6871109: G1: remove the concept of the scan only prefix
Summary: Removed scan only regions and associated code. The young portion of the collection set is now constructed incrementally - when a young region is retired as the current allocation region it is added to the collection set.
Reviewed-by: apetrusenko, iveresov, tonyp

Summary: ensure_parsability() must be called even if GC_locker prevents GC.
Reviewed-by: ysr, chrisphi

Summary: Replaces the G1-specific parameter with the existing ones that are used by the other GCs (YoungPLABSize and OldPLABSize)
Reviewed-by: tonyp, johnc

Summary: The outgoing region map is not maintained properly and it's causing an assert failure. Given that we don't actually use it, I'm removing it. I'm piggy-backing a small change on this which removes a message that it's printed before a Full GC when DisableExplicitGC is set.
Reviewed-by: apetrusenko, ysr

Summary: The expression that calculates the live bytes for a heap region can overflow for a suitably large humongous region/object. Cache the object size in a suitably sized local variable so that the expression is converted to a wider type.
Reviewed-by: tonyp, jmasa, iveresov, apetrusenko

Summary: Various fixes to the G1 debugging output.
Reviewed-by: johnc, iveresov

Summary: Ensure a full GC that clears SoftReferences before throwing an out-of-memory
Reviewed-by: ysr, jcoomes

Summary: Humongous regions may contain multiple objects as a result of being retained as to-space from a previous GC and then re-used as to-space after being tagged as humongous. These changes include a check that causes retained to-space regions that are now tagged as humongous to be disregarded and a new to-space region allocated.
Reviewed-by: tonyp, iveresov

Summary: Make sure that two marking cycles do not overlap, i.e., a new one can only start after the concurrent marking thread finishes all its work. In the fix I piggy-back a couple of minor extra fixes: some general code reformatting for consistency (only around the code I modified), the removal of a field (G1CollectorPolicy::_should_initiate_conc_mark) which doesn't seem to be used at all (it's only set but never read), as well as moving the "is GC locker active" test earlier into the G1 pause / Full GC and using a more appropriate method for it.
Reviewed-by: johnc, jmasa, jcoomes, ysr

Summary: Calling the methods region_stack_push() and region_stack_pop() concurrent is not MT-safe. The assumption is that we will only call region_stack_push() during a GC pause and region_stack_pop() during marking. Unfortunately, we also call region_stack_push() during marking which seems to be introducing subtle marking failures. This change introduces lock-based methods for pushing / popping to be called during marking.
Reviewed-by: iveresov, johnc

Summary: Fix typo.
Reviewed-by: never

Summary: Enable parallel RSet updating and scanning.
Reviewed-by: iveresov, jmasa

Summary: Update the HS18 build number to 02
Reviewed-by: jcoomes

Reviewed-by: kvn

Reviewed-by: never
Contributed-by: ed@camswl.com

Summary: The changes of 6934494 have broken the Zero build.
Reviewed-by: twisti
Contributed-by: NGary Benson <gbenson@redhat.com>

Summary: Remove the G1GCPercent parameter, that specifies the desired GC overhead percentage in G1, and observe the GCTimeRatio parameter instead.
Reviewed-by: jmasa, johnc

Summary: When Zero is running with Shark enabled threads can be left with their _do_not_unlock_if_synchronized flag incorrectly set.
Reviewed-by: twisti
Contributed-by: NGary Benson <gbenson@redhat.com>

Summary: Fix build.bat so invoking command shell doesn't exit on error. Fix dirname assumptions. Document some MKS environment dependencies.
Reviewed-by: coleenp

Summary: Remove assert to decouple JDK and HotSpot additions of known types.
Reviewed-by: mchung

Summary: Update the Major and build numbers for HS18 fork
Reviewed-by: jcoomes

Reviewed-by: twisti