RFR: 8187033: [PPC] Imporve performance of ObjectStreamClass.getClassDataLayout()

[Kazunori Ogata]

Hi all,

Please review a change for JDK-8187033.

Bug report: https://bugs.openjdk.java.net/browse/JDK-8187033
Webrev: http://cr.openjdk.java.net/~horii/8187033/webrev.00/

This change removes a volatile qualifier of a private static variable used 
by ObjectStreamClass.getClassDataLayout().  Making this variable 
non-volatile improved performance of GradientBoostingTree test in Intel 
HiBench [1] by 5% on a POWER8 machine.  On an x86 machine, this change did 
not affect the performance.

[1] Intel HiBench: https://github.com/intel-hadoop/HiBench

Regards,
Ogata