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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Loop unrolling lead to program crash"
href="https://llvm.org/bugs/show_bug.cgi?id=28828">28828</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Loop unrolling lead to program crash
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Loop Optimizer
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>feishenniubi@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=16869" name="attach_16869" title="The original program, in .ll form">attachment 16869</a> <a href="attachment.cgi?id=16869&action=edit" title="The original program, in .ll form">[details]</a></span>
The original program, in .ll form
Running the trunk version of the loop unroller will transform a non-crashing
program into a crashing one.
Here's how the original program behaves:
<span class="quote">> llc test.ll -o test.s
> g++ test.s -o test
> ./test</span >
// Program terminates normally
Here's how the loop-unrolled program behaves:
<span class="quote">> opt test.ll -loop-unroll -o test_opt.bc
> llc test_opt.bc -o test_opt.s
> g++ test_opt.s -o test_opt
> ./test_opt</span >
// Segmentation fault
I can reproduce the issue on two different Linux platforms: RHEL 7.2 and Ubuntu
14.04. Both platform use gcc 5.3 toolchain.
Also, I am not able to shrink the test case further using bugpoint due to an
unfixed bug in bugpoint itself: <a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Bugpoint's basic block extraction produce codes that get rejected by the verifier"
href="show_bug.cgi?id=28803">https://llvm.org/bugs/show_bug.cgi?id=28803</a></pre>
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