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<p class="MsoNormal"><span style="color:windowtext">Thanks for the reply, Fedor!<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext">>You dont need to operate with classes defined in PassManagerInternal.h<br>
>They are, well, internal.<br>
>Unless you want to hack into the details of PassManager implementation</span><span style="color:windowtext"><o:p></o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"><span style="color:windowtext"><o:p> </o:p></span></a></p>
<p class="MsoNormal"><span style="color:windowtext">Apologies, this was a bit of miscommunication on my part: I am indeed trying to “open the box” of the new PM, not merely use it; it’s a good opportunity to learn about the techniques employed there.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext">In order to do so, I was trying to understand some of the decisions made in that header, and two of them stood out as odd.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext">The first one is a case where we are using override on a method but allowing a function signature mismatch (PreservedAnalysisT vs PreservedAnalysis).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext">The second is the use AnalysisManagerT vs AnalysisManager in a seemingly arbitrary way.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext">> </span><span style="font-size:12.0pt;font-family:"Times New Roman",serif;color:windowtext">Again, it is not an inconsistency, just an implementation detail<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman",serif;color:windowtext"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:windowtext">That’s what I have, so far, failed to see; I will keep exploring though – the PassManager.h file is still being digested.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><a name="_____replyseparator"></a><b><span style="color:windowtext">From:</span></b><span style="color:windowtext"> Fedor Sergeev [mailto:fedor.sergeev@azul.com]
<br>
<b>Sent:</b> Sunday, September 2, 2018 7:07 PM<br>
<b>To:</b> De Azevedo Piovezan, Felipe <felipe.de.azevedo.piovezan@intel.com>; llvm-dev@lists.llvm.org<br>
<b>Subject:</b> Re: [llvm-dev] possible inconsistency in PassManagerInternal.h<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt">You dont need to operate with classes defined in PassManagerInternal.h<br>
They are, well, internal.<br>
<br>
Unless you want to hack into the details of PassManager implementation all you need<br>
is to write a pass/analysis - which means implementing corresponding ::run() method - and register<br>
it with the PassBuilder one way or another.<br>
<br>
There are plenty of real examples of how you can write a pass in llvm source tree.<br>
Also there was a recent blog post mentioned on this list with an introduction to new pass manager.<span style="font-size:12.0pt"><o:p></o:p></span></p>
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<p class="MsoNormal">On 09/02/2018 11:22 PM, De Azevedo Piovezan, Felipe via llvm-dev wrote:<o:p></o:p></p>
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<p class="MsoNormal">Hello,<o:p></o:p></p>
<p class="MsoNormal">(fairly new around here, apologies if the question has an obvious answer)<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">I’ve been studying the structure of the new PassManager in the hopes of using it soon. After watching a couple of talks (Chandler / Sergeev), I decided to start with the Concept/Model classes in PassManagerInternal.h<o:p></o:p></p>
<p class="MsoNormal">While I could make sense of almost everything there, two details caught my attention:<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">1- The PassConcept abstract class has a function `run = 0;` which returns an object of type `PreservedAnalysis`. Such object is forward-declared in this header, but it is defined in PassManager.h This is the only place in the file where
we reference this class.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">However, right after, we define the PassModel class which derives from PassConcept, and one of its template parameters is a typename `PreservedAnalysisT`. The implementation of the `run` method uses the keyword override and it returns an
object of type `PreservedAnalysisT`. <o:p></o:p></p>
<p class="MsoNormal">This should raise a warning if PreservedAnalysisT != PreservedAnalysis. Is this intentional? My naive intuition is that we should have removed PreservedAnalysisT from the template and used PreservedAnalysis. However, everywhere else in
the file PreservedAnalysisT is used as template parameter.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Am I missing something obvious?<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">PassModel is a generic template helper used deep inside PassManager template.<br>
You should neither be modifying anything in it nor using it directly.<br>
<br>
And yes - PreservedAnalyses is the type that your Pass' run() method should return.<br>
<br>
<br>
<o:p></o:p></span></p>
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<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">2- A similar issue arises when using AnalysisManager. <o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Both PassConcept and PassModel have a template typename `AnalysisManagerT`.<o:p></o:p></p>
<p class="MsoNormal">However, AnalysisPassConcept and AnalysisPassModel have no such template parameter; instead, they use the forward-declared AnalysisManager type, defined in PassManager.h<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Again, is there a particular reason for this apparent inconsistency?<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:12.0pt;font-family:"Times New Roman",serif">Again, it is not an inconsistency, just an implementation detail.<br>
Ignore it and jump straight to using various AnalysisManagers defined in PassManager.h/LoopPassManager.h etc.<br>
<br>
regards,<br>
Fedor.<o:p></o:p></span></p>
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