[8] RFR (XS): 8031695: CHA ignores default methods during analysis leading to incorrect code generation

[Vladimir Ivanov]

John, Karen, thanks for review!

Special thanks goes to Lois for initial analysis and instructions how to 
reproduce the issue. It saved me lots of time.

Best regards,
Vladimir Ivanov

On 1/22/14 11:16 PM, Karen Kinnear wrote:
> Looks good.
>
> many thanks,
> Karen
>
> On Jan 22, 2014, at 12:29 PM, Vladimir Ivanov wrote:
>
>> http://cr.openjdk.java.net/~vlivanov/8031695/webrev.00/
>> https://bugs.openjdk.java.net/browse/JDK-8031695
>>
>> CHA erroneously ignores default methods when looking for different versions of a method in a class hierarchy.
>>
>> Consider the following hierarchy:
>>   interface I { default void m() { ... }}
>>   class A implements I {}
>>
>>   class C extends A { }
>>   class D extends A { public void m() { ... } }
>>
>> Call site: invokevirtual A.m()
>>
>> A.m resolves to I.m. Searching from A, CHA finds only D.m and concludes that D.m is the only implementation of I.m, since Dependencies::is_concrete_method returns false for I.m.
>>
>> But there is C with default implementation from I. So, if VM inlines D.m and then C's instance is passed as objectref, the wrong method is invoked (D.m instead of I.m).
>>
>> The fix is to take default methods into account doing CHA analysis and treat the call site as non-monomorphic when a concrete method is found for a default method.
>>
>> Conservative approach is chosen, since the fix is targeted for 8.
>>
>> Testing: failing application, regression test, vm.defmeth.testlist, JDK regression tests (java/util/, java/lang)
>>
>> Thanks!
>>
>> Best regards,
>> Vladimir Ivanov
>