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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Worse codegen than gcc for heaps of bit arith"
href="http://llvm.org/bugs/show_bug.cgi?id=20647">20647</a>
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<th>Summary</th>
<td>Worse codegen than gcc for heaps of bit arith
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<th>Product</th>
<td>libraries
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<th>Version</th>
<td>3.4
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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
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Backend: X86
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>kvanberendonck@gmail.com
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>Look here for a comparison and related source code side-by-side.
<a href="https://gist.github.com/kvanberendonck/3d072ae0f450f20cf1ed">https://gist.github.com/kvanberendonck/3d072ae0f450f20cf1ed</a>
What I've noticed mainly is that while gcc performs the arith directly on the
memory location, llvm produces many more instructions because it chooses to
load it into a register first, perform the arith and then write it back. It
also generates twice as many ORs... not sure why.</pre>
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</p>
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