Request for reviews (S): 6916062: assert(_inserts <= _insert_limit, "hash table overflow") in NodeHash::hash_insert

[Vladimir Kozlov]

I ran full CTW with 10*unique and did not get bailouts.
Only when I used 2*unique I got 6 cases. I rerun them with product VM
and they exited gracefully:

2234   COMPILE SKIPPED: infinite loop in PhaseIterGVN::optimize (not retryable)

Vladimir

On 9/30/10 12:54 PM, Vladimir Kozlov wrote:
> I ran throw CTW previous code webrev.02 (only with assert fastdebug VM) and it is never triggered. It also passed
> nsk.stress testing. All exits from igvn.optimize() are checked with C->failing(). But I will check if it exit
> correctly with lower limit.
>
> Thanks,
> Vladimir
>
> On 9/30/10 12:19 PM, Tom Rodriguez wrote:
>> 1024 * unique seems like a high enough limit but did you check ctw to see if it ever triggers? Also would we handle a
>> bailout here gracefully? It would be good to set the limit lower and make sure we handle it properly. I'd be curious
>> to see some statistics on how many iterations we normally perform in that loop but maybe that's a question for another
>> day.
>>
>> tom
>>
>> On Sep 30, 2010, at 12:00 PM, Vladimir Kozlov wrote:
>>
>>> I updated changes with bailout from IGVM optimization loop:
>>>
>>> http://cr.openjdk.java.net/~kvn/6916062/webrev.03
>>>
>>> Thanks,
>>> Vladimir
>>>
>>> On 9/29/10 12:14 PM, Vladimir Kozlov wrote:
>>>> Thank you, Tom
>>>>
>>>> On 9/29/10 12:00 PM, Tom Rodriguez wrote:
>>>>> That seems fine for a backport. Maybe we should consider some product level code to bailout if we do too many rounds
>>>>> of IGVN?
>>>>
>>>> Yes, it is good idea to bailout. I will add it.
>>>>
>>>> Thanks,
>>>> Vladimir
>>>>
>>>>>
>>>>> tom
>>>>>
>>>>> On Sep 28, 2010, at 7:08 PM, Vladimir Kozlov wrote:
>>>>>
>>>>>> http://cr.openjdk.java.net/~kvn/6916062/webrev.02
>>>>>>
>>>>>> Fixed 6916062: assert(_inserts<= _insert_limit,"hash table overflow") in NodeHash::hash_insert
>>>>>>
>>>>>> Changes for 6711117 put a memory node back on IGVN
>>>>>> worklist if address type does not match cached type
>>>>>> in a hope that address nodes will be processed and
>>>>>> the type will be updated. But it does not check that
>>>>>> there are nodes on worklist which will trigger address
>>>>>> processing. As result the memory node is pulled from
>>>>>> and pushed on IGVN worklist infinitely.
>>>>>> On each iteration NodeHash::_inserts value is incremented
>>>>>> forcing hash table grow until integer value NodeHash::_max
>>>>>> is overflow (became 0) which triggers bug's assert.
>>>>>>
>>>>>> I decided to go with simplest fix which is easy to backport
>>>>>> and leave fixing address type inconsistency for later
>>>>>> (I have bug 6715629).
>>>>>> I also added asserts to catch such situations.
>>>>>>
>>>>>> Tested with failing case, CTW, JPRT.
>>>>>
>>