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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Failure to recognise commutable binop intrinsics"
href="https://bugs.llvm.org/show_bug.cgi?id=46897">46897</a>
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<th>Summary</th>
<td>Failure to recognise commutable binop intrinsics
</td>
</tr>
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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
</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
</td>
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<th>Component</th>
<td>Scalar Optimizations
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>llvm-dev@redking.me.uk
</td>
</tr>
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<th>CC</th>
<td>lebedev.ri@gmail.com, llvm-bugs@lists.llvm.org, spatel+llvm@rotateright.com
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<p>
<div>
<pre>define <2 x i64> @smax(<2 x i64> %a, <2 x i64> %b) {
%x = call <2 x i64> @llvm.smax.v2i64(<2 x i64> %a, <2 x i64> %b)
%y = call <2 x i64> @llvm.smax.v2i64(<2 x i64> %b, <2 x i64> %a)
%o = or <2 x i64> %x, %y
ret <2 x i64> %o
}
declare <2 x i64> @llvm.smax.v2i64(<2 x i64>, <2 x i64>)
opt -O3
define <2 x i64> @smax(<2 x i64> %a, <2 x i64> %b) {
%x = tail call <2 x i64> @llvm.smax.v2i64(<2 x i64> %a, <2 x i64> %b)
%y = tail call <2 x i64> @llvm.smax.v2i64(<2 x i64> %b, <2 x i64> %a)
%o = or <2 x i64> %x, %y
ret <2 x i64> %o
}
but we should be able to recognise that %x and %y are equivalent:
define <2 x i64> @smax(<2 x i64> %a, <2 x i64> %b) {
%x = tail call <2 x i64> @llvm.smax.v2i64(<2 x i64> %a, <2 x i64> %b)
ret <2 x i64> %x
}</pre>
</div>
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