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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Failure to recognise 'equivalent' constant vectors with different undef elements"
href="https://bugs.llvm.org/show_bug.cgi?id=47744">47744</a>
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<th>Summary</th>
<td>Failure to recognise 'equivalent' constant vectors with different undef elements
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<th>Product</th>
<td>libraries
</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
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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>Common Code Generator Code
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>llvm-dev@redking.me.uk
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</tr>
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<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, spatel+llvm@rotateright.com
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<pre>As mentioned on D88570:
Looks like a general shortcoming of combining/hoisting constants:
$ cat vec_const.ll
define <4 x i32> @f(<4 x i32> %x) {
%a1 = add <4 x i32> %x, <i32 1, i32 2, i32 3, i32 4>
%a2 = xor <4 x i32> %a1, <i32 1, i32 2, i32 3, i32 undef>
ret <4 x i32> %a2
}
$ llc -o - vec_const.ll
LCPI0_0:
.long 1 ## 0x1
.long 2 ## 0x2
.long 3 ## 0x3
.long 4 ## 0x4
LCPI0_1:
.long 1 ## 0x1
.long 2 ## 0x2
.long 3 ## 0x3
.space 4
_f:
paddd LCPI0_0(%rip), %xmm0
pxor LCPI0_1(%rip), %xmm0
retq</pre>
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