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

[Christian Thalinger]

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