtr::NULL_PTR &&
>> 1062:         (in2->Opcode() != Op_ShenandoahLoadReferenceBarrier ||
> 
> This is a bugfix, right? It changes `in1` (seemingly incorrect) to `in2` (seemingly correct). If so, maybe we should split it out to fix previous releases too?

Actually I think I *introduced* a bug there. It seems curious that it worked that way :-) I'm fixing it.

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PR: https://git.openjdk.java.net/jdk/pull/505