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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Undefined behaviour passing sanitizers and not reproducible in other compilers"
href="https://bugs.llvm.org/show_bug.cgi?id=52177">52177</a>
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<th>Summary</th>
<td>Undefined behaviour passing sanitizers and not reproducible in other compilers
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>12.0
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<th>Hardware</th>
<td>Other
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<th>OS</th>
<td>Linux
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>C++
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>Golovanov12345@gmail.com
</td>
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<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<div>
<pre>Hello. I have the following code: <a href="https://pastebin.com/nxsF75JV">https://pastebin.com/nxsF75JV</a>. Basically it
computes sines and cosines for all multiples of pi/32, most of the time
multiplying the previous complex representation by the same constant, but every
8-th time calling expensive functions cos/sin to avoid precision-related
issues. It is clear that the code should report that the cosine of the
outputted angle is zero both times, which happens in ideone/godbolt/wherever,
except my compiler in termux for Android. I compile using the following line:
`g++ -std=c++17 qwe.cpp -o qwe`. When I add `-O0`, everything works properly.
When I add `-O2`, I receive the following output:
```
1
angles: 1.57080 1.57080
cosines: -0.70711 0.00000
```
When I also pass `-fsanitize=undefined` or `-fsanitize=address`, nothing
changes. My g++ version is clang 12.0.1, but a friend of mine confirmed the
same effect on his clang 11.1.0, also in termux. Please investigate or tell me
that I am wrong.</pre>
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