RFR: Add 'generational' as value choice for JVM option 'ShenandoahGCMode'.

[Roman Kennke]

On Wed, 21 Oct 2020 12:53:41 GMT, Bernd Mathiske <bmathiske at openjdk.org> wrote:

> All upcoming GenShen code will be guarded by this JVM option. If generational mode is not set, Shenandoah will function in its original single-generational form, without changes or degradations.

You should merge-in the master branch from openjdk/shenandoah, this should hopefully fix the jcheck complaints.

src/hotspot/share/gc/shenandoah/mode/shenandoahGenerationalMode.cpp line 2:

> 1: /*
> 2:  * Copyright (c) 2019, 2020, Red Hat, Inc. All rights reserved.

I believe "Copyright (c) 2020 ..." would be correct there.

src/hotspot/share/gc/shenandoah/mode/shenandoahGenerationalMode.cpp line 32:

> 30: #include "gc/shenandoah/heuristics/shenandoahStaticHeuristics.hpp"
> 31: #include "gc/shenandoah/mode/shenandoahGenerationalMode.hpp"
> 32: #include "logging/log.hpp"

Those includes for logging/* look unused. Probably leftovers?

src/hotspot/share/gc/shenandoah/mode/shenandoahGenerationalMode.hpp line 2:

> 1: /*
> 2:  * Copyright (c) 2019, Red Hat, Inc. All rights reserved.

Same as above. 2020 is the year ;-)

src/hotspot/share/gc/shenandoah/mode/shenandoahMode.hpp line 28:

> 26: #define SHARE_GC_SHENANDOAH_MODE_SHENANDOAHMODE_HPP
> 27: 
> 28: #include "runtime/java.hpp"

This include looks unused.

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Changes requested by rkennke (Reviewer).

PR: https://git.openjdk.java.net/shenandoah/pull/4