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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - std::rotate can be order of magnitude faster, if it can allocate a buffer."
href="https://bugs.llvm.org/show_bug.cgi?id=35614">35614</a>
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<th>Summary</th>
<td>std::rotate can be order of magnitude faster, if it can allocate a buffer.
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<th>Product</th>
<td>libc++
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<th>Version</th>
<td>unspecified
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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
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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>All Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>denis.yaroshevskij@gmail.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
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<pre>Hi!
For one sided rotation you do optimize for one element on the stack:
<a href="https://github.com/llvm-mirror/libcxx/blob/master/include/algorithm#L2435">https://github.com/llvm-mirror/libcxx/blob/master/include/algorithm#L2435</a>
Actually this is a valid optimization for arbitrary number of elements and it
can give you an order of magnitude speed up.
Here is a very naive implementation with measurements:
<a href="http://quick-bench.com/KjyAe88UUBAjSmDAbUsbkt1mLxQ">http://quick-bench.com/KjyAe88UUBAjSmDAbUsbkt1mLxQ</a>
Is it ok for std::rotate to do this?
I'm happy to create a patch but some guidance on the benchmark and restrictions
would be nice.
Best,
Dennis</pre>
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