VarHandle instance methods performance

[Remi Forax]

Hi Frank,
a VarHandle is a glorified integer value that correspond to the number of bytes from a pointer to a field address,
so you give it a reference and you have access to the field at the address: reference + shift, given that the shift value is the same for all the instances of the same class,
it should be declared static (and final so it's a constant for the VM).

Rémi

----- Mail original -----
> De: "Frank Yuan" <frank.yuan at oracle.com>
> À: "Aleksey Shipilev" <shade at redhat.com>
> Cc: "core-libs-dev" <core-libs-dev at openjdk.java.net>
> Envoyé: Mercredi 24 Avril 2019 12:11:11
> Objet: RE: VarHandle instance methods performance

>> On 4/24/19 11:51 AM, Frank Yuan wrote:
>> > My test code is as below:
>> > ...
>> >     final VarHandle vhf;
>> >     final VarHandle vhvf;
>> > ...
>> 
>> Make these two "static final", initialize them in class initializer, then try
>> again.
>> 
>> VarHandle (like Atomic*FieldUpdaters, MethodHandle, etc), have internal checks
>> that can only be
>> folded away when the VH/MH/A*FU instance is constant.
>> 
> 
> Thank you, it works!
> 
> YC
> 
> > -Aleksey