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

[Erik Österlund]

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
>>>>>
>>>>
>>>
>>
>