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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Failure to optimize comparison of float with itself when it's converted to double and -ftrapping-math is on"
href="https://bugs.llvm.org/show_bug.cgi?id=49161">49161</a>
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<th>Summary</th>
<td>Failure to optimize comparison of float with itself when it's converted to double and -ftrapping-math is on
</td>
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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>Linux
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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>Scalar Optimizations
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>gabravier@gmail.com
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<p>
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<pre>bool f(float x)
{
return x == (float)(double)x;
}
This can be optimized with `return x == x;`, even with `-ftrapping-math` (at
least according to GCC). This transformation is done by GCC, but not by LLVM.
Godbolt comparison: <a href="https://godbolt.org/z/TdozY4">https://godbolt.org/z/TdozY4</a>
(if someone knows how to do alive2 checks for stuff that involves floating
point comparisons, I would be glad to know)</pre>
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