[llvm-dev] Questions about moving from MCJIT to Orc JIT

Thu Jun 27 10:46:05 PDT 2019

Awesome!

On Thu, 27 Jun 2019 at 15:17, Gaier, Bjoern <Bjoern.Gaier at horiba.com> wrote:

> Thanks for the input! I was able to write my own Generator function for
> the JITDylib!
> Thank you a lot x3
>
>
>
> *From:* Praveen Velliengiri <praveenvelliengiri at gmail.com>
> *Sent:* Donnerstag, 27. Juni 2019 10:55
> *To:* Gaier, Bjoern <Bjoern.Gaier at horiba.com>
> *Cc:* Lang Hames <lhames at gmail.com>; llvm-dev <llvm-dev at lists.llvm.org>
> *Subject:* Re: [llvm-dev] Questions about moving from MCJIT to Orc JIT
>
>
>
> Nice!
>
> Let me try to answer some questions,
>
> Before that I have to mention this is ORC version 2 APIs and this is where
> the project is moving forward.
>
> JITDylib is the symbol table, basically for a JIT Symbol it have an
> associated materializers, (you can think of it like an entity that generate
> the address for that symbol),
>
> Example: compiler are materializers.
>
> So to add symbols to your own JIT you can define them in JITDylib.
>
>
>
> For example, Suppose you want to add "your host process (on which JIT
> runs) symbols to the JIT".
>
> You can do
>
> JD.setGenerator(DynamicLibrarySearchGenerator::GetForCurrentProcess(DL.getGlobalPrefix()))
>
>
>
>
> Under hood, ORC normally search for your host symbols in the defGenerator
> if it can't find symbols anywhere else.
>
> You can look at core.cpp at line 1163 to see how it works!
>
>
>
> I highly recommended you to watch "Updating ORC for Concurrency" dev
> meeting talks, it is explained in detail,,
>
> For question 4, I don't know maybe If I know after sometime I will write
> here :)
>
>
>
> Thanks
>
>
>
> On Thu, 27 Jun 2019 at 14:00, Gaier, Bjoern <Bjoern.Gaier at horiba.com>
> wrote:
>
> Hey Praveen,
>
>
>
> Thanks for your help! I still have questions and try providing some
> context.
>
>
>
> For questions:
>
> 2.) I exactly mean that! Sadly I was not able to understand how to use the
> ‘define’ function, I tried that:
>
> I had no idea how to deal with that >o<
>
>
>
> 2.1.) With MCJIT I was actually used to getting the name of a function and
> then ‘answering’ with an address. Is that behavior not possible with OrcJIT
> anymore? I actually tried looking into the ‘setGenerator’ function of the
> JITDylib. As a test I came up with this:
>
> This was pretty cool, because I actually saw the missing function ‘puts’
> but I have no idea how to reply with an  address for ‘puts’. Returning
> ‘Names’ actually makes the application pause and not go on.
>
>
>
> 4.) I used the code of Kaleidoscope JIT for my little experiments. If I
> understood it correctly, the JIT process is completed after I used the
> lookup function to find a symbol in the code. Now I would like to reset the
> instance of the Kaleidoscope JIT I had, to jit new modules, which are not
> related to the previous modules I jitted.
>
> Kind greetings
>
> Björn
>
>
>
> *From:* Praveen Velliengiri <praveenvelliengiri at gmail.com>
> *Sent:* Donnerstag, 27. Juni 2019 08:21
> *To:* Gaier, Bjoern <Bjoern.Gaier at horiba.com>; Lang Hames <
> lhames at gmail.com>
> *Cc:* llvm-dev <llvm-dev at lists.llvm.org>
> *Subject:* Re: [llvm-dev] Questions about moving from MCJIT to Orc JIT
>
>
>
> Hi Bjoern,
>
> CC'ing Lang hames
>
>
>
> For questions,
>
> 1. In short yes, you can replace the memory manager, default one provided
> is section memory manager.
>
>
>
> 2. If you mean by " address of already compiled code", yes you can do
> that.
>
>  Like this
>
>  JITDylib.define(absoluteSymbols, ( Your_own_symbol ,
> JITTargetAddress(Address of function))), now ORC can resolve all the
> references to Your_own_symbol to the provided the Address.
>
>
>
> 3. Yes, all the class/function with legacy prefix will be removed in
> subsequent releases.
>
>
>
> 4. Could please provide some more context on this? Like it's usage model,
> what goal you are aiming for?
>
>
>
> Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816,
> USt.ID-Nr. DE 114 165 789 Geschäftsführer: Dr. Hiroshi Nakamura, Dr. Robert
> Plank, Markus Bode, Heiko Lampert, Takashi Nagano, Takeshi Fukushima.
> Junichi Tajika
>
> Als GmbH eingetragen im Handelsregister Bad Homburg v.d.H. HRB 9816,
> USt.ID-Nr. DE 114 165 789 Geschäftsführer: Dr. Hiroshi Nakamura, Dr. Robert
> Plank, Markus Bode, Heiko Lampert, Takashi Nagano, Takeshi Fukushima.
> Junichi Tajika
>
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