[9] RFR (XS): 8079135: C2 disables some optimizations when a large number of unique nodes exist

[Vladimir Ivanov]

http://cr.openjdk.java.net/~vlivanov/8079135/webrev.00/

Incremental inlining produces lots of dead nodes, so # of unique and # 
of live nodes can differ significantly. But actual IR size is what 
matters.

Performance experiments show that octane doesn't hit the problem (no 
difference).

Testing: octane/nashorn

Best regards,
Vladimir Ivanov