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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Hi
</span><span style="font-family:"Calibri",sans-serif;color:black">Emmanouil,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">Seems like when you comment out a loop in “compute” function, it gets inlined, this helps LV by finding the bounds and vectorizes it.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">With the presence of all the loops LAA is not able to identify the bounds for the accesses:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">LAA: Can't find bounds for ptr: %arrayidx.i159 = getelementptr inbounds double, double* %30, i64 %and.i158, !dbg !46<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">LAA: Can't find bounds for ptr: %arrayidx.i155 = getelementptr inbounds double, double* %36, i64 %and.i154, !dbg !66<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">LAA: Can't find bounds for ptr: %arrayidx.i151 = getelementptr inbounds double, double* %42, i64 %and.i150, !dbg !91<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">Its bit strange as its able to identify the bounds correctly for the first loop.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">Without commenting the loop, if you make the “compute” function inline, it gets vectorize:<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:.5in"><span style="font-family:"Calibri",sans-serif;color:black">- void compute( size_t batchSize,<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:.5in"><span style="font-family:"Calibri",sans-serif;color:black">+ void inline compute( size_t batchSize,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">Ashutosh<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> llvm-dev <llvm-dev-bounces@lists.llvm.org>
<b>On Behalf Of </b>manolis mi via llvm-dev<br>
<b>Sent:</b> Friday, August 23, 2019 9:13 PM<br>
<b>To:</b> via llvm-dev <llvm-dev@lists.llvm.org><br>
<b>Cc:</b> Stephan Hageboeck <stephan.hageboeck@cern.ch><br>
<b>Subject:</b> [llvm-dev] Vectorization fails when dealing with a lot of for loops.<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">[CAUTION: External Email] <o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">Hello, could you please have a look at this code posted on godbolt.org:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><a href="https://godbolt.org/z/O-O-Q7">https://godbolt.org/z/O-O-Q7</a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">The problem is that inside the compute function, only the first loop vectorizes while the rest copies of it don't. But if I remove any of the for loops, then the rest vectorize
successfully. Could you please confirm that this is a bug, otherwise give me more insight on why the vectorization fails? The message "Cannot identify array bounds" is not helpful.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">Thank you for your time,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black">Emmanouil Michalainas, CERN<o:p></o:p></span></p>
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