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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [X86] Failure to optimize float vector reduction to haddps"
href="https://bugs.llvm.org/show_bug.cgi?id=51989">51989</a>
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<th>Summary</th>
<td>[X86] Failure to optimize float vector reduction to haddps
</td>
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<th>Product</th>
<td>libraries
</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>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Backend: X86
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>gabravier@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, pengfei.wang@intel.com, spatel+llvm@rotateright.com
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<p>
<div>
<pre>#include <stddef.h>
typedef float simde_float32x2_t __attribute__((__vector_size__(8)));
float simde_vaddv_f32(simde_float32x2_t a) {
float r = 0;
for (size_t i = 0; i < (sizeof(a) / sizeof(a[0])); i++) {
r += a[i];
}
return r;
}
With -O3 -mssse3, LLVM outputs this:
simde_vaddv_f32(float __vector(2)):
movshdup xmm1, xmm0 # xmm1 = xmm0[1,1,3,3]
addss xmm0, xmm1
ret
GCC instead manages this:
simde_vaddv_f32(float __vector(2)):
haddps xmm0, xmm0
ret</pre>
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