RFR (M): 8200545: Improve filter for enqueued deferred cards

[Thomas Schatzl]

Hi all,

  can I have reviews for this change that improves the check whether
the destination region for a reference has a remembered set that needs
updating?

This removes the need to use two distinct closures for scanning oops
during evacuation, as both the new and the old variant are now equal in
performance, so not only simplifying existing code, but also
simplifying the follow-up change JDK-8213108 a lot.

The idea of this change is to put the information whether a region
needs remembered set updates into the InCSetState table. This results
in that for every reference we do not need to (re-)calculate the
destination region, and then do the walk across several data structures
(HeapRegion->HeapRegionRemSet) every time - this simply combines this
with the existing calculation of InCSetState.

The code adds a new member to InCSetState that indicates whether the
region needs remembered set updates.

As a second, seperate step, there is a change that renames InCSetState
in a imho more understandable G1RegionAttr(ibutes); if wanted I can do
this in a separate CR, but here I will just present them as separate
webrevs.

CR:
https://bugs.openjdk.java.net/browse/JDK-8200545
Webrev:
http://cr.openjdk.java.net/~tschatzl/8200545/webrev/ (add InCSetState
member only)
http://cr.openjdk.java.net/~tschatzl/8200545/webrev.rename/ (rename
InCSetstate only)
http://cr.openjdk.java.net/~tschatzl/8200545/webrev.full/ (full change)
Testing:
hs-tier1-5, internal perf testing;

While testing I found JDK-8222426 - however that one also occurs
without the changes, so I think we can go ahead with this regardless.

Thanks,
  Thomas