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

[Remi Forax]

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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