RFR: 8252041: G1: Fix incorrect uses of HeapRegionManager::max_length [v2]

[Thomas Schatzl]

> Hi all,
> 
>   can I have reviews for this change that fixes some uses of HeapRegionManager::max_regions()/max_expandable_regions() in
>   our code to use the correct variant?
> 
> HeapRegionManager::max_length gives the absolute maximum number of regions reserved for the heap based on the
> reservation.
> HeapRegionmanager::max_expandable_regions() returns the maximum number of regions the heap can grow to (can be
> committed).
> Typically they are exchangeable, but if the reservation is larger than what -Xmx allows (like when file-mapping old
> gen), this is not the case, and causes assertions. In some cases the existing region manager code could (if it reserved
> more than -Xmx) give back more than -Xmx allows.  Testing: tier1-5.

Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:

  Renaming

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/178/files
  - new: https://git.openjdk.java.net/jdk/pull/178/files/8db28c10..b916c003

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=178&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=178&range=00-01

  Stats: 94 lines in 16 files changed: 0 ins; 0 del; 94 mod
  Patch: https://git.openjdk.java.net/jdk/pull/178.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/178/head:pull/178

PR: https://git.openjdk.java.net/jdk/pull/178