RFR: 8265132 : C2 compilation fails with assert "missing precedence edge" [v4]

[Jamsheed Mohammed C M]

> Issue is similar to https://bugs.openjdk.java.net/browse/JDK-8261730
> but happens at next https://github.com/jamsheedcm/jdk/blob/master/src/hotspot/share/opto/gcm.cpp#L830
> 
> Request for review

Jamsheed Mohammed C M has updated the pull request incrementally with one additional commit since the last revision:

  improving the fix for raise_LCA_above_marks

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4200/files
  - new: https://git.openjdk.java.net/jdk/pull/4200/files/1a390c7d..080d2270

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4200&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4200&range=02-03

  Stats: 29 lines in 2 files changed: 25 ins; 0 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4200.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4200/head:pull/4200

PR: https://git.openjdk.java.net/jdk/pull/4200