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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - PPC64: Possible endian issue in optimization"
href="http://llvm.org/bugs/show_bug.cgi?id=16147">16147</a>
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</tr>
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<th>Summary</th>
<td>PPC64: Possible endian issue in optimization
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Other
</td>
</tr>
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<th>OS</th>
<td>Linux
</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>
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<th>Component</th>
<td>Backend: PowerPC
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>kai@redstar.de
</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>Created <span class=""><a href="attachment.cgi?id=10584" name="attach_10584" title="IR file demonstrating the problem.">attachment 10584</a> <a href="attachment.cgi?id=10584&action=edit" title="IR file demonstrating the problem.">[details]</a></span>
IR file demonstrating the problem.
You get 2 different results for the attached file y.ll depending on
optimization level:
[u0012540@172-29-171-104 build-ldc]$ llvm-as y.ll; opt -O1 y.bc | llc
-filetype=obj >y.o ; gcc -m64 -o y y.o ; ./y ; echo $?
1
[u0012540@172-29-171-104 build-ldc]$ llvm-as y.ll; opt -O2 y.bc | llc
-filetype=obj >y.o ; gcc -m64 -o y y.o ; ./y ; echo $?
0
The result from level -O1 is the right one. The wrong output does not occur if
you only use llc. The IR code is derived from the following D code:
private union EndianSwapper
{
bool value;
ubyte[bool.sizeof] array;
}
int main()
{
EndianSwapper es = void;
es.array[0] = 1;
immutable retval = es.value;
return retval;
}
which is derived from the failure of the following identity:
assert(bigEndianToNative!bool(nativeToBigEndian(bool.max)) == bool.max);</pre>
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