Currently, there is no way to determine in Node::Identity() and Node::Value() if we were called from GVN or IGVN but sometimes we would like to do optimizations based on this information (for example, see discussion in RFR for JDK-8136469 [1])

[1] http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2016-January/020670.html