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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Struct not passed correctly in vararg"
href="http://llvm.org/bugs/show_bug.cgi?id=18725">18725</a>
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<th>Summary</th>
<td>Struct not passed correctly in vararg
</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>
</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>
<tr>
<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 3.5 (based on LLVM 3.5svn) for x86_64 target miscompiles the following
code.
$ cat error.c
#include <stdarg.h>
struct S { float m0[2]; int m1; };
void func(int x, ... )
{
va_list ap;
va_start(ap, x);
struct S y = va_arg(ap, struct S);
va_end(ap);
if( y.m1 != 1 ) { __builtin_abort(); }
}
int main(void)
{
int x;
struct S s = {{1,1},1};
func(x, s);
return 0;
}
$ clang error.c
$ ./a.out
Abort trap: 6
The value of y.m1 was 1065353216 instead of 1.
There was no problem with an i686 target.
$ clang -v
clang version 3.5 (trunk 200763)
Target: x86_64-apple-darwin13.0.0
Thread model: posix</pre>
</div>
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