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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - error in backend: Cannot emit physreg copy instruction, after _mm_hadd_pd"
href="https://bugs.llvm.org/show_bug.cgi?id=44111">44111</a>
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<th>Summary</th>
<td>error in backend: Cannot emit physreg copy instruction, after _mm_hadd_pd
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>9.0
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>C++
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>agner@agner.org
</td>
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<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<pre>Created <span class=""><a href="attachment.cgi?id=22853" name="attach_22853" title="Complete code and diagnostics">attachment 22853</a> <a href="attachment.cgi?id=22853&action=edit" title="Complete code and diagnostics">[details]</a></span>
Complete code and diagnostics
The attached program containing the intrinsic function for horizontal addition,
_mm_hadd_pd, causes errors in Clang 9.0 (Windows/msys2 version).
Three situations are tested:
1: No bugs with -O1.
2: Wrong result with -O2 (or -O3).
3: The compiler crashes with -O2 when additional printf statements are added to
trace the error.
Disassembly of (2) shows that _mm_hadd_pd is implemented correctly, but the
value is somehow lost in the subsequent code. Both errors disappear when
_mm_hadd_pd is replaced by alternatives.</pre>
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