<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 12 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body lang=EN-GB link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi,<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'>I imagine this optimization is for FP math stuff that doesn't involve functions which might set errno (or when we've specified we don't care about that)?<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'>Cheers,<br>Dave<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><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US 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>Chad Rosier<br><b>Sent:</b> 06 August 2013 15:46<br><b>To:</b> llvmdev<br><b>Subject:</b> [LLVMdev] Potential SimplifyCFG optimization; hammock to diamond transformation<o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>All,<br>I have some code that looks like the following:<br><br>{<br> double a, b, c;<br> for (...) {<br> ...<br> a = lots of FP math;<br> b = lots of FP math;<br> c = lots of FP math;<br> if (cond) {<br> a = 0.0;<br> b = 0.1;<br> c = 0.2;<br> }<br> ...<br> }<br>}<br><br>Could we not convert the hammock into a diamond and move the initial computation of a, b, and c into the else block. Something like this:<br><br>{<br> double a, b, c;<br> for (...) {<br> ...<br> if (cond) {<br> a = 0.0;<br> b = 0.1;<br> c = 0.2;<br> } else {<br> a = lots of FP math;<br> b = lots of FP math;<br> c = lots of FP math;<br> }<br> ...<br> }<br>}<br><br>Does a similar optimization exist? If not, would the SimplifyCFG pass be an appropriate home for such an optimization?<br><br> Chad<o:p></o:p></p></div></body></html>