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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 Chad,<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’ve taken a look at the performance of that code sequence, and can confirm that it is no worse in all situations than the current sequence. In some situations it causes a ~5% performance uplift on A53, and in some cases a ~20% performance uplift in A57 (on a microbenchmark running this sequence in a loop).<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'>So the code sequence itself looks good to me, but I haven’t yet looked at the implementation.<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,<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'>James<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-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt'><div><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"'> Chad Rosier [mailto:mcrosier@codeaurora.org] <br><b>Sent:</b> 09 July 2014 21:22<br><b>To:</b> 'James Molloy'; reviews+D4438+public+a452d711668fdd91@reviews.llvm.org<br><b>Cc:</b> 'Tim Northover'; 'Chandler Carruth'; 'Jiangning Liu'; James Molloy; 'Jim Grosbach'; 'LLVM Commits'; silviu.baranga@gmail.com<br><b>Subject:</b> RE: [PATCH] [AArch64] Lower sdiv x, pow2 using add + select + shift.<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>James,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><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"'> <a href="mailto:mankeyrabbit@gmail.com">mankeyrabbit@gmail.com</a> [<a href="mailto:mankeyrabbit@gmail.com">mailto:mankeyrabbit@gmail.com</a>] <b>On Behalf Of </b>James Molloy<br><b>Sent:</b> Wednesday, July 09, 2014 3:25 PM<br><b>To:</b> <a href="mailto:reviews+D4438+public+a452d711668fdd91@reviews.llvm.org">reviews+D4438+public+a452d711668fdd91@reviews.llvm.org</a><br><b>Cc:</b> <a href="mailto:mcrosier@codeaurora.org">mcrosier@codeaurora.org</a>; Tim Northover; Chandler Carruth; Jiangning Liu; James Molloy; Jim Grosbach; LLVM Commits; <a href="mailto:silviu.baranga@gmail.com">silviu.baranga@gmail.com</a><br><b>Subject:</b> Re: [PATCH] [AArch64] Lower sdiv x, pow2 using add + select + shift.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><div><p class=MsoNormal><span lang=EN-US>><span style='color:#1F497D'>></span> </span><span lang=EN-US style='font-size:10.0pt;font-family:"Arial","sans-serif"'>I can create a synthetic benchmark, if that helps.</span><span lang=EN-US><o:p></o:p></span></p><div><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div><div><p class=MsoNormal><span lang=EN-US style='font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D'>></span><span lang=EN-US style='font-size:10.0pt;font-family:"Arial","sans-serif"'>That would help a lot, and would save me from doing the exact same thing to test it on C-A57 :)</span><span lang=EN-US><o:p></o:p></span></p></div></div><div><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Ok, I’ll try to put something together shortly.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> Chad<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p></div></div></div></body></html>