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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Vectorizer generates useless vector.memcheck block"
href="http://llvm.org/bugs/show_bug.cgi?id=19651">19651</a>
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<th>Summary</th>
<td>Vectorizer generates useless vector.memcheck block
</td>
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<tr>
<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>MacOS X
</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>Loop Optimizer
</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>nicola.gigante@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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</tr>
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<th>Classification</th>
<td>Unclassified
</td>
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=12474" name="attach_12474" title="Test source code">attachment 12474</a> <a href="attachment.cgi?id=12474&action=edit" title="Test source code">[details]</a></span>
Test source code
In the attached code, TBAA correctly recognize the pointers being of different
type, but the vectorizer emits anyway the vector.memcheck block to check if the
buffers overlap.
This happens even in the second part of the attached source code, where the
inputs are not pointers but std::array objects of different element types. The
input arrays are passed by value but the vectorizer still checks for
overlapping buffers.
In a pure compliant C++ context (so no 'restrict' keyword) it seems impossible
to tell the optimizer that I know my arrays won't overlap...</pre>
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