RFR(xs): 8198271: Make CollectedHeap::create_heap_space_summary() virtual

[Per Liden]

Thanks Kim and Thomas for reviewing.

/Per

On 02/16/2018 08:15 PM, Thomas Schatzl wrote:
> Hi,
> 
> On Fri, 2018-02-16 at 14:56 +0100, Per Liden wrote:
>> This patch makes CollectedHeap::create_heap_space_summary() virtual,
>> to
>> allow a GC to override it. The current default implementation
>> assumes
>> that the "heap space" is the same as the "reserved_region", which
>> isn't
>> necessarily true. ZGC (and possibly Shenandoah in the future?) have
>> a
>> different heap layout and thus needs to override this function.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8198271
>> Webrev: http://cr.openjdk.java.net/~pliden/8198271/webrev.0/
> 
>    good.
> 
> Thomas
>