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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [X86] 64-bit integer stores are not always illegal on a 32-bit system"
href="https://llvm.org/bugs/show_bug.cgi?id=23049">23049</a>
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<th>Summary</th>
<td>[X86] 64-bit integer stores are not always illegal on a 32-bit system
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: X86
</td>
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<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>spatel+llvm@rotateright.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>If you have SSE2, then 64-bit integer stores should be possible from an SSE
register even with i386.
$ cat st64.ll
define void @foo(i64* %p, <2 x i64> %a) {
%ext = extractelement <2 x i64> %a, i32 0
store i64 %ext, i64* %p
ret void
}
$ ./llc -march=x86 -mattr=sse2 st64.ll -o -
...
movl 4(%esp), %eax
pshufd $229, %xmm0, %xmm1 ## xmm1 = xmm0[1,1,2,3]
movd %xmm0, (%eax) <--- store low 32-bits
movd %xmm1, 4(%eax) <--- store high 32-bits
retl
GCC knows better:
_foo:
movl 4(%esp), %eax
movq %xmm0, (%eax)
ret</pre>
</div>
</p>
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