RFR: 8311843: GenShen: assertion failed "Old generation affiliated regions must be less than capacity" [v4]

[William Kemper]

> There are a few fixes here:
> 
> During a Full GC, the compaction process is not constrained by the maximum capacity for young and old generations. We must, therefore, reestablish these constraints after the Full GC completes by _forcing_ the transfer of regions to old, if necessary.
> 
> When a region is "flipped" from the Mutator's free set to the Collector's, we cannot _force_ the transfer of the region because the young generation may not have any free regions.
> 
> A logic error in the loop which rebuilds the free set could prevent transferring free regions from the mutator to the collector reserves.
> 
> Some unused methods and fields were removed.

William Kemper has updated the pull request incrementally with one additional commit since the last revision:

  Improve assertion

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

Changes:
  - all: https://git.openjdk.org/shenandoah/pull/311/files
  - new: https://git.openjdk.org/shenandoah/pull/311/files/2b3380d9..8048c611

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=shenandoah&pr=311&range=03
 - incr: https://webrevs.openjdk.org/?repo=shenandoah&pr=311&range=02-03

  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/shenandoah/pull/311.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah.git pull/311/head:pull/311

PR: https://git.openjdk.org/shenandoah/pull/311