Where does the openjdk JVM interpreter execute the bytecode instanceof operation

[Julian Waters]

By the way, when you reply to someone, you should also cc to
hotspot-dev at openjdk.org, for your message to show up on the mailing lists.
That way, more people will see it and your chances of them helping you
increase

best regards,
Julian

On Fri, May 3, 2024 at 3:54 PM zhengxianwei <baikaishiuc at gmail.com> wrote:

> I carefully analyzed it and found that what you said is actually correct.
>
> I didn't understand it correctly initially.
>
> Thanks again for your explanation
>
> On Fri, May 3, 2024 at 11:03 AM Julian Waters <tanksherman27 at gmail.com>
> wrote:
>
>> Hi Xian Wei,
>>
>> No, you are right! The code in templateTable_x86.cpp that you linked to
>> in your post is not part of the Just in Time Compilers, it is part of the
>> x86 Interpreter! The Java HotSpot VM actually has 2 different Interpreters,
>> the primary Interpreter is written in large chunks of assembly specific to
>> each platform, which is then processed by the HotSpot macro assemblers. The
>> bytecodeInterpreter.cpp file you linked to is part of the second and less
>> often used Interpreter, which is why modifying the bytecodeInterpreter.cpp
>> instanceof implementation did nothing in your case (The Interpreter used
>> actually depends on the platform, and the secondary Interpreter is not used
>> on ARM or x86). The details on the macro assemblers unfortunately elude me
>> since I am not a HotSpot expert (Although I hope to be one day), but to
>> understand how instanceof works on x86 and ARM, you need to understand both
>> x86 and ARM assembly. The Interpreter's instanceof opcode is implemented on
>> x86 in
>> https://github.com/openjdk/jdk/blob/6bef0474c8b8773d0d20c0f25c36a2ce9cdbd7e8/src/hotspot/cpu/x86/templateTable_x86.cpp#L4243
>> and on ARM, it is implemented in
>> https://github.com/openjdk/jdk/blob/6bef0474c8b8773d0d20c0f25c36a2ce9cdbd7e8/src/hotspot/cpu/arm/templateTable_arm.cpp#L4182
>>
>> Happy to help!
>>
>> best regards,
>> Julian
>>
>
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