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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - UBSAN: right shift by negative value is not caught for some values"
href="https://bugs.llvm.org/show_bug.cgi?id=33442">33442</a>
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<th>Summary</th>
<td>UBSAN: right shift by negative value is not caught for some values
</td>
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<th>Product</th>
<td>clang
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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>All
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Frontend
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>babokin@gmail.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<p>
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<pre>clang trunk
RHS of shift operator is negative, but UBSAN doesn't trigger. Effect is value
sensitive (change to x-1 to see that UBSAN triggers). Computation in the
example do not involve overflow/underflow.
<span class="quote">> cat f.cpp</span >
long long int x = -2869500996303312813LL;
int i;
int main() {
i = 0 >> (x - 280373316);
return 0;
}
<span class="quote">> clang++ -std=c++11 -fsanitize=undefined f.cpp -o out
> ./out</span ></pre>
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