RFR: 8214377: ZGC: Don't use memset to initialize array of ZForwardingTableEntry

[Per Liden]

Thanks Erik!

/Per

On 12/3/18 11:38 AM, Erik Österlund wrote:
> Hi Per,
> 
> Looks good.
> 
> Thanks
> /Erik
> 
> On 2018-11-29 13:49, Per Liden wrote:
>> Use placement new instead of memset() to avoid compiler warning/error 
>> when using GCC 8 with -Werror=class-memaccess (memset to initialize 
>> non-trivial object).
>>
>> To avoid any undefined behavior I also added a loop to destruct the 
>> objects properly, but this loop will be compiled down to nothing.
>>
>> I ran SPECjbb2015 to see if the execution time for "Prepare Relocation 
>> Set" was noticeably affected by this change (assuming memset does a 
>> batter job than then loop), but I can't see any real difference. I'll 
>> run a few more iterations over night just to make sure.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8214377
>> Webrev: http://cr.openjdk.java.net/~pliden/8214377/webrev.0
>>
>> /Per