RFR (M): 8034842: Parallelize the Free CSet phase in G1

[Thomas Schatzl]

Hi Jon,

On Mon, 2016-07-11 at 08:57 -0700, Jon Masamitsu wrote:
> Thomas,
> 
> Looks correct as is.  Just some comments about readability
> for your considerations.
> 

  there is a new webrev + diff at

http://cr.openjdk.java.net/~tschatzl/8034842/webrev.7/ (full)
http://cr.openjdk.java.net/~tschatzl/8034842/webrev.6_to_7/ (diff)

In addition to your comments I incorporated suggestions by Erik:

- tried to minimize some assert before recording survivor words.

- renamed work_item_t to WorkItem to conform to naming conventions.

- removed the trick with using the sign bit of a double as a boolean to
know whether it had been changed for better readability.

Thanks a lot,
  Thomas