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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 --- - stack protector generating sse3 instructions in unoptimized 32-bit build"
href="http://llvm.org/bugs/show_bug.cgi?id=21173">21173</a>
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<th>Summary</th>
<td>stack protector generating sse3 instructions in unoptimized 32-bit build
</td>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
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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>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<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>phantall+llvm@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>clang --version
echo 'void test() { char blah[127] = {}; }' | clang++ -g -m32 -xc++ -c -o
/tmp/blah1.o
echo 'void test() { char blah[127] = {}; }' | clang++ -g -fstack-protector-all
-Wstack-protector -m32 -xc++ -c -o /tmp/blah2.o
If you look at the disassembly for /tmp/blah{1,2}.o, the former generates some
instructions that are valid for any of the Pentium processors, whereas the
latter uses %xmm0 & movaps instructions to initialize `blah`.
Without really digging into it I can only speculate, but my best guess is stack
protector is potentially enabling one or more optimizations that would
otherwise not be enabled in a typical debug build w/out optimizations.</pre>
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