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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 - [FastMath] Failure to fold 1 / powf(x,y) -> powf(x, -y)"
href="https://bugs.llvm.org/show_bug.cgi?id=49147">49147</a>
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<th>Summary</th>
<td>[FastMath] Failure to fold 1 / powf(x,y) -> powf(x, -y)
</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>
</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>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Scalar Optimizations
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>llvm-dev@redking.me.uk
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>#include <cmath>
float invpow_i(float x, int y) {
return 1.0f / __builtin_powf(x, y);
}
float invpow_f(float x, float y) {
return 1.0f / __builtin_powf(x, y);
}
<a href="https://simd.godbolt.org/z/YxaW96">https://simd.godbolt.org/z/YxaW96</a>
Clang fails to merge the fdiv into the pow by negating the exponent arg</pre>
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