RFR: JDK-8323190: Segfault during deoptimization of C2-compiled code [v2]

[Cesar Soares Lucas]

> Currently, if `ReduceAllocationMerges` reduces an allocation merge that is used as a monitor C2 will SIGFAULT in `Process_OopMap_Node` because it's missing code to handle that case.  This patch fixes C2 to properly handle reduced allocation merges that are used as monitors. 
> 
> Tested with Linux x86_64 hotspot_all.

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

 - Update test/hotspot/jtreg/compiler/escapeAnalysis/TestInvalidLocation.java
   
   Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>
 - Update src/hotspot/share/opto/output.cpp
   
   Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>
 - Update test/hotspot/jtreg/compiler/escapeAnalysis/TestInvalidLocation.java
   
   Co-authored-by: Tobias Hartmann <tobias.hartmann at oracle.com>

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17333/files
  - new: https://git.openjdk.org/jdk/pull/17333/files/95fe08dd..5e2f0089

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17333&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17333&range=00-01

  Stats: 4 lines in 2 files changed: 1 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/17333.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17333/head:pull/17333

PR: https://git.openjdk.org/jdk/pull/17333