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<p class="MsoNormal">Hi Chouhan,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">From a brief inspection of the bug report and the attached IR (lifetime-end.ll), you have a couple of options:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">1- You can run `opt lifetime-end.ll -basicaa -gvn -S`. If your change did what it’s supposed to, you should see that `ret i8 %0` was replaced with `ret i8 undef`.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">2- The IR attached in the case is in the form of a LIT. You can read more about it here:
<a href="https://www.llvm.org/docs/TestingGuide.html#writing-new-regression-tests">
https://www.llvm.org/docs/TestingGuide.html#writing-new-regression-tests</a> <o:p>
</o:p></p>
<p class="MsoNormal">You would probably commit it as a test with your patch. This test should fail without your change and pass with your change. To run it, you can call `lit lifetime-end.ll` and examine the output of the command.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><a name="_____replyseparator"></a><b>From:</b> llvm-dev <llvm-dev-bounces@lists.llvm.org>
<b>On Behalf Of </b>Shreyansh Chouhan via llvm-dev<br>
<b>Sent:</b> Saturday, August 10, 2019 7:34 AM<br>
<b>To:</b> llvm-dev@lists.llvm.org<br>
<b>Subject:</b> [llvm-dev] Bug 20811<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi!<o:p></o:p></p>
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<p class="MsoNormal">This is my first time contributing to the llvm project, I took up bug #20811 [<a href="https://bugs.llvm.org/show_bug.cgi?id=20811">https://bugs.llvm.org/show_bug.cgi?id=20811</a>]. From my understanding, what I had to do was to assign
an undef to a variable if it is loading from a pointer after its lifetime has ended (please correct me if I am wrong.) I would like to ask for help on how could I check if a variable has been assigned undef to verify my changes.<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 in advance :)<o:p></o:p></p>
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