AOT code JEP text updated

[Vladimir Kozlov]

Thank you, John, for working on it.

 > This will greatly reduce the initial load on the JIT compiler, 
reducing its interference with the application, in configurations with 
fewer cores.

May be: "reducing its interference with the application during startup, 
particularly in configurations with fewer cores."

---

I agree that `(Delete this digression?)` should be removed. It describes 
how JIT compiler works. May be put it into wiki when you have time: 
https://wiki.openjdk.org/display/HotSpot/Compiler

----

Description

 > Even when peak performance requires additional JIT activity (to 
generate T4 code),

T4 is unknown. May be "new optimized code"?

 > (If you run a typical Java application with the option 
-XX:+PrintCompilation, and search for the string “made not entrant”, you 
will see many instances of the JIT replacing methods.)

It is too specific for this JEP. I don't think we need it.

May be also mention that we record execution environment during training 
run (CPU's features, VM's flags) and compare them with environment 
during production run and completely discard AOT code if they don't match.

---

AOT code implementation details

I think it should be moved to Implementation RFE. It is too technical 
for JEP.

 > The AOT code tier A3 works the same as the JIT tier T3: It runs at a 
low optimization level, but collects the same kind of profile 
information that the VM interpreter gathers.

We don't cache T3.

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Alternatives

 > Since AOT code can be loaded immediately on startup, it might seem 
that profiles in the AOT cache (added by JEP 515) are now useless. But 
they still have their role, when AOT code is replaced by the JIT.

As you mention in previous text, profiles trigger AOT code (A4) loading 
when all referenced in code classes are initialized. So you can't say 
that AOT profiles are useless for AOT code.


Thanks,
Vladimir K


On 9/29/25 7:18 PM, John Rose wrote:
> I have updated the text for the AOT code JEP:
> 
> https://openjdk.org/jeps/8335368
> 
> I would appreciate any editorial comments.
> 
> My present goal is to come closer to the style of our previous JEPs,
> and also to reflect recent conversations about AOT code.
> 
> (That style is relatively non-technical and light on details, FTR.
> This is just the way things are with JEPs.)
> 
> The recent conversations involve discussions about different AOT
> code shapes (AP4 vs. A4) and concerns about ISA compatibility.
> Please remind me of other recent conversations that may also be
> applicable to this JEP.
> 
> Thanks!
> 
> — John
> 
> P.S. This is not urgent.  I don’t think this JEP will be in the
> current release.  But it is important!