RFR: ShenandoahWBMemProjNode doesn't need to subclass ProjNode

[Aleksey Shipilev]

On 10/22/2018 11:04 AM, Roland Westrelin wrote:
> http://cr.openjdk.java.net/~roland/shenandoah/ShenandoahWBMemProjNode-not-proj/webrev.00/

Looks good to me.

*) This looks weird: it checks that n->in(0) is NULL, and then dereferences through it?

1091     } else if (n->Opcode() == Op_ShenandoahWBMemProj) {
1092       assert(n->in(0) == NULL && n->in(ShenandoahWBMemProjNode::WriteBarrier)->Opcode() ==
Op_ShenandoahWriteBarrier, "strange ShenandoahWBMemProj");

Or maybe I am misreading it, and input 0 is actually ShenandoahWBMemProjNode::Control (implied to be
at zero always?) and ShenandoahWBMemProjNode::WriteBarrier is 1?

-Aleksey