RFR: 8170455: C2: Access to [].clone from interfaces fails

[Jamsheed C m]

Thank you, Vladimir!

Best Regards,

Jamsheed

On 2/6/2017 7:22 PM, Vladimir Ivanov wrote:
>> revised webrev: http://cr.openjdk.java.net/~jcm/8170455/webrev.01/
>
> Looks good.
>
> Best regards,
> Vladimir Ivanov
>
>> On 1/31/2017 3:55 PM, Jamsheed C m wrote:
>>> Hi,
>>>
>>> Array type are treated as Object type in Compiler  (see [1]) and
>>> lookup happens in Object Class in compiler interface. This used to
>>> work before default method got introduced. with default methods
>>> protected Object methods are inaccessible from interface , so lookup
>>> fails,   caller method always deopt as unloaded and decompile in C2.
>>> This causes considerable degradation in performance.
>>>
>>> Fix: array types are directly passed to lookup code(fix), all other
>>> code is kept as it is.
>>>
>>> bug id: https://bugs.openjdk.java.net/browse/JDK-8170455
>>>
>>> webrev:  http://cr.openjdk.java.net/~jcm/8170455/webrev.00/
>>>
>>> Best Regards,
>>>
>>> Jamsheed
>>>
>>> [1]
>>>
>>> ciInstanceKlass*
>>> ciEnv::get_instance_klass_for_declared_method_holder(ciKlass*
>>> method_holder) {
>>>   // For the case of <array>.clone(), the method holder can be a
>>> ciArrayKlass
>>>   // instead of a ciInstanceKlass.  For that case simply pretend 
>>> that the
>>>   // declared holder is Object.clone since that's where the call will
>>> bottom out.
>>>   // A more correct fix would trickle out through many interfaces in 
>>> CI,
>>>   // requiring ciInstanceKlass* to become ciKlass* and many more
>>> places would
>>>   // require checks to make sure the expected type was found. Given
>>> that this
>>>   // only occurs for clone() the more extensive fix seems like
>>> overkill so
>>>   // instead we simply smear the array type into Object.
>>>
>>>
>>>
>>>
>>>
>>