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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Compiler overlooks vhadd operation given widen/add/shift/narrow operation"
href="http://llvm.org/bugs/show_bug.cgi?id=21122">21122</a>
</td>
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<th>Summary</th>
<td>Compiler overlooks vhadd operation given widen/add/shift/narrow operation
</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>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: ARM
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>simon.hosie@arm.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=13113" name="attach_13113" title="addh.c">attachment 13113</a> <a href="attachment.cgi?id=13113&action=edit" title="addh.c">[details]</a></span>
addh.c
For the attached file and this command line:
clang --target=arm-linux-gnueabihf -mfpu=neon -O3 addh.c -S -o-
The compiler currently emits:
vaddl.u8 q8, d1, d3
vshrn.i16 d17, q8, #1
vaddl.u8 q9, d0, d2
vshrn.i16 d16, q9, #1
vorr q0, q8, q8
bx lr
Should be:
vhadd.u8 q0, q0, q1
bx lr
I want to extend this bug to include things like vqadd (which might use min
instead of shrn) but I can't seem to wring the relevant LLVM code out of Clang.</pre>
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