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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Compiler producing suboptimal code for vector packed fp operation followed by a vector insert"
href="https://bugs.llvm.org/show_bug.cgi?id=38197">38197</a>
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<th>Summary</th>
<td>Compiler producing suboptimal code for vector packed fp operation followed by a vector insert
</td>
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<th>Product</th>
<td>new-bugs
</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>Linux
</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>new bugs
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>douglas_yung@playstation.sony.com
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>Change r336971 caused a regression in the codegen for a certain pattern that
was fixed previously in r197145.
Consider the following code:
/* test.c */
#include <x86intrin.h>
__m128 foo(__m128 a, __m128 b) {
__m128 c = a + b;
return (__m128) { c[0], a[1], a[2], a[3] };
}
Prior to upstream r197145, the compiler would generate the following code for
foo() when compiled with optimizations (-O2):
addps %xmm0, %xmm1
movss %xmm1, %xmm0
After the fix in r197145, the compiler generated the more optimal:
addss %xmm1, %xmm0
But now after r336971, we are no longer generating the optimal code and are now
generating the original code
addps %xmm0, %xmm1
movss %xmm1, %xmm0</pre>
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</p>
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