[8u-dev] Request for approval: Backport of 8011858

[Zoltán Majó]

Hi Vladimir,


On 09/15/2015 05:10 PM, Vladimir Kozlov wrote:
> On 9/15/15 6:54 AM, Zoltán Majó wrote:
>> Hi Vladimir,
>>
>>
>> thank you for the feedback!
>>
>> On 09/14/2015 06:00 PM, Vladimir Kozlov wrote:
>>> On 9/14/15 7:31 AM, Zoltán Majó wrote:
>>>> Hi,
>>>>
>>>>
>>>> I would like to request the backport of the fix for JDK-8011858 to 
>>>> 8u-dev. The fix can help reducing the memory usage of
>>>> the C2 compiler and is therefore needed to fix JDK-8129847.
>>>>
>>>> Original (9) bug: https://bugs.openjdk.java.net/browse/JDK-8011858
>>>> Original changeset: 
>>>> http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/af60f1cb36f2
>>>>
>>>> Unfortunately, the fix does not apply cleanly, as two affected 
>>>> files are different in 9 and in 8u-dev. Here are the
>>>> changes that I did not (could not) apply to the 8u-dev tree:
>>>
>>> Can you scan jdk8u C2 code for other cases where C->unique() is used 
>>> for stack. May be some were removed in jdk9. But
>>> we still need to fix them.
>>
>> I found two places where we can use live_nodes() instead of unique():
>> 1) in matcher.cpp on line 345 for determining the stack size used in 
>> xform();
>> 2) in compile.cpp on line 330 for the estimated worklist size.
>>
>> I updated these source code locations accordingly.
>
> Nice!

thank you for the feedback!

>
>
>>
>> These changes could be applied to 9 as well. Do we want to do that? 
>> If yes, I guess a good way to do it would be to file
>> a separate bug/enhancment for 9. Or do you see some other way?
>
> Yes, file separate rfe. No other way. And check again - may be we 
> missed more in jdk9.

I will do so.

Thank you and best regards,


Zoltan

>
>>>
>>>> - 
>>>> http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/af60f1cb36f2#l6.8
>>>> - 
>>>> http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/af60f1cb36f2#l9.8
>>>
>>> node.cpp has next code in dump_nodes() which you should fix (I look 
>>> on jdk8u/jdk8u/hotspot code):
>>
>> Thanks for catching that. I changed that code as well.
>>
>> Here is the newest webrev:
>> http://cr.openjdk.java.net/~zmajo/8011858_8u/webrev.01/
>
> Looks good.
>
> Thanks,
> Vladimir
>
>>
>> All JPRT tests and all JTREG compiler tests (that pass with an 
>> unmodified VM) pass.
>>
>> Thank you and best regards,
>>
>>
>> Zoltan
>>
>>>
>>> GrowableArray <Node *> nstack(C->unique());
>>>
>>> Thanks,
>>> Vladimir
>>>
>>>>
>>>> Webrev: http://cr.openjdk.java.net/~zmajo/8011858_8u/webrev.00/
>>>>
>>>> Testing:
>>>> - the fix was pushed into 9 on Aug 11 and did not cause any nightly 
>>>> failures;
>>>> - all JPRT tests pass;
>>>> - all JTREG tests pass that pass with the unmodified VM.
>>>>
>>>> Thank you and best regards,
>>>>
>>>>
>>>> Zoltan
>>>>
>>