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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - After r311849 Loop Vectorizer generates broken code"
href="https://bugs.llvm.org/show_bug.cgi?id=34711">34711</a>
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<th>Summary</th>
<td>After r311849 Loop Vectorizer generates broken code
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<th>Product</th>
<td>tools
</td>
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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>Windows NT
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>enhancement
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>opt
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>Alberto.Magni@microsoft.com
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<th>CC</th>
<td>ayal.zaks@intel.com, llvm-bugs@lists.llvm.org
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<pre>Created <span class=""><a href="attachment.cgi?id=19194" name="attach_19194" title="Reproducer">attachment 19194</a> <a href="attachment.cgi?id=19194&action=edit" title="Reproducer">[details]</a></span>
Reproducer
The loop vectorizer breaks the two attached programs:
Instruction does not dominate all uses!
%6 = shufflevector <2 x i16> %vector.recur, <2 x i16> %5, <2 x i32> <i32 1,
i32 2>
%1 = sext <2 x i16> %6 to <2 x i32>
The file before_lv.ll is the one that originally triggered the problem for me.
reduced.ll has been obtained with bugpoint starting from before_lv.ll
To reproduce:
opt -force-vector-width=2 -loop-vectorize reduced.ll -S -o x.ll
opt -force-vector-width=2 -loop-vectorize before_lv.ll -S -o x.ll</pre>
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