RFR: 8262443: GenerateOopMap::do_interpretation can spin for a long time. [v2]

[Robbin Ehn]

> With Safepoint/Handshake timeout enabled in rare cases this methods spins for a long time, blocking safepoints/handshakes, so timeout (with a long delay) is triggered.
> 
> In some cases we are in native while executing this method and in some in vm.
> That's why there is an check for state in vm.
> 
> Tested with other changes in t-1-7 this specific case of timeout is no longer an issue.
> This change-set passes T1 stand alone.

Robbin Ehn has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Comment, local JavaThread variable
 - Merge branch 'master' into 8262443-gen-oop-map
 - Go to blocked when loop

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2742/files
  - new: https://git.openjdk.java.net/jdk/pull/2742/files/3e4fc18b..bdb68d24

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2742&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2742&range=00-01

  Stats: 9244 lines in 328 files changed: 5992 ins; 1967 del; 1285 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2742.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2742/head:pull/2742

PR: https://git.openjdk.java.net/jdk/pull/2742