Request for review(M): 6964776: c2 should ensure the polling page is reachable on 64 bit

[Vladimir Kozlov]

x86_64.ad:
+ // It does it the polling page is more than disp32 away.
---
   // It needs it when polling page is more than disp32 away.

Usually predicate is first in instructions definitions.

Vladimir

Igor Veresov wrote:
> C1 and C2 could only use rip-relative addressing when emitting the 
> page-polling code, which limited the distance from the code cache to the 
> polling page is more than 2G (doesn't fit in a signed 32bit 
> displacement). The solution in this case is to materialize the absolute 
> pointer to the polling page in a register first, as we do on SPARC.
> 
> Webrev: http://cr.openjdk.java.net/~iveresov/6964776/webrev.00/
> 
> Thanks,
> igor