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<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">I firmly believe that something that almost works is a lot better than nothing that certainly won’t work at all so I suggest we go for the short term hack as you described.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">I can try giving it a go but please provide all the details you have on that option.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">So as far as I can see getting pass names using
</span><span lang="EN-US">`PIC->getPassNameForClassName(PassID)` seems straight forward. Looks like we can get printouts when a PassManager and PassAdopter starts but I cannot see any callbacks that would be called when it is finished so maybe that needs to
be added to be able to get the nesting right.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I think that reduction of the passes string can be handled by an external tool and for starters I would be happy to do it manually.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">br<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">-Markus</span><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Arthur Eubanks <aeubanks@google.com>
<br>
<b>Sent:</b> den 30 juli 2021 20:54<br>
<b>To:</b> Markus Lavin <markus.lavin@ericsson.com><br>
<b>Cc:</b> llvm-dev <llvm-dev@lists.llvm.org><br>
<b>Subject:</b> Re: [llvm-dev] Pass reduction with new PM<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">There still is nothing like bugpoint's pass list reduce for the new PM.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">The issue is that ideally we'd be able to map a pass pipeline to the string version of it. But we can't really do that right now. We could attempt to do that, but a generated argument list won't be exact since passes added via code (e.g.
PassManagerBuilder/PassBuilder.cpp) often have parameters that can't be represented via opt arguments. Maybe getting an approximate textual representation of the pipeline is good enough for some cases? But that doesn't seem ideal.<o:p></o:p></p>
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<p class="MsoNormal">We could also go down the route of making all pipelines representable via text, but that's a non-trivial project.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Note that even the legacy PM has this problem, and I've heard that this has bitten people in the past.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Perhaps as a short term hack, we could get an approximation of the pipeline by hacking PrintPassInstrumentation to print the textual name of each pass that's run via `PIC->getPassNameForClassName(PassID)` (like PrintIRInstrumentation).
Then run `opt -debug-pass-manager with that hacked up version of PrintPassInstrumentation. We'd also need another version of -debug-pass-manager that prints adaptors/pass managers but doesn't print analyses. We'd run `opt` over a file with one function that
contains one loop, e.g. the IR in new-pm-defaults.ll. Then cleanup the output of -debug-pass-manager with proper pass nesting.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Or of course you could attempt to manually recreate the proper textual representation by looking at PassBuilder.cpp.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Then we'd need something that reduces the textual pass pipeline.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Let me know if you'd like more details.<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 Fri, Jul 30, 2021 at 12:25 AM Markus Lavin via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</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-US">Hi,</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">Right now I am trying to analyze a bug that appears with new PM pipeline as follows</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">$ opt -enable-new-pm=1 -disable-basic-aa -tbaa -O1 -o /dev/null reduced.ll</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">the crashing pass is LICM but simply exporting IR before that pass and then running just that pass does not seem to capture enough state to reproduce the problem.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">So here one would either want bugpoint to help automatically reduce the pass list or simply use -debug-pass=Arguments and do it manually but as I understand it
neither of those options work with the new PM.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">This has already been brought up in
</span><a href="https://protect2.fireeye.com/v1/url?k=f586695a-aa1d5188-f58629c1-866132fe445e-6110e351e37b7346&q=1&e=2ba6e21d-2217-4037-91d5-479923a5d53a&u=https%3A%2F%2Flists.llvm.org%2Fpipermail%2Fllvm-dev%2F2021-March%2F148994.html" target="_blank"><span lang="EN-US">[llvm-dev]
How to get from "opt -O3" to "opt <a-single-pass>" with the new PM?</span></a> <o:p>
</o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">Has there been any progress since then?</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">br</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US">Markus</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span lang="EN-US"> </span><o:p></o:p></p>
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<p class="MsoNormal">_______________________________________________<br>
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