<div dir="ltr">Thanks Aurthur. <div><br></div><div>That seems to have been the problem. I changed the code to use a new instances for all the pass and analysis managers for every new module added and that fixed the issue. Didn't try using the 'clear()' method since the code seems to be working for now and I can move on to solving some other problems.</div><div><br></div><div>Thanks a lot for your help.</div><div><br></div><div>Best,</div><div>Sanket</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Oct 18, 2021 at 12:21 PM Arthur Eubanks <<a href="mailto:aeubanks@google.com">aeubanks@google.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">The issue is probably that the analyses are not being cleared between runs and you end up using stale analyses. I'd recommend that you use a new instance of all the pass/analysis managers every time you perform codegen. (if you really want, you could call the `clear()` method on all the analysis managers, but that's a bit more sketchy)<br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Oct 16, 2021 at 5:37 PM Sanket Diwale via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><p style="margin-top:0px;margin-right:0px;margin-left:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:-apple-system,system-ui,"Segoe UI","Liberation Sans",sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(231,233,235);background-color:rgb(45,45,45)">I am currently writing a frontend language compiling to LLVM IR using the LLVM c++ API (LLVM version 13), however I see some erratic behavior with segmentation faults when running the new ModulePassManager. Specifically I see the debugger halts execution in the llvm::EarlyCSEPass::run function call when a segmentation fault occurs. Can't see where exactly the seg fault happens inside this function as I am not currently using a debug build for the LLVM source code itself.</p><p style="margin-top:0px;margin-right:0px;margin-left:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:-apple-system,system-ui,"Segoe UI","Liberation Sans",sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(231,233,235);background-color:rgb(45,45,45)">I think the seg fault might have something to do with the way I set up my pass manager and run the pass manger on new instances of llvm::Module without any kind of reset to the pass analysis manager (not sure if this guess is correct though). I have highlighted my current code that sets up and runs the pass manager below. I would be grateful if you could give any insights into what I might be doing wrong and how it should be done correctly.</p><p style="margin-top:0px;margin-right:0px;margin-left:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:-apple-system,system-ui,"Segoe UI","Liberation Sans",sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(231,233,235);background-color:rgb(45,45,45)">Best, Sanket</p><pre style="margin-top:0px;padding:12px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:1.30769;font-size:13px;vertical-align:baseline;box-sizing:inherit;width:auto;max-height:600px;overflow:auto;border-radius:5px"><code style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;background-color:transparent;white-space:inherit">
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">/*
I have a "CodeGenerator" class object that holds the pass manager and the other related objects as public members
*/</span>
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">class</span> <span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">CodeGenerator</span> {</code></pre><pre style="margin-top:0px;padding:12px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:1.30769;font-size:13px;vertical-align:baseline;box-sizing:inherit;width:auto;max-height:600px;overflow:auto;border-radius:5px"><code style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;background-color:transparent;white-space:inherit">public:
llvm::PassBuilder passBuilder;
llvm::LoopAnalysisManager loopAnalysisManager;
llvm::FunctionAnalysisManager functionAnalysisManager;
llvm::CGSCCAnalysisManager cGSCCAnalysisManager;
llvm::ModuleAnalysisManager moduleAnalysisManager;
llvm::ModulePassManager modulePassManager;
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">CodeGenerator</span>(); <span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// constructor for the class</span>
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// other code that handles emitting the LLVM IR from the parsed AST of the front-end code</span>
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// I keep the llvm::Module and llvm::Context instances to which the ir is emitted within this class as members</span>
llvm::orc::ThreadSafeContext Ctx;
std::unique_ptr<llvm::Module> TheModule;
}
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">/*
I initialize the ModulePassManager in the class constructor
*/</span>
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">CodeGenerator</span>(): <span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">Ctx</span>(std::<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">make_unique</span><llvm::LLVMContext>()) {
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">public</span>:
passBuilder.<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">registerModuleAnalyses</span>(moduleAnalysisManager);
passBuilder.<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">registerCGSCCAnalyses</span>(cGSCCAnalysisManager);
passBuilder.<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">registerFunctionAnalyses</span>(functionAnalysisManager);
passBuilder.<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">registerLoopAnalyses</span>(loopAnalysisManager);
passBuilder.<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">crossRegisterProxies</span>(
loopAnalysisManager, functionAnalysisManager, cGSCCAnalysisManager,
moduleAnalysisManager);
modulePassManager = passBuilder.<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">buildPerModuleDefaultPipeline</span>(llvm::PassBuilder::OptimizationLevel::O0);
}
</code></pre><p style="margin-top:0px;margin-right:0px;margin-left:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:-apple-system,system-ui,"Segoe UI","Liberation Sans",sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(231,233,235);background-color:rgb(45,45,45)">After calling the constructor for the above class</p><p style="margin-top:0px;margin-right:0px;margin-left:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:-apple-system,system-ui,"Segoe UI","Liberation Sans",sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(231,233,235);background-color:rgb(45,45,45)">I initialize the Module to which the llvm ir is emitted.</p><pre style="margin-top:0px;padding:12px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:1.30769;font-size:13px;vertical-align:baseline;box-sizing:inherit;width:auto;max-height:600px;overflow:auto;border-radius:5px"><code style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;background-color:transparent;white-space:inherit">CodeGenerator CG = <span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">CodeGenerator</span>();
CG.TheModule = std::<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">make_unique</span><llvm::Module>(<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">"module_name"</span>, *(CG.Ctx.<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">getContext</span>()));
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// I parse my front end code and emit my llvm ir code to TheModule here</span>
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// then I call the ModulePassManager here to optimize the module</span>
CG.modulePassManager.<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">run</span>(*CG.TheModule, CG.moduleAnalysisManager);
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// I move the optimized module to my JIT interpreter</span>
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">auto</span> TSM = llvm::orc::<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">ThreadSafeModule</span>(std::<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">move</span>(CG.TheModule),CG.Ctx);
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">ExitOnErr</span>(TheJIT-><span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">addModule</span>(std::<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">move</span>(TSM)));
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// Then, I create a new instance of llvm::Module to emit some other ir code</span>
CG.TheModule = std::<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">make_unique</span><llvm::Module>(ModuleName, *(CG.Ctx.<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">getContext</span>()));
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// emit ir </span>
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// then call the optimizer again</span>
CG.modulePassManager.<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">run</span>(*CG.TheModule, CG.moduleAnalysisManager);
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// I repeat this several times changing TheModule to a new instance</span>
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// of llvm::Module to contain some new ir code and run the optimizer.</span>
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// one of these calls to CG.modulePassManager.run ends up giving the segmentation fault </span>
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// there is no specific fixed instance of llvm::Module that this happens for</span>
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// The segmentation fault seems to happen at random for any one of the instances, on some runs there is no seg fault </span>
<span style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">// The ir being emitted is also not changed on any of the runs</span>
</code></pre><p style="margin-top:0px;margin-right:0px;margin-left:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:-apple-system,system-ui,"Segoe UI","Liberation Sans",sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(231,233,235);background-color:rgb(45,45,45)">My suspicion is that CG.moduleAnalysisManager might need some kind of reset after I change the Module instance before I can run the ModulePassManager on the newly emitted ir. Or maybe I am missing something else in how the pass manager needs to be setup. Any help would be great.</p><p style="margin:0px;padding:0px;border:0px;font-variant-numeric:inherit;font-variant-east-asian:inherit;font-stretch:inherit;line-height:inherit;font-family:-apple-system,system-ui,"Segoe UI","Liberation Sans",sans-serif;font-size:15px;vertical-align:baseline;box-sizing:inherit;clear:both;color:rgb(231,233,235);background-color:rgb(45,45,45)">Thanks.</p></div>
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</blockquote></div>
</blockquote></div>