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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Borja,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">In this situation, you need to find the place where shl is generated and add a check to see if shl is legal before allowing it to do the transform.<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">Micah<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""> llvmdev-bounces@cs.uiuc.edu [mailto:llvmdev-bounces@cs.uiuc.edu]
<b>On Behalf Of </b>Borja Ferrer<br>
<b>Sent:</b> Sunday, August 26, 2012 11:49 AM<br>
<b>To:</b> llvmdev@cs.uiuc.edu<br>
<b>Subject:</b> [LLVMdev] Illegal node introduced by DAGCombiner after legal phase<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hello,<br>
<br>
I'm getting an instruction selection error because DAGCombiner is introducing an illegal node after the legalizeDAG phase. Basically this is what is going on:<br>
<br>
1) During legalization, BR_JT gets expanded introducing a (mul x, 2).<br>
2) After legalization (AfterLegalizeDAG), that (mul x, 2) is converted to an (shl x, 1).<br>
<br>
However, that shl node introduced is illegal, and since my custom lowering code won't run after this phase it gets into the instruction selector. I would like to know if this is really a bug or it has to be handled by the target code. I guess I could add a
custom dagcombine hook for this node and revert it in my target, but I want to hear what is the best thing to do.<br>
<br>
Thanks!<o:p></o:p></p>
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