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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Incorrect transformation: (llvm.maximum undef, %x) -> undef"
href="https://bugs.llvm.org/show_bug.cgi?id=47567">47567</a>
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<th>Summary</th>
<td>Incorrect transformation: (llvm.maximum undef, %x) -> undef
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>All
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Scalar Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>liuz@cs.utah.edu
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Test case from Transforms/InstSimplify/floating-point-arithmetic.ll
define <2 x double> @maxnum_nan_op0_vec(<2 x double> %x) {
; CHECK-LABEL: @maxnum_nan_op0_vec(
; CHECK-NEXT: ret <2 x double> [[X:%.*]]
;
%r = call <2 x double> @llvm.maxnum.v2f64(<2 x double> <double
0x7ff8000000000000, double undef>, <2 x double> %x)
ret <2 x double> %r
}
The second lane for this case performs the rewrite (llvm.maximum undef, %x) ->
undef. The rewrite is illegal. The domain for (llvm.maximum undef, %x) depends
on %x, and obviously the result of llvm.maximum does not fully cover the range
of undef in most of cases.</pre>
</div>
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