RFR: JDK-8312617: SIGSEGV in ConnectionGraph::verify_ram_nodes [v3]

[Cesar Soares Lucas]

> - Return early from `verify_ram_nodes` if compilation is already failing.
> - Add back check for `failing()` after `eliminate_macro_nodes()`.
> - Print additional diagnostic information when an unexpected user of RAM is encountered.
> 
> Tested with tier1-3 on Linux x64.

Cesar Soares Lucas has updated the pull request incrementally with three additional commits since the last revision:

 - Update src/hotspot/share/opto/compile.cpp
   
   Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>
 - Update src/hotspot/share/opto/escape.cpp
   
   Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>
 - Update src/hotspot/share/opto/escape.cpp
   
   Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15048/files
  - new: https://git.openjdk.org/jdk/pull/15048/files/b55cba76..2e91dc5f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15048&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15048&range=01-02

  Stats: 3 lines in 2 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/15048.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15048/head:pull/15048

PR: https://git.openjdk.org/jdk/pull/15048