https://bugs.llvm.org/show_bug.cgi?id=52177
Bug ID: 52177
Summary: Undefined behaviour passing sanitizers and not
reproducible in other compilers
Product: clang
Version: 12.0
Hardware: Other
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: C++
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected], [email protected],
[email protected], [email protected],
[email protected]
Hello. I have the following code: https://pastebin.com/nxsF75JV. 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.
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