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<p class="MsoNormal"><span style="font-size:14.0pt">I am trying to convert some very old code based on LLVM 3.4.2 to LLVM 7. So I want to replace some old LLVM JIT code with OrcJIT. I am new to this stuff and when I study the Kaleidoscope example, I started
wondering about this.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">LLVMContext stores raw pointers to Module and will destroy the Module when the context is destroyed. But in the example, the module’s ownership is transferred to IRCompileLayer (which in trunk seems to be
now LegacyIRCompileLayer) which will destroy the module after eagerly compiling it using SimpleCompiler. Wouldn’t that leave the pointer to the same Module held in LLVMContext’s OwnedModules dangling?
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">AFAIK, LLVMContext always owns the modules with which it is constructed (it holds them as Module*) unless it is explicitly removed from the Context. So it is not clear how std::unique_ptr can be used on the
same pointer.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">Specifically, the problem is in this line:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"> </span><span style="font-size:14.0pt;font-family:"Courier New"">TheModule = llvm::make_unique<Module>("my cool jit", TheContext);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">TheModule owns the new module but so does TheContext (though not explicitly via unique_ptr).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">And then later we have:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Courier New"">TheJIT->addModule(std::move(TheModule));<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">The ownership is transferred but TheContext is still pointing to Module.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">Note my question is not specifically about Kaleidoscope example but more about orc::LegacyIRCompileLayer::addModule expecting the caller to transfer ownership of a module.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">Am I missing something here? TIA.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt">/Riyaz<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt"><o:p> </o:p></span></p>
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