RFR: 8166840: Synthetic bridge constructor in ArrayList$Itr blocks inlining

[Claes Redestad]

Thanks for the quick reviews!

/Claes

On 2016-09-28 14:14, Remi Forax wrote:
> yes,
> thumb up.
>
> Rémi
>
>
> On September 28, 2016 1:51:18 PM GMT+02:00, Michael Haupt <michael.haupt at oracle.com> wrote:
>> Hi Claes,
>>
>> yes please. Thumbs up. :-)
>>
>> Best,
>>
>> Michael
>>
>>> Am 28.09.2016 um 13:48 schrieb Claes Redestad
>> <claes.redestad at oracle.com>:
>>> Hi,
>>>
>>> as discussed recently on hotspot-compiler-dev[1], having a private
>> class with no default constructor can lead to C2 failing to inline, due
>> to the synthetic bridge constructor using a dummy argument of an
>> uninitialized class. This is really a problem in C2, as well as
>> something which could ultimately be resolved by nestmates...
>>> However, there is an easy workaround in adding an empty
>> package-private constructor. In the most recently found case - a
>> microbenchmark stressing MethodHandles.iteratedLoop - adding this to
>> ArrayList$Itr lead to a 2.5-3x speedup.
>>> This is me asking nicely to do a quick-fix for this in
>> java.util.ArrayList$Itr now:
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8166840
>>> Webrev: http://cr.openjdk.java.net/~redestad/8166840/webrev.01/
>>>
>>> Thanks!
>>>
>>> /Claes
>>>
>>> [1]
>> http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2016-September/024407.html
>>
>> -- 
>>
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