RFR: 8154096: Extend WhiteBox API with methods which retrieve from VM information about available GC

[Kim Barrett]

> On Apr 29, 2016, at 8:03 PM, Kim Barrett <kim.barrett at oracle.com> wrote:
> 
>> On Apr 29, 2016, at 7:34 AM, Dmitry Fazunenko <dmitry.fazunenko at oracle.com> wrote:
>> 
>> Hello,
>> 
>> To address the offline comments from Igor I completely reimplemented the fix.
>> The main change is introduction a new class sun.hotspot.gc.GC which could be used by tests to:
>> http://cr.openjdk.java.net/~dfazunen/8154096/webrev.02/test/raw_files/new/test/lib/sun/hotspot/gc/GC.java
>> - get the currently used GC
>> - check if the current GC was selected by ergo or set explicitly
>> - get list of supported GC
>> 
>> The new version also minimize the changes to the WhiteBox API
>> 
>> So reviewers are still very welcome!
>> 
>> http://cr.openjdk.java.net/~dfazunen/8154096/webrev.02/
>> https://bugs.openjdk.java.net/browse/JDK-8154096

> ------------------------------------------------------------------------------ 
> hotspot/src/share/vm/prims/whitebox.cpp 
> 298   assert(false, "No GC selected yet");
> and
> 322   assert(false, "No GC selected yet”);

Forgot to include the comment I was going to make.

I think these should be ShouldNotReachHere().

These entry points for Java clearly can’t be called from Java before the GC selection.