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<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">Hey Lang,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">> </span>
Thanks for your patience.<span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">I'm happy you consider me patient x3<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">> </span>
<span lang="EN-GB">Out of interest -- Is it necessary for your JIT itself to be split across two or more processes?</span><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">In general I agree with your approach, but sadly - the current software design does not allow this yet. So I try understanding how to tackle both solutions - one process managing all
the modules vs multiple processes manging just there modules. I would prefer just having one process doing it, because it makes way more sense.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">However... About your solution. This looks really promising – Thank you! - but sadly, I'm not experienced enough with ORC yet to understand how to use it.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">I create a llvm::orc::LLJIT and then add my llvm::Module to it.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">Can I use the getExecutionSession function of LLJIT to get access to this special lookup function after I added the module?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">Also I have some difficulties with providing the parameters .w. For example... I don't have a "JITDylibSearchList" nor "SymbolNameSet" (I probably have it hidden somewhere). I do know
those from when I do the symbol resolving. I didn't created a JITDylib for it, instead I attached a generator function to the MainJITDylib – because I have to lookup symbols from the shared memory and that list changes.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">So I'm not sure how to use it yet - sorry for the noobie question >o<<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">Kind greetings<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">Björn<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Lang Hames <lhames@gmail.com>
<br>
<b>Sent:</b> 18 March 2020 17:26<br>
<b>To:</b> Gaier, Bjoern <Bjoern.Gaier@horiba.com><br>
<b>Cc:</b> LLVM Developers Mailing List <llvm-dev@lists.llvm.org><br>
<b>Subject:</b> Re: [llvm-dev] [ORC JIT] -Resolving cross references in a multi-process scenario<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi Bjoern,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thanks for your patience. The good news is that there is a neater way to do this: ExecutionSession's lookup methods take a orc::SymbolState parameter which describes the state that symbols must reach before a query can return (See
<a href="https://github.com/llvm/llvm-project/blob/d1a7bfca74365c6523e647fcedd84f8fa1972dd3/llvm/include/llvm/ExecutionEngine/Orc/Core.h#L1273).In">
https://github.com/llvm/llvm-project/blob/d1a7bfca74365c6523e647fcedd84f8fa1972dd3/llvm/include/llvm/ExecutionEngine/Orc/Core.h#L1273).In</a> your case you want to use orc::SymbolState::Resolved, which will cause the query to return as soon as the searched-for
symbols have been assigned an address.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">So if your process is generating a set of symbols that may need to be transmitted to other sessions then you would write something like:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">auto Syms = ES.lookup(SearchOrder, SymbolsToTransmit, LookupKind::Static, SymbolState::Resolved);</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">if (!Syms)</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New""> reportError(Syms.takeError());</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">sendSymbolsToRemote(*Syms);</span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Out of interest -- Is it necessary for your JIT itself to be split across two or more processes? I had always anticipated having a single ExecutionSession attached to the target process and then running just the compilers on other processes.
That gives you a star-like IPC network with N + 1 connections: One between the execution session and each of the N compilers, and one between the execution session and the target processs. In your model it sounds like the risk is that you may end up with N(N
+ 1) IPC links with every execution session having to communicate with every other and also with the target process.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-- Lang.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Tue, Mar 17, 2020 at 12:34 AM Gaier, Bjoern <<a href="mailto:Bjoern.Gaier@horiba.com" target="_blank">Bjoern.Gaier@horiba.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">Hello LLVM-Mailing-List and Lang,</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">I played around with this problem a bit and found a way of doing this – however I’m not sure about the consequences and if this is really a good idea.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">I went trough all of the global symbols and functions being defined in the llvm::Module and set for each of them a new section name (based on there name). With
this approach the memorymanager could tell me already the addresses of my symbols, which I could then share with the other process. However, this approach needed to load the module two times, first to get the future address and in a second run to use the addresses
to resolve the symbols.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">The only disadvantage I noticed so far was that the overall size of the emitted code was bigger then having the regular sections. Are there any other risks I
might have overseen? </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">Kind greetings</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">Björn</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB"> </span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> llvm-dev <<a href="mailto:llvm-dev-bounces@lists.llvm.org" target="_blank">llvm-dev-bounces@lists.llvm.org</a>>
<b>On Behalf Of </b>Gaier, Bjoern via llvm-dev<br>
<b>Sent:</b> 06 March 2020 14:24<br>
<b>To:</b> LLVM Developers Mailing List <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>>; Lang Hames <<a href="mailto:lhames@gmail.com" target="_blank">lhames@gmail.com</a>><br>
<b>Subject:</b> [llvm-dev] [ORC JIT] -Resolving cross references in a multi-process scenario</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">Hello LLVM-Mailing-List and Lang,</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">I have a very weird (or strict?) scenario and was curious if the ORC JIT can help me with it. Soo here it comes:</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">I have currently a windows process ("Runtime") which does nothing but creating a shared memory with read, write and execute rights - and also writing some function
addresses like from printf to it. </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">Then I have two or more processes which are using the ORC JIT to load modules to this shared memory, in "perspective" of the process I mentioned above ("Runtime").
The sections are remapped from the other processes to be correct for "Runtime", also they resolve the undefined references for "Runtime" - like for printf and so on.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">This works quite well so far! Wuhuhu x3</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">However, there is one issue about it. Given that those two (or more processes) are now loading modules that reference each other. Like Module A is using a function
of Module B - but Module B also uses a function of Module A. How could I resolve those modules when they are loaded from different processes? Normally I would use llvm-link to link those modules but in my current scenario this is sadly not possible.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">Can the ORC JIT help me with that? Can I solve this problem differently? Like replacing all the functions of Module A that rely on Module B with function pointers?
Is something like that possible?</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">I know this situation is pretty uncommon but sadly I ran into that issue.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">Kind greetings</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB">Björn</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-GB"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">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 <o:p></o:p></p>
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<p class="MsoNormal">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
<o:p></o:p></p>
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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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