RFR(s): 8013171: G1: C1 x86_64 barriers use 32-bit accesses to 64-bit PtrQueue::_index

[Per Liden]

> On 23 Apr 2015, at 15:32, Roland Westrelin <roland.westrelin at oracle.com> wrote:
> 
>> Yes, it happens to be the same thing is this case, but bordering on being sloppy given that it's not a pointer. But if this is the preferred way then I can live with that.
> 
> You could add a comment that says you’re using the *ptr variants for non pointer things.
> I don’t know if it’s the preferred way but that’s what I would do because less #ifdef makes the code easier to read.
> 
>> Updated webrev: http://cr.openjdk.java.net/~pliden/8013171/webrev.1/
> 
> That looks good to me.
> 

Thanks for reviewing Roland!

/Per