[9] RFR (S): 8172844: Assert fails in deoptimization due to original PC at the end of code section

[Zoltán Majó]

Hi Rickard,


On 01/19/2017 02:22 PM, Rickard Bäckman wrote:
> Looks good to me.

thank you for the review and for the suggestions.

>
> Some clean up if you don't mind.
>
> frame_aarch64.inline.hpp:
>
> 85     assert(((CompiledMethod*)_cb)->insts_contains(_pc), "original PC must be in CompiledMethod");
> should use _cb->as_compiled_method() instead of the cast.
>
> frame_x86.inline.hpp:
> same as above.

That makes sense. Here is the updated webrev:
http://cr.openjdk.java.net/~zmajo/8172844/webrev.01/

Thank you!

Best regards,


Zoltan

>
> Thanks
> /R
>
> On 01/19, Zoltán Majó wrote:
>> Hi,
>>
>>
>> please review the fix for 8172844.
>>
>> https://bugs.openjdk.java.net/browse/JDK-8172844
>> http://cr.openjdk.java.net/~zmajo/8172844/webrev.00/
>>
>> The assert checking the "original pc" (i.e., the pc that was on the
>> stack before the stack location was overwritten to point to the
>> deoptimization handler) is too strict. If the last instruction of
>> the (to-be-)deoptimized method is a call, the pc will point to the
>> instruction following the call. That instruction is outside of the
>> code section (as the call is the last instruction in the code
>> section).
>>
>> I suggest we relax the assert to accept the original pc being at the
>> end of the code section as well. I tested the change with JPRT and
>> locally with the reproducer, the failure did not appear. RBT is in
>> progress.
>>
>> Thank you!
>>
>> Best regards,
>>
>>
>> Zoltan
>>