RFR 8203466: intermittent crash at jdk.internal.misc.Unsafe::getObjectVolatile (native)

[coleen.phillimore at oracle.com]

Thanks Erik!
Coleen

On 9/18/18 5:45 AM, Erik Österlund wrote:
> Hi Coleen,
>
> Looks good. I guess the whole thing looks horrible in a way, but the 
> patch is good.
> Thanks for fixing this.
>
> /Erik
>
> On 2018-09-18 01:47, coleen.phillimore at oracle.com wrote:
>>
>>
>> On 9/17/18 5:17 PM, dean.long at oracle.com wrote:
>>> Can you move the JavaThread _WIN64 changes to thread_windows_x86.hpp?
>>
>> Thanks for looking at this.  I moved it to the better place:
>>
>> http://cr.openjdk.java.net/~coleenp/8203466.02/webrev/index.html
>>
>> Retested with build and ran one test 100 times that failed once.
>>
>> Thanks,
>> Coleen
>>
>>>
>>> dl
>>>
>>> On 9/17/18 5:05 AM, coleen.phillimore at oracle.com wrote:
>>>>
>>>>
>>>> On 9/14/18 4:01 PM, dean.long at oracle.com wrote:
>>>>> Hi Coleen.  In the bug you asked:
>>>>>
>>>>> > Why can't we just push rdi and rsi to the stack and restore 
>>>>> them? This code appears to be leaf code so shouldn't care about 
>>>>> stack format
>>>>>
>>>>> Did that ever get answered?  If there is concern about the pushes 
>>>>> and pops canceling out at the end, you could always reserve the 
>>>>> stack space at the beginning, after
>>>>>
>>>>> __ enter();
>>>>>
>>>>> and then setup_arg_regs/restore_arg_regs would not need to adjust 
>>>>> the stack pointer.
>>>>
>>>> The reason I didn't do this is that I couldn't get it to work for 
>>>> all the various call sites.  Also, the barrier code is going to 
>>>> need the thread register sometimes which wasn't available. So I 
>>>> went with this.  I'm somewhat unclear with how this is called from 
>>>> the c2 code.  If you want to try this solution, I should probably 
>>>> give up and reassign it to compiler.
>>>>
>>>> thanks,
>>>> coleen
>>>>
>>>>>
>>>>> dl
>>>>>
>>>>> On 9/14/18 11:32 AM, coleen.phillimore at oracle.com wrote:
>>>>>> Summary: Save windows 64 callee saved registers rsi, rdi to 
>>>>>> Thread, save r15, also callee saved to r9
>>>>>>
>>>>>> This is done for generated stubs that do arraycopy that need GC 
>>>>>> barrier code because GC assumes that r10 is scratch, since it's 
>>>>>> defined as rscratch1.  See bug for more details. Thanks Erik for 
>>>>>> your help and the diagnosis.
>>>>>>
>>>>>> Tested with mach5 hs-tier1-7.  We don't have a reproduceable test 
>>>>>> case.
>>>>>>
>>>>>> open webrev at http://cr.openjdk.java.net/~coleenp/8203466.01/webrev
>>>>>> bug link https://bugs.openjdk.java.net/browse/JDK-8203466
>>>>>>
>>>>>> Thanks,
>>>>>> Coleen
>>>>>>
>>>>>
>>>>
>>>
>>
>