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<body><span class="vcard"><a class="email" href="mailto:gonzalobg88@gmail.com" title="Gonzalo BG <gonzalobg88@gmail.com>"> <span class="fn">Gonzalo BG</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - Canonicalization of rbit for ARMv8 64 bit fails"
href="https://llvm.org/bugs/show_bug.cgi?id=31803">bug 31803</a>
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<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
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<td style="text-align:right;">Status</td>
<td>NEW
</td>
<td>RESOLVED
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<td style="text-align:right;">Resolution</td>
<td>---
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<td>INVALID
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - Canonicalization of rbit for ARMv8 64 bit fails"
href="https://llvm.org/bugs/show_bug.cgi?id=31803#c4">Comment # 4</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - Canonicalization of rbit for ARMv8 64 bit fails"
href="https://llvm.org/bugs/show_bug.cgi?id=31803">bug 31803</a>
from <span class="vcard"><a class="email" href="mailto:gonzalobg88@gmail.com" title="Gonzalo BG <gonzalobg88@gmail.com>"> <span class="fn">Gonzalo BG</span></a>
</span></b>
<pre>So i've failed to reproduce this with clang trunk on aarch64:
<a href="https://godbolt.org/g/DHS2xz">https://godbolt.org/g/DHS2xz</a>
clang 4.0 lowers __builtin_bitreverse to rbit properly.
On x86 the 32 and 64 bit versions of bitreverse look very good, but the
generated code for the 8-bit version looks worse than the naive implementation:
<a href="https://godbolt.org/g/kAlOC7">https://godbolt.org/g/kAlOC7</a>
I'm closing this and filling a new issue for the bitreverse.i8 instruction.</pre>
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