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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - __ARM_ARCH incorrect for armv8.1-a and above"
href="https://bugs.llvm.org/show_bug.cgi?id=49671">49671</a>
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<th>Summary</th>
<td>__ARM_ARCH incorrect for armv8.1-a and above
</td>
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<th>Product</th>
<td>new-bugs
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
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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
</td>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>new bugs
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>clang@evan.coeusgroup.com
</td>
</tr>
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<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>According to the ACLE Q3 2020 documentation
(<<a href="https://developer.arm.com/documentation/101028/0012">https://developer.arm.com/documentation/101028/0012</a>>), section 5.4.1
("A32/T32 instruction set architecture"), for 8.1+ __ARM_ARCH is supposed to be
801 for armv8.1-a, 802 for armv8.2-a, 803 for armv8.3-a, etc.
Clang currently just uses 8 for all versions of armv8. Testing is pretty
straightforward: `clang --target=aarch64-linux-gnu -march=armv8.6-a -dM -E -
</dev/null | grep __ARM_ARCH`.
This makes it difficult to determine support for features which are only
available in later revisions but don't have an __ARM_FEATURE_* macro, such as
complex MLA (8.3).
Similar GCC bug: <a href="https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99312">https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99312</a></pre>
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