RFR: 8201647: Make initial clearing of CHeapBitMap optional

[Per Liden]

Thanks Stefan!

/Per

On 04/17/2018 02:41 PM, Stefan Karlsson wrote:
> Looks good.
> 
> StefanK
> 
> On 2018-04-17 14:38, Per Liden wrote:
>> CHeapBitMap objects will by default clear the underlying bitmap during 
>> construction. In ZGC we don't want mark bitmaps to be cleared on 
>> construction, since we instead do this lazily during concurrent marking.
>>
>> This patch adds a "bool clear = true" argument to CHeapBitMap's 
>> constructor to be able to opt-out of this behavior.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8201647
>> Webrev: http://cr.openjdk.java.net/~pliden/8201647/webrev.0
>>
>> /Per