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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - clang should not copy parameters into local allocas if it can avoid it"
href="http://llvm.org/bugs/show_bug.cgi?id=20419">20419</a>
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<th>Summary</th>
<td>clang should not copy parameters into local allocas if it can avoid it
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>unspecified
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>Windows NT
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>enhancement
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>LLVM Codegen
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>rnk@google.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>In general, clang copies LLVM SSA arguments into allocas so that it can take
the address of the argument and allow the user to store to it.
We could probably improve our -O0 codegen a bit if we avoided creating allocas
for implicit 'this', vtt, and reference parameters, because their addresses
can't be taken.
We could hypothetically extend this to scalar arguments that are not stored or
address-taken, but that is extra work that might not be a compile time win.
This isn't particularly high priority, but I wanted to get it filed away.</pre>
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