some undefined behaviors in llvm/clang

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1

Hi folks,

Below is a short list of integer undefined behaviors executed by Clang
when compiling the LLVM test suite. They seem pretty self explanatory,
but let me know if not, if you cannot reproduce any of them, or if it
would be better for me to file bugzillas on them. This is on x64 Linux,
using r108984.

Thanks,

John

2

Hi John,

Below is a short list of integer undefined behaviors executed by Clang
when compiling the LLVM test suite. They seem pretty self explanatory,
but let me know if not, if you cannot reproduce any of them, or if it
would be better for me to file bugzillas on them. This is on x64 Linux,
using r108984.

how did you obtain this interesting info?

Thanks,

Duncan.

3

See also: A Guide to Undefined Behavior in C and C++, Part 2 – Embedded in Academia

-Chris

4

My student Peng Li has a hacked clang that emits checks for lots of bad integer behaviors. The code still has rough edges but we'll contribute it soon.

John