[8u] RFR 8244407: JVM crashes after transformation in C2 IdealLoopTree::split_fall_in

[Yangfei (Felix)]

Hi,

Original bug:
  https://bugs.openjdk.java.net/browse/JDK-8244407 
  https://hg.openjdk.java.net/jdk/jdk/rev/c9f5a16d6980 

Original patch doesn't apply cleanly due to conflict on the copyright header update and file path difference, no other conflicts witnessed.

8u webrev:
  http://cr.openjdk.java.net/~fyang/8244407-8u-backport/

Testing: Run full jtreg test with a x86-64 & aarch64 release build.

OK to backport?

Thanks,
Felix