Request for code review - JDK-8141135,Remove G1RemSet::write_ref

[Kim Barrett]

On Nov 9, 2015, at 12:12 PM, Alexander Harlap <alexander.harlap at oracle.com> wrote:
> 
> Remove some unused code:
> 
> JDK-8141135 
> 
> Proposed change:
> http://cr.openjdk.java.net/~aharlap/8141135/webrev.00
> 
> Alex

The description of write_ref / par_write_ref doesn't entirely match
the implementation.

The description says "from" must be non-NULL.  However, the assertion
validating "from" and that "p" is within it explicitly checks for and
allows "from" == NULL.

There appears to only be one call site, in
UpdateRSOopClosure::do_oop_work.  That call site is preceeded by an
assertion that the region value that will be passed to par_write_ref
is non-NULL.  So I think the allowance of NULL "from" in par_write_ref
is unnecessary, and contrary to its description.