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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - shared_ptr's increment/decrement uses sequential consistency."
href="http://llvm.org/bugs/show_bug.cgi?id=22803">22803</a>
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<th>Summary</th>
<td>shared_ptr's increment/decrement uses sequential consistency.
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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>All
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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>martin.horenovsky@gmail.com
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu, mclow.lists@gmail.com
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>Current shared_ptr implementation uses sequential consistency for reference
counting, even though less strong atomics are good enough. This leads to
suboptimal performance for platforms other than x86 (x64).
Relaxed and acq/rel atomics (for increment and decrement respectively) should
be sufficient for thread safety. The reason it is currently implemented like
this was that Clang at the time didn't support full range of C++11 atomics and
noone ever got back to cleaning it up.</pre>
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