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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - LoopVectorizer: Mistakenly vectorize multi reduction value users"
href="http://llvm.org/bugs/show_bug.cgi?id=18526">18526</a>
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<th>Summary</th>
<td>LoopVectorizer: Mistakenly vectorize multi reduction value users
</td>
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<th>Product</th>
<td>tools
</td>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>opt
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>aschwaighofer@apple.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</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=11889" name="attach_11889" title="Test case">attachment 11889</a> <a href="attachment.cgi?id=11889&action=edit" title="Test case">[details]</a></span>
Test case
t3025 and t1519 from <a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [icFuzz] Incorrect results at -O2 optimization and infinite loop in the Clang optimizer"
href="show_bug.cgi?id=16431#c22">http://llvm.org/bugs/show_bug.cgi?id=16431#c22</a> are
misoptimized.
As described in
<a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [icFuzz] Incorrect results at -O2 optimization and infinite loop in the Clang optimizer"
href="show_bug.cgi?id=16431#c23">http://llvm.org/bugs/show_bug.cgi?id=16431#c23</a>
"The diff tests are vectorizer bugs (look like the same bug): t3025 and t1519.
They disappear with -fno-vectorize.
Furthermore,
it seems to be the loops:
for (k1 = 54; k1 > 2; k1--) {
gp += gp - ((++n) + k1);
// Test Loop Vectorization
for (ju = 1; ju < 1; ++ju) {
d5[ju] = ff[k1][k1];
}
}
and
for (k = 2; k < 61; ++k) {
n += n - ((f + k7) + (nf++));
xs5[k] = 13 + 5;
xs5[k] += nt7--;
}
We should not be vectorizing them. “gp” and “n” are not reductions. But we seem
to :(."</pre>
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