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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Failure to optimize loop that does nothing and ends when result is used in comparison that is optimized out"
href="https://bugs.llvm.org/show_bug.cgi?id=48516">48516</a>
</td>
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<th>Summary</th>
<td>Failure to optimize loop that does nothing and ends when result is used in comparison that is optimized out
</td>
</tr>
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<th>Product</th>
<td>libraries
</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>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Scalar Optimizations
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>gabravier@gmail.com
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>void f(int *x, int *y)
{
long res = 0;
for (int i = 0; i < 100; i++)
res += x[i] * y[i];
if (res != 0)
__builtin_abort();
__builtin_unreachable();
}
This entire function can be optimized into `abort()`. This transformation is
done by GCC, but not by LLVM.
See also comparison here : <a href="https://godbolt.org/z/anzYMa">https://godbolt.org/z/anzYMa</a></pre>
</div>
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