RFR(S): 8223138: Small clean-up in loop-tree support.

[Patric Hedlin]

Dear all,

I would like to ask for help to review the following change/update:

Issue:  https://bugs.openjdk.java.net/browse/JDK-8223138
Webrev: http://cr.openjdk.java.net/~phedlin/tr8223138/

8223138: Small clean-up in loop-tree support.

     Rename predicate 'is_inner()' to 'is_innermost()' to be accurate.
     Add 'is_root()' predicate for root parent test in loop-tree.
     Change definition of 'is_loop()' to always lazy-read the tail,
     since it should never be NULL. Clean-up of 'tail()' definition.


Testing: Part of 8216137 (hs-tier1..4, hs-precheckin-comp, Kitchensink24h)


Best regards,
Patric