RFR: Use R15-relative bad-mask in interpreter and C1 on x86_64

[Rickard Bäckman]

Thank you for the review!

/R

On 03/07, Per Liden wrote:
> Looks good!
> 
> (I also took this for a spin in our testing, no issues found)
> 
> /Per
> 
> On 03/07/2018 09:49 AM, Rickard Bäckman wrote:
> > The Interpreter and C1 have so far used a test reg, [rip+offset] to
> > execute the ZGC barrier.
> > On some machines it seems the distance between the CodeCache and global
> > statics are larger than what is possible to represent with a 32-bit
> > displacement, causing crashes.
> > 
> > This patch modifies the barrier used by C1 and the Interpreter to
> > instead use what C2 has been using by default. mov reg, [r15+offset],
> > which is the thread local copy of the mask.
> > 
> > Here is the webrev:
> > http://cr.openjdk.java.net/~rbackman/zgc_r15_barrier/
> > 
> > Thanks
> > /R
> >