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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Incorrect code for accessing a struct variable with bit fields"
href="http://llvm.org/bugs/show_bug.cgi?id=16551">16551</a>
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<th>Summary</th>
<td>Incorrect code for accessing a struct variable with bit fields
</td>
</tr>
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<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>
</tr>
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<th>OS</th>
<td>MacOS X
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>LLVM Codegen
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>ishiura-compiler@ml.kwansei.ac.jp
</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>Clang 3.4 (based on LLVM 3.4svn) for x86_64 target miscompiles the
following code.
$ cat error.c
struct S1 {
unsigned int m1 : 32;
unsigned int m2 : 24;
unsigned char m3;
};
struct S1 x = { 1U, 1U, 1U };
int main(void)
{
if ( x.m2 != 1U ) __builtin_abort();
return 0;
}
$ clang error.c
$ ./a.out
Abort trap: 6
The value of the x.m2 was 16777217 (x01000001).
There was no problem with an x86 (32bit) target.</pre>
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