RFR 8178150: Regression in logic for handling inference stuck constraints

[Maurizio Cimadamore]

Hi,
this issue has already been discussed in [1].

The issue has to do with the fact that logic for picking a deferred node 
to unstick ignores the can-influence relationship (aka inference graph 
dependencies).

The implemented code is not optimized (almost deliberately); I wanted 
the code to follow the spec more or less cleanly. While I'm open to 
small improvements, I would please ask to focus on correctness for the 
time being since (i) this code is not an hot execution path and (ii) 
other performance improvements in this area will follow, see [2].

http://cr.openjdk.java.net/~mcimadamore/8178150/

[1] - 
http://mail.openjdk.java.net/pipermail/compiler-dev/2017-October/011192.html
[2] - 
http://mail.openjdk.java.net/pipermail/compiler-dev/2017-October/011126.html

Cheers
Maurizio