Where does the openjdk JVM interpreter execute the bytecode instanceof operation

[David Holmes]

I think the only open question remaining was about logging in the 
interpreter, in which case AFAIK the only way to log would be to define 
an InterpreterRuntime function to do it and call that from the assembly 
code - passing and preserving whatever args/regs are needed. I am not an 
expert on the details.

David

On 5/05/2024 6:13 pm, zhengxianwei wrote:
> 
> Thank you. This is my first time using the mailing list, and I wasn't 
> aware of this issue.
> 
> 
> I'll make sure to cc o hotspot-dev at openjdk.org 
> <mailto:hotspot-dev at openjdk.org> now. :-)
> 
> On Sun, May 5, 2024 at 3:47 PM Julian Waters <tanksherman27 at gmail.com 
> <mailto:tanksherman27 at gmail.com>> wrote:
> 
>     By the way, when you reply to someone, you should also cc to
>     hotspot-dev at openjdk.org <mailto: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
>     <mailto: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 <mailto: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 <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 <https://github.com/openjdk/jdk/blob/6bef0474c8b8773d0d20c0f25c36a2ce9cdbd7e8/src/hotspot/cpu/arm/templateTable_arm.cpp#L4182>
> 
>             Happy to help!
> 
>             best regards,
>             Julian
>