RFR 8129547 (S): Excess entries in BootstrapMethods with the same (bsm, bsmKind, bsmStaticArgs), but different dynamicArgs

[Maurizio Cimadamore]

Cool - many thanks!

I'd say we can go ahead with this.

Maurizio

On 21/08/15 16:10, Aleksey Shipilev wrote:
> Hey Maurizio,
>
> I have tried to slim down TestInvokeDynamic to make a regression test.
> It fails on current javac, and passes on a patched one:
>    http://cr.openjdk.java.net/~shade/8129547/webrev.02/
>
> Thanks,
> -Aleksey
>
> On 08/18/2015 12:23 AM, Maurizio Cimadamore wrote:
>> Whoops - that's what I meant to write, sorry; I'm glad you like the
>> overall scheme. I will cook up a test tomorrow - we do have one test
>> which attaches fake dynamic symbols to AST nodes, (using an annotation
>> processor) then invokes code generation and checks the resulting
>> bytecode [1]. I think one such test might be useful here.
>>
>> [1] -
>> http://hg.openjdk.java.net/jdk9/jdk9/langtools/file/tip/test/tools/javac/lambda/TestInvokeDynamic.java
>>
>>
>> Maurizio
>>
>> On 17/08/15 20:24, Aleksey Shipilev wrote:
>>> Hi Maurizio,
>>>
>>> Thanks for an idea! It almost works, but not quite: super.equals() from
>>> Method checks the type, so we need to guard super.*, as you did in
>>> hashCode(). We also need a proper subclass check for the keys alone,
>>> which means we might move equals() there, and make key a proper subclass
>>> to gain access to "other".
>>>
>>> In short, this version works:
>>>    http://cr.openjdk.java.net/~shade/8129547/webrev.01/
>>>
>>> Thanks,
>>> -Aleksey
>>>
>>> On 17.08.2015 17:15, Maurizio Cimadamore wrote:
>>>> Ok, I think I know what you meant now; DynamicMethod is used for two
>>>> different purposes:
>>>>
>>>> * for the NameAndType CP entry associated with an invokedynamic
>>>> instruction (pointed by the CONSTANT_InvokeDynamic entry); this bit
>>>> _requires_ dynamic info to be taken into account - as different invoked
>>>> types need to map to different entries - even if their underlying BSM
>>>> entry is the same.
>>>>
>>>> * as keys in the BootstrapMethod attribute; in this case you want the
>>>> dynamic info to be gone, as all it's going to be stored in the table is
>>>> a bsmKind + static args list.
>>>>
>>>> How about something like this:
>>>>
>>>> http://cr.openjdk.java.net/~mcimadamore/8129547/
>>>>
>>>> Maurizio
>>>>
>>>>
>>>>
>>>> On 17/08/15 14:48, Maurizio Cimadamore wrote:
>>>>> Hi Alex,
>>>>> the only dfference I see between your patch and the current code is
>>>>> that the current code is comparing the invokedType, while yours is not
>>>>> - am I reading your patch correctly?
>>>>>
>>>>> If that's the case, wouldn't dropping the call to super.equals from
>>>>> Pool.DynamicMethod also resolve the issue?
>>>>>
>>>>> I'm, saying this because, from a design perspective, javac symbols
>>>>> usually don't care about uniqueness etc. - that's an extra value added
>>>>> when storing them into a constant pool.
>>>>>
>>>>> Maurizio
>>>>>
>>>>> On 17/08/15 13:33, Aleksey Shipilev wrote:
>>>>>> Hi,
>>>>>>
>>>>>> This issue gets into way with my current work:
>>>>>>      https://bugs.openjdk.java.net/browse/JDK-8129547
>>>>>>
>>>>>> There is a proof-of-concept patch:
>>>>>>      http://cr.openjdk.java.net/~shade/8129547/webrev.00/
>>>>>>
>>>>>> The crux of an issue seems to be the Method.equals() call in
>>>>>> DynamicMethod.equals(), that compares the type. The type of
>>>>>> DynamicMethod includes the DynamicMethodSymbol.type, that includes
>>>>>> dynamic args. It seems DynamicMethodSymbol is a better fit for
>>>>>> BootstrapMethod table key, since it includes BSM symbol and static
>>>>>> arguments only.
>>>>>>
>>>>>> I would be grateful if somebody from compiler team can help me out
>>>>>> with
>>>>>> this. Is this the fix above valid? Can you do it better?
>>>>>>
>>>>>> How would one write a regression test for it? My cursory grep through
>>>>>> langtools tests does not yield a clear way to emit a special-shaped
>>>>>> indy
>>>>>> for such a test.
>>>>>>
>>>>>> Thanks,
>>>>>> -Aleksey
>>>>>>
>