RFR (11): [backport] 8221766: Load-reference barriers for Shenandoah

[Roman Kennke]

>> Right. This was there to make dominated_by() public, because we're using
>> it in ShBSC2::ideal_node(). However, we don't actually use that code
> 
> Ah. Right.
> 
>> path and can remove it and revert the cfgnode.hpp change back:
> 
> Why don't we use that code anymore?

In jdk11, we don't use it *not yet*. We have sprinkled a bunch of code
over Ideal() calls to do the things that we do via BSC2::ideal_node() in
jdk12 and up.

I believe the corresponding code in sh/jdk11 is in ifnode.cpp:

https://builds.shipilev.net/patch-openjdk-shenandoah-jdk11/src/hotspot/share/opto/ifnode.cpp.udiff.html

Roman