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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - MS Inline assembly with vector type causes a bad trunc emission."
href="https://bugs.llvm.org/show_bug.cgi?id=34021">34021</a>
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<th>Summary</th>
<td>MS Inline assembly with vector type causes a bad trunc emission.
</td>
</tr>
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<th>Product</th>
<td>clang
</td>
</tr>
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<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>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>LLVM Codegen
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>erich.keane@intel.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, rnk@google.com
</td>
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<p>
<div>
<pre>Code:
typedef int v4si __attribute__ ((vector_size (16)));
v4si rep() {
v4si res;
__asm {}
return res;
}
Compile with: -O0 -fms-extensions -m32
Result is a crash in DAG due to a trunc that widens instead of narrows.
Higher optimizer levels cause this to disappear, presumably due to instcombine.
Our original repro:
#include <emmintrin.h>
__m128i x;
__m128i foo ()
{
__asm {
movdqu xmm0, xmm1
}
return x;
}
Also should validate that the following works:
#include <emmintrin.h>
__m128i x;
__m128i foo ()
{
__asm {
movdqu xmm0, x
}
}
int main () {
foo();
return 0;
}</pre>
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