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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Loop peeling is errneously not performed - only considers inequality predicates"
href="https://bugs.llvm.org/show_bug.cgi?id=43840">43840</a>
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<th>Summary</th>
<td>Loop peeling is errneously not performed - only considers inequality predicates
</td>
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<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Loop Optimizer
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>lebedev.ri@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>Trivial example:
void init();
void sink();
void bad(int len) {
for(int i = 0; i < len; i++) {
if(i == 0) {
init();
}
sink();
}
}
It would make sense to peel the first iteration, so we no longer have
the always-false condition for the rest of the loop.
But the peeling does not happen!
<a href="https://godbolt.org/z/Y_wBgM">https://godbolt.org/z/Y_wBgM</a>
It does happen if *two* iterations should be peeled:
<a href="https://godbolt.org/z/RTf_QS">https://godbolt.org/z/RTf_QS</a>
This appears to be an oversight: it only considers inequality comparisons,
it does not know how to deal with equality comparisons:
<a href="https://godbolt.org/z/1xmCKx">https://godbolt.org/z/1xmCKx</a></pre>
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</p>
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