RFR: 8016538: volatile double access via Unsafe.cpp is not atomic

[Yumin Qi]

Hi,

   Can i have your codereview of this change:
   Unsafe_Get[SET]DoubleVolatile are not atomic on 32bit x86 linux 
caused test for 
org.openjdk.concurrent.torture.tests.atomicity.primitives.reflect.DoubleAtomicityTest 
failed.
   The fix is using same treatment for jdouble as for jlong. Tests 
passed on failed test case, vm quick tests. It only happens on linux 
32bit platform, on solaris, the inlined code be compiled into code of 
using fldl/fstpl which are atomic instructions.

   Contributed by: dholmes

   URL: http://cr.openjdk.java.net/~minqi/8016538/01

   Thanks
   Yumin