8238691: C2: turn subtype check into macro node

[Tobias Hartmann]

On 14.02.20 10:39, Roland Westrelin wrote:
> record_for_igvn doesn't do anything on an PhaseIterGVN:
> 
>  virtual void record_for_igvn(Node *n) { }

You are right, we only changed that for Valhalla:
http://hg.openjdk.java.net/valhalla/valhalla/file/3a51926f7196/src/hotspot/share/opto/phaseX.hpp#l478

Thanks,
Tobias