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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 - Missing optimization opportunity: overlapping ranges optimization (condition simplification) after inlining"
href="https://bugs.llvm.org/show_bug.cgi?id=39854">39854</a>
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<th>Summary</th>
<td>Missing optimization opportunity: overlapping ranges optimization (condition simplification) after inlining
</td>
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<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>All
</td>
</tr>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>LLVM Codegen
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>nok.raven@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
</td>
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<p>
<div>
<pre>bool foo(char c)
{
return c >= '0' && c <= '9';
}
bool bar(char c)
{
return c != '\0' && foo(c);
}
bool foobar(char c)
{
return c != '\0' && c >= '0' && c <= '9';
}
All the functions above must result in the same instruction sequence (after
inlining and optimization), but Clang fails to optimize the condition in the
`bar` function. GCC makes the optimization perfectly in all cases (since 4.8.1
version). <a href="https://godbolt.org/z/fmXuT5">https://godbolt.org/z/fmXuT5</a></pre>
</div>
</p>
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