Request for review(M): 6627983: G1: Bad oop deference during marking

[Igor Veresov]

Bulk zeroing reduction didn't work with G1, because arraycopy would call 
pre-barriers on uninitialized oops. The solution is to have version of 
arraycopy stubs that don't have pre-barriers.
Also refactored arraycopy stubs generation on SPARC to be more readable 
and reduced the number of stubs necessary in some cases.

Webrev: http://cr.openjdk.java.net/~iveresov/6627983/webrev.00/

Thanks,
igor