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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Clang generates improperly aligned code for aarch64, cortex-a53 for O2"
href="https://bugs.llvm.org/show_bug.cgi?id=45960">45960</a>
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<th>Summary</th>
<td>Clang generates improperly aligned code for aarch64, cortex-a53 for O2
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>MacOS X
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>C
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>jazzman40@tamuraweb.com
</td>
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<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=23499" name="attach_23499" title="Source code and generated code for O1 and O2 for test case">attachment 23499</a> <a href="attachment.cgi?id=23499&action=edit" title="Source code and generated code for O1 and O2 for test case">[details]</a></span>
Source code and generated code for O1 and O2 for test case
Using Clang 11.0.0
Cross compile on macOS Catalina 10.15.4 to Arm cortex-A53 (Raspberry Pi 3)
Clang generates incorrect code for Optimization level 2 (-O2). Same source code
works for -O1. The problem is in the optimization. It tries to optimize string
handling by using halfword and word instructions, but on a character buffer,
the data can be unaligned on the proper boundary, and thus a data exception is
raised at run time.</pre>
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