<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Suboptimal codegen for {x, y} ↦ {x+x, x+y}"
href="https://bugs.llvm.org/show_bug.cgi?id=41456">41456</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Suboptimal codegen for {x, y} ↦ {x+x, x+y}
</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>Linux
</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>Backend: X86
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>hello@dsprenkels.com
</td>
</tr>
<tr>
<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, spatel+llvm@rotateright.com
</td>
</tr></table>
<p>
<div>
<pre><a href="https://godbolt.org/z/2GE_vO">https://godbolt.org/z/2GE_vO</a>
-----
The code snippet
```
#include <xmmintrin.h>
__m128i example(const __m128i vec) {
return (__m128i){2 * vec[0], vec[0] + vec[1]};
}
```
is compiled to code that unpacks and repacks the values to the general purpose
registers. This uses 7 instructions. However, the same could easily be achieved
using
```
example:
vpbroadcastq xmm1, xmm0
vpaddq xmm0, xmm0, xmm1
ret
```.
Other instructions, instead of vpbroadcastq can also be used; like vmovddup,
vpermilpd, etc.</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>