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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - conversion from double to unsigned raises invalid operation"
href="https://llvm.org/bugs/show_bug.cgi?id=30885">30885</a>
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<tr>
<th>Summary</th>
<td>conversion from double to unsigned raises invalid operation
</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>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: X86
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>jay.foad@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>I don't know if this counts as a bug, but it's certainly an annoyance in my
application: conversion from double to unsigned can raise an FP invalid
operation exception, even when the value being converted fits in the result
type.
$ cat fptoui.c
#include <stdio.h>
unsigned fptoui(double d) {
return (unsigned)d;
}
int main() {
printf("%04x\n", __builtin_ia32_stmxcsr());
fptoui(3e9);
printf("%04x\n", __builtin_ia32_stmxcsr());
}
$ ~/llvm/build/bin/clang --version
clang version 4.0.0 (trunk) (llvm/trunk 285680)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/jay/llvm/build/bin
$ clang -m32 -msse2 -o fptoui fptoui.c && ./fptoui
1f80
1f81
The "1f81" in the last line indicates that the invalid operation bit has been
set in mxcsr register.</pre>
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</p>
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