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<p class="MsoNormal" style="margin-left:.5in">"What caused you to notice not running the DAG combiner was a problem?"<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">A fuzzer that we wrote generated some functions with 'optnone' and they crashed the compiler with instruction-selection failures.<o:p></o:p></span></a></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Being mostly vector-related, Andrea looked at them, and didn't take long to point the finger at DAG combine (or lack thereof!).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Should I take this to imply you'd rather have one of the causes-a-crash functions as the test, instead of this one?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">--paulr<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Eric Christopher [mailto:echristo@gmail.com]
<br>
<b>Sent:</b> Wednesday, March 25, 2015 4:44 PM<br>
<b>To:</b> reviews+D8614+public+1ca59dfb9fe35dfd@reviews.llvm.org; Robinson, Paul; dblaikie@gmail.com<br>
<b>Cc:</b> llvm-commits@cs.uiuc.edu<br>
<b>Subject:</b> Re: [PATCH] Verify 'optnone' can run DAG combiner when appropriate<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">On Wed, Mar 25, 2015 at 1:28 PM Eric Christopher <<a href="mailto:echristo@gmail.com">echristo@gmail.com</a>> wrote:<o:p></o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt">Inline comment.<br>
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Comment at: test/CodeGen/X86/dag-optnone.ll:7<br>
@@ +6,3 @@<br>
+; that the combine is expected.<br>
+; Note, this will start failing if somebody decides that this combine should<br>
+; not occur at -O0 (because 'optnone' essentially sets -O0 for the function).<br>
----------------<br>
Could you describe the problem that would occur were the dag combiner not run? That hasn't been clear either in this test or in your original commit reverting.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Resending because I typoed and it's unclear I think:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">"What caused you to notice not running the DAG combiner was a problem?"<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-eric<o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal"><a href="http://reviews.llvm.org/D8614" target="_blank">http://reviews.llvm.org/D8614</a><br>
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EMAIL PREFERENCES<br>
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http://reviews.llvm.org/settings/panel/emailpreferences/</a><br>
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<a href="http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits" target="_blank">http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits</a><o:p></o:p></p>
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