RFR(S): 8042997: Make intrinsic some or all check index/range methods

[Roland Westrelin]

http://cr.openjdk.java.net/~roland/8042997/webrev.00/
http://cr.openjdk.java.net/~roland/8042997.jdk/webrev.00/

This intrinsifies Objects.checkIndex() as a CmpU + RangeCheck node sequence that C2 then optimizes using the existing range check optimizations. The goal is allow library code to have range checks that are guaranteed to be properly optimized.

I’m not sure if we want to leave the comment on c2 in the library code.

Roland.