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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - clang 6 generates invalid instruction on ARM64"
href="https://bugs.llvm.org/show_bug.cgi?id=36707">36707</a>
</td>
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<th>Summary</th>
<td>clang 6 generates invalid instruction on ARM64
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>6.0
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>-New Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>mikulas@artax.karlin.mff.cuni.cz
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=20055" name="attach_20055" title="a file that reproduces the bug">attachment 20055</a> <a href="attachment.cgi?id=20055&action=edit" title="a file that reproduces the bug">[details]</a></span>
a file that reproduces the bug
clang 6.0 generates invalid instruction "fmov h0,wzr". This instruction is
allowed starting with ARMv8.2, but clang generates it even for ARMv8.0. On
ARMv8.0 processor, the instruction causes SIGILL.
This bug is new to clang 6.0, clang 5.0 behaves correctly.
See the attached file and compile it with -O2.
00000000004005c0 <ret0>:
4005c0: 1ee703e0 fmov h0, wzr
4005c4: d65f03c0 ret
Note that if you compile the file with "-O2 -no-integrated-as", you get this
error:
/tmp/ret-fp16-87b066.s: Assembler messages:
/tmp/ret-fp16-87b066.s:8: Error: selected processor does not support `fmov
h0,wzr'
clang-6.0: error: assembler command failed with exit code 1 (use -v to see
invocation)</pre>
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