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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Erroneous (?) error "invalid output size for constraint '=Yz'" (AVX2)"
href="https://bugs.llvm.org/show_bug.cgi?id=45806">45806</a>
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<th>Summary</th>
<td>Erroneous (?) error "invalid output size for constraint '=Yz'" (AVX2)
</td>
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<th>Product</th>
<td>new-bugs
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
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<th>Status</th>
<td>NEW
</td>
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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>new bugs
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>nemo@self-evident.org
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</tr>
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<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
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<p>
<div>
<pre>Background: <a href="https://stackoverflow.com/q/61601902/">https://stackoverflow.com/q/61601902/</a>
I am not certain whether this is a bug. However, this inline asm is accepted by
both GCC and ICC and produces the output I expect:
__m256i mask()
{
__m256i result;
__asm__ ("vpcmpeqd %%xmm0,%%xmm0,%%xmm0" : "=Yz" (result));
return result;
}
What I want is to operate on a YMM register using an XMM operation with a VEX
prefix so that the high lane of the YMM register gets cleared. Inline asm is
the only way I have found to get any compiler to emit this.
But Clang rejects this code with an "invalid output size" error (live example:
<a href="https://gcc.godbolt.org/z/vnqQfR">https://gcc.godbolt.org/z/vnqQfR</a>).</pre>
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