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<p class="MsoNormal"><span style="color:#1F497D">Hi Silviu,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Thanks for letting me know, I didn’t understand the loop is actually required – and you are of course right.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">By the way, since the loop is required anyway, I don’t really see the benefit of using isConstantSplat() over just anding the lanes (paying in isConstantSplat() time to just decrease AND iterations). But it’s
a small thing, of course :)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Thanks for correcting me! My patch should not be applied.<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l1 level1 lfo3"><![if !supportLists]><span style="color:#1F497D"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span dir="LTR"></span><span style="color:#1F497D">Alon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="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""> Silviu Baranga [mailto:silbar01@arm.com]
<br>
<b>Sent:</b> Tuesday, August 28, 2012 11:55<br>
<b>To:</b> Mishne, Alon; llvm-commits@cs.uiuc.edu<br>
<b>Cc:</b> James Molloy<br>
<b>Subject:</b> RE: [llvm-commits] [PATCH] Bug fix to enable zextload on targets that support it<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D">Hi Alon,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D">I noticed that you are removing the code that ands every lane<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D">of the splat value. That code(the loop) is actually required, since<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D">we might not have the same value for all lanes and we would<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D">still want to fold the AND node.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D">Related to this, I’ve sent a patch a couple of days ago to handle<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D">the same issue:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D"><a href="http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120820/148839.html">http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20120820/148839.html</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D">Cheers,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D">Silviu<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="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"">
<a href="mailto:llvm-commits-bounces@cs.uiuc.edu">llvm-commits-bounces@cs.uiuc.edu</a>
<a href="mailto:[mailto:llvm-commits-bounces@cs.uiuc.edu]">[mailto:llvm-commits-bounces@cs.uiuc.edu]</a>
<b>On Behalf Of </b>Mishne, Alon<br>
<b>Sent:</b> 26 August 2012 08:27<br>
<b>To:</b> <a href="mailto:llvm-commits@cs.uiuc.edu">llvm-commits@cs.uiuc.edu</a><br>
<b>Subject:</b> [llvm-commits] [PATCH] Bug fix to enable zextload on targets that support it<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’ve noticed a clever trick in lib/CodeGen/SelectionDAG/DAGCombiner.cpp of identifying an AND whose only purpose is to reset the top bits as a potential zextload instead of extload in targets that support it. However, the code for identifying
the constant used in such an AND with a vector is wrong – it makes incorrect usage of the isConstantSplat() method, assuming it works differently from how it really does.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Attached is a patch that fixes this by using that method correctly, enabling a nice optimization on targets that support zextload. The fixed code is also much simpler and more efficient than the incorrect usage, becomes it removes an unneeded
loop.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Please review this patch and commit if acceptable,<o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo2"><![if !supportLists]><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span dir="LTR"></span>Alon<o:p></o:p></p>
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