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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [SLP] Missing vectorization"
href="https://bugs.llvm.org/show_bug.cgi?id=47623">47623</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[SLP] Missing 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>int a[8], b[8];
void foo(void)
{
a[0] = b[0];
a[1] = b[2];
a[2] = b[0];
a[3] = b[2];
a[4] = b[0];
a[5] = b[2];
a[6] = b[0];
a[7] = b[2];
}
Clang:
foo(): # @foo()
mov eax, dword ptr [rip + b]
mov dword ptr [rip + a], eax
mov ecx, dword ptr [rip + b+8]
mov dword ptr [rip + a+4], ecx
mov dword ptr [rip + a+8], eax
mov dword ptr [rip + a+12], ecx
mov dword ptr [rip + a+16], eax
mov dword ptr [rip + a+20], ecx
mov dword ptr [rip + a+24], eax
mov dword ptr [rip + a+28], ecx
ret
a:
.zero 32
b:
.zero 32
GCC:
foo():
movd xmm0, DWORD PTR b[rip]
movd xmm1, DWORD PTR b[rip+8]
punpckldq xmm0, xmm1
punpcklqdq xmm0, xmm0
movaps XMMWORD PTR a[rip], xmm0
movaps XMMWORD PTR a[rip+16], xmm0
ret
b:
.zero 32
a:
.zero 32
<a href="https://godbolt.org/z/nosYfb">https://godbolt.org/z/nosYfb</a></pre>
</div>
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