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<p style="margin-top:0;margin-bottom:0">Hi,</p>
<p style="margin-top:0;margin-bottom:0"><br>
</p>
<p style="margin-top:0;margin-bottom:0">Florian has been working on loop peeling to remove control flow from loop bodies in <a href="https://reviews.llvm.org/D43876" class="OWAAutoLink">https://reviews.llvm.org/D43876</a>. For larger constants or other loop
invariant bounds, such like:<span style="font-size: 12pt;"></span></p>
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<div><span style="font-family: "Courier New", monospace;">for (unsigned i = 0; i; i < 1000; ++i) {</span></div>
<div><span style="font-size: 12pt; font-family: "Courier New", monospace;"> if (i < M)</span><br>
</div>
<div><span style="font-family: "Courier New", monospace;"> ... something</span></div>
<div><span style="font-family: "Courier New", monospace;"> else</span></div>
<div><span style="font-family: "Courier New", monospace;"> ... something else</span></div>
<div><span style="font-family: "Courier New", monospace;">}</span></div>
<div><span style="font-family: "Courier New", monospace;"><br>
</span></div>
<div><span style="font-family: "Courier New", monospace;"><span style="font-family: Calibri, Helvetica, sans-serif;">The loop could be split into two, like so:</span><br>
</span></div>
<div><br>
</div>
<div><span style="font-family: "Courier New", monospace;">Min = min(1000, M);</span></div>
<div><span style="font-family: "Courier New", monospace;">unsigned i;</span></div>
<div><span style="font-family: "Courier New", monospace;">for (i = 0; i; i < Min; ++i) {</span></div>
<div><span style="font-family: "Courier New", monospace;"> ... something</span></div>
<div><span style="font-family: "Courier New", monospace;">}</span></div>
<div><br>
</div>
<div><span style="font-family: "Courier New", monospace;">for (; i; i < 1000; ++i) {</span></div>
<div><span style="font-family: "Courier New", monospace;"> ... something else</span></div>
<div><span style="font-family: "Courier New", monospace;">}</span></div>
<br>
<p></p>
<p style="margin-top:0;margin-bottom:0">Both loop distribute and versioning are designed to analyze memory and enable vectorization, but is there much preventing them from being able to split loops to remove control-flow instead? If this seems feasible, could
someone give some advice on what would be needed?</p>
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</p>
<p style="margin-top:0;margin-bottom:0">Thanks,</p>
<p style="margin-top:0;margin-bottom:0">sam</p>
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</p>
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<p style="font-family:"Times New Roman""><span style="font-family:Calibri,Helvetica,sans-serif">Sam Parker</span></p>
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<p style="font-family:"Times New Roman""><span style="font-family:Calibri,Helvetica,sans-serif">Compilation Tools Engineer | Arm</span></p>
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<p style="font-family:"Times New Roman""><span style="font-family:Calibri,Helvetica,sans-serif">Arm.com</span></p>
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