Request for reviews (M): 7105605: Use EA info to optimize pointers compare

[Vladimir Kozlov]

 >> In general sense they don't need to be created before ConnectionGraph 
construction since they are not oops and not part of constructed graph. But EA 
have several checks that C->_unique stays the same during graph construction and 
they will fail if pcmp_* nodes are added lazily.
 >
 > I see.  Thanks for the explanation.

I am taking this back. They are used only after Connection Graph construction so 
they don't need to be pregenerated. I will change this code and run tests to verify.

Thanks again.

Vladimir

Christian Thalinger wrote:
> On Nov 9, 2011, at 4:58 PM, Vladimir Kozlov wrote:
> 
>> Thank you, Christian
>>
>> Christian Thalinger wrote:
>>> On Nov 9, 2011, at 5:27 AM, Vladimir Kozlov wrote:
>>>> http://cr.openjdk.java.net/~kvn/7105605/webrev
>>> src/share/vm/opto/escape.cpp:
>>> You should set _pcmp_neq and _pcmp_eq to NULL in the ConnectionGraph constructor.
>> Done. I also added assert in optimize_ptr_compare() to check that OptimizePtrCompare is set.
>>
>>> ConnectionGraph::do_analysis:
>>> +   Node* pcmp_neq = OptimizePtrCompare ? igvn->makecon(TypeInt::CC_GT) : NULL;
>>> +   Node* pcmp_eq  = OptimizePtrCompare ? igvn->makecon(TypeInt::CC_EQ) : NULL;
>>> Are these two also added for the same reason as the comment says?
>>>    // Add ConP#NULL and ConN#NULL nodes before ConnectionGraph construction
>>>    // to create space for them in ConnectionGraph::_nodes[].
>>> Weird.
>> In general sense they don't need to be created before ConnectionGraph construction since they are not oops and not part of constructed graph. But EA have several checks that C->_unique stays the same during graph construction and they will fail if pcmp_* nodes are added lazily.
> 
> I see.  Thanks for the explanation.
> 
>>> ConnectionGraph::optimize_ptr_compare:
>>> Is it intentional that the variables are called "has_unknow_obj1" instead of "unknown"?
>> Typo and terrible name. I renamed it to set1_has_unknown_ptr. And renamed has_null_ptr1 to set1_has_null_ptr.
> 
> Better :-)
> 
> -- Chris
> 
>>> Otherwise this looks good, as far as I can tell.
>> Thanks,
>> Vladimir
>>
>>> -- Chris
>>>> 7105605: Use EA info to optimize pointers compare
>>>>
>>>> EA Connection Graph can help to optimize pointers compare for non escaping allocations.
>>>>
>>>> Tested with CTW, jtreg, NSK, refworkload.
>>>>
>>>> Thanks,
>>>> Vladimir
>