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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - suboptimal vectorization on function call with >10 parameters with -march=znver2"
href="https://bugs.llvm.org/show_bug.cgi?id=50598">50598</a>
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<th>Summary</th>
<td>suboptimal vectorization on function call with >10 parameters with -march=znver2
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>new bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>ehb5643@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>example code can be found on [github](<a href="https://github.com/Apache-HB/bench">https://github.com/Apache-HB/bench</a>).
when benchmarking this code on a 2700X (znver2) the highest optimization level
performs 10% slower than GCC generated code on average.
llvm pushes arguments onto the stack with
```
vbroadcastsd r256, m64
vmovups m256, r256
```
which is slower on znver2 than the less vectorized
```
push r64
push r64
push r64
push r64
```
currently llvm generates
```
mov m64, imm64
mov m64, imm64
mov m64, imm64
mov m64, imm64
```
without vectorization enabled which is 20% slower than GCC and 10% slower than
the vectorized equivalent on znver2.</pre>
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