Making PrintEscapeAnalysis a diagnostic option on product VM?

[Vladimir Kozlov]

Thank you for doing this, Chris

Each call node (and allocation is call node) has associated jvm state (the information needed to deoptimize compiled 
code on the return from the call). Deoptimization info allow to restart execution in interpreter so it has all bci and 
inlined methods information.

Regards,
Vladimir

On 7/9/15 1:49 PM, Chris Newland wrote:
> Please ignore previous message.
>
> All this time I've been digging around the connection graph logging in
> escape.cpp when I should have been looking in macro.cpp.
>
> I believe the BCI information I need is actually already output by
> PhaseMacroExpand::eliminate_allocate_node() so I'll attempt to visualise
> this in JITWatch and submit a patch if I need anything further.
>
> Thanks,
>
> Chris
>
> On Thu, July 9, 2015 21:10, Chris Newland wrote:
>> Hi,
>>
>>
>> I've found a way to output EA information via LogCompilation from the
>> product VM including BCIs so that I can annotate bytecode but it relies on
>>   the following block from opto/compile.cpp being entered:
>>
>> void Compile::Init(int aliaslevel) { ...
>>
>>
>> if (debug_info()->recording_non_safepoints()) {
>> set_node_note_array(new(comp_arena()) GrowableArray<Node_Notes*>
>> (comp_arena(), 8, 0, NULL));
>> set_default_node_notes(Node_Notes::make(this));
>> }
>>
>>
>> Without this, the Note_Notes are not present in the ideal nodes and I
>> can't fully identify what was eliminated.
>>
>> It looks like this will only execute when DebugNonSafepoints is true and
>> this is a diagnostic VM option.
>>
>> Does anyone have an alternative method for getting BCIs for eliminated
>> allocs without using Note_Notes?
>>
>> Thanks,
>>
>>
>> Chris
>>
>>
>>
>>
>>
>> On Fri, June 19, 2015 16:09, Vladimir Kozlov wrote:
>>
>>> Agree.
>>>
>>>
>>>
>>> Vladimir K
>>>
>>>
>>>
>>> On 6/19/15 5:10 AM, Vladimir Ivanov wrote:
>>>
>>>
>>>>> What do you think the next step is?
>>>>>
>>>>>
>>>>>
>>>>> I'm not a committer but I'd be happy to submit a patch/webrev that
>>>>> outputs LogCompilation XML for the kind of EA info I think would be
>>>>> useful.
>>>> Go for it. If you are a Contributor (signed OCA), we'll review and
>>>> accept your patch with gratitude. Keep in mind, that when you touch
>>>> LogCompilation output format, you should update logc tool
>>>> (src/share/tools/LogCompilation/ [1]) as well.
>>>>
>>>>
>>>>
>>>>> I've just seen Vitaly's post and I agree a tty 1-liner for each
>>>>> elimination would also be nice.
>>>> Feel free to enhance -XX:+PrintEscapeAnalysis output as well, if you
>>>> find it useful.
>>>>
>>>> Best regards,
>>>> Vladimir Ivanov
>>>>
>>>>
>>>>
>>>> [1]
>>>> http://hg.openjdk.java.net/jdk9/jdk9/hotspot/file/tip/src/share/tools/
>>>> L
>>>> ogCompilation
>>>>>
>>>>> Thanks,
>>>>>
>>>>>
>>>>>
>>>>> Chris
>>>>>
>>>>>
>>>>>
>>>>> On Fri, June 19, 2015 12:03, Vladimir Ivanov wrote:
>>>>>
>>>>>
>>>>>> Chris,
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> I'd suggest to look into enhancing LogCompilation output instead
>>>>>> of parsing VM output. It doesn't require any flag changes and fits
>>>>>>   nicely into existing LogCompilation functionality, so we can
>>>>>> integrate it into the product, relieving you and JITWatch users
>>>>>> from building a companion VM.
>>>>>>
>>>>>> Best regards,
>>>>>> Vladimir Ivanov
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 6/19/15 1:16 PM, Chris Newland wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>> Hi, hope this is the correct list (perhaps serviceability?)
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> I'm experimenting with some HotSpot changes that log escape
>>>>>>> analysis decisions so that I can visualise eliminated
>>>>>>> allocations at the source and bytecode levels in JITWatch[1].
>>>>>>>
>>>>>>> My plan was to build a companion VM for JITWatch based on the
>>>>>>> product VM that would allow users to inspect some of the deeper
>>>>>>> workings such as EA and DCE that are not present in the
>>>>>>> LogCompilation output.
>>>>>>>
>>>>>>>
>>>>>>> I mentioned this to some performance guys at Devoxx and they
>>>>>>> didn't like the custom VM idea and suggested I put in a request
>>>>>>> to consider making -XX:+PrintEscapeAnalysis available under
>>>>>>> -XX:+UnlockDiagnosticVMOptions on
>>>>>>> the product VM (it's currently a notproduct option).
>>>>>>>
>>>>>>> If this is something you would consider than could I also
>>>>>>> request consideration of -XX:+PrintEliminateAllocations.
>>>>>>>
>>>>>>> All I would need is the class, method, and bci of each NoEscape
>>>>>>>   detected.
>>>>>>>
>>>>>>> Kind regards,
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Chris
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> [1] https://github.com/AdoptOpenJDK/jitwatch
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>>
>>>
>>
>>
>>
>
>