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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Missed SLP vectorization"
href="https://bugs.llvm.org/show_bug.cgi?id=49933">49933</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Missed SLP vectorization
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Windows NT
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Scalar Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>david.bolvansky@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>typedef unsigned char uint8_t;
static inline uint8_t bar( uint8_t x )
{
return x&(~63) ? -x : x;
}
void foo( uint8_t *__restrict dst, uint8_t *__restrict src)
{
for( int x = 0; x < 8; x++ )
dst[x] = bar(src[x]);
}
ICC:
foo(unsigned char*, unsigned char*):
vpmovzxbd ymm2, QWORD PTR [rsi] #5.25
vpand ymm0, ymm2, YMMWORD PTR .L_2il0floatpacket.0[rip] #5.12
vpxor ymm1, ymm1, ymm1 #5.25
vptestmd k1, ymm0, ymm0 #5.12
vpsubd ymm2{k1}, ymm1, ymm2 #5.25
vpmovdb QWORD PTR [rdi], ymm2 #13.6
vzeroupper #14.1
ret
LLVM does not vectorize it with avx/avx2/avx512 - cost model issue?
<a href="https://godbolt.org/z/Kheeec4cG">https://godbolt.org/z/Kheeec4cG</a></pre>
</div>
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