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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - -O1 breaks std::abs"
href="http://llvm.org/bugs/show_bug.cgi?id=19174">19174</a>
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<th>Summary</th>
<td>-O1 breaks std::abs
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>release blocker
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>-New Bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>quixote72@hotmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>The appended snippet, when compiled and executed thus:
clang++ -o a.out t.cpp -O1 && ./a.out
produces the following output:
z: -1372777060 abs(z): -1372777060
Removing -O1 results in the correct output.
My clang version:
Ubuntu clang version 3.5.0-1~exp1 (trunk) (based on LLVM 3.5.0)
Target: x86_64-pc-linux-gnu
Thread model: posix
#include <cmath>
#include <cstdlib>
#include <iostream>
int main ()
{
int z = std::rand () * 4;
std::cout << "z: " << z << " abs(z): " << std::abs (z) << std::endl;
return 0;
}</pre>
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