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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - __cxa_throw performance issue"
href="https://bugs.llvm.org/show_bug.cgi?id=51037">51037</a>
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<th>Summary</th>
<td>__cxa_throw performance issue
</td>
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<th>Product</th>
<td>libc++abi
</td>
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<th>Version</th>
<td>12.0
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>All Bugs
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>glibcxx.chrono@gmail.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
</td>
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=25012" name="attach_25012" title="File with code in issue">attachment 25012</a> <a href="attachment.cgi?id=25012&action=edit" title="File with code in issue">[details]</a></span>
File with code in issue
Hi, i noticed this unusual behaviour of exception-throwing system.
This is small analysis of `Storage::StorageRecord* Storage::find` function most
expensive operations from my project (full code available in file below):
flags: -std=c++1z -O1 -fno-stack-protector
ldflags: <none>
сlang++ - QtCreator profiler:
__cxa_throw cost (instruction read access):
171,241,920
|__ _Unwind_RaiseException cost (instruction read access):
170,541,920
g++ - QtCreator profiler:
__cxa_throw cost (instruction read access):
133,161,906
|__ _Unwind_RaiseException: cost (instruction read access):
132,541,906
You can see, that performance difference between GCC and Clang almost 30%.
I think, for same optimization level Clang's exception-throwing costs are too
high compared to GCC.
Thank you for your attention.</pre>
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