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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - X86 SSE4.1 instruction problem"
href="https://bugs.llvm.org/show_bug.cgi?id=51371">51371</a>
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<th>Summary</th>
<td>X86 SSE4.1 instruction problem
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>7.0
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>MacOS X
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>C
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>oucwangshiwei@163.com
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<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<pre>Hi,
I was build SSE performance work on mac intel. But I found the performance of
my SSE4.1 version code using in xcode 12.4 is not as good as xcode 10.1, so I
checked the assembly of my code. The one _mm_mul_epi() instruction was
translated into three pmuludq, which is the SSE2 instruction, while this was
normal when compiling on xcode 10.1 and _mm_mul_epi() was translated into
pmuldq. So I checked the clang version, and I found this error occured when
clang version larger than 7.0.0.
The simple case can be found: <a href="https://godbolt.org/z/Tf7qeocvz">https://godbolt.org/z/Tf7qeocvz</a>
I probably think this is a clang compiler bug. And I hope to get some advice
on how to solve this issue.
Thanks.
Best,
Wade</pre>
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