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

[Yumin Qi]

Hi,  Vladimir and all

   New webrev
http://cr.openjdk.java.net/~minqi/8016538/03 
<http://cr.openjdk.java.net/%7Eminqi/8016538/03>

   Changed for other x86 platforms too even they did not show the 
symptom, to keep codes as consistent for x86 arch.

   Thanks
   Yumin

On 7/9/2013 3:11 PM, Yumin Qi wrote:
> Vladimir,
>
> On 7/9/2013 2:16 PM, Vladimir Kozlov wrote:
>> Hi Yumin,
>>
>> load_acquire() could be more expensive with this changes even for 
>> 64bit VM because you first loading from volatile address into local 
>> variable. Please, check what code is generated in 64-bit with your 
>> changes
> I will check for that. Or we can guard by AMD64.
>> Why you did not use release_store_fence() in 
>> OrderAccess::release_store_fence() and where is cast to jlong* ?
>>
> You  are right,  it is better with release_store_fence() on 64bit.
> There is no functions for casting pointer I think.
>
> Thanks
> Yumin
>> Thanks,
>> Vladimir
>>
>> On 7/9/13 11:32 AM, Yumin Qi wrote:
>>> 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
>