[ping] RFR(S): 8156992: [ppc] Implement template interpreter stack overflow checks as on x86/sparc.

[David Holmes]

On 28/05/2016 1:35 AM, Lindenmaier, Goetz wrote:
> Hi David,
>
> well, yes, Dean had similar questions.
> X86/sparc load stack_base and stack_size, compute stack_end and then add the
> Max(shadow, quard). All in assembly in the template interpreter prolog.  On ppc,
> we load it from the precomputed field stackoverflow_limit.  The value in that field
> differed from what x86/sparc computed, which is the error I want to fix here.

That all sounds a bit broken. :(

> I adapted the drawing to the change of that field.

I still don't see how the drawing matches the code given the MAX usage.

I can't convince myself that any of this stuff is correct. Given 
Frederic was working in this area most recently I wonder if he can 
comment (but I know he may not be around at the moment).

Thanks,
David

> Best regards,
>   Goetz
>
>
>
>> -----Original Message-----
>> From: David Holmes [mailto:david.holmes at oracle.com]
>> Sent: Donnerstag, 26. Mai 2016 00:36
>> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>; hotspot-runtime-
>> dev at openjdk.java.net
>> Subject: Re: [ping] RFR(S): 8156992: [ppc] Implement template interpreter
>> stack overflow checks as on x86/sparc.
>>
>> Hi Goetz,
>>
>> I know you were having discussions with Dean in relation to this but I
>> really don't understand the change to the diagram in thread.hpp nor the
>> change to the definition of stackoverflow_limit. To me the limit has to
>> be the sum of the guard zone and shadow zone. With your MAX change the
>> diagram doesn't even make sense AFAICS.
>>
>> ??
>>
>> David
>>
>> On 25/05/2016 6:07 PM, Lindenmaier, Goetz wrote:
>>> Hi,
>>>
>>> could someone else have a look at this change?  I need a reviewer, please.
>>> I also please need a sponsor.
>>>
>>> Best regards,
>>>   Goetz.
>>>
>>>> -----Original Message-----
>>>> From: Lindenmaier, Goetz
>>>> Sent: Mittwoch, 18. Mai 2016 12:02
>>>> To: hotspot-runtime-dev at openjdk.java.net
>>>> Subject: RFR(S): 8156992: [ppc] Implement template interpreter stack
>>>> overflow checks as on x86/sparc.
>>>>
>>>> Hi,
>>>>
>>>> When porting the template interpreter, we implemented a different
>>>> approach to
>>>> Stack overflow handling.  See also the detailed description in the Jira bug.
>>>>
>>>> This change implements the stack overflow check as on x86/sparc.
>>>> It requires simple shared changes, but only to code only used on ppc.
>>>> The changes should not affect the other platforms.
>>>>
>>>> Please review this change. I please need a sponsor.
>>>> http://cr.openjdk.java.net/~goetz/wr16/8156922-
>> ppcStackFix/webrev.01/
>>>>
>>>> Best regards,
>>>>   Goetz.
>>>