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<base href="https://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Wrong constant folding"
href="https://llvm.org/bugs/show_bug.cgi?id=26407">26407</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Wrong constant folding
</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>
<tr>
<th>OS</th>
<td>MacOS X
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Backend: C
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>ishiura-compiler@ml.kwansei.ac.jp
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>LLVM + clang 3.9 for x86_64 miscompiles the following code.
% cat test.c
int x = 0;
int y = -1;
int main (void)
{
int a = 0x7fffffff + x;
int b = 0x7fffffff + y;
int f = (unsigned int) a >= (unsigned int) b;
if ( f != 1 ) { __builtin_abort(); }
return 0;
}
% clang-3.9 test.c -O1
% ./a.out
zsh: abort ./a.out
% clang-3.9 -v
clang version 3.9.0 (trunk 259289)
Target: x86_64-apple-darwin14.5.0
Thread model: posix</pre>
</div>
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